Kai C Sonntag | Harvard Medical School, McLean Hospital (original) (raw)
Papers by Kai C Sonntag
Methods in Molecular Biology
Cell type-specific laser microdissection technologies in combination with molecular techniques to... more Cell type-specific laser microdissection technologies in combination with molecular techniques to determine gene expression profiles have become powerful tools to gain insight into the neurobiological basis of neural circuit disturbances in various neurologic or psychiatric diseases. To identify specific cell populations in human postmortem brain tissue, one can use the inherent properties of the cells, such as pigmentation and morphology or their structural composition through immunohistochemistry (IHC). Here, we describe the isolation of homogeneous neurons and oligodendrocytes and the extraction of high-quality RNA from these cells in human postmortem brain using a combination of rapid IHC, Nissl staining, or simple morphology with Laser Capture Microdissection (LCM), or Laser Microdissection (LMD).
Journal of Psychiatric Research
Schizophrenia is a neurodevelopmental disorder with the typical age of onset of overt symptoms an... more Schizophrenia is a neurodevelopmental disorder with the typical age of onset of overt symptoms and deficits occurring during late adolescence or early adulthood, coinciding with the final maturation of the cortical network involving the prefrontal cortex. These observations have led to the hypothesis that disturbances of the developmental events that take place in the prefrontal cortex during this period, specifically the remodeling of synaptic connectivities between pyramidal neurons, may contribute to the onset of illness. In this context, we investigated the gene expression changes of pyramidal neurons in the human prefrontal cortex during normal periadolescent development in order to gain insight into the possible molecular mechanisms involved in synaptic remodeling of pyramidal neuronal circuitry. Our data suggest that genes associated with the ubiquitination system, which has been implicated in the biology of synaptic plasticity, may play a major role. Among these genes, UBE3B, which encodes the ubiquitin ligase E3, was found to undergo periadolescent increase and was validated at the protein level to be upregulated during periadolescent development. Furthermore, we found that the density of UBE3B-immunoreactive pyramidal neurons was decreased in schizophrenia subjects, consistent with the result of a previous study of decreased UBE3B mRNA expression in pyramidal neurons in this illness. Altogether these findings point to the novel hypothesis that this specific ligase may play a role in the developmental pathogenesis of schizophrenia onset by possibly altering the synaptic remodeling process.
Acta neuropathologica, Jan 7, 2018
MicroRNAs (miRNA) regulate fundamental biological processes, including neuronal plasticity, stres... more MicroRNAs (miRNA) regulate fundamental biological processes, including neuronal plasticity, stress response, and survival. Here, we describe a neuroprotective function of miR-132, the miRNA most significantly downregulated in neurons in Alzheimer's disease. We demonstrate that miR-132 protects primary mouse and human wild-type neurons and more vulnerable Tau-mutant neurons against amyloid β-peptide (Aβ) and glutamate excitotoxicity. It lowers the levels of total, phosphorylated, acetylated, and cleaved forms of Tau implicated in tauopathies, promotes neurite elongation and branching, and reduces neuronal death. Similarly, miR-132 attenuates PHF-Tau pathology and neurodegeneration, and enhances long-term potentiation in the P301S Tau transgenic mice. The neuroprotective effects are mediated by direct regulation of the Tau modifiers acetyltransferase EP300, kinase GSK3β, RNA-binding protein Rbfox1, and proteases Calpain 2 and Caspases 3/7. These data suggest miR-132 as a master re...
Progress in neurobiology, Jan 11, 2018
Parkinson's disease (PD) is one of the most common neurodegenerative disorders, which affects... more Parkinson's disease (PD) is one of the most common neurodegenerative disorders, which affects about 0.3% of the general population. As the population in the developed world ages, this creates an escalating burden on society both in economic terms and in quality of life for these patients and for the families that support them. Although currently available pharmacological or surgical treatments may significantly improve the quality of life of many patients with PD, these are symptomatic treatments that do not slow or stop the progressive course of the disease. Because motor impairments in PD largely result from loss of midbrain dopamine neurons in the substantia nigra pars compacta, PD has long been considered to be one of the most promising target diseases for cell-based therapy. Indeed, numerous clinical and preclinical studies using fetal cell transplantation have provided proof of concept that cell replacement therapy may be a viable therapeutic approach for PD. However, the ...
Journal of neurochemistry, 2016
The RNA integrity number (RIN) is often considered to be a critical measure of the quality of pos... more The RNA integrity number (RIN) is often considered to be a critical measure of the quality of postmortem human brains. However, it has been suggested that RINs do not necessarily reflect the availability of intact mRNA. Using the Agilent bioanalyzer and qRT-PCR, we explored whether RINs provide a meaningful way of assessing mRNA degradation and integrity in human brain samples by evaluating the expression of 3'-5' mRNA sequences of the cytochrome C-1 (CYC1) gene. Analysis of electropherograms showed that RINs were not consistently correlated with RNA or cDNA profiles and appeared to be poor predictors of overall cDNA quality. Cycle thresholds from qRT-PCR analysis to quantify the amount of CYC1 mRNA revealed positive correlations of RINs with amplification of full-length transcripts, despite the variable degree of linear degradation along the 3'-5' sequence. These data demonstrate that in postmortem human brain tissue the RIN is an indicator of mRNA quantity independ...
MicroRNAs (miRs) are important post-transcriptional regulators of gene expression implicated in n... more MicroRNAs (miRs) are important post-transcriptional regulators of gene expression implicated in neuronal development, differentiation, aging and neurodegenerative diseases, including Parkinson's disease (PD). Several miRs have been linked to PD-associated genes, apoptosis and stress response pathways, suggesting that deregulation of miRs may contribute to the development of the neurodegenerative phenotype. Here, we investigate the cell-autonomous role of miR processing RNAse Dicer in the functional maintenance of adult dopamine (DA) neurons. We demonstrate a reduction of Dicer in the ventral midbrain and altered miR expression profiles in laser-microdissected DA neurons of aged mice. Using a mouse line expressing tamoxifen-inducible CreERT2 recombinase under control of the DA transporter promoter, we show that a tissue-specific conditional ablation of Dicer in DA neurons of adult mice led to decreased levels of striatal DA and its metabolites without a reduction in neuronal body...
Molecular Therapy, 2016
Introduction The use of TLR9 agonists as immunomodulators is supported by preclinical and clinica... more Introduction The use of TLR9 agonists as immunomodulators is supported by preclinical and clinical studies, showing their anti-tumor effect by enhancing both cellular and humoral immune responses. So far, two different families of DNA molecules containing non-methylated CG-motifs for TLR9 activation have been established: Dumbbell-shaped dSLIM (R) molecules are protected against exonucleolytic degradation by their covalently-closed, natural phosphodiester (PO) backbone. In contrast, single-stranded, oligodeoxynucleotides (CpG-ODN) are most commonly chemicallystabilized by phosphorothioates (PTO) in their phosphate moieties. PTO modification, however, produce off-target effects in immune cell populations and have resulted in an unfavorable risk-to-benefit ratio. Methods To avoid the off-target effects of PTO-modified CpG-ODN, linear single-stranded ODN were synthezised using L-deoxyribonucleotides at their 3'-ends, which are the natural enantiomers of Ddeoxyribonucleotides. The vast majority of deoxyribose in present organisms are D-deoxyribose, thus co-evolved nucleases are blind for L-deoxyribose thereby leaving L-protected ODN intact. We selected nucleotide sequences of such L-protected, CG-motif containing, single-stranded ODN, EnanDIM (R) , for high secretion of IFN-alpha and IP-10 from human peripheral blood mononuclear cells (PBMC). In a maximum feasible dose approach in CD-1 mice EnanDIM (R) doses of 10 to 50 mg per mice were injected subcutaneously to evaluate the acute toxicity and immunomodulatory properties of EnanDIM (R) molecules in vivo. Results EnanDIM581 and EnanDIM532 were chosen since they caused high secretion of IFN-alpha and IP-10 from human PBMC and resulted in a strong activation of monocytes, NK cells and plasmacytoid dendritic cells (pDC) in vitro. Notably, both showed a distinct immune activation pattern, with the highest secretion of IFNalpha by EnanDIM581 and the strongest maturation of TLR9-bearing pDC by EnanDIM532. EnanDIM744, comprising EnanDIM581 with additional 5'-end L-nucleotide protection and exhibiting an immune activation pattern similar to EnanDIM581, was selected as third EnanDIM (R) for in vivo studies. In the maximum feasible dose approach, safety assessments were performed throughout the study period and no mortality, clinical signs and body weight changes were observed, despite the fact that extremely high doses of app. 300 to 1700 mg/kg were used. A gross necropsy consisting of a macroscopic organ evaluation at day 15 revealed also no toxicity. Regarding immune activation, increased levels of IP-10 in serum were observed 24 hours after injection but not after 15 days confirming that L-nucleotides in EnanDIM (R) do not change the kinetic profile known from other DNA-based TLR9 agonists. Conclusions EnanDIM (R) , a new family of TLR9 agonists with conformation-mediated nuclease-resistance, broadly activates the immune system in vitro. Maximal feasible doses of EnanDIM (R) resulted in no signs of toxicity and confirmed immunomodulatory effects in vivo. Therefore EnanDIM (R) has the potential for clinical development in the treatment of cancer.
European Neuropsychopharmacology, 2016
Schizophrenia research, 2015
The pathophysiology of schizophrenia involves disturbances of information processing across brain... more The pathophysiology of schizophrenia involves disturbances of information processing across brain regions, possibly reflecting, at least in part, a disruption in the underlying axonal connectivity. This disruption is thought to be a consequence of the pathology of myelin ensheathment, the integrity of which is tightly regulated by oligodendrocytes. In order to gain insight into the possible neurobiological mechanisms of myelin deficit, we determined the messenger RNA (mRNA) expression profile of laser captured cells that were immunoreactive for 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), a marker for oligodendrocyte progenitor cells (OPCs) in addition to differentiating and myelinating oligodendrocytes, in the white matter of the prefrontal cortex in schizophrenia subjects. Our findings pointed to the hypothesis that OPC differentiation might be impaired in schizophrenia. To address this hypothesis, we quantified cells that were immunoreactive for neural/glia...
Psychopharmacology, 2016
Increased activity of prefrontal D1 dopamine receptors (D1R) is involved in reward-related behavi... more Increased activity of prefrontal D1 dopamine receptors (D1R) is involved in reward-related behavior found in bipolar disorder and drug addiction. While the effects of elevated D1R are known, depressive-like behaviors also occur in these disorders after reward-seeking ends. The goal is to characterize how termination of D1R overexpression influences depressive-like behaviors. An inducible (Tet.On), lentiviral vector was used to manipulate the expression of the DRD1 gene in glutamate neurons within the prefrontal cortex in male, adult rats. Sexual activity and sucrose preference were studied in both D1R elevated ON and relatively reduced OFF states. Following termination of the D1R ON state, depressive-like behavior was determined in the OFF state. Expression of the transcriptional regulator, cyclic AMP-responsive element-binding protein (CREB), was used as an indication of downstream effects in the nucleus accumbens (NA). ON D1R expression increased sexual activity that returned to baseline in the OFF state. Sucrose preferences increased ~6 % in ON state but fell 11 % below control levels when OFF. Consistent with a depressive-like phenotype, D1R OFF decreased activity by 40 %, impaired the ability to control (43 %) and motivation to escape shock (27 % more impaired) relative to dsRed OFF. CREB increased 29 % in the NA in the D1R OFF state relative to the ON state. This novel approach demonstrates that elevated D1R expression increased hedonic behavior, whereas the termination of D1R overexpression often resulted in depressive-like behavior. These observations support a role for D1R expression cycling in bipolar-associated behaviors and addiction.
Brain research, Jan 3, 2015
The degeneration of substantia nigra (SN) dopamine (DA) neurons in sporadic Parkinson׳s disease (... more The degeneration of substantia nigra (SN) dopamine (DA) neurons in sporadic Parkinson׳s disease (PD) is characterized by disturbed gene expression networks. Micro(mi)RNAs are post-transcriptional regulators of gene expression and we recently provided evidence that these molecules may play a functional role in the pathogenesis of PD. Here, we document a comprehensive analysis of miRNAs in SN DA neurons and PD, including sex differences. Our data show that miRNAs are dysregulated in disease-affected neurons and differentially expressed between male and female samples with a trend of more up-regulated miRNAs in males and more down-regulated miRNAs in females. Unbiased Ingenuity Pathway Analysis (IPA) revealed a network of miRNA/target-gene associations that is consistent with dysfunctional gene and signaling pathways in PD pathology. Our study provides evidence for a general association of miRNAs with the cellular function and identity of SN DA neurons, and with deregulated gene expres...
Neuropharmacology, 2015
Extinction of behaviors in response to drug-associated cues and prevention of reinstatement are i... more Extinction of behaviors in response to drug-associated cues and prevention of reinstatement are integral for addiction treatment, and can reverse or ameliorate the harmful consequences of drug use. The mechanisms controlling extinction and reinstatement involve prefrontal cortical dopamine receptors, which change in expression and activity during the juvenile and adolescent transitions until they mature in adulthood. Little is known about the role that PFC D1 dopamine receptors play in extinction of drug-paired associations early in life. We used extinction of place preferences for cocaine in juvenile male and female rats following genetic, cell-specific overexpression of D1 on glutamatergic cells in the PFC. All subjects needed to demonstrate cocaine preferences for inclusion in the extinction studies. Here, male juveniles with a preference to 10 mg/kg cocaine took longer to extinguish preferences compared to both male adults and female juveniles. Female juveniles extinguished more rapidly than male juveniles at 20 mg/kg cocaine. Overexpression of D1 in juvenile males significantly facilitated extinction relative to juvenile male controls, whereas D1 prolonged expression of extinction in adults overexpressing D1 and adolescents who naturally have elevated D1 expression. These data suggest that an immature D1 profile in juveniles prevented the learning of new associations, and D1 overexpression may provide sufficient activity to facilitate extinction learning. D1 overexpression reduced reinstatement to a priming dose of cocaine in juvenile males. Together, these data show D1 expression may re-program motivational circuitry to facilitate extinction learning during juvenility that is normally unavailable to juveniles and that sex differences exist.
Molecular Psychiatry, 2015
Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation ... more Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation because their purported potential to manifest signaling and pharmacological properties that differ from the component receptors makes them highly attractive for the development of more selective Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 5, 2008
Adolescence is a transitional period during development that is associated with a greater likelih... more Adolescence is a transitional period during development that is associated with a greater likelihood of addiction to drugs than any other age. In the prefrontal cortex (PFC), D(1) dopamine receptors mediate motivational salience attribution, which plays a role in addiction. Here, we investigated the relationship of age-related D(1) dopamine receptor expression in the PFC with the maturation of cocaine place conditioning. Confocal microscopy revealed that retrogradely traced cortical output neurons to the nucleus accumbens express higher levels of D(1) receptors during adolescence compared with younger and older ages. D(1) expression does not change on GABAergic interneurons across age. Adolescent differences in D(1) expression occur independently of cortical-accumbens connectivity, which proliferates through adulthood. Behaviorally, adolescent rats are more sensitive to cocaine place conditioning than younger and older rats. However, microinjections of the D(1) antagonist SCH23390 i...
Molecular Neurobiology, 2014
Dysfunction of growth factor (GF) activities contributes to the decline and death of neurons duri... more Dysfunction of growth factor (GF) activities contributes to the decline and death of neurons during aging and in neurodegenerative diseases. In addition, neurons become more resistant to GF signaling with age. Micro (mi)RNAs are posttranscriptional regulators of gene expression that may be crucial to age- and disease-related changes in GF functions. MiR-126 is involved in regulating insulin/IGF-1/phosphatidylinositol-3-kinase (PI3K)/AKT and extracellular signal-regulated kinase (ERK) signaling, and we recently demonstrated a functional role of miR-126 in dopamine neuronal cell survival in models of Parkinson's disease (PD)-associated toxicity. Here, we show that elevated levels of miR-126 increase neuronal vulnerability to ubiquitous toxicity mediated by staurosporine (STS) or Alzheimer's disease (AD)-associated amyloid beta 1-42 peptides (Aβ1-42). The neuroprotective factors IGF-1, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and soluble amyloid precursor protein α (sAPPα) could diminish but not abrogate the toxic effects of miR-126. In miR-126 overexpressing neurons derived from Tg6799 familial AD model mice, we observed an increase in Aβ1-42 toxicity, but surprisingly, both Aβ1-42 and miR-126 promoted neurite sprouting. Pathway analysis revealed that miR-126 overexpression downregulated elements in the GF/PI3K/AKT and ERK signaling cascades, including AKT, GSK-3β, ERK, their phosphorylation, and the miR-126 targets IRS-1 and PIK3R2. Finally, inhibition of miR-126 was neuroprotective against both STS and Aβ1-42 toxicity. Our data provide evidence for a novel mechanism of regulating GF/PI3K signaling in neurons by miR-126 and suggest that miR-126 may be an important mechanistic link between metabolic dysfunction and neurotoxicity in general, during aging, and in the pathogenesis of specific neurological disorders, including PD and AD.
Frontiers in Synaptic Neuroscience, 2014
Background: Early drug intervention in childhood disorders aims to maximize individual potential ... more Background: Early drug intervention in childhood disorders aims to maximize individual potential in the short-and long-term. Consistently, juvenile exposure to psychostimulants, such as methylphenidate (MPH), reduces risk for substance use in animals and sub-populations of individuals with attention deficit hyperactivity disorder (ADHD). We investigated the effects of MPH on brain plasticity via dopamine receptor D3 (D3R) and brain-derived neurotrophic factor (BDNF) expression in developing rats. Methods: Between postnatal days 20-35, rat pups were administered saline vehicle (Veh) or MPH (2 mg/kg), the D3R-preferring agonist ±7-OHDPAT, or the antagonist nafadotride (0.05 mg/kg) alone, or in combination with MPH twice a day. In adulthood, subjects were challenged to Veh or cocaine (10 mg/kg for two days). The prefrontal cortex was analyzed for protein and mRNA levels of total BDNF, its splice variants I, IIc, III/IV, and IV/VI, and D3 receptors. A separate group of subjects was assessed for splice variants at 20, 35, 40, and 60 days of age. Results: Across age strong correlations were evident between Drd3 and Bdnf mRNA levels (r = 0.65) and a negative relationship between Drd3 and exon IIc after MPH treatment (r = −0.73). BDNF protein levels did not differ between Veh-and MPH subjects at baseline, but were significantly lower in MPH-treated and cocaine challenged subjects (30.3 ± 9.7%). Bdnf mRNA was significantly higher in MPH-treated subjects, and reversed upon exposure to cocaine. This effect was blocked by nafadotride. Furthermore, Bdnf total and Bdnf splice variants I, IIc, III/IV, and IV/VI changed across the transitions between juvenility and late adolescence. Conclusions: These data suggest a sensitive window of vulnerability to modulation of BDNF expression around adolescence, and that compared to normal animals, juvenile exposure to MPH permanently reduces prefrontal BDNF transcription and translation upon cocaine exposure in adulthood by a D3R-mediated mechanism.
Psychopharmacology, 2014
Adolescents are often described as &a... more Adolescents are often described as "lacking brakes" resulting in an increase in several behaviors associated with risk for addiction. Prefrontal cortex dopamine and cortico-limbic interaction play an important role in addiction, and we have previously shown that the dopamine D1 receptor is elevated on prelimbic prefrontal output neurons in adolescent rats. We hypothesized that a constellation of risk-related behaviors is mediated by prefrontal output neuron expression of D1. We aimed to determine the role of the dopamine D1 receptor in behavioral and neural correlates of risk for addiction that are often observed in adolescents. Therefore, high-risk behaviors as well as subcortical D2 receptor expression were investigated in adult animals with experimentally elevated D1 on prefrontal glutamatergic neurons. A lentiviral vector that selectively expressed the D1 receptor within glutamate neurons was injected in the prelimbic prefrontal cortex of adult male rats. Place conditioning to cocaine, alcohol, and nicotine, as well as delay discounting, novelty preferences, anxiety, cocaine self-administration, and sucrose preferences were assessed. Virally mediated D1 over-expression in adults leads to stronger drug-cue associations and greater consumption of sweet solutions, elevates bias towards immediate satisfaction rather than delaying gratification, decreases anxiety, and causes rats to work harder for and take more cocaine. Furthermore, elevated cortical D1 reduces D2 receptors in the accumbens (a putative risk marker). Together, these data suggest a common mechanism for increased motivational drive to seek and consume substances with hedonic value, consistent with adolescent addictive processes.
PLoS ONE, 2010
Background: Epidemiological data suggest that the male gender is one of the risks factors for the... more Background: Epidemiological data suggest that the male gender is one of the risks factors for the development of Parkinson Disease (PD). Also, differences in the clinical manifestation and the course of PD have been observed between males and females. However, little is known about the molecular aspects underlying gender-specificity in PD. To address this issue, we determined the gene expression profiles of male and female dopamine (DA) neurons in sporadic PD. Methodology/Principal Findings: We analyzed Affymetrix-based microarrays on laser microdissected DA neurons from postmortem brains of sporadic PD patients and age-matched controls across genders. Pathway enrichment demonstrated that major cellular pathways involved in PD pathogenesis showed different patterns of deregulation between males and females with more prominent downregulation of genes related to oxidative phosporylation, apoptosis, synaptic transmission and transmission of nerve impulse in the male population. In addition, we found upregulation of gene products for metabolic processes and mitochondrial energy consumption in the age-matched male control neurons. On the single cell level, selected data validation using quantitative Real-Time (qRT)-PCR was consistent with microarray raw data and supported some of the observations from data analysis. Conclusions/Significance: On the molecular level, our results provide evidence that the expression profiles of aged normal and PD midbrain DA neurons are gender-specific. The observed differences in the expression profiles suggest a disease bias of the male gender, which could be in concordance with clinical observations that the male gender represents a risk factor for sporadic PD. Validation of gene expression by qRT-PCR supported the microarray results, but also pointed to several caveats involved in data interpretation.
Experimental Neurology, 2012
A growing body of information on the biology of miRNAs has revealed new insight into their roles ... more A growing body of information on the biology of miRNAs has revealed new insight into their roles in normal homeostasis and pathology of disease. miRNAs control all steps of the cellular expression machinery acting through a "single miRNA/multiple targets" or "multiple miRNAs/ single target" mechanism. They have profound impact on the regulation of signaling pathways, which govern common and specific functions across different cellular phenotypes. There is increasing evidence that various diseases share similar disturbances in gene expression networks. Since miRNAs have both common and varying effects in different cellular contexts, they might also influence overlapping signaling pathways in different organs and disease entities. Here, we review this concept for two miRNAs highly abundant in the brain, miR-124 and miR-126, and their potential role in diseases of the brain.
Methods in Molecular Biology
Cell type-specific laser microdissection technologies in combination with molecular techniques to... more Cell type-specific laser microdissection technologies in combination with molecular techniques to determine gene expression profiles have become powerful tools to gain insight into the neurobiological basis of neural circuit disturbances in various neurologic or psychiatric diseases. To identify specific cell populations in human postmortem brain tissue, one can use the inherent properties of the cells, such as pigmentation and morphology or their structural composition through immunohistochemistry (IHC). Here, we describe the isolation of homogeneous neurons and oligodendrocytes and the extraction of high-quality RNA from these cells in human postmortem brain using a combination of rapid IHC, Nissl staining, or simple morphology with Laser Capture Microdissection (LCM), or Laser Microdissection (LMD).
Journal of Psychiatric Research
Schizophrenia is a neurodevelopmental disorder with the typical age of onset of overt symptoms an... more Schizophrenia is a neurodevelopmental disorder with the typical age of onset of overt symptoms and deficits occurring during late adolescence or early adulthood, coinciding with the final maturation of the cortical network involving the prefrontal cortex. These observations have led to the hypothesis that disturbances of the developmental events that take place in the prefrontal cortex during this period, specifically the remodeling of synaptic connectivities between pyramidal neurons, may contribute to the onset of illness. In this context, we investigated the gene expression changes of pyramidal neurons in the human prefrontal cortex during normal periadolescent development in order to gain insight into the possible molecular mechanisms involved in synaptic remodeling of pyramidal neuronal circuitry. Our data suggest that genes associated with the ubiquitination system, which has been implicated in the biology of synaptic plasticity, may play a major role. Among these genes, UBE3B, which encodes the ubiquitin ligase E3, was found to undergo periadolescent increase and was validated at the protein level to be upregulated during periadolescent development. Furthermore, we found that the density of UBE3B-immunoreactive pyramidal neurons was decreased in schizophrenia subjects, consistent with the result of a previous study of decreased UBE3B mRNA expression in pyramidal neurons in this illness. Altogether these findings point to the novel hypothesis that this specific ligase may play a role in the developmental pathogenesis of schizophrenia onset by possibly altering the synaptic remodeling process.
Acta neuropathologica, Jan 7, 2018
MicroRNAs (miRNA) regulate fundamental biological processes, including neuronal plasticity, stres... more MicroRNAs (miRNA) regulate fundamental biological processes, including neuronal plasticity, stress response, and survival. Here, we describe a neuroprotective function of miR-132, the miRNA most significantly downregulated in neurons in Alzheimer's disease. We demonstrate that miR-132 protects primary mouse and human wild-type neurons and more vulnerable Tau-mutant neurons against amyloid β-peptide (Aβ) and glutamate excitotoxicity. It lowers the levels of total, phosphorylated, acetylated, and cleaved forms of Tau implicated in tauopathies, promotes neurite elongation and branching, and reduces neuronal death. Similarly, miR-132 attenuates PHF-Tau pathology and neurodegeneration, and enhances long-term potentiation in the P301S Tau transgenic mice. The neuroprotective effects are mediated by direct regulation of the Tau modifiers acetyltransferase EP300, kinase GSK3β, RNA-binding protein Rbfox1, and proteases Calpain 2 and Caspases 3/7. These data suggest miR-132 as a master re...
Progress in neurobiology, Jan 11, 2018
Parkinson's disease (PD) is one of the most common neurodegenerative disorders, which affects... more Parkinson's disease (PD) is one of the most common neurodegenerative disorders, which affects about 0.3% of the general population. As the population in the developed world ages, this creates an escalating burden on society both in economic terms and in quality of life for these patients and for the families that support them. Although currently available pharmacological or surgical treatments may significantly improve the quality of life of many patients with PD, these are symptomatic treatments that do not slow or stop the progressive course of the disease. Because motor impairments in PD largely result from loss of midbrain dopamine neurons in the substantia nigra pars compacta, PD has long been considered to be one of the most promising target diseases for cell-based therapy. Indeed, numerous clinical and preclinical studies using fetal cell transplantation have provided proof of concept that cell replacement therapy may be a viable therapeutic approach for PD. However, the ...
Journal of neurochemistry, 2016
The RNA integrity number (RIN) is often considered to be a critical measure of the quality of pos... more The RNA integrity number (RIN) is often considered to be a critical measure of the quality of postmortem human brains. However, it has been suggested that RINs do not necessarily reflect the availability of intact mRNA. Using the Agilent bioanalyzer and qRT-PCR, we explored whether RINs provide a meaningful way of assessing mRNA degradation and integrity in human brain samples by evaluating the expression of 3'-5' mRNA sequences of the cytochrome C-1 (CYC1) gene. Analysis of electropherograms showed that RINs were not consistently correlated with RNA or cDNA profiles and appeared to be poor predictors of overall cDNA quality. Cycle thresholds from qRT-PCR analysis to quantify the amount of CYC1 mRNA revealed positive correlations of RINs with amplification of full-length transcripts, despite the variable degree of linear degradation along the 3'-5' sequence. These data demonstrate that in postmortem human brain tissue the RIN is an indicator of mRNA quantity independ...
MicroRNAs (miRs) are important post-transcriptional regulators of gene expression implicated in n... more MicroRNAs (miRs) are important post-transcriptional regulators of gene expression implicated in neuronal development, differentiation, aging and neurodegenerative diseases, including Parkinson's disease (PD). Several miRs have been linked to PD-associated genes, apoptosis and stress response pathways, suggesting that deregulation of miRs may contribute to the development of the neurodegenerative phenotype. Here, we investigate the cell-autonomous role of miR processing RNAse Dicer in the functional maintenance of adult dopamine (DA) neurons. We demonstrate a reduction of Dicer in the ventral midbrain and altered miR expression profiles in laser-microdissected DA neurons of aged mice. Using a mouse line expressing tamoxifen-inducible CreERT2 recombinase under control of the DA transporter promoter, we show that a tissue-specific conditional ablation of Dicer in DA neurons of adult mice led to decreased levels of striatal DA and its metabolites without a reduction in neuronal body...
Molecular Therapy, 2016
Introduction The use of TLR9 agonists as immunomodulators is supported by preclinical and clinica... more Introduction The use of TLR9 agonists as immunomodulators is supported by preclinical and clinical studies, showing their anti-tumor effect by enhancing both cellular and humoral immune responses. So far, two different families of DNA molecules containing non-methylated CG-motifs for TLR9 activation have been established: Dumbbell-shaped dSLIM (R) molecules are protected against exonucleolytic degradation by their covalently-closed, natural phosphodiester (PO) backbone. In contrast, single-stranded, oligodeoxynucleotides (CpG-ODN) are most commonly chemicallystabilized by phosphorothioates (PTO) in their phosphate moieties. PTO modification, however, produce off-target effects in immune cell populations and have resulted in an unfavorable risk-to-benefit ratio. Methods To avoid the off-target effects of PTO-modified CpG-ODN, linear single-stranded ODN were synthezised using L-deoxyribonucleotides at their 3'-ends, which are the natural enantiomers of Ddeoxyribonucleotides. The vast majority of deoxyribose in present organisms are D-deoxyribose, thus co-evolved nucleases are blind for L-deoxyribose thereby leaving L-protected ODN intact. We selected nucleotide sequences of such L-protected, CG-motif containing, single-stranded ODN, EnanDIM (R) , for high secretion of IFN-alpha and IP-10 from human peripheral blood mononuclear cells (PBMC). In a maximum feasible dose approach in CD-1 mice EnanDIM (R) doses of 10 to 50 mg per mice were injected subcutaneously to evaluate the acute toxicity and immunomodulatory properties of EnanDIM (R) molecules in vivo. Results EnanDIM581 and EnanDIM532 were chosen since they caused high secretion of IFN-alpha and IP-10 from human PBMC and resulted in a strong activation of monocytes, NK cells and plasmacytoid dendritic cells (pDC) in vitro. Notably, both showed a distinct immune activation pattern, with the highest secretion of IFNalpha by EnanDIM581 and the strongest maturation of TLR9-bearing pDC by EnanDIM532. EnanDIM744, comprising EnanDIM581 with additional 5'-end L-nucleotide protection and exhibiting an immune activation pattern similar to EnanDIM581, was selected as third EnanDIM (R) for in vivo studies. In the maximum feasible dose approach, safety assessments were performed throughout the study period and no mortality, clinical signs and body weight changes were observed, despite the fact that extremely high doses of app. 300 to 1700 mg/kg were used. A gross necropsy consisting of a macroscopic organ evaluation at day 15 revealed also no toxicity. Regarding immune activation, increased levels of IP-10 in serum were observed 24 hours after injection but not after 15 days confirming that L-nucleotides in EnanDIM (R) do not change the kinetic profile known from other DNA-based TLR9 agonists. Conclusions EnanDIM (R) , a new family of TLR9 agonists with conformation-mediated nuclease-resistance, broadly activates the immune system in vitro. Maximal feasible doses of EnanDIM (R) resulted in no signs of toxicity and confirmed immunomodulatory effects in vivo. Therefore EnanDIM (R) has the potential for clinical development in the treatment of cancer.
European Neuropsychopharmacology, 2016
Schizophrenia research, 2015
The pathophysiology of schizophrenia involves disturbances of information processing across brain... more The pathophysiology of schizophrenia involves disturbances of information processing across brain regions, possibly reflecting, at least in part, a disruption in the underlying axonal connectivity. This disruption is thought to be a consequence of the pathology of myelin ensheathment, the integrity of which is tightly regulated by oligodendrocytes. In order to gain insight into the possible neurobiological mechanisms of myelin deficit, we determined the messenger RNA (mRNA) expression profile of laser captured cells that were immunoreactive for 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), a marker for oligodendrocyte progenitor cells (OPCs) in addition to differentiating and myelinating oligodendrocytes, in the white matter of the prefrontal cortex in schizophrenia subjects. Our findings pointed to the hypothesis that OPC differentiation might be impaired in schizophrenia. To address this hypothesis, we quantified cells that were immunoreactive for neural/glia...
Psychopharmacology, 2016
Increased activity of prefrontal D1 dopamine receptors (D1R) is involved in reward-related behavi... more Increased activity of prefrontal D1 dopamine receptors (D1R) is involved in reward-related behavior found in bipolar disorder and drug addiction. While the effects of elevated D1R are known, depressive-like behaviors also occur in these disorders after reward-seeking ends. The goal is to characterize how termination of D1R overexpression influences depressive-like behaviors. An inducible (Tet.On), lentiviral vector was used to manipulate the expression of the DRD1 gene in glutamate neurons within the prefrontal cortex in male, adult rats. Sexual activity and sucrose preference were studied in both D1R elevated ON and relatively reduced OFF states. Following termination of the D1R ON state, depressive-like behavior was determined in the OFF state. Expression of the transcriptional regulator, cyclic AMP-responsive element-binding protein (CREB), was used as an indication of downstream effects in the nucleus accumbens (NA). ON D1R expression increased sexual activity that returned to baseline in the OFF state. Sucrose preferences increased ~6 % in ON state but fell 11 % below control levels when OFF. Consistent with a depressive-like phenotype, D1R OFF decreased activity by 40 %, impaired the ability to control (43 %) and motivation to escape shock (27 % more impaired) relative to dsRed OFF. CREB increased 29 % in the NA in the D1R OFF state relative to the ON state. This novel approach demonstrates that elevated D1R expression increased hedonic behavior, whereas the termination of D1R overexpression often resulted in depressive-like behavior. These observations support a role for D1R expression cycling in bipolar-associated behaviors and addiction.
Brain research, Jan 3, 2015
The degeneration of substantia nigra (SN) dopamine (DA) neurons in sporadic Parkinson׳s disease (... more The degeneration of substantia nigra (SN) dopamine (DA) neurons in sporadic Parkinson׳s disease (PD) is characterized by disturbed gene expression networks. Micro(mi)RNAs are post-transcriptional regulators of gene expression and we recently provided evidence that these molecules may play a functional role in the pathogenesis of PD. Here, we document a comprehensive analysis of miRNAs in SN DA neurons and PD, including sex differences. Our data show that miRNAs are dysregulated in disease-affected neurons and differentially expressed between male and female samples with a trend of more up-regulated miRNAs in males and more down-regulated miRNAs in females. Unbiased Ingenuity Pathway Analysis (IPA) revealed a network of miRNA/target-gene associations that is consistent with dysfunctional gene and signaling pathways in PD pathology. Our study provides evidence for a general association of miRNAs with the cellular function and identity of SN DA neurons, and with deregulated gene expres...
Neuropharmacology, 2015
Extinction of behaviors in response to drug-associated cues and prevention of reinstatement are i... more Extinction of behaviors in response to drug-associated cues and prevention of reinstatement are integral for addiction treatment, and can reverse or ameliorate the harmful consequences of drug use. The mechanisms controlling extinction and reinstatement involve prefrontal cortical dopamine receptors, which change in expression and activity during the juvenile and adolescent transitions until they mature in adulthood. Little is known about the role that PFC D1 dopamine receptors play in extinction of drug-paired associations early in life. We used extinction of place preferences for cocaine in juvenile male and female rats following genetic, cell-specific overexpression of D1 on glutamatergic cells in the PFC. All subjects needed to demonstrate cocaine preferences for inclusion in the extinction studies. Here, male juveniles with a preference to 10 mg/kg cocaine took longer to extinguish preferences compared to both male adults and female juveniles. Female juveniles extinguished more rapidly than male juveniles at 20 mg/kg cocaine. Overexpression of D1 in juvenile males significantly facilitated extinction relative to juvenile male controls, whereas D1 prolonged expression of extinction in adults overexpressing D1 and adolescents who naturally have elevated D1 expression. These data suggest that an immature D1 profile in juveniles prevented the learning of new associations, and D1 overexpression may provide sufficient activity to facilitate extinction learning. D1 overexpression reduced reinstatement to a priming dose of cocaine in juvenile males. Together, these data show D1 expression may re-program motivational circuitry to facilitate extinction learning during juvenility that is normally unavailable to juveniles and that sex differences exist.
Molecular Psychiatry, 2015
Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation ... more Hetero-oligomers of G-protein-coupled receptors have become the subject of intense investigation because their purported potential to manifest signaling and pharmacological properties that differ from the component receptors makes them highly attractive for the development of more selective Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 5, 2008
Adolescence is a transitional period during development that is associated with a greater likelih... more Adolescence is a transitional period during development that is associated with a greater likelihood of addiction to drugs than any other age. In the prefrontal cortex (PFC), D(1) dopamine receptors mediate motivational salience attribution, which plays a role in addiction. Here, we investigated the relationship of age-related D(1) dopamine receptor expression in the PFC with the maturation of cocaine place conditioning. Confocal microscopy revealed that retrogradely traced cortical output neurons to the nucleus accumbens express higher levels of D(1) receptors during adolescence compared with younger and older ages. D(1) expression does not change on GABAergic interneurons across age. Adolescent differences in D(1) expression occur independently of cortical-accumbens connectivity, which proliferates through adulthood. Behaviorally, adolescent rats are more sensitive to cocaine place conditioning than younger and older rats. However, microinjections of the D(1) antagonist SCH23390 i...
Molecular Neurobiology, 2014
Dysfunction of growth factor (GF) activities contributes to the decline and death of neurons duri... more Dysfunction of growth factor (GF) activities contributes to the decline and death of neurons during aging and in neurodegenerative diseases. In addition, neurons become more resistant to GF signaling with age. Micro (mi)RNAs are posttranscriptional regulators of gene expression that may be crucial to age- and disease-related changes in GF functions. MiR-126 is involved in regulating insulin/IGF-1/phosphatidylinositol-3-kinase (PI3K)/AKT and extracellular signal-regulated kinase (ERK) signaling, and we recently demonstrated a functional role of miR-126 in dopamine neuronal cell survival in models of Parkinson's disease (PD)-associated toxicity. Here, we show that elevated levels of miR-126 increase neuronal vulnerability to ubiquitous toxicity mediated by staurosporine (STS) or Alzheimer's disease (AD)-associated amyloid beta 1-42 peptides (Aβ1-42). The neuroprotective factors IGF-1, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and soluble amyloid precursor protein α (sAPPα) could diminish but not abrogate the toxic effects of miR-126. In miR-126 overexpressing neurons derived from Tg6799 familial AD model mice, we observed an increase in Aβ1-42 toxicity, but surprisingly, both Aβ1-42 and miR-126 promoted neurite sprouting. Pathway analysis revealed that miR-126 overexpression downregulated elements in the GF/PI3K/AKT and ERK signaling cascades, including AKT, GSK-3β, ERK, their phosphorylation, and the miR-126 targets IRS-1 and PIK3R2. Finally, inhibition of miR-126 was neuroprotective against both STS and Aβ1-42 toxicity. Our data provide evidence for a novel mechanism of regulating GF/PI3K signaling in neurons by miR-126 and suggest that miR-126 may be an important mechanistic link between metabolic dysfunction and neurotoxicity in general, during aging, and in the pathogenesis of specific neurological disorders, including PD and AD.
Frontiers in Synaptic Neuroscience, 2014
Background: Early drug intervention in childhood disorders aims to maximize individual potential ... more Background: Early drug intervention in childhood disorders aims to maximize individual potential in the short-and long-term. Consistently, juvenile exposure to psychostimulants, such as methylphenidate (MPH), reduces risk for substance use in animals and sub-populations of individuals with attention deficit hyperactivity disorder (ADHD). We investigated the effects of MPH on brain plasticity via dopamine receptor D3 (D3R) and brain-derived neurotrophic factor (BDNF) expression in developing rats. Methods: Between postnatal days 20-35, rat pups were administered saline vehicle (Veh) or MPH (2 mg/kg), the D3R-preferring agonist ±7-OHDPAT, or the antagonist nafadotride (0.05 mg/kg) alone, or in combination with MPH twice a day. In adulthood, subjects were challenged to Veh or cocaine (10 mg/kg for two days). The prefrontal cortex was analyzed for protein and mRNA levels of total BDNF, its splice variants I, IIc, III/IV, and IV/VI, and D3 receptors. A separate group of subjects was assessed for splice variants at 20, 35, 40, and 60 days of age. Results: Across age strong correlations were evident between Drd3 and Bdnf mRNA levels (r = 0.65) and a negative relationship between Drd3 and exon IIc after MPH treatment (r = −0.73). BDNF protein levels did not differ between Veh-and MPH subjects at baseline, but were significantly lower in MPH-treated and cocaine challenged subjects (30.3 ± 9.7%). Bdnf mRNA was significantly higher in MPH-treated subjects, and reversed upon exposure to cocaine. This effect was blocked by nafadotride. Furthermore, Bdnf total and Bdnf splice variants I, IIc, III/IV, and IV/VI changed across the transitions between juvenility and late adolescence. Conclusions: These data suggest a sensitive window of vulnerability to modulation of BDNF expression around adolescence, and that compared to normal animals, juvenile exposure to MPH permanently reduces prefrontal BDNF transcription and translation upon cocaine exposure in adulthood by a D3R-mediated mechanism.
Psychopharmacology, 2014
Adolescents are often described as &a... more Adolescents are often described as "lacking brakes" resulting in an increase in several behaviors associated with risk for addiction. Prefrontal cortex dopamine and cortico-limbic interaction play an important role in addiction, and we have previously shown that the dopamine D1 receptor is elevated on prelimbic prefrontal output neurons in adolescent rats. We hypothesized that a constellation of risk-related behaviors is mediated by prefrontal output neuron expression of D1. We aimed to determine the role of the dopamine D1 receptor in behavioral and neural correlates of risk for addiction that are often observed in adolescents. Therefore, high-risk behaviors as well as subcortical D2 receptor expression were investigated in adult animals with experimentally elevated D1 on prefrontal glutamatergic neurons. A lentiviral vector that selectively expressed the D1 receptor within glutamate neurons was injected in the prelimbic prefrontal cortex of adult male rats. Place conditioning to cocaine, alcohol, and nicotine, as well as delay discounting, novelty preferences, anxiety, cocaine self-administration, and sucrose preferences were assessed. Virally mediated D1 over-expression in adults leads to stronger drug-cue associations and greater consumption of sweet solutions, elevates bias towards immediate satisfaction rather than delaying gratification, decreases anxiety, and causes rats to work harder for and take more cocaine. Furthermore, elevated cortical D1 reduces D2 receptors in the accumbens (a putative risk marker). Together, these data suggest a common mechanism for increased motivational drive to seek and consume substances with hedonic value, consistent with adolescent addictive processes.
PLoS ONE, 2010
Background: Epidemiological data suggest that the male gender is one of the risks factors for the... more Background: Epidemiological data suggest that the male gender is one of the risks factors for the development of Parkinson Disease (PD). Also, differences in the clinical manifestation and the course of PD have been observed between males and females. However, little is known about the molecular aspects underlying gender-specificity in PD. To address this issue, we determined the gene expression profiles of male and female dopamine (DA) neurons in sporadic PD. Methodology/Principal Findings: We analyzed Affymetrix-based microarrays on laser microdissected DA neurons from postmortem brains of sporadic PD patients and age-matched controls across genders. Pathway enrichment demonstrated that major cellular pathways involved in PD pathogenesis showed different patterns of deregulation between males and females with more prominent downregulation of genes related to oxidative phosporylation, apoptosis, synaptic transmission and transmission of nerve impulse in the male population. In addition, we found upregulation of gene products for metabolic processes and mitochondrial energy consumption in the age-matched male control neurons. On the single cell level, selected data validation using quantitative Real-Time (qRT)-PCR was consistent with microarray raw data and supported some of the observations from data analysis. Conclusions/Significance: On the molecular level, our results provide evidence that the expression profiles of aged normal and PD midbrain DA neurons are gender-specific. The observed differences in the expression profiles suggest a disease bias of the male gender, which could be in concordance with clinical observations that the male gender represents a risk factor for sporadic PD. Validation of gene expression by qRT-PCR supported the microarray results, but also pointed to several caveats involved in data interpretation.
Experimental Neurology, 2012
A growing body of information on the biology of miRNAs has revealed new insight into their roles ... more A growing body of information on the biology of miRNAs has revealed new insight into their roles in normal homeostasis and pathology of disease. miRNAs control all steps of the cellular expression machinery acting through a "single miRNA/multiple targets" or "multiple miRNAs/ single target" mechanism. They have profound impact on the regulation of signaling pathways, which govern common and specific functions across different cellular phenotypes. There is increasing evidence that various diseases share similar disturbances in gene expression networks. Since miRNAs have both common and varying effects in different cellular contexts, they might also influence overlapping signaling pathways in different organs and disease entities. Here, we review this concept for two miRNAs highly abundant in the brain, miR-124 and miR-126, and their potential role in diseases of the brain.