Thomas Perlmann - Academia.edu (original) (raw)

Papers by Thomas Perlmann

Research paper thumbnail of Dopaminergic control of autophagic-lysosomal function implicates Lmx1b in Parkinson's disease

Nature neuroscience, 2015

The role of developmental transcription factors in maintenance of neuronal properties and in dise... more The role of developmental transcription factors in maintenance of neuronal properties and in disease remains poorly understood. Lmx1a and Lmx1b are key transcription factors required for the early specification of ventral midbrain dopamine (mDA) neurons. Here we show that conditional ablation of Lmx1a and Lmx1b after mDA neuron specification resulted in abnormalities that show striking resemblance to early cellular abnormalities seen in Parkinson's disease. We found that Lmx1b was required for the normal execution of the autophagic-lysosomal pathway and for the integrity of dopaminergic nerve terminals and long-term mDA neuronal survival. Notably, human LMX1B expression was decreased in mDA neurons in brain tissue affected by Parkinson's disease. Thus, these results reveal a sustained and essential requirement of Lmx1b for the function of midbrain mDA neurons and suggest that its dysfunction is associated with Parkinson's disease pathogenesis.

Research paper thumbnail of Elevated locomotor activity without altered striatal dopamine contents in Nurr1 heterozygous mice after acute exposure to methamphetamine

Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that... more Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that this molecule plays an essential role in the development of midbrain dopaminergic neurons, as shown by the loss of dopaminergic markers and the neurotransmitter dopamine (DA) in the ventral mesencephalon of Nurr1 null mutant mice. Nurr1-deficient mice die within a few hours of birth. Herein, we investigated whether adult mice (12-15-month-old), heterozygous for the Nurr1 mutation (Nurr1 +/− ), show alterations in locomotor function and in the nigrostriatal dopaminergic system after acute exposure to methamphetamine. We first evaluated spontaneous and amphetamine-induced (5 mg/kg) locomotor response of >12-month-old wildtype (Nurr1 +/+ ) and Nurr1 +/− mice. Both, spontaneous and methamphetamine-induced locomotor behavior was significantly increased in the Nurr1 +/− animals as compared to Nurr1 +/+ mice. Striatal DA and DA metabolite levels were measured in untreated animals and methamphetamine-treated animals. No significant differences in striatal dopamine levels or its metabolites DOPAC and HVA were found in the Nurr1 +/− as compared to Nurr1 +/+ mice in untreated or methamphetamine-treated animals. These data show that deletion of a single allele of the Nurr1 gene alters the locomotor activity of 12-15-month-old Nurr1 +/− animals. While total dopamine levels were not altered in the striatum of Nurr1 +/− mice, future studies will be necessary to determine if processes involved with the dynamics of DA release/clearance within the nigrostriatal system may be altered in Nurr1 +/− mutant mice.

Research paper thumbnail of Digging deep into the pockets of orphan nuclear receptors: insights from structural studies

Trends in Cell Biology, 2004

Nuclear receptors comprise a large family of proteins that shares a common structure and mechanis... more Nuclear receptors comprise a large family of proteins that shares a common structure and mechanism of action. Members of this family, first cloned 20 years ago, are regulated by small lipophilic signaling molecules such as steroid hormones, retinoids and thyroid hormone. More recently, the characterization of proteins that resemble nuclear receptors (referred to as orphan receptors) has resulted in the determination of novel signaling pathways. However, many orphan-receptor ligands remain unidentified, and recent structural studies of the binding domains for orphan-receptor ligands suggest that not all of these receptors use ligand binding in a classical way. Notably, it is now evident that some orphan receptors lack the capacity for ligand binding, which suggests that they are regulated by alternative, ligand-independent mechanisms.

Research paper thumbnail of Retinoid Receptor Signaling in Postmitotic Motor Neurons Regulates Rostrocaudal Positional Identity and Axonal Projection Pattern

Neuron, 2003

The identity of motor neurons diverges markedly at different rostrocaudal levels of the spinal co... more The identity of motor neurons diverges markedly at different rostrocaudal levels of the spinal cord, but the signals that specify their fate remain poorly defined. We show that retinoid receptor activation in newly generated spinal motor neurons has a crucial role in specifying motor neuron columnar subtypes. Blockade of retinoid receptor signaling in brachial motor neurons inhibits lateral motor column differentiation and converts many of these neurons to thoracic columnar subtypes. Conversely, expression of a constitutively active retinoid receptor derivative impairs the differentiation of thoracic motor neuron columnar subtypes. These findings provide evidence for a regionally restricted role for retinoid signaling in the postmitotic specification of motor neuron columnar identity.

Research paper thumbnail of Structure and function of Nurr1 identifies a class of ligand-independent nuclear receptors

Nature, 2003

Members of the nuclear receptor (NR) superfamily of transcription factors modulate gene transcrip... more Members of the nuclear receptor (NR) superfamily of transcription factors modulate gene transcription in response to small lipophilic molecules. Transcriptional activity is regulated by ligands binding to the carboxy-terminal ligand-binding domains (LBDs) of cognate NRs. A subgroup of NRs referred to as 'orphan receptors' lack identified ligands, however, raising issues about the function of their LBDs. Here we report the crystal structure of the LBD of the orphan receptor Nurr1 at 2.2 A resolution. The Nurr1 LBD adopts a canonical protein fold resembling that of agonist-bound, transcriptionally active LBDs in NRs, but the structure has two distinctive features. First, the Nurr1 LBD contains no cavity as a result of the tight packing of side chains from several bulky hydrophobic residues in the region normally occupied by ligands. Second, Nurr1 lacks a 'classical' binding site for coactivators. Despite these differences, the Nurr1 LBD can be regulated in mammalian cells. Notably, transcriptional activity is correlated with the Nurr1 LBD adopting a more stable conformation. Our findings highlight a unique structural class of NRs and define a model for ligand-independent NR function.

Research paper thumbnail of Neuropilin1 is a direct downstream target of Nurr1 in the developing brain stem

Journal of Neurochemistry, 2006

The orphan nuclear receptor Nurr1 is expressed in the developing and adult central nervous system... more The orphan nuclear receptor Nurr1 is expressed in the developing and adult central nervous system. Previous studies have shown that Nurr1 is essential for the generation of midbrain dopamine neurons. Furthermore, Nurr1 is critical for respiratory functions associated with the brain stem. Very few Nurr1 regulated genes have been identified and it remains unclear how Nurr1 influences the function and development of neurons. To identify novel Nurr1 target genes we have searched for regulated genes in the dopaminergic MN9D cell line. These experiments identified Neuropilin-1 (Nrp1), a receptor protein involved in axon guidance and angiogenesis, as a novel Nurr1 target gene. Nrp1 expression was rapidly up-regulated by Nurr1 in MN9D cells and in situ hybridization analysis showed that Nrp1 was coexpressed with Nurr1 in the brain stem dorsal motor nucleus. Importantly, Nrp1 expression was down-regulated in this area in Nurr1 null mice. Moreover, two functional Nurr1 binding sites were identified in the Nrp1 promoter and Nurr1 was found to be recruited to these sites in MN9D cells, further supporting that Nrp1 is a direct downstream target of Nurr1. Taken together, our findings suggest that Nurr1 might influence the processes of axon guidance and/or angiogenesis via the regulation of Nrp1 expression.

Research paper thumbnail of Nurr1 regulates dopamine synthesis and storage in MN9D dopamine cells

Experimental Cell Research, 2003

Nurr1, a transcription factor belonging to the nuclear receptor family, is essential for the gene... more Nurr1, a transcription factor belonging to the nuclear receptor family, is essential for the generation of midbrain dopamine (DA) cells during embryonic development. Nurr1 continues to be expressed in adult DA neurons but the role for Nurr1 in inducing and regulating basic dopaminergic functions such as dopamine synthesis and storage has remained unknown. We have previously used MN9D dopamine cells to analyze the role of Nurr1 and retinoids in DA cell maturation. These studies demonstrated that both Nurr1 and retinoids induce cell cycle arrest and a mature morphology. Here we used MN9D cells to investigate how Nurr1 regulates dopaminergic functions. Our results demonstrate that Nurr1, but not retinoids, increases DA content and the expression of aromatic L-amino acid decarboxylase (AADC) and vesicular monoamine transporter-2 (VMAT2) in MN9D cells. In a Nurr1-inducible cell line upregulation of VMAT2 is dependent on continuous Nurr1 expression. Moreover, AADC and VMAT2 are deregulated in midbrain DA cells of Nurr1 knockout embryos as revealed by in situ hybridization. Together, the results provide evidence indicating an instructive role for Nurr1 in controlling DA synthesis and storage.

Research paper thumbnail of Positive and negative thymic selection in T cell receptor-transgenic mice correlate with Nur77 mRNA expression

European Journal of Immunology, 1997

The orphan nuclear receptor Nur77 has been implicated in thymic negative selection. We studied th... more The orphan nuclear receptor Nur77 has been implicated in thymic negative selection. We studied the effect of two T cell receptor (TCR) transgenes on positive selection and Nur77 mRNA expression in thymus. DO11.10 mice, expressing a transgenic TCR specific for an ovalbumin (OVA) 323-339 peptide presented by I-Ad, were found to have an enlarged thymus with a reduced apoptotic activity, measured by flow cytometry, reduced mitochondrial membrane potential and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) techniques. In contrast, in F5 mice expressing a transgenic TCR recognizing the influenza virus nucleoprotein (NP) 366-374 peptide restricted by Db, this positive selection effect was much less pronounced. Positive thymic selection in DO11.10 TCR+ mice correlated with a reduced level of Nur77 mRNA expression shown by Northern blot. F5 mice expressed levels close to those expressed by the wild type. Both transgenic mouse strains responded with extensive cortical apoptosis, and with up-regulation of Nur77 mRNA, to injection of cognate peptides. As 9-cis-Retinoic acid (9-cis-RA) inhibits Nur77-dependent apoptosis in T cell hybridomas in vitro, mice were pretreated with the drug to investigate a similar effect in vivo. However, the drug itself, at saturating concentrations, caused extensive apoptosis in immature CD4+/CD8+ thymocytes. The result demonstrates a correlation between Nur77 expression and thymic apoptotic activity, both during positive and negative selection events.

Research paper thumbnail of An Orphan Nuclear Receptor Activated by Pregnanes Defines a Novel Steroid Signaling Pathway

Research paper thumbnail of Identification of Intrinsic Determinants of Midbrain Dopamine Neurons

Research paper thumbnail of Cellular expression of the immediate early transcription factors Nurr1 and NGFI-B suggests a gene regulatory role in several brain regions including the nigrostriatal dopamine system

Molecular Brain Research, 1996

Nurrl and NGFI-Bare closelyrelated orphanmembersof the steroid-thyroidhormonereceptorfamily invol... more Nurrl and NGFI-Bare closelyrelated orphanmembersof the steroid-thyroidhormonereceptorfamily involvedin immediateearly responsesto stimulisuchas growthfactors.In-situhybridizationin the developingandadultmouseandrat demonstratedNurrl mRNAin severalregionsduringearly centralnervoussystem(CNS)development. Expressionpersistedthroughthe pre-and postnatalperiodsand was also foundin severalareasin the adultCNS.Positiveareasincludethe olfactorybulb,partsof the cortex,the hippocampalformation and substantial nigra where Nurrl and tyrosinehydroxylasemRNAswere co-expressed.6-Hydroxydopamine-induced degenerationof mesencephalicdopamineneuronsled to a correspondingloss of Nurrl mRNA, demonstratinga link betweenNurrl and dopaminergic neurons.NGFI-BmRNAwas not foundin the prenatalCNS but was highlyexpressedin the adult brain in many areas includingthe olfactorybulb, cortex,basal gangliaand hippocampus. The spatiotemporal distributionof Nurrl andNGFI-BmRNAssuggeststhat these transcriptionfactors are involvedin the developmentand maturationof specificsets of CNS neurons.The experimentaldata imply that one of these functionsmaybe to controlgeneregulato~eventsimportantfor development and functionof thoseneuronsthat degenerate in patientswith Parkinson'sdisease.

Research paper thumbnail of NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

Biochemical and Biophysical Research Communications, 2009

The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system an... more The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPARb/d signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4A NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPARb/d and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.

Research paper thumbnail of Elevated locomotor activity without altered striatal dopamine contents in Nurr1 heterozygous mice after acute exposure to methamphetamine

Behavioural Brain Research, 2003

Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that... more Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that this molecule plays an essential role in the development of midbrain dopaminergic neurons, as shown by the loss of dopaminergic markers and the neurotransmitter dopamine (DA) in the ventral mesencephalon of Nurr1 null mutant mice. Nurr1-deficient mice die within a few hours of birth. Herein, we investigated whether adult mice (12-15-month-old), heterozygous for the Nurr1 mutation (Nurr1 +/− ), show alterations in locomotor function and in the nigrostriatal dopaminergic system after acute exposure to methamphetamine. We first evaluated spontaneous and amphetamine-induced (5 mg/kg) locomotor response of >12-month-old wildtype (Nurr1 +/+ ) and Nurr1 +/− mice. Both, spontaneous and methamphetamine-induced locomotor behavior was significantly increased in the Nurr1 +/− animals as compared to Nurr1 +/+ mice. Striatal DA and DA metabolite levels were measured in untreated animals and methamphetamine-treated animals. No significant differences in striatal dopamine levels or its metabolites DOPAC and HVA were found in the Nurr1 +/− as compared to Nurr1 +/+ mice in untreated or methamphetamine-treated animals. These data show that deletion of a single allele of the Nurr1 gene alters the locomotor activity of 12-15-month-old Nurr1 +/− animals. While total dopamine levels were not altered in the striatum of Nurr1 +/− mice, future studies will be necessary to determine if processes involved with the dynamics of DA release/clearance within the nigrostriatal system may be altered in Nurr1 +/− mutant mice.

Research paper thumbnail of Abnormal Reaction to Central Nervous System Injury in Mice Lacking Glial Fibrillary Acidic Protein and Vimentin

The Journal of Cell Biology, 1999

In response to injury of the central nervous system, astrocytes become reactive and express high ... more In response to injury of the central nervous system, astrocytes become reactive and express high levels of the intermediate filament (IF) proteins glial fibrillary acidic protein (GFAP), vimentin, and nestin. We have shown that astrocytes in mice deficient for both GFAP and vimentin (GFAP Ϫ / Ϫ vim Ϫ / Ϫ ) cannot form IFs even when nestin is expressed and are thus devoid of IFs in their reactive state. Here, we have studied the reaction to injury in the central nervous system in GFAP Ϫ / Ϫ , vimentin Ϫ / Ϫ , or GFAP Ϫ / Ϫ vim Ϫ / Ϫ mice. Glial scar formation appeared normal after spinal cord or brain lesions in GFAP Ϫ / Ϫ or vimentin Ϫ / Ϫ mice, but was impaired in GFAP Ϫ / Ϫ vim Ϫ / Ϫ mice that developed less dense scars frequently accompanied by bleeding. These results show that GFAP and vimentin are required for proper glial scar formation in the injured central nervous system and that some degree of functional overlap exists between these IF proteins.

Research paper thumbnail of Dopaminergic control of autophagic-lysosomal function implicates Lmx1b in Parkinson's disease

Nature neuroscience, 2015

The role of developmental transcription factors in maintenance of neuronal properties and in dise... more The role of developmental transcription factors in maintenance of neuronal properties and in disease remains poorly understood. Lmx1a and Lmx1b are key transcription factors required for the early specification of ventral midbrain dopamine (mDA) neurons. Here we show that conditional ablation of Lmx1a and Lmx1b after mDA neuron specification resulted in abnormalities that show striking resemblance to early cellular abnormalities seen in Parkinson's disease. We found that Lmx1b was required for the normal execution of the autophagic-lysosomal pathway and for the integrity of dopaminergic nerve terminals and long-term mDA neuronal survival. Notably, human LMX1B expression was decreased in mDA neurons in brain tissue affected by Parkinson's disease. Thus, these results reveal a sustained and essential requirement of Lmx1b for the function of midbrain mDA neurons and suggest that its dysfunction is associated with Parkinson's disease pathogenesis.

Research paper thumbnail of Elevated locomotor activity without altered striatal dopamine contents in Nurr1 heterozygous mice after acute exposure to methamphetamine

Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that... more Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that this molecule plays an essential role in the development of midbrain dopaminergic neurons, as shown by the loss of dopaminergic markers and the neurotransmitter dopamine (DA) in the ventral mesencephalon of Nurr1 null mutant mice. Nurr1-deficient mice die within a few hours of birth. Herein, we investigated whether adult mice (12-15-month-old), heterozygous for the Nurr1 mutation (Nurr1 +/− ), show alterations in locomotor function and in the nigrostriatal dopaminergic system after acute exposure to methamphetamine. We first evaluated spontaneous and amphetamine-induced (5 mg/kg) locomotor response of >12-month-old wildtype (Nurr1 +/+ ) and Nurr1 +/− mice. Both, spontaneous and methamphetamine-induced locomotor behavior was significantly increased in the Nurr1 +/− animals as compared to Nurr1 +/+ mice. Striatal DA and DA metabolite levels were measured in untreated animals and methamphetamine-treated animals. No significant differences in striatal dopamine levels or its metabolites DOPAC and HVA were found in the Nurr1 +/− as compared to Nurr1 +/+ mice in untreated or methamphetamine-treated animals. These data show that deletion of a single allele of the Nurr1 gene alters the locomotor activity of 12-15-month-old Nurr1 +/− animals. While total dopamine levels were not altered in the striatum of Nurr1 +/− mice, future studies will be necessary to determine if processes involved with the dynamics of DA release/clearance within the nigrostriatal system may be altered in Nurr1 +/− mutant mice.

Research paper thumbnail of Digging deep into the pockets of orphan nuclear receptors: insights from structural studies

Trends in Cell Biology, 2004

Nuclear receptors comprise a large family of proteins that shares a common structure and mechanis... more Nuclear receptors comprise a large family of proteins that shares a common structure and mechanism of action. Members of this family, first cloned 20 years ago, are regulated by small lipophilic signaling molecules such as steroid hormones, retinoids and thyroid hormone. More recently, the characterization of proteins that resemble nuclear receptors (referred to as orphan receptors) has resulted in the determination of novel signaling pathways. However, many orphan-receptor ligands remain unidentified, and recent structural studies of the binding domains for orphan-receptor ligands suggest that not all of these receptors use ligand binding in a classical way. Notably, it is now evident that some orphan receptors lack the capacity for ligand binding, which suggests that they are regulated by alternative, ligand-independent mechanisms.

Research paper thumbnail of Retinoid Receptor Signaling in Postmitotic Motor Neurons Regulates Rostrocaudal Positional Identity and Axonal Projection Pattern

Neuron, 2003

The identity of motor neurons diverges markedly at different rostrocaudal levels of the spinal co... more The identity of motor neurons diverges markedly at different rostrocaudal levels of the spinal cord, but the signals that specify their fate remain poorly defined. We show that retinoid receptor activation in newly generated spinal motor neurons has a crucial role in specifying motor neuron columnar subtypes. Blockade of retinoid receptor signaling in brachial motor neurons inhibits lateral motor column differentiation and converts many of these neurons to thoracic columnar subtypes. Conversely, expression of a constitutively active retinoid receptor derivative impairs the differentiation of thoracic motor neuron columnar subtypes. These findings provide evidence for a regionally restricted role for retinoid signaling in the postmitotic specification of motor neuron columnar identity.

Research paper thumbnail of Structure and function of Nurr1 identifies a class of ligand-independent nuclear receptors

Nature, 2003

Members of the nuclear receptor (NR) superfamily of transcription factors modulate gene transcrip... more Members of the nuclear receptor (NR) superfamily of transcription factors modulate gene transcription in response to small lipophilic molecules. Transcriptional activity is regulated by ligands binding to the carboxy-terminal ligand-binding domains (LBDs) of cognate NRs. A subgroup of NRs referred to as 'orphan receptors' lack identified ligands, however, raising issues about the function of their LBDs. Here we report the crystal structure of the LBD of the orphan receptor Nurr1 at 2.2 A resolution. The Nurr1 LBD adopts a canonical protein fold resembling that of agonist-bound, transcriptionally active LBDs in NRs, but the structure has two distinctive features. First, the Nurr1 LBD contains no cavity as a result of the tight packing of side chains from several bulky hydrophobic residues in the region normally occupied by ligands. Second, Nurr1 lacks a 'classical' binding site for coactivators. Despite these differences, the Nurr1 LBD can be regulated in mammalian cells. Notably, transcriptional activity is correlated with the Nurr1 LBD adopting a more stable conformation. Our findings highlight a unique structural class of NRs and define a model for ligand-independent NR function.

Research paper thumbnail of Neuropilin1 is a direct downstream target of Nurr1 in the developing brain stem

Journal of Neurochemistry, 2006

The orphan nuclear receptor Nurr1 is expressed in the developing and adult central nervous system... more The orphan nuclear receptor Nurr1 is expressed in the developing and adult central nervous system. Previous studies have shown that Nurr1 is essential for the generation of midbrain dopamine neurons. Furthermore, Nurr1 is critical for respiratory functions associated with the brain stem. Very few Nurr1 regulated genes have been identified and it remains unclear how Nurr1 influences the function and development of neurons. To identify novel Nurr1 target genes we have searched for regulated genes in the dopaminergic MN9D cell line. These experiments identified Neuropilin-1 (Nrp1), a receptor protein involved in axon guidance and angiogenesis, as a novel Nurr1 target gene. Nrp1 expression was rapidly up-regulated by Nurr1 in MN9D cells and in situ hybridization analysis showed that Nrp1 was coexpressed with Nurr1 in the brain stem dorsal motor nucleus. Importantly, Nrp1 expression was down-regulated in this area in Nurr1 null mice. Moreover, two functional Nurr1 binding sites were identified in the Nrp1 promoter and Nurr1 was found to be recruited to these sites in MN9D cells, further supporting that Nrp1 is a direct downstream target of Nurr1. Taken together, our findings suggest that Nurr1 might influence the processes of axon guidance and/or angiogenesis via the regulation of Nrp1 expression.

Research paper thumbnail of Nurr1 regulates dopamine synthesis and storage in MN9D dopamine cells

Experimental Cell Research, 2003

Nurr1, a transcription factor belonging to the nuclear receptor family, is essential for the gene... more Nurr1, a transcription factor belonging to the nuclear receptor family, is essential for the generation of midbrain dopamine (DA) cells during embryonic development. Nurr1 continues to be expressed in adult DA neurons but the role for Nurr1 in inducing and regulating basic dopaminergic functions such as dopamine synthesis and storage has remained unknown. We have previously used MN9D dopamine cells to analyze the role of Nurr1 and retinoids in DA cell maturation. These studies demonstrated that both Nurr1 and retinoids induce cell cycle arrest and a mature morphology. Here we used MN9D cells to investigate how Nurr1 regulates dopaminergic functions. Our results demonstrate that Nurr1, but not retinoids, increases DA content and the expression of aromatic L-amino acid decarboxylase (AADC) and vesicular monoamine transporter-2 (VMAT2) in MN9D cells. In a Nurr1-inducible cell line upregulation of VMAT2 is dependent on continuous Nurr1 expression. Moreover, AADC and VMAT2 are deregulated in midbrain DA cells of Nurr1 knockout embryos as revealed by in situ hybridization. Together, the results provide evidence indicating an instructive role for Nurr1 in controlling DA synthesis and storage.

Research paper thumbnail of Positive and negative thymic selection in T cell receptor-transgenic mice correlate with Nur77 mRNA expression

European Journal of Immunology, 1997

The orphan nuclear receptor Nur77 has been implicated in thymic negative selection. We studied th... more The orphan nuclear receptor Nur77 has been implicated in thymic negative selection. We studied the effect of two T cell receptor (TCR) transgenes on positive selection and Nur77 mRNA expression in thymus. DO11.10 mice, expressing a transgenic TCR specific for an ovalbumin (OVA) 323-339 peptide presented by I-Ad, were found to have an enlarged thymus with a reduced apoptotic activity, measured by flow cytometry, reduced mitochondrial membrane potential and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) techniques. In contrast, in F5 mice expressing a transgenic TCR recognizing the influenza virus nucleoprotein (NP) 366-374 peptide restricted by Db, this positive selection effect was much less pronounced. Positive thymic selection in DO11.10 TCR+ mice correlated with a reduced level of Nur77 mRNA expression shown by Northern blot. F5 mice expressed levels close to those expressed by the wild type. Both transgenic mouse strains responded with extensive cortical apoptosis, and with up-regulation of Nur77 mRNA, to injection of cognate peptides. As 9-cis-Retinoic acid (9-cis-RA) inhibits Nur77-dependent apoptosis in T cell hybridomas in vitro, mice were pretreated with the drug to investigate a similar effect in vivo. However, the drug itself, at saturating concentrations, caused extensive apoptosis in immature CD4+/CD8+ thymocytes. The result demonstrates a correlation between Nur77 expression and thymic apoptotic activity, both during positive and negative selection events.

Research paper thumbnail of An Orphan Nuclear Receptor Activated by Pregnanes Defines a Novel Steroid Signaling Pathway

Research paper thumbnail of Identification of Intrinsic Determinants of Midbrain Dopamine Neurons

Research paper thumbnail of Cellular expression of the immediate early transcription factors Nurr1 and NGFI-B suggests a gene regulatory role in several brain regions including the nigrostriatal dopamine system

Molecular Brain Research, 1996

Nurrl and NGFI-Bare closelyrelated orphanmembersof the steroid-thyroidhormonereceptorfamily invol... more Nurrl and NGFI-Bare closelyrelated orphanmembersof the steroid-thyroidhormonereceptorfamily involvedin immediateearly responsesto stimulisuchas growthfactors.In-situhybridizationin the developingandadultmouseandrat demonstratedNurrl mRNAin severalregionsduringearly centralnervoussystem(CNS)development. Expressionpersistedthroughthe pre-and postnatalperiodsand was also foundin severalareasin the adultCNS.Positiveareasincludethe olfactorybulb,partsof the cortex,the hippocampalformation and substantial nigra where Nurrl and tyrosinehydroxylasemRNAswere co-expressed.6-Hydroxydopamine-induced degenerationof mesencephalicdopamineneuronsled to a correspondingloss of Nurrl mRNA, demonstratinga link betweenNurrl and dopaminergic neurons.NGFI-BmRNAwas not foundin the prenatalCNS but was highlyexpressedin the adult brain in many areas includingthe olfactorybulb, cortex,basal gangliaand hippocampus. The spatiotemporal distributionof Nurrl andNGFI-BmRNAssuggeststhat these transcriptionfactors are involvedin the developmentand maturationof specificsets of CNS neurons.The experimentaldata imply that one of these functionsmaybe to controlgeneregulato~eventsimportantfor development and functionof thoseneuronsthat degenerate in patientswith Parkinson'sdisease.

Research paper thumbnail of NR4A orphan nuclear receptors influence retinoic acid and docosahexaenoic acid signaling via up-regulation of fatty acid binding protein 5

Biochemical and Biophysical Research Communications, 2009

The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system an... more The orphan nuclear receptor (NR) Nurr1 is expressed in the developing and adult nervous system and is also induced as an immediate early gene in a variety of cell types. In silico analysis of human promoters identified fatty acid binding protein 5 (FABP5), a protein shown to enhance retinoic acid-mediated PPARb/d signaling, as a potential Nurr1 target gene. Nurr1 has previously been implicated in retinoid signaling via its heterodimerization partner RXR. Since NRs are commonly involved in cross-regulatory control we decided to further investigate the regulatory relationship between Nurr1 and FABP5. FABP5 expression was up-regulated by Nurr1 and other NR4A NRs in HEK293 cells, and Nurr1 was shown to activate and bind to the FABP5 promoter, supporting that FABP5 is a direct downstream target of NR4A NRs. We also show that the RXR ligand docosahexaenoic acid (DHA) can induce nuclear translocation of FABP5. Moreover, via up-regulation of FABP5 Nurr1 can enhance retinoic acid-induced signaling of PPARb/d and DHA-induced activation of RXR. We also found that other members of the NR4A orphan NRs can up-regulate FABP5. Thus, our findings suggest that NR4A orphan NRs can influence signaling events of other NRs via control of FABP5 expression levels.

Research paper thumbnail of Elevated locomotor activity without altered striatal dopamine contents in Nurr1 heterozygous mice after acute exposure to methamphetamine

Behavioural Brain Research, 2003

Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that... more Gene targeting experiments, in which both alleles of the Nurr1 gene were deleted, have shown that this molecule plays an essential role in the development of midbrain dopaminergic neurons, as shown by the loss of dopaminergic markers and the neurotransmitter dopamine (DA) in the ventral mesencephalon of Nurr1 null mutant mice. Nurr1-deficient mice die within a few hours of birth. Herein, we investigated whether adult mice (12-15-month-old), heterozygous for the Nurr1 mutation (Nurr1 +/− ), show alterations in locomotor function and in the nigrostriatal dopaminergic system after acute exposure to methamphetamine. We first evaluated spontaneous and amphetamine-induced (5 mg/kg) locomotor response of >12-month-old wildtype (Nurr1 +/+ ) and Nurr1 +/− mice. Both, spontaneous and methamphetamine-induced locomotor behavior was significantly increased in the Nurr1 +/− animals as compared to Nurr1 +/+ mice. Striatal DA and DA metabolite levels were measured in untreated animals and methamphetamine-treated animals. No significant differences in striatal dopamine levels or its metabolites DOPAC and HVA were found in the Nurr1 +/− as compared to Nurr1 +/+ mice in untreated or methamphetamine-treated animals. These data show that deletion of a single allele of the Nurr1 gene alters the locomotor activity of 12-15-month-old Nurr1 +/− animals. While total dopamine levels were not altered in the striatum of Nurr1 +/− mice, future studies will be necessary to determine if processes involved with the dynamics of DA release/clearance within the nigrostriatal system may be altered in Nurr1 +/− mutant mice.

Research paper thumbnail of Abnormal Reaction to Central Nervous System Injury in Mice Lacking Glial Fibrillary Acidic Protein and Vimentin

The Journal of Cell Biology, 1999

In response to injury of the central nervous system, astrocytes become reactive and express high ... more In response to injury of the central nervous system, astrocytes become reactive and express high levels of the intermediate filament (IF) proteins glial fibrillary acidic protein (GFAP), vimentin, and nestin. We have shown that astrocytes in mice deficient for both GFAP and vimentin (GFAP Ϫ / Ϫ vim Ϫ / Ϫ ) cannot form IFs even when nestin is expressed and are thus devoid of IFs in their reactive state. Here, we have studied the reaction to injury in the central nervous system in GFAP Ϫ / Ϫ , vimentin Ϫ / Ϫ , or GFAP Ϫ / Ϫ vim Ϫ / Ϫ mice. Glial scar formation appeared normal after spinal cord or brain lesions in GFAP Ϫ / Ϫ or vimentin Ϫ / Ϫ mice, but was impaired in GFAP Ϫ / Ϫ vim Ϫ / Ϫ mice that developed less dense scars frequently accompanied by bleeding. These results show that GFAP and vimentin are required for proper glial scar formation in the injured central nervous system and that some degree of functional overlap exists between these IF proteins.