Mitradas Panicker - Academia.edu (original) (raw)

Papers by Mitradas Panicker

Molecular Microbiology, May 1, 1992

SummaryThe gene product of F tral is a bifunctional protein which nicks and unwinds the F plasmid... more SummaryThe gene product of F tral is a bifunctional protein which nicks and unwinds the F plasmid during conjugal DNA transfer. Further biochemical characterization of the Tral protein reveals that it has a second, much lower, Km for ATP hydrolysis, in addition to that previously identified. Measurement of the single‐stranded DNA‐stimulated ATPase rate indicates that there is co‐operative interaction between the enzyme monomers for maximal activity. Furthermore, 18O‐exchange experiments indicate that Tral protein hydrolyses ATP with, at most, a low‐level reversal of the hydrolytic step during each turnover.

Proceedings of the National Academy of Sciences of the United States of America, Oct 18, 2002

Construction of SR2-GFP, the 5-HT2A-EGFP Fusion Receptor. The 1.8-kb cDNA fragment containing the... more Construction of SR2-GFP, the 5-HT2A-EGFP Fusion Receptor. The 1.8-kb cDNA fragment containing the entire rat 5-HT 2A receptor-coding region was obtained from the plasmid pSR2 by PCR.

Neuroscience, Jul 1, 2020

Serotonin is an important neurotransmitter and neuromodulator. Disruption of the serotonergic sys... more Serotonin is an important neurotransmitter and neuromodulator. Disruption of the serotonergic system has been implicated in various psychiatric disorders such as schizophrenia and bipolar disorder. Most of the drugs targeting these neurotransmitter systems are classified primarily as agonists or inverse agonists/antagonists, with their described function being limited to activating the canonical signalling pathway(s), or inhibiting the pathway(s) respectively. Previous work with the human 5-HT 2A has shown the receptor to be activated by dopamine, also an endogenous ligand. Dopamine, is the cognate ligand of the dopaminergic system, which significantly overlaps with the serotonergic system in the brain. The two systems innervate many of the same brain areas and, the central serotonergic systems also regulate dopamine functions. Our aim was to investigate the downstream signalling set up by the receptor on being activated by dopamine. We show that dopamine is a functionally selective ligand at 5-HT 2A and have examined dopamine as a ligand with respect to some receptor-dependent phenotypes. Our results show that dopamine acts as an agonist at the human serotonin 2A receptor and brings about its activation and internalization. Using in vitro assays, we have established differences in the signalling pathways set up by dopamine as compared to serotonin. Using site-specific mutagenesis we have identified residues important for this functional selectivity, shown by dopamine at this receptor. Our identification of specific residues important in the functional selectivity of dopamine at 5-HT 2A could have far reaching implications for the field of GPCR signalling and drug-design.

Stem Cell Research, Mar 1, 2017

A major cause of spontaneous abortions is chromosomal abnormality of foetal cells. We report the ... more A major cause of spontaneous abortions is chromosomal abnormality of foetal cells. We report the generation of an induced pluripotent stem cell line from the fibroblasts isolated from chorionic villi of an early spontaneously aborted foetus with Turner syndrome. The Turner syndrome villus induced pluripotent stem cell line is transgene free, retains the original XO karyotype, expresses pluripotency markers and undergoes trilineage differentiation. This pluripotent stem cell model of Turner syndrome should serve as a tool to study the developmental abnormalities of foetus and placenta that lead to early embryo lethality and profound symptoms like infertility in 45 XO survivors.

medRxiv (Cold Spring Harbor Laboratory), Jan 30, 2023

Suicide is a condition resulting from complex environmental and genetic risks that affect million... more Suicide is a condition resulting from complex environmental and genetic risks that affect millions of people globally. Both structural and functional studies identified the hippocampus as one of the vulnerable brain regions contributing to suicide risk. Here, we have identified the hippocampal transcriptomes, gene ontology, cell type proportions, dendritic spine morphology, and transcriptomic signature in iPSC-derived neuronal precursor cells (NPCs) and neurons in postmortem brain tissue from suicide deaths. The hippocampal tissue transcriptomic data revealed that NPAS4 gene expression was downregulated while ALDH1A2, NAAA, and MLXIPL gene expressions were upregulated in tissue from suicide deaths. The gene ontology identified 29 significant pathways including NPAS4-associated gene ontology terms "excitatory post-synaptic potential", "regulation of postsynaptic membrane potential" and "long-term memory" indicating alteration of glutamatergic synapses in the hippocampus of suicide deaths. The cell type deconvolution identified decreased excitatory neuron proportion and an increased inhibitory neuron proportion providing evidence of excitation/inhibition imbalance in the hippocampus of suicide deaths. In addition, suicide deaths had increased dendric spine density, due to an increase of thin (relatively unstable) dendritic spines, compared to controls. The transcriptomes of iPSCderived hippocampal-like NPCs and neurons revealed 31 and 33 differentially expressed genes in NPC and neurons, respectively, of suicide deaths. The suicide-associated differentially expressed genes in NPCs were RELN, CRH, EMX2, OXTR, PARM1 and IFITM2 which overlapped with previously published results. The previously-known suicide-associated differentially expressed genes in differentiated neurons were COL1A1, THBS1, IFITM2, AQP1, and NLRP2. Together, these findings would help better understand the hippocampal neurobiology of suicide for identifying therapeutic targets to prevent suicide.

Journal of Bacteriology, May 1, 1985

Donor bacteria containing JCFL39, a temperature-sensitive traD mutant of the F sex factor, were u... more Donor bacteria containing JCFL39, a temperature-sensitive traD mutant of the F sex factor, were used at the nonpermissive temperature to accumulate stable mating pairs with recipient cells. At this stage in conjugation, extracellular F pili were removed by treatment with 0.01% sodium dodecyl sulfate. Upon then shifting to the permissive temperature for JCFL39, transfer of the F plasmid was observed. The mating pairs that were accumulated with JCFL39 at the nonpermissive temperature were readily observed by electron microscopy in wall-to-wall contact with the recipient bacteria. These results demonstrate that the traD product, which is known to be required in transferring DNA to a recipient bacterium, acts after the stage at which extracellular F pili are required. In addition, we concluded that DNA transfer takes place while donor and recipient cells are in surface contact and not necessarily through an extended F pilus as envisioned in some models of bacterial conjugation.

ABSTRACTBackgroundMental illnesses often cluster in families, and their impact on affected and un... more ABSTRACTBackgroundMental illnesses often cluster in families, and their impact on affected and unaffected members within families need to be understood from a social perspective.MethodsData was derived from 202 families with multiple affected individuals, identified under Accelerator program for Discovery in Brain disorders using Stem cells (ADBS) study. Affected individuals (N=259) had a diagnosis of schizophrenia, bipolar disorder, obsessive-compulsive disorder or substance use disorder. For comparison, we used the unaffected siblings from the same families (N=229), and a matched random subset of healthy control (HC) data (N=229) from the National Mental Health Survey (NMHS). We compared educational attainment, functional marital status and occupational status between the groups.ResultsThe groups were matched across age, gender and place of residence. The highest educational attainment was significantly different between the groups. The affected (9.9 years) and unaffected siblings...

Journal of General Physiology

Mechanical forces and tissue mechanics influence the morphology of the developing brain, but the ... more Mechanical forces and tissue mechanics influence the morphology of the developing brain, but the underlying molecular mechanisms have been elusive. Here, we examine the role of mechanotransduction in brain development by focusing on Piezo1, a mechanically activated ion channel. We find that Piezo1 deletion results in a thinner neuroepithelial layer, disrupts pseudostratification, and reduces neurogenesis in E10.5 mouse embryos. Proliferation and differentiation of Piezo1 knockout (KO) mouse neural stem cells (NSCs) isolated from E10.5 embryos are reduced in vitro compared to littermate WT NSCs. Transcriptome analysis of E10.5 Piezo1 KO brains reveals downregulation of the cholesterol biosynthesis superpathway, in which 16 genes, including Hmgcr, the gene encoding the rate-limiting enzyme of the cholesterol biosynthesis pathway, are downregulated by 1.5-fold or more. Consistent with this finding, membrane lipid composition is altered, and the cholesterol levels are reduced in Piezo1 ...

Background: Family studies in obsessive-compulsive disorder (OCD) indicate higher rates of psycho... more Background: Family studies in obsessive-compulsive disorder (OCD) indicate higher rates of psychosis among their first-degree relatives (FDRs). However, the etiological and clinical relationships between the two disorders remain unclear. We compared the clinical characteristics & pharmacological treatment response in patients diagnosed with OCD with a family history of psychosis (OCD-FHP), with a family history of OCD (OCD-FHO) and those with sporadic OCD (OCD-S). Methods: A total of 226 patients who met DSM-IV criteria for OCD (OCD-FHP=59, OCD-FHO=112, OCD-S=55) were included for analysis. All patients were evaluated using the Mini International Neuropsychiatric Interview (MINI 6.0.0), Yale-Brown Obsessive-Compulsive Scale (YBOCS), and the Family Interview for Genetic Studies (FIGS). Treatment response was characterized over naturalistic follow-up. Results: The three groups did not differ across any demographic or clinical variables other than treatment response. Patients in the OC...

When data is pooled across multiple sites, the extracted features are confounded by site effects.... more When data is pooled across multiple sites, the extracted features are confounded by site effects. Harmonization methods attempt to correct these site effects while preserving the biological variability within the features. However, little is known about the sample size requirement for effectively learning the harmonization parameters and their relationship with the increasing number of sites. In this study, we performed experiments to find the minimum sample size required to achieve multisite harmonization (using neuroHarmonize) using volumetric and surface features by leveraging the concept of learning curves. Our first two experiments show that site-effects are effectively removed in a univariate and multivariate manner; however, it is essential to regress the effect of covariates from the harmonized data additionally. Our following two experiments with actual and simulated data showed that the minimum sample size required for achieving harmonization grows with the increasing aver...

Journal of Neuroradiology, 2021

BACKGROUND AND PURPOSE Facial features can be potentially reconstructed from structural magnetic ... more BACKGROUND AND PURPOSE Facial features can be potentially reconstructed from structural magnetic resonance images, thereby compromising the confidentiality of study participants. Defacing methods can be applied to MRI images to ensure privacy of study participants. These methods remove facial features, thereby rendering the image unidentifiable. It is commonly assumed that defacing would not have any impact on quantitative assessments of the brain. In this study, we have assessed the impact of different defacing methods on quality and volumetric estimates. MATERIALS AND METHODS We performed SPM-, Freesurfer-, pydeface, and FSL-based defacing on 30 T1-weighted images. We statistically compared the change in quality measurements (from MRIQC) and volumes (from SPM, CAT, and Freesurfer) between non-defaced and defaced images. We also calculated the Dice coefficient of each tissue class between non-defaced and defaced images. RESULTS Almost all quality measurements and tissue volumes changed after defacing, irrespective of the method used. All tissue volumes decreased post-defacing for CAT, but no such consistent trend was seen for SPM and Freesurfer. Dice coefficients indicated that segmentations are relatively robust; however, partial volumes might be affected leading to changed volumetric estimates. CONCLUSION In this study, we demonstrated that volumes and quality measurements get affected differently by defacing methods. It is likely that this will have a significant impact on the reproducibility of experiments. We provide suggestions on ways to minimize the impact of defacing on outcome measurements. Our results warrant the need for robust handling of defaced images at different steps of image processing.

In Vitro Cellular & Developmental Biology - Animal, 2019

Recent approaches of using decellularized organ matrices for cardiac tissue engineering prompted ... more Recent approaches of using decellularized organ matrices for cardiac tissue engineering prompted us to culture human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) on the human amniotic membrane (hAM). Since hAM has been used lately to patch diseased hearts in patients and has shown anti-inflammatory and anti-fibrotic benefits, it qualifies as a cardiac compatible and clinically relevant heart tissue scaffold. The aim of this study was to test the ability of the hAM to support attachment, differentiation, and maturation of hiPSC-derived CMs in vitro. hAMs were prepared from term placenta. An in-house generated hiPSC line was used for CM derivation. hiPSC-derived cardiac progenitors were cultured on the surface of cryopreserved hAMs and in the presence of cytokines promoting cardiac differentiation. CMs grown on hAM and popular basement membrane matrix (BMM) Matrigel™ were compared for the following aspects of cardiac development: the morphology of cardiomyocytes with respect to shape and cellular alignments, levels of cardiac-related gene transcript expression, functionality in terms of spontaneous calcium fluxes and mitochondrial densities and distributions. hAM is biocompatible with hiPSC-derived CMs. hAM increased cardiac transcription regulator and myofibril protein transcript expression, accelerated intracellular calcium transients, and enhanced cellular mitochondrial complexity of its cardiomyocytes in comparison to cardiomyocytes differentiated on Matrigel™. Our data suggests that hAM supports differentiation and improves cardiomyogenesis in comparison to Matrigel™. hAMs are natural, easily and largely available. The method of preparing hAM cardiac sheets described here is simple with potential for clinical transplantation.

ObjectiveAdverse Childhood Experiences (ACEs) are linked to the development of a number of psychi... more ObjectiveAdverse Childhood Experiences (ACEs) are linked to the development of a number of psychiatric illnesses in adulthood. Our study examined the pattern of ACEs and their relation to the age of onset (AAO) of major psychiatric conditions in individuals from families that had ≥ 2 first degree relatives with major psychiatric conditions (multiplex families) identified as part of an ongoing longitudinal study.MethodsOur sample consisted of 509 individuals from 215 families. Of these, 268 were affected i.e diagnosed with bipolar disorder (BPAD) (n=61), obsessive-compulsive disorder (OCD) (n=58), schizophrenia (n=52), substance dependence (SUD) (n=59), or co-occurring diagnoses (n=38); while 241 were at-risk first degree relatives (FDRs) who were either unaffected (n=210) or had other depressive or anxiety disorders (n=31). All individuals were evaluated using the Adverse Childhood Experiences – International Questionnaire (ACE-IQ) and ACE binary and frequency scores were calculated...

Stem Cell Research, 2018

The current prevalence of diagnosable dementia in India is 1% of people over 60 years (~3.7 milli... more The current prevalence of diagnosable dementia in India is 1% of people over 60 years (~3.7 million people), but is estimated to increase significantly, as~15% world's aged population (> 65 years) would be resident here by 2020 (Shah et al., 2016). While several mutations that pose a familial risk have been identified, the ethnic background may influence disease susceptibility, clinical presentation and treatment response. In this study, we report a detailed characterization of two representative HiPSC lines from a well-characterized dementia cohort from India. Availability of these lines, and associated molecular and clinical information, would be useful in the detailed exploration of the genomic contribution(s) to AD. Resource table Unique stem cell line identifier 1. NCBSi001-A 2. NCBSi002-A Alternative names of stem cell lines NA Inducible/constitutive system NA Date archived/stock date Dec 2017 Cell line repository/bank These cell lines were generated under the aegis of the

Psychiatry and clinical neurosciences, Jan 27, 2018

Severe Mental Illnesses, such as bipolar disorder and schizophrenia, are highly heritable, and ha... more Severe Mental Illnesses, such as bipolar disorder and schizophrenia, are highly heritable, and have a complex pattern of inheritance. Genome wide association studies detect a part of the heritability, which can be attributed to common genetic variation. Examination of rare variants with Next Generation Sequencing may add to the understanding of genetic architecture of SMIs. We analyzed 32 ill subjects from 8 multiplex families; and 33 healthy individuals by whole exome sequencing. Prioritized variants were selected by a 3-step filtering process, which included deleteriousness by 5 in silico algorithms; sharing within families by affected individuals, rarity in South Asian sample estimated using the Exome Aggregation Consortium data and complete absence of these variants in a control-individuals from the same gene pool. We identified 42 rare, non-synonymous deleterious variants (~5 per pedigree) in this study. None of the variants were shared across families, indicating a 'privat...

Asian journal of psychiatry, Jan 16, 2018

Aberrant re-entry of neurons into cell cycle appears to be an early event in Alzheimer's dise... more Aberrant re-entry of neurons into cell cycle appears to be an early event in Alzheimer's disease (AD) and targeting this dysregulation may have therapeutic potential. We have examined whether cell cycle dysregulation in AD can be detected using patient and control derived B-lymphocytes. Cell cycle analysis using flow cytometry demonstrated that cell cycle dysregulation occurs in AD lymphocytes, with a significant difference in the distribution of cells in G0/G1, S and G2/M phases of cell cycle as compared to control lymphocytes. Using global gene expression analysis by RNA sequencing and cell cycle analysis, we examined the role of Retinoic Acid (RA), a candidate molecule predicted to be of therapeutic potential in cell cycle dysregulation associated with AD. CCND1, CCNE2, E2F transcription factors which are known to be dysregulated in AD were among the 32 genes that showed differential expression in response to RA treatment thus suggesting a protective role of RA. However, the ...

Journal of Hepatology, 2015

Background and Aims: Reprogramming of somatic cells into pluripotent stem cells by using exogenou... more Background and Aims: Reprogramming of somatic cells into pluripotent stem cells by using exogenous factors, hold great promises in development of personalized regenerative medicine and can produce valuable in vitro models of diseases. iPSCs have been generated from multiple sources including skin, extra embryonic tissues, which have their own advantages or disadvantages. The ideal cell source should be easily accessible, susceptible, and universal. Urine is the most easily accessible sample which can be collected from any individual. In the present study, we have generated iPSCs. from urine cells that has the potential to differentiate into hepatic lineages Material and Methods: Urine samples were collected in sampling bottles. Exfoliated urine cells were isolated and cultured from adult human urine. After the appearance of colonies at 2-3 weeks, these cells were reprogrammed to iPSCs using commercially available "Keisuke Okita plasmid". Appeared stem cell like colonies were further characterized for stemness by studying the expression of pluripotent markers and by in-vitro tri-lineage differentiation. Results: Stem cell like colonies generated from urine cells (urine iPSCs) on immunocytochemistry, were found to be positive for different pluripotent markers like OCT3/4, nanog, They also exhibited robust diffentation property when cultured as Embryoid bodies without growth factors. And differentiated in to hepatocytes like cells showing marker of Hepatocytes like albumin. Conclusions: We document here for the first time, generation of transgene free urine cell derived induced pluripotent stem cells showing pluripotency. These UiPSCs are advantageous over from other sources as this process is purely non-invasive and generates transgene free iPSCs.

ABSTRACTCellular migration is a ubiquitous feature that brings brain cells into appropriate spati... more ABSTRACTCellular migration is a ubiquitous feature that brings brain cells into appropriate spatial relationships over time; and it helps in the formation of a functional brain. We studied the migration patterns of induced pluripotent stem cell (IPSC)-derived neural precursor cells (NPCs) from individuals with familial bipolar disorder (BD), in comparison with healthy controls. The BD patients also had morphological brain abnormalities in magnetic resonance imaging. Time-lapse analysis of migrating cells was conducted, through which we were able to identify several parameters to be abnormal in cellular migration, including the speed and directionality of NPCs. We also performed transcriptomic analysis to probe the mechanisms behind aberrant cellular phenotype identified. Our analysis showed downregulation of a network of genes, centering on EGF/ERBB proteins. Present findings indicate that collective, systemic dysregulation may produce the aberrant cellular phenotype; which could co...

Functional selectivity in serotonin receptor 2A (5-HT2A) endocytosis, recycling and phosphorylation

Reproduction, 2008

Serotonin is reported to be present in early embryos of many species and plays an important role ... more Serotonin is reported to be present in early embryos of many species and plays an important role in early patterning. Since it is a fluorophore, it can be directly visualized using fluorescence microscopy. Here, we use three-photon microscopy to image serotonin in live pre-implantation mouse embryos. We find that it is present as puncta averaging 1.3 square microns and in concentrations as high as 442 mM. The observed serotonin puncta were found to co-localize with mitochondria. Live embryos pre-incubated with serotonin showed a higher mitochondrial potential, indicating that it can modulate mitochondrial potential. Pre-implantation mouse embryos were also examined at various developmental stages for the presence of transcripts of the peripheral and neuronal forms of tryptophan hydroxylase (Tph1 and Tph2 respectively) and the classical serotonin transporter (Slc6a4). Transcripts of Tph2 were seen in oocytes and in two-cell stages, whereas transcripts of Tph1 were not detected at any...