Publications by authors named "Meera P"

Aminergic nuclei in mammals are generally composed of relatively small numbers of cells with broad projection patterns. Despite the gross similarity of many individual neurons, recent transcriptomic, anatomic and behavioral studies suggest previously unsuspected diversity. Smaller clusters of aminergic neurons in the model organism provide an opportunity to explore the ramifications of neuronal diversity at the level of individual cells.

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Dementia and autoimmune diseases are prevalent conditions with limited treatment options. Taurine and homotaurine (HT) are naturally occurring sulfonate amino acids, with taurine being highly abundant in animal tissues, but declining with age in the blood. HT is a blood-brain barrier permeable drug under investigation for Alzheimer's disease.

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Impairment of excretion and enzymatic processing of nitrogen, for example, because of liver or kidney failure, or with urea cycle and creatine synthesis enzyme defects, surprisingly leads to primarily neurologic symptoms, yet the exact mechanisms remain largely mysterious. In guanidinoacetate N-methyltransferase (GAMT) deficiency, the guanidino compound guanidinoacetate (GAA) increases dramatically, including in the cerebrospinal fluid (CSF), and has been implicated in mediating the neurological symptoms in GAMT-deficient patients. GAA is synthesized by arginine-glycine amidinotransferase (AGAT), a promiscuous enzyme that not only transfers the amidino group from arginine to glycine, but also to primary amines in, for example, GABA and taurine to generate γ-guanidinobutyric acid (γ-GBA) and guanidinoethanesulfonic acid (GES), respectively.

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Ubiquitylation is a posttranslational modification of proteins that is necessary for a variety of cellular processes. E1 ubiquitin activating enzyme, E2 ubiquitin conjugating enzyme, and E3 ubiquitin ligase are all involved in transferring ubiquitin to the target substrate to regulate cellular function. The objective of this review is to provide an overview of different aspects of E3 ubiquitin ligases that can lead to major biological system failure in several deadly diseases.

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The CRISPR-Cas genome editing system is an intrinsic property of a bacteria-based immune system. This employs a guide RNA to detect and cleave the PAM-associated target DNA or RNA in subsequent infections, by the invasion of a similar bacteriophage. The discovery of Cas systems has paved the way to overcome the limitations of existing genome editing tools.

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Social interactions and relationships are often rewarding, but the neural mechanisms through which social interaction drives positive experience remain poorly understood. In this study, we developed an automated operant conditioning system to measure social reward in mice and found that adult mice of both sexes display robust reinforcement of social interaction. Through cell-type-specific manipulations, we identified a crucial role for GABAergic neurons in the medial amygdala (MeA) in promoting the positive reinforcement of social interaction.

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Environmental toxicants have the potential to contribute to the pathophysiology of multiple complex diseases, but the underlying mechanisms remain obscure. One such toxicant is the widely used fungicide ziram, a dithiocarbamate known to have neurotoxic effects and to increase the risk of Parkinson's disease. We have used Drosophila melanogaster as an unbiased discovery tool to identify novel molecular pathways by which ziram may disrupt neuronal function.

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Spinocerebellar ataxias (SCA) are a genetically heterogeneous family of cerebellar neurodegenerative diseases characterized by abnormal firing of Purkinje neurons and degeneration. We recently demonstrated the slowed firing rates seen in several SCAs share a common etiology of hyper-activation of the Src family of non-receptor tyrosine kinases (SFKs). However, the lack of clinically available neuroactive SFK inhibitors lead us to investigate alternative mechanisms to modulate SFK activity.

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Muscimol, the major psychoactive ingredient in the mushroom Amanita muscaria, has been regarded as a universal non-selective GABA-site agonist. Deletion of the GABA receptor (GABA R) δ subunit in mice (δKO) leads to a drastic reduction in high-affinity muscimol binding in brain sections and to a lower behavioral sensitivity to muscimol than their wild type counterparts. Here, we use forebrain and cerebellar brain homogenates from WT and δKO mice to show that deletion of the δ subunit leads to a > 50% loss of high-affinity 5 nM [ H]muscimol-binding sites despite the relatively low abundance of δ-containing GABA Rs (δ-GABA R) in the brain.

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The genetically heterogeneous spinocerebellar ataxias (SCAs) are caused by Purkinje neuron dysfunction and degeneration, but their underlying pathological mechanisms remain elusive. The Src family of nonreceptor tyrosine kinases (SFK) are essential for nervous system homeostasis and are increasingly implicated in degenerative disease. Here we reveal that the SFK suppressor Missing-in-metastasis (MTSS1) is an ataxia locus that links multiple SCAs.

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Peste des petits ruminants (PPR) is a highly contagious transboundary animal disease with a severe socio-economic impact on the livestock industry, particularly in poor countries where it is endemic. Full understanding of PPR virus (PPRV) pathobiology and molecular biology is critical for effective control and eradication of the disease. To achieve these goals, establishment of stable reverse genetics systems for PPRV would play a key role.

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Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease caused by CAG repeat expansion in the ATXN2 gene. The repeat resides in an encoded region of the gene resulting in polyglutamine (polyQ) expansion which has been assumed to result in gain of function, predominantly, for the ATXN2 protein. We evaluated temporal cerebellar expression profiles by RNA sequencing of ATXN2Q127 mice versus wild-type (WT) littermates.

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Metabotropic glutamate receptor 1 (mGluR1) function in Purkinje neurons (PNs) is essential for cerebellar development and for motor learning and altered mGluR1 signaling causes ataxia. Downstream of mGluR1, dysregulation of calcium homeostasis has been hypothesized as a key pathological event in genetic forms of ataxia but the underlying mechanisms remain unclear. We find in a spinocerebellar ataxia type 2 (SCA2) mouse model that calcium homeostasis in PNs is disturbed across a broad range of physiological conditions.

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There are no disease-modifying treatments for adult human neurodegenerative diseases. Here we test RNA-targeted therapies in two mouse models of spinocerebellar ataxia type 2 (SCA2), an autosomal dominant polyglutamine disease. Both models recreate the progressive adult-onset dysfunction and degeneration of a neuronal network that are seen in patients, including decreased firing frequency of cerebellar Purkinje cells and a decline in motor function.

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Degenerative ataxias are a common form of neurodegenerative disease that affect about 20 individuals per 100,000. The autosomal dominant spinocerebellar ataxias (SCAs) are caused by a variety of protein coding mutations (single nucleotide changes, deletions and expansions) in single genes. Affected genes encode plasma membrane and intracellular ion channels, membrane receptors, protein kinases, protein phosphatases and proteins of unknown function.

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Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative condition characterized by loss of motor neurons in the brain and spinal cord. Expansions of a hexanucleotide repeat (GGGGCC) in the noncoding region of the C9ORF72 gene are the most common cause of the familial form of ALS (C9-ALS), as well as frontotemporal lobar degeneration and other neurological diseases. How the repeat expansion causes disease remains unclear, with both loss of function (haploinsufficiency) and gain of function (either toxic RNA or protein products) proposed.

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GABAA receptors (GABARs) are the targets of a wide variety of modulatory drugs which enhance chloride flux through GABAR ion channels. Certain GABAR modulators appear to acutely enhance the function of δ subunit-containing GABAR subtypes responsible for tonic forms of inhibition. Here we identify a reinforcing circuit mechanism by which these drugs, in addition to directly enhancing GABAR function, also increase GABA release.

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Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited disorder, which is caused by a pathological expansion of a polyglutamine (polyQ) tract in the coding region of the ATXN2 gene. Like other ataxias, SCA2 most overtly affects Purkinje cells (PCs) in the cerebellum. Using a transgenic mouse model expressing a full-length ATXN2(Q127)-complementary DNA under control of the Pcp2 promoter (a PC-specific promoter), we examined the time course of behavioral, morphologic, biochemical and physiological changes with particular attention to PC firing in the cerebellar slice.

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In the title complex, [Co(CO(3))(C(12)H(12)N(2))(2)]Br·3H(2)O, the Co(III) cation has a distorted octa-hedral coordination environment. It is chelated by four N atoms of two different 5,5'-dimethyl-2,2'-bipyridyl (dmbpy) ligands in axial and equatorial positions, and by two O atoms of a carbonate anion completing the equatorial positions. Although the water mol-ecules are disordered and their H atoms were not located, there are typical O⋯O distances between 2.

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The Rbfox proteins (Rbfox1, Rbfox2, and Rbfox3) regulate the alternative splicing of many important neuronal transcripts and have been implicated in a variety of neurological disorders. However, their roles in brain development and function are not well understood, in part due to redundancy in their activities. Here we show that, unlike Rbfox1 deletion, the CNS-specific deletion of Rbfox2 disrupts cerebellar development.

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Extrasynaptic GABA(A) receptors (eGABARs) allow ambient GABA to tonically regulate neuronal excitability and are implicated as targets for ethanol and anesthetics. These receptors are thought to be heteropentameric proteins made up of two α subunits-either α4 or α6-two β2 or β3 subunits, and one δ subunit. The GABA analog 4,5,6,7-tetrahydroisoxazolo (5,4-c)pyridin-3(-ol) (THIP) has been proposed as a selective ligand for eGABARs.

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The asymmetric unit of the title complex, [Co(C(14)H(11)N(2)O(2))(2)Cl(H(2)O)]·2H(2)O or [Co(dpgH)(2)Cl(H(2)O)]·2H(2)O, where dpgH(-) is diphenyl glyoximate, consists of one-half of a [Co(dpgH)(2)Cl(H(2)O)] complex and one solvent water mol-ecule. The complex is completed through inversion symmetry, with the Co(III) atom situated at the centre of symmetry. The coordination geometry around the Co(III) atom is distorted octa-hedral with the four N atoms of the two dpgH(-) ligands forming an approximate square plane with N-Co-N bite angles of 81.

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In the title complex, [CoBr(C(4)H(7)N(2)O(2))(2)(H(2)O)], a crystallo-graphic mirror plane bis-ects the mol-ecule, perpendicular to the glyoximate ligands. The geometry around the cobalt(III) atom is approximately octa-hedral with the four glyoximate N atoms forming the square base. A bromide ion and the O atom of a water mol-ecule occupy the remaining coordination sites.

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GABA(A) receptors (GABA(A)Rs) have long been a focus as targets for alcohol actions. Recent work suggests that tonic GABAergic inhibition mediated by extrasynaptic δ subunit-containing GABA(A)Rs is uniquely sensitive to ethanol and enhanced at concentrations relevant for human alcohol consumption. Ethanol enhancement of recombinant α4β3δ receptors is blocked by the behavioral alcohol antagonist 8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiazepine-3-carboxylic acid ethyl ester (Ro15-4513), suggesting that EtOH/Ro15-4513-sensitive receptors mediate important behavioral alcohol actions.

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The Co centre in the title compound, [Co(C(14)H(11)N(2)O(2))(2)Cl(C(3)H(4)N(2))]·0.5H(2)O, shows a slightly distorted octa-hedral coordination geometry. The glyoximate units of the mol-ecule are linked by O-H⋯O hydrogen bonds with the H atom almost in the middle of the two O atoms.

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