18 research outputs found
5-HT2A deletion protects against Clozapine-induced hyperglycemia
Clozapine is an antipsychotic known for its superior efficacy in treating drug-resistant Schizophrenia. However, Clozapine induces various side effects such as hyperglycemia, agranulocytosis, weight gain etc. The mechanisms of these Clozapine-induced side effects have remained largely elusive though an important role is ascribed to 5-HT2A (Serotonin receptor subtype-2A). In this pilot study, we report for the first time that the 5-HT2A ‘global’ knockout mice (Htr2a−/−) are resistant to the Clozapine-induced hyperglycemia. Importantly though, the Htr2a−/− mice exhibit near normal basal glucose metabolism in the glucose tolerance tests. Collectively, the Htr2a−/− mice provide an important tool to study the Clozapine-induced hyperglycemia. Keywords: 5-HT2A, Clozapine, Hyperglycemi
Fluorescence Anisotropy Uncovers Changes in Protein Packing with Inclusion Growth in a Cellular Model of Polyglutamine Aggregation
The aggregation of polyglutamine-rich
proteins is closely linked
with numerous neurodegenerative disorders. In pathological and cellular
models, the appearance of protein-rich inclusions in cells acts as
a read out of protein aggregation. The precise organization of aggregated
protein in these inclusions and their mode of growth are still poorly
understood. Here, fluorescence anisotropy-based measurements have
been used to probe protein packing across inclusions of varying brightness,
formed by an monomeric enhanced green fluorescent protein (mEGFP)-tagged
polyglutamine model peptide in cells. High-resolution, confocal-based
steady-state anisotropy measurements report a large depolarization,
consistent with extensive homo-Förster (fluorescence) resonance
energy transfer (FRET) between the sequestered mEGFP-tagged protein
molecules. An inverse correlation of fluorescence anisotropy with
intensity is seen across inclusions, which becomes emphasized when
the observed fluorescence anisotropy values of inclusions are corrected
for the fluorescence contribution of the diffusible protein, present
within and around smaller inclusions. Homo-FRET becomes enhanced as
inclusion size increases. This enhancement is confirmed by two-photon
excitation-based time-resolved fluorescence anisotropy decay measurements,
which also suggest that the mEGFP-tagged protein molecules are arranged
in multiple ways within inclusions. Bright inclusions display faster
FRET rates with a larger number of mEGFP moieties participating in
homo-FRET than faint inclusions do. These results are consistent with
a model in which the protein is more closely packed in the brighter
inclusions. In such a possible mechanism, the higher packing density
of protein molecules in brighter inclusions would suggest that inclusion
growth could involve an intermolecular compaction event within the
inclusion, as more monomers and aggregates are recruited into the
growing inclusion
Controlled induction, enhancement, and guidance of neuronal growth cones by use of line optical tweezers
We report an optical tweezers based approach for efficient and controlled manipulation of neuronal growth cones. The approach exploits asymmetric transverse gradient force created in a line optical tweezers to transport actin monomers in the desired growth direction. With this approach induction of artificial growth cones from the neuronal cell body and enhancement of the growth rate of the natural growth cones have been achieved. The use of this approach to bring two growth cones into close proximity for establishing a neuronal connection is also discussed
Fold prediction and comparative modeling of Bdm1: a probable α/β hydrolase associated with hot water epilepsy
Hot water epilepsy (HWE) is a benign and rare form of reflex epilepsy that occurs most commonly in humans. Bdm1 is one of the proteins whose mRNA transcript is overexpressed during HWE in a rat model. We show, by sequence analysis and fold recognition methods, that Bdm1 has strong structural similarities to α/β hydrolases like the thioesterases. A three-dimensional model derived by comparative modeling methods allowed the search for catalytic residues using a flexible functional template characteristic of these enzymes. We predict that Bdm1 might be regulated by homocysteine levels by means of direct participation in degradation pathways
Serotonin in pre-implantation mouse embryos is localized to the mitochondria and can modulate mitochondrial potential
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 stage. Transcripts of the transporter, Slc6a4, were present in all pre-implantation stages investigated. These results suggest that serotonin in embryos can arise from a combination of synthesis and uptake from the surrounding milieu
Derivation of iPSC lines from two patients with familial Alzheimer's disease from India
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