Biology subjects

Karthikeyan, M.

Publications and source records attributed to Karthikeyan, M..

4 recordsLinked to original sources

bioRxiv2022

Identification of Mfn2-S249 as a Phosphoregulatory Switch of Mitochondrial Fusion Dynamics

Mitochondrial remodeling is a fundamental process underlying cellular respiration and metabolism. Here we report TAK1 as a direct regulator of mitochondrial fusion. TAK1 is activated by a variety of mitogenic factors, cytokines and environmental stimuli, which we find induces rapid fragmentation through Mfn2 inactivation. TAK1 phosphorylates Mfn2 at Ser249, which inhibits the binding of GTP required for Mfn trans-dimerization and mitochondrial membrane fusion. Accordingly, expression of Mfn2-S249 phosphomimetics (Mfn2-E/D) constitutively promote fission whereas alanine mutant (Mfn2-A) yields hyperfused mitochondria and increased bioenergetics in cells. In mice, Mfn2-E knock-in yields embryonic lethality in homozygotes whereas heterozygotes are viable but exhibit increased visceral fat accumulation despite normal body weight and cognitive/motor functions compared to wildtype and Mfn2-A mice. Mature white adipocytes isolated from mutant mice reveal cell-autonomous TAK1-related effects on mitochondrial remodeling and lipid metabolism. These results identify Mfn2-S249 as a dynamic phosphoregulatory switch of mitochondrial fusion during development and energy homeostasis.

cell biology↗

bioRxiv2021

BESFA: Bioinformatics based Evolutionary, Structural & Functional Analysis of Prostrate, Placenta, Ovary, Testis, and Embryo (POTE) Paralogs

The POTE family comprises 14 paralogues and is primarily expressed in Prostrate, Placenta, Ovary, Testis, Embryo (POTE), and cancerous cells. The prospective function of the POTE protein family under physiological conditions is less understood. We systematically analyzed their cellular localization and molecular docking analysis to elucidate POTE proteins structure, function, and Adaptive Divergence. Our result discerns that group three POTE paralogs (POTEE, POTEF, POTEI, POTEJ, and POTEKP (a pseudogene)) exhibits significant variation among other members could be because of their Adaptive Divergence. Furthermore, our molecular docking studies on POTE protein revealed the highest binding affinity with NCI-approved anticancer compounds. Additionally, POTEE, POTEF, POTEI, and POTEJ were subject to an explicit molecular dynamic simulation for 50ns. MM-GBSA and other essential electrostatics were calculated that showcased that only POTEE and POTEF have absolute binding affinities with minimum energy exploitation. Thus, this studys outcomes are expected to drive cancer research to successful utilization of POTE genes family as a new biomarker, which could pave the way for the discovery of new therapies.

cancer biology↗

bioRxiv2021

Nicotinic acetylcholine receptor partial antagonist polyamides from tunicates and their predatory sea slugs

In our efforts to discover new drugs to treat pain, we identified molleamines A-E (1-5) as major neuroactive components of the sea slug, Pleurobranchus forskalii and their prey, Didemnum molle tunicates. The chemical structures of molleamines were elucidated by spectroscopy and confirmed by the total synthesis of molleamines A (1) and C (3). Synthetic 3 completely blocked acetylcholine-induced calcium flux in peptidergic nociceptors (PNs) in the somatosensory nervous system. Compound 3 affected neither the 7 nAChR nor the muscarinic acetylcholine receptors in calcium flux assays. In addition to nociceptors, 3 partially blocked the acetylcholine-induced calcium flux in the sympathetic nervous system, including neurons from the superior cervical ganglion. Electrophysiology revealed a block of 3{beta}4 (mouse) and 6/3{beta}4 (rat) nicotinic acetylcholine receptors (nAChRs), with IC50 values of 1.4 and 3.1 {micro}M, respectively. Molleamine C (3) is a partial antagonist, reaching a maximum block of 76-82% of the acetylcholine signal and showing no partial agonist response. Molleamine C (3) may thus provide a lead compound for the development of neuroactive compounds with unique biological properties.

neuroscience↗

bioRxiv2021

The tunicate metabolite 2-(3,5-diiodo-4-methoxyphenyl)ethan-1-amine targets ion channels of vertebrate sensory neurons

Marine tunicates produce defensive amino-acid derived metabolites, including 2-(3,5-diiodo-4-methoxyphenyl)ethan-1-amine (DIMTA), but their mechanisms of action are rarely known. Using an assay-guided approach, we found that out of the many different sensory cells in the mouse dorsal root ganglion (DRG), DIMTA selectively affected low-threshold cold thermosensors. Whole-cell electrophysiology experiments using DRG cells, channels expressed in Xenopus oocytes and human cell lines revealed that DIMTA blocks several potassium channels, reducing the magnitude of the afterhyperpolarization and increasing the baseline [Ca2+]i of low-threshold cold thermosensors. When injected into mice, DIMTA increased the threshold of cold sensation by >3 oC. DIMTA may thus serve as a lead in the further design of compounds that inhibit problems in the cold-sensory system, such as cold allodynia and other neuropathic pain conditions.

neuroscience↗