Biology subjects

McGarrah, R. W.

Publications and source records attributed to McGarrah, R. W..

3 recordsLinked to original sources

bioRxiv2026

BCKDK Inhibitors Directly Antagonize Angiotensin II Type 1 Receptor and Induce Vasodilation Independently of BCAA Catabolism or BCKDK

Branched-chain amino acids (BCAA) have been implicated in diabetes and heart failure, leading to ongoing clinical trials with inhibitors of BCKDK, a key regulator of BCAA catabolism. We have previously shown that these inhibitors promote vasodilation and lower blood pressure, well-known cardioprotective effects, but how this occurs remained unclear. We show here, using explanted vessels, in vivo hemodynamics and telemetry, and genetically modified mice, that the vasodilatory effect of BCKDK inhibitors is direct, rapid, independent of nitric oxide, independent of BCAA catabolism, and most strikingly, independent of BCKDK itself. Instead, we demonstrate, using structural and biochemical studies, that BCKDK inhibitors directly antagonize the angiotensin II type I receptor (AT1R) and consequent angiotensin-mediated vasoconstriction. These data demonstrate a strong off-target effect of BCKDK inhibitors, independent of BCAA or BCKDK, which may explain their cardioprotective effects but also questions if this protection would be additive to existing AT1R blockers.

physiology↗

bioRxiv2026

Mitochondrial carrier SLC25A34 links clock, diet, and temperature control of interorganellar lipid cycling

Adipocyte lipid metabolism is coordinated by circadian rhythms, diet, and environmental temperature. Yet how these diverse signals are molecularly integrated remains unknown. Here we show that clock, diet, and temperature cues converge on the orphan mitochondrial transporter, SLC25A34, to orchestrate thermogenic cycling of lipid synthesis and oxidation. During sleep, the clock suppresses Slc25a34 transcription through REV-ERB. Waking, lipid-rich diets, or cold exposure abolish this repression, allowing lipolytic signals to stimulate Slc25a34 expression via PPAR. SLC25A34 then imports oxaloacetate into mitochondria to accelerate the export of substrates used for acetyl-CoA production in the cytosol. This feeds into cytosolic lipid synthesis and transcriptional induction of mitochondrial biogenesis, which collectively promote mitochondrial lipid oxidation. Thus, SLC25A34 confers circadian, dietary, and environmental control of thermogenic metabolism through interorganellar lipid cycling.

molecular biology↗

bioRxiv2022

Nervous system reduction in branched-chain amino acid metabolism disrupts hippocampal neurogenesis and memory

A role for macronutrient metabolism in learning and memory is supported by numerous epidemiological studies. The Ppm1k gene encodes the branched-chain keto acid dehydrogenase (BCKDH) phosphatase that promotes the metabolism of branched-chain amino acids (BCAA). Here we show that nervous system deletion of Ppm1k in mice increases BCAA levels in brain tissue but not in plasma. These mice have significant impairments in working memory accompanied by a robust accumulation of DCX+/NeuroD1+ immature neurons within the dentate gyrus granule cell layer. Through single cell RNA sequencing and pathway analysis we identified substantial increases in transit-amplifying cells and immature neurons along with activated hedgehog signaling in Ppm1k deficient primary neural stem cells (NSCs). Inhibition of mTOR signaling reversed the effects of Ppm1k deletion on neuronal progenitor gene activation in primary NSCs. Together our findings uncover a new molecular link between BCAA metabolism, hippocampal neurogenesis, and cognitive performance.

neuroscience↗