Biology subjects

Premont, R. T.

Publications and source records attributed to Premont, R. T..

5 recordsLinked to original sources

bioRxiv2026

S-nitrosylation of protein kinase A is required for its activation by GPCRs

Stimulation of many G protein-coupled receptors (GPCRs) increases cyclic adenosine monophosphate (cAMP) and nitric oxide (NO). While cAMP-dependent activation of protein kinase A (PKA) is a central regulatory mechanism, a parallel role for NO in GPCR transduction has not been established. Here we show that upon stimulation of multiple GPCRs in heart, brain, and fat, the regulatory subunits of PKA undergo enzymatic S-nitrosylation by SNO-CoA-assisted nitrosylase (SCAN). S-nitrosylation by SCAN is required for dissociation of PKA holoenzymes and activation of PKA. In transgenic and cardiovascular disease models, impaired adrenergic stimulation is identified with deficient S-nitrosylation of PKA, which can be rescued by the drug sodium nitroprusside. Our work suggests a new understanding of GPCR physiology with direct application to the clinical setting.

physiology↗

bioRxiv2025

The denitrosylase SCoR2 controls cardioprotective metabolic reprogramming

Acute myocardial infarction (MI) is a leading cause of morbidity and mortality, and therapeutic options remain limited. Endogenously generated nitric oxide (NO) is highly cardioprotective, but protection is not replicated by nitroso-vasodilators (e.g., nitrates, nitroprusside) used in clinical practice, highlighting specificity in NO-based signaling and untapped therapeutic potential. Signaling by NO is mediated largely by S-nitrosylation, entailing specific enzymes that form and degrade S-nitrosothiols in proteins (SNO-proteins), termed nitrosylases and denitrosylases, respectively. SNO-CoA Reductase 2 (SCoR2; product of the Akr1a1 gene) is a recently discovered protein denitrosylase. Genetic variants in SCoR2 have been associated with cardiovascular disease, but its function is unknown. Here we show that mice lacking SCoR2/Akr1a1 exhibit robust protection in an animal model of MI. SCoR2 regulates ketolytic energy availability, antioxidant levels and polyol homeostasis via S-nitrosylation of key metabolic effectors. Human cardiomyopathy shows reduced SCoR2 expression and an S-nitrosylation signature of metabolic reprogramming, mirroring SCoR2-/- mice. Deletion of SCoR2 thus coordinately reprograms multiple metabolic pathways--ketone body utilization, glycolysis, pentose phosphate shunt and polyol metabolism--to limit infarct size, establishing SCoR2 as a novel regulator in the injured myocardium and a potential drug target. Impact statementMice lacking the denitrosylase enzyme SCoR2 demonstrate robust cardioprotection resulting from coordinate reprogramming of multiple metabolic pathways. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=196 SRC="FIGDIR/small/642752v2_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@72bfbborg.highwire.dtl.DTLVardef@189cbc4org.highwire.dtl.DTLVardef@1a0cc51org.highwire.dtl.DTLVardef@1c61004_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2021

Intercellular crosstalk regulating ARRB2/RARRES1 is involved in transition from fibrosis to cancer

Progressive fibrogenesis in chronic liver injury is often associated with cancer development. Beta-arrestin-2 (ARRB2) is a regulator of the profibrotic Angiotensin II type 1 receptor (AGTR1). The role of ARRB2 in liver fibrosis and in the transition from fibrosis to cancer is not fully understood and was investigated in this study. This study demonstrates that upregulation of the retinoic acid receptor responder 1 (RARRES1) in HSC mediated by ARRB2 leads to fibrosis. This process is driven by exosomal ARRB2 transfer to HSC, major fibrosis contributors, from injured hepatocytes, which highly express ARRB2. By contrast, downregulation of RARRES1 in hepatocytes induces malignant transformation and hepatocellular carcinoma (HCC) development. Consequently, Arrb2-deficient mice show higher number and size of liver tumors than wild-type mice in a hepatocellular carcinoma model with fibrosis. The identified relationship between ARRB2 and RARRES1 was observed in at least two species, including human cells and tissues in fibrosis and HCC and has a predictive value for survival in cancer patients. This study describes the discovery of a novel molecular pathway mediating the transition from fibrosis to cancer offering potential diagnostics and therapeutics.

molecular biology↗

bioRxiv2019

GIT2 is dispensable for normal learning and memory function due to a predominant brain GIT2 splice variant that evades GIT/PIX complexes.

G protein-coupled receptor kinase-interacting protein 2 (GIT2) and GIT1 are highly similar, sharing the same domain structure and many binding partners. The most important GIT partners are the p21-activated protein kinase-interacting exchange factor (PIX) proteins, since through homomeric and heteromeric interactions, GIT and PIX proteins form oligomeric GIT/PIX complexes. Oligomeric GIT/PIX complexes function both as regulators of small GTP-binding proteins and as scaffolds for signalling molecules, including p21-activated protein kinases (PAKs). Deficits in learning and memory have been demonstrated in GIT1 knockout mice, and it has been assumed that GIT2 also would affect learning and memory. Unexpectedly, we find that GIT2-deficient mice respond normally in multiple tests of learning and memory, and have normal hippocampal long-term potentiation. Further, we find no evidence that GIT2 regulates ADHD-like phenotypes. To investigate why GIT2 and GIT1 differ so markedly in the brain, we identified the major isoform of GIT2 in the brain as a previously uncharacterized splice variant, GIT2({Delta}BCE). This variant cannot dimerize or form oligomeric complexes with PIX proteins, and is thus incapable of regulating PAK in synapses, compared to oligomeric GIT1/PIX complexes. Because localized activation of PAK in synapses is required for structural plasticity underlying cognitive performance, loss of monomeric GIT2({Delta}BCE) in the brain does not influence these responses.

animal behavior and cognition↗

bioRxiv2018

Brain-Specific Deletion of GIT1 Impairs Cognition and Alters Phosphorylation of Synaptic Protein Networks Implicated in Schizophrenia Susceptibility

Despite tremendous effort, the molecular and cellular basis of cognitive deficits in schizophrenia remain poorly understood. Recent progress in elucidating the genetic architecture of schizophrenia has highlighted the association of multiple loci and rare variants that may impact susceptibility. One key example, given their potential etiopathogenic and therapeutic relevance, is a set of genes that encode proteins that regulate excitatory glutamatergic synapses in brain. A critical next step is to delineate specifically how such genetic variation impacts synaptic plasticity and to determine if and how the encoded proteins interact biochemically with one another to control cognitive function in a convergent manner. Towards this goal, here we study the roles of GPCR-kinase interacting protein 1 (GIT1), a synaptic scaffolding and signaling protein with damaging coding variants found in schizophrenia patients, as well as copy number variants found in patients with neurodevelopmental disorders. We generated conditional neural-selective GIT1 knockout mice and find that these mice have deficits in fear conditioning learning and spatial memory. Using global quantitative phospho-proteomics, we revealed that GIT1 deletion in brain perturbs specific networks of GIT1-interacting synaptic proteins. Importantly, several schizophrenia and neurodevelopmental disorder risk genes are present within these networks. We propose that GIT1 regulates the phosphorylation of a network of synaptic proteins and other critical regulators of neuroplasticity, and that perturbation of these networks may contribute to cognitive deficits observed in schizophrenia and neurodevelopmental disorders.

neuroscience↗