Biology subjects

Minerath, R. A.

Publications and source records attributed to Minerath, R. A..

3 recordsLinked to original sources

bioRxiv2025

Cardiomyocyte-expressed TGFβ signals to fibroblasts to program early heart maturation and adult myocyte identity

Transforming growth factor {beta} (TGF{beta}) is a secreted growth factor that is sequestered to the extracellular matrix (ECM) as a latent complex. In adult disease TGF{beta} release in the heart transforms fibroblasts into a differentiated state that synthesizes more ECM. However, it is not known how TGF{beta} functions in the early developing heart to impact resident fibroblasts. Here, we observe that deletion of the Tgfb1, Tgfb2, and Tgfb3 genes (TGF{beta} ligands) from cardiomyocytes in the early developing heart results in cardiac dysfunction by 6 weeks of age with altered fibroblast activity and altered ECM content. Early postnatal hearts from Tgfb1/2/3 cardiomyocyte-deleted mice are dysmorphic and cardiac fibroblasts have incorrect activity and produce inappropriate ECM with reduced stiffness. Gene expression profiling of hearts from myocyte-specific Tgfb1/2/3 deleted mice reveal defects in both cardiomyocyte and fibroblast maturation with ectopic expression of multiple skeletal muscle-specific genes beginning at embryonic day 17.5 and progressing with age. However, cardiomyocyte-specific deletion of TGF{beta} receptors I/II encoding genes (Tgfbr1/2) or Smad2/3 encoding genes (Smad2/3) do not recapitulate this phenotype suggesting that TGF{beta} directly programs early heart fibroblast development that in turn specifies cardiomyocyte maturation. Importantly, Col1a2-/-;Col6a2-/- mice with defective cardiac ECM stiffness, mice lacking cardiomyocyte Itgb1 with reduced ECM load sensing, and Tcf21-/- embryos at E17.5 lacking cardiac fibroblasts each fail to generate the same pathologic ECM program with ectopic cardiomyocyte differentiation observed with Tgfb1/2/3 myocyte-specific deletion. These and additional results indicate that TGF{beta} generated by cardiomyocytes in the embryonic heart mediates fibroblast differentiation that co-evolves the ECM environment that in turn programs cardiomyocyte maturation to establish their identity.

developmental biology↗

bioRxiv2020

The SWELL1-LRRC8 complex regulates endothelial AKT-eNOS-mTOR signaling and vascular function

The endothelium responds to a multitude of chemical and mechanical factors in regulating vascular tone, angiogenesis, blood pressure and blood flow. The endothelial volume regulatory anion channel (VRAC) has been proposed to be mechano-sensitive, to activate in response to fluid flow/hydrostatic pressure and putatively regulate vascular reactivity and angiogenesis. Here, we show that the Leucine Rich Repeat Containing Protein 8a, LRRC8a (SWELL1) functionally encodes VRAC in human umbilical vein endothelial cells (HUVECs). Endothelial SWELL1 (SWELL1) expression positively regulates AKT-eNOS signaling while negatively regulating mTOR signaling, via a SWELL1-GRB2-Cav1-eNOS signaling complex. Endothelium-restricted SWELL1 KO (SWELL1 KO) mice exhibit enhanced tube formation from ex-vivo aortic ring explants in matrigel angiogenesis assays, develop hypertension in response to chronic angiotensin II infusion and have impaired retinal blood flow with both diffuse and focal blood vessel narrowing in the setting of Type 2 diabetes (T2D). These data demonstrate that SWELL1 antithetically regulates AKT-eNOS and mTOR signaling in endothelium and is required for maintaining vascular function, particularly in the setting of T2D.

cell biology↗

bioRxiv2020

SWELL1-LRRC8 complex regulates skeletal muscle cell size, intracellular signalling, adiposity and glucose metabolism

Maintenance of skeletal muscle is beneficial in obesity and Type 2 diabetes. Mechanical stimulation can regulate skeletal muscle differentiation, growth and metabolism, however the molecular mechanosensor remains unknown. Here, we show that SWELL1 (LRRC8a) functionally encodes a swell-activated anion channel that regulates PI3K-AKT, ERK1/2, mTOR signaling, muscle differentiation, myoblast fusion, cellular oxygen consumption, and glycolysis in skeletal muscle cells. SWELL1 over-expression in SWELL1 KO myotubes boosts PI3K-AKT-mTOR signaling to supra-normal levels and fully rescues myotube formation. Skeletal muscle targeted SWELL1 KO mice have smaller myofibers, generate less force ex vivo, and exhibit reduced exercise endurance, associated with increased adiposity under basal conditions, and glucose intolerance and insulin resistance when raised on a high-fat diet, compared to WT mice. These results reveal that the SWELL1-LRRC8 complex regulates insulin-PI3K-AKT-mTOR signalling in skeletal muscle to influence skeletal muscle differentiation in vitro and skeletal myofiber size, muscle function, adiposity and systemic metabolism in vivo.

cell biology↗