Targeting Galectin-3 C-epitope oligomers associated maladaptive mechanotransductive signaling in pressure-overload induced left ventricular cardiac hypertrophy
BackgroundAging and various pathological conditions lead to pressure-overload in the left ventricle, promoting maladaptive hypertrophic remodeling and subsequent cardiac dysfunction, ultimately increasing the risk of heart failure. Galectin-3 (Gal-3) plays a central role in this process; however, its critical intracellular functions complicate direct therapeutic targeting. Notably, pathological microenvironments trigger the proteolytic cleavage of Gal-3 into distinct N- and C-terminal fragments. The specific contributions of these cleaved epitope forms to adverse cardiomyocyte mechanotransduction, and their potential as precision therapeutic targets in contrast to the full-length protein, remain unresolved. MethodsTo address this gap, we combined rodent models of aging and pressure-overload (PO) -induced cardiac hypertrophy with PO mechanobiology-driven in vitro assays and validation in human cardiac tissue and serum. Gal-3 epitope abundance, localization, phosphorylation, oligomerization, and downstream signaling were quantified using biochemical, imaging, and functional approaches. ResultsWe found that extracellular oligomers of the Gal-3 C-terminal epitope accumulated in serum and on cardiomyocyte surfaces in hypertrophic rodents and human subjects, where they correlated with adverse remodeling and cardiomyocyte loss. Treatment with Amalaki Rasayana (AR), a standardized nutraceutical-based cardioprotective Ayurvedic phytomedicine, and its bioactive component gallic acid (GA) significantly reduced circulating and surface-associated Gal-3 C-epitope oligomers and attenuated hypertrophy-associated cytotoxic signaling. Mechanistically, AR/GA enhanced Ser6 phosphorylation of Gal-3, promoting intracellular retention, while limiting pathological secretion and deleterious extracellular oligomerization. Following AR/GA treatment, the binding of preformed Gal-3 C-epitope oligomers to cardiomyocyte surfaces were further inhibited, thereby suppressing maladaptive mechanotransductive signaling. Importantly, circulating Gal-3 C-epitope oligomers, together with atrial natriuretic peptide (ANP), constituted a drug-responsive biomarker panel that accurately tracked hypertrophy regression, serving as an indicator of drug efficacy. ConclusionsIn summary, Gal-3 C-epitope oligomers represent pathogenic signaling, drug-responsive therapeutic targets and circulating biomarkers of cardiac hypertrophy, with broader relevance to other Gal-3-driven neoplastic, fibrotic, and inflammatory diseases. HighlightsO_LIGalectin-3 C-epitope forms pathogenic extracellular oligomers in pressure-overload induced cardiac hypertrophy. C_LIO_LISurface binding of excess C-epitope oligomers triggers an adverse mechanotransductive remodelling in cardiomyocytes. C_LIO_LIPhytomedicine -Amalaki Rasayana (AR) and its key bioactive compound, gallic acid (GA), effectively inhibit the surface binding and mitigate harmful effects of Gal-3 C-epitope oligomers. C_LIO_LIAR/GA induces the phosphorylation of Gal-3, limiting pathological secretion, extracellular oligomer assembly, and glycan-mediated surface binding. C_LIO_LIIntracellular retention of Gal-3 preserves its crucial cellular functions. C_LIO_LICirculating levels of Gal-3 C-epitope oligomers can be used to monitor the therapeutic regression of cardiac hypertrophy, serving as an indicator of drug efficacy C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=164 HEIGHT=200 SRC="FIGDIR/small/704762v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@4702e9org.highwire.dtl.DTLVardef@10361eorg.highwire.dtl.DTLVardef@51118eorg.highwire.dtl.DTLVardef@57ba37_HPS_FORMAT_FIGEXP M_FIG C_FIG Pressure-overload induces excessive secretion of Galectin-3 and triggers its proteolytic cleavage into the N- and C-terminal epitopes. The extracellular oligomerization of the C-terminal epitope facilitates high-affinity glycan binding and promotes pathological mechanotransductive signaling in cardiomyocytes. Phytochemical modulation by Amalaki rasayana and its bioactive component, gallic acid, induces the phosphorylation of Gal-3, limiting pathological secretion, extracellular oligomer assembly, and glycan-mediated surface binding, while preserving intracellular function. Circulating levels of Gal-3 C-epitope oligomers can be used to monitor the therapeutic regression of cardiac hypertrophy, serving as an indicator of drug efficacy.