Galectin-1 Attenuates Cardiac Hypertrophy By Splice Variant Specifically Modulating Cav1.2 Calcium Channel

BackgroundPressure overload-induced cardiac hypertrophy is a relatively common cardiomyopathy which occurred in response to chronic pressure increase.Dysregulation of L-type calcium channel(LTCC)Cav1.2 which anticipates multiple essential physiological processes including excitation-contraction coupling(ECC)and smooth muscle contraction also play some roles in cardiac hypertrophic processes by unbalancing intracellular calciun concentration([Ca2+]i)in cardiovascular system.Furthermore,as a ?-galactoside binding protein,galectin-1(Gal-1)was found to bind with Cavl.2 calcium channel and regulated its function in blood vessel by a splice specific manner.However,the roles of Gal-1 in cardiac Cav 1.2 calcium channel and cardiac hypertrophy remains unknown.ObjectiveThe study is to investigate the change of Gal-1 and exon 9*expression in cardiac hypertrophy progress and furthermore,to elucidate the function of Gal-1 in cardiac hypertrophy.MethodDifferent ages' WKY/SHR rats and sham/TAC rats model were used to investigate the expression of Gal-1 and exon 9*by Western blot and RT-PCR in cardiac hypertrophy progress;Isolated neonatal rat ventricular myocytes and transfected with different splicing type of Cav 1.2 calcium channels HEK293 cells were used to whole cell patch clamp study to investigate the role of Gal-1 in calcium channel current;Fluo-4 staining was used to monitor the dynamic changes of[Ca2+]i in different treated cardiomyoctyes overexpression with Gal-1 or not;Fetal genes were detected after overexpression Gal-1 plasmid or not in ISO induced hypertrophic primary cardiomyocytes or control group by real-time PCR;Cell surface area were measured after overexpression Gal-1 plasimd or not in ISO induced primary cardiomyocytes or control group by immunofluorescence;KN93,H89 and ISO were used to find the impact of Gal-1 in CaMKII-HDAC4 signaling pathway.ResultWe found that 1)Gal-1 was increased in cardiac hypertrophy progress,it was correlated with exon 9*upregulating;2)Gal can reduce the calcium current both in Cav1.2CM?9*expressed HEK293 cells and in neonatal rat ventricular myocytes,it can also diminish the elevation in cardiomyocytes.Moreover.3)overexpression of Gal-1 could decrease the ISO or LTCC agonist Bay K8644-induced phosphorylation of?CaMKII and HDAC4 to attributed to the pathological process of cardiac hypertrophy.ConclusionOur study demonstrated that Gal-1 reduced the ICa,L via binding to ?-? loop of Cavl.2 without exon 9*,which otherwise decreases[Ca2+]i of cardiomyocytes,in turn,downregulating ?CaMKII-HDAC4 signaling in the heart,with concomitant decrease in fetal genes' transcription and attenuation of cardiac hypertrophy.More importantly,the increased expression of Gal-1 in hypertrophic heart suggests a compensatory mechanism against cardiac hypertrophic remodeling.