环状RNA circSLC8A1_021通过结合miR-144-3p发挥抑制心肌细胞肥大作用OA

AIM:To elucidate the mechanism by which circular RNA solutecarrier family 8 member A1(circ-SLC8A1_021)regulates cardiac hypertrophy.METHODS:RT-qPCR was used to measure the expression of circ-SLC8A1_021 and its host gene in myocardial tissue samples from healthy human donors(n=20)and patients with heart failure(n=20),as well as the expression of circSLC8A1_021 in neonatal mouse ventricular cardiomyocytes(NMVCs)treated with angiotensin II(Ang II)to induce hypertrophy.Subcellular fractionation was performed to determine the nucle-ar and cytoplasmic distribution of circSLC8A1_021,and actinomycin D(ActD)treatment was used to assess its stability.CircSLC8A1_021 was overexpressed in Ang II-treated NMVCs using an adenoviral vector.Western blot was used to evalu-ate the expression of hypertrophy-associated proteins,including β-myosin heavy chain,actin alpha 1 and atrial natriuretic peptide,and phalloidin staining was performed to assess cardiomyocyte surface area.A mouse model of cardiac hypertro-phy was established by transverse aortic constriction.After tail-vein injection of an adeno-associated virus serotype 9 vec-tor encoding circSLC8A1_021,hypertrophy-related protein expression,cardiomyocyte area determined by wheat germ ag-glutinin staining,and left ventricular systolic function assessed by echocardiography were evaluated.RNA immunoprecipi-tation(RIP)was performed to identify candidate molecules associated with circSLC8A1_021.Western blot and phalloidin staining were further used to determine whether microRNA-144-3p(miR-144-3p)mediates the antihypertrophic effect of circSLC8A1_021 in an Argonaute RISC catalytic component 2(AGO2)-dependent manner.RESULTS:The expression levels of circSLC8A1_021 and its host gene were significantly increased in myocardial tissues from patients with heart fail-ure,and circSLC8A1_021 expression was also increased in Ang II-stimulated NMVCs(P<0.05).CircSLC8A1_021 was predominantly localized to the cytoplasm of the human cardiomyocyte cell line AC16 and was significantly more stable than its linear transcript,SLC8A1(P<0.01).Functional experiments showed that circSLC8A1_021 overexpression suppressed the expression of hypertrophy-associated proteins(P<0.01)and attenuated the increase in cell surface area(P<0.01)in Ang II-induced NMVCs.In vivo,circSLC8A1_021 overexpression attenuated TAC-induced cardiac hypertrophy and im-proved left ventricular systolic function.RIP demonstrated an association between circSLC8A1_021 and miR-144-3p.Moreover,Western blot and phalloidin staining showed that miR-144-3p reversed the inhibitory effect of circSLC8A1_021 on the Ang II-induced hypertrophic phenotype(P<0.01).After Ago2 knockdown in NMVCs,circSLC8A1_021 could no longer effectively suppress the upregulation of hypertrophy-related proteins(P<0.01)or reduce cardiomyocyte surface ar-ea(P<0.05).CONCLUSION:circSLC8A1_021 inhibits cardiac hypertrophy by interacting with miR-144-3p in an AGO2-dependent manner.