RESUMEN
Human pluripotent stem cell-derived cardiomyocytes have potential applications in disease modeling and drug screening. Therefore, it is important to understand the mechanisms and signaling pathways underlying the survival and death of these cells. Endoplasmic reticulum (ER) stress is triggered by various cellular stresses that disturb protein folding in the ER. Cells cope with ER stress by activating the unfolded protein response (UPR), a homeostatic signaling network that orchestrates the recovery of ER function. In the present study, we hypothesized that ER stress may upregulate the expression of transient receptor potential channel TRPV6, which in turn serves to protect human embryonic stem cell-derived cardiomyocytes (hESC-CMs) from ER stress-induced apoptotic cell death. Indeed, we found that ER stress induced by thapsigargin and tunicamycin led to increased expression of TRPV6 via ATF6α signaling branch. siRNA-mediated knockdown of TRPV6 aggravated ER stress-induced apoptotic cell death, whereas overexpression of TRPV6 attenuated ER stress-induced apoptosis in hESC-CMs. Furthermore, the signaling pathway downstream of TRPV6 was MAPK-JNK. Taken together, these results provide strong evidence that, under ER stress, TRPV6 is upregulated to protect hESC-CMs from apoptotic cell death via ATF6α-TRPV6-JNK pathway.
Asunto(s)
Factor de Transcripción Activador 6/metabolismo , Apoptosis/fisiología , Canales de Calcio/genética , Canales de Calcio/metabolismo , Estrés del Retículo Endoplásmico/fisiología , Células Madre Embrionarias Humanas/metabolismo , Miocitos Cardíacos/metabolismo , Canales Catiónicos TRPV/genética , Canales Catiónicos TRPV/metabolismo , Análisis de Varianza , Calcio/metabolismo , Línea Celular , Técnicas de Silenciamiento del Gen , Vectores Genéticos , Humanos , Sistema de Señalización de MAP Quinasas , Pliegue de Proteína , ARN Interferente Pequeño , Transducción de Señal , Respuesta de Proteína DesplegadaRESUMEN
Dilated cardiomyopathy (DCM) is cardiac disease characterized by increased left ventricular chamber volume and decreased systolic function. DCM patient-specific human induced-pluripotent stem cells-derived cardiomyocytes (DCM-hiPSC-CMs) were generated. We found that uniaxial stretch elicited a cytosolic [Ca2+]i rise in hiPSC-CMs. Compared to control-hiPSC-CMs, DCM-hiPSC-CMs displayed a greater magnitude of [Ca2+]i responses to the cell stretch of 10-15% elongation in length. This stretch-induced [Ca2+]i rise was abolished by removal of extracellular Ca2+ and markedly attenuated by TRPV4 inhibitors HC-067047 and RN-1734. Application of nifedipine and tranilast also reduced the [Ca2+]i response but to a lesser degree. Moreover, the augmented [Ca2+]i was decreased by cytochalasin D treatment. Taken together, our study for the first time demonstrated an abnormal TRPV4-related mechanosensitive Ca2+ signaling in DCM-hiPSC-CMs.
