TY - JOUR
T1 - Hypoxia induces autophagy in primary human trophoblasts
AU - Chen, Baosheng
AU - Longtine, Mark S.
AU - Nelson, D. Michael
PY - 2012/10/1
Y1 - 2012/10/1
N2 - Autophagy is a highly regulated and dynamic process that maintains cellular homeostasis and plays a prosurvival role in most cells. Although hypoxia has been shown to induce apoptosis in placental trophoblasts, the hypoxic effect on autophagy has not been studied. We hypothesized that autophagy plays a prosurvival role in the placental trophoblasts by antagonizing hypoxia-induced apoptosis. Our data show that the expression of Light chain 3-II (LC3-II), an autophagic marker and cleaved poly(ADP-ribose) polymerase, an apoptosis marker, are inversely related in cultured trophoblasts. Exposure to rapamycin or hypoxia inactivated mammalian target of rapamycin, as reflected by reduced phosphorylation of ribosomal protein S6, indicating that mammalian target of rapamycin regulates autophagy in cultured cytotrophoblasts. Bafilomycin prevented the degradation of cargo and increased LC3-II and p62 in cytotrophoblasts exposed to hypoxia, revealing enhanced autophagic flux. Importantly, bafilomycin enhanced expression of autophagy-related protein 7 (Atg7), parallel to the increased apoptosis measured by cleaved poly(ADP-ribose) polymerase. LY294002, a phosphatidylinositol 3-kinase inhibitor, increased apoptosis in the trophoblasts under hypoxia or standard conditions. Silencing of Atg7 decreased both apoptosis and LC3-II in the trophoblasts, suggesting a dual role of Atg7 in both autophagy and apoptosis. We conclude that there is a cross talk between autophagy and apoptosis in the placental trophoblasts; autophagy plays a prosurvival role and Atg7 has roles in both autophagy and apoptosis under hypoxia.
AB - Autophagy is a highly regulated and dynamic process that maintains cellular homeostasis and plays a prosurvival role in most cells. Although hypoxia has been shown to induce apoptosis in placental trophoblasts, the hypoxic effect on autophagy has not been studied. We hypothesized that autophagy plays a prosurvival role in the placental trophoblasts by antagonizing hypoxia-induced apoptosis. Our data show that the expression of Light chain 3-II (LC3-II), an autophagic marker and cleaved poly(ADP-ribose) polymerase, an apoptosis marker, are inversely related in cultured trophoblasts. Exposure to rapamycin or hypoxia inactivated mammalian target of rapamycin, as reflected by reduced phosphorylation of ribosomal protein S6, indicating that mammalian target of rapamycin regulates autophagy in cultured cytotrophoblasts. Bafilomycin prevented the degradation of cargo and increased LC3-II and p62 in cytotrophoblasts exposed to hypoxia, revealing enhanced autophagic flux. Importantly, bafilomycin enhanced expression of autophagy-related protein 7 (Atg7), parallel to the increased apoptosis measured by cleaved poly(ADP-ribose) polymerase. LY294002, a phosphatidylinositol 3-kinase inhibitor, increased apoptosis in the trophoblasts under hypoxia or standard conditions. Silencing of Atg7 decreased both apoptosis and LC3-II in the trophoblasts, suggesting a dual role of Atg7 in both autophagy and apoptosis. We conclude that there is a cross talk between autophagy and apoptosis in the placental trophoblasts; autophagy plays a prosurvival role and Atg7 has roles in both autophagy and apoptosis under hypoxia.
UR - http://www.scopus.com/inward/record.url?scp=84866753804&partnerID=8YFLogxK
U2 - 10.1210/en.2012-1472
DO - 10.1210/en.2012-1472
M3 - Article
C2 - 22878401
AN - SCOPUS:84866753804
SN - 0013-7227
VL - 153
SP - 4946
EP - 4954
JO - Endocrinology
JF - Endocrinology
IS - 10
ER -