TIM   To investigate the effect of HSP110 expression regulated by ATF3 on the proliferation and autophagy of human pulmonary artery smooth muscle cells stimulated by hypoxia.

  METHODS   Human pulmonary artery smooth muscle cells were cultured in vitro and infected with ATF3 silencing adenovirus alone or co-infected with HSP110 over-expressing adenovirus. After 48 h, the autophagy activator rapamycin was added and pretreated for 3 h, and then the hypoxic cell model was established. After 24 h, CCK-8 assay was used to detect the proliferation ability of the cells and cell apoptosis was analyzed by flow cytometry. Real-time PCR was used to detect the mRNA expression of ATF3 and HSP110 and Western blot was used to detect the protein expression of ATF3, HSP110, LC3Ⅱ/Ⅰ, Beclin-1 and p62. The formation of LC3 puncta was observed by immunofluorescence and the regulatory effect of ATF3 on HSP110 was identified by luciferase reporting system.

  RESULTS   The expressions of ATF3 and HSP110 were significantly increased in hypoxia group (P<0.01), the proliferation ability of cells was decreased and the apoptosis rate was increased after ATF3 silencing (P<0.01). Meanwhile, the expressions of autophagy protein LC3 Ⅱ/Ⅰ, Beclin-1 and LC3 puncta were significantly decreased (P<0.01), and theexpression of autophagy degradation substrate p62 was significantly increased(P<0.01). However, after addition of rapamycin or co-infection with HSP110 over-expressing adenovirus, the inhibition of cell proliferation and autophagy by ATF3 silencing was significantly reduced (P<0.01).

  CONCLUSION   ATF3 up-regulates the expression of HSP110 and promotes the proliferation of human pulmonary artery smooth muscle cells, and the mechanism may be related to autophagy.