OSBP-related protein 8 (ORP8) interacts with Homo sapiens sperm associated antigen 5 (SPAG5) and mediates oxysterol interference of HepG2 cell cycle

详细信息    查看全文

• 作者：Wenbin Zhong^a ; You Zhou^b ; Jiwei Li^a ; Raghavendra Mysore^b ; Wei Luo^a ; Shiqian Li^a ; Mau-Sun Chang^c ; Vesa M. Olkkonen^b ; Daoguang Yan^a ; ^{tydg@jnu.edu.cn" class="auth_mail}
• 关键词：Astrin ; Cell cycle ; 25-Hydroxycholesterol ; ORP8 ; Oxysterol-binding protein ; SPAG5
• 刊名：Experimental Cell Research
• 出版年：1 April, 2014
• 年：2014
• 卷：322
• 期：2
• 页码：227-235
• 全文大小：3354 K

文摘

We earlier identified OSBP-related protein 8 (ORP8) as an endoplasmic reticulum/nuclear envelope oxysterol-binding protein implicated in cellular lipid homeostasis, migration, and organization of the microtubule cytoskeleton. Here, a yeast two-hybrid screen identified Homo sapiens sperm associated antigen 5 (SPAG5)/Astrin as interaction partner of ORP8. The putative interaction was further confirmed by pull-down and co-immunoprecipitation assays. ORP8 did not colocalize with kinetochore-associated SPAG5 in mitotic HepG2 or HuH7 cells, but overexpressed ORP8 was capable of recruiting SPAG5 onto endoplasmic reticulum membranes in interphase cells. In our experiments, 25-hydroxycholesterol (25OHC) retarded the HepG2 cell cycle, causing accumulation in G2/M phase; ORP8 overexpression resulted in the same phenotype. Importantly, ORP8 knock-down dramatically inhibited the oxysterol effect on HepG2 cell cycle, suggesting a mediating role of ORP8. Furthermore, knock-down of SPAG5 significantly reduced the effects of both ORP8 overexpression and 25OHC on the cell cycle, placing SPAG5 downstream of the two cell-cycle interfering factors. Taken together, the present results suggest that ORP8 may via SPAG5 mediate oxysterol interference of the HepG2 cell cycle.