کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2131997 | 1086668 | 2007 | 12 صفحه PDF | دانلود رایگان |
Oxysterol-binding protein (OSBP) and OSBP-related protein 4 (ORP4; also designated OSBP2 and HLM) are implicated in sterol-transport and/or sensing via binding to protein partners. The aggregation of vimentin by an N-terminal-truncated variant of ORP4 (ORP4S), but not full-length ORP4L, suggested a functional interaction with this intermediate filament. Herein, we identify ORP4 domains that interact with vimentin, and determine how sterols and OSBP influence this activity. In CHO cells, ORP4L co-localized with filamentous vimentin but extensive remodeling of vimentin filaments required mutation of a leucine repeat motif (amino acids 361–382) adjacent to the oxysterol-binding domain. Similarly, the absence of the leucine repeat in ORP4S 418–878 resulted in co-localization with aggregated vimentin filaments, suggesting that both the sterol-binding domain and leucine repeat are involved. Transient expression of OSBP leucine repeat mutants also promoted vimentin aggregation by a mechanism involving heterodimerization with ORP4L. Glutathione S-transferase (GST)–ORP4 380–878 bound vimentin, cholesterol and 25-hydroxycholesterol in vitro. However, sterol-binding or a mutation that ablated sterol-binding did not influence the interaction of GST–ORP4 with vimentin. Thus the sterol-binding domain of ORP4 binds vimentin, cholesterol and oxysterols, and interacts with the filamentous vimentin network.
Journal: Experimental Cell Research - Volume 313, Issue 7, 15 April 2007, Pages 1426–1437