CyrA, a matricellular protein that modulates cell motility in Dictyostelium discoideum

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• 作者：Robert J. Huber^a ; ^{robert.huber@utoronto.ca} ; Andres Suarez^b ; ^{andres.suarez@utoronto.ca} ; Danton H. O'Day^a ; ^b ; ^{danton.oday@utoronto.ca}
• 关键词：CaM ; Calmodulin ; CaMBP ; CaM-binding protein ; CaMBD ; CaM-binding domain ; CaMBOT ; CaM-binding overlay technique ; EGFL ; Epidermal growth factor-like ; EGFR ; EGF receptor ; ECM ; Extracellular matrix ; Ten14 ; 14th EGFL repeat of tenascin C ; MMP2 ; Matrix metallopr
• 刊名：Matrix Biology
• 出版年：2012
• 出版时间：May, 2012
• 年：2012
• 卷：31
• 期：4
• 页码：271-280
• 全文大小：914 K

文摘

CyrA, an extracellular matrix (slime sheath), calmodulin (CaM)-binding protein in Dictyostelium discoideum, possesses four tandem EGF-like repeats in its C-terminus and is proteolytically cleaved during asexual development. A previous study reported the expression and localization of CyrA cleavage products CyrA-C45 and CyrA-C40. In this study, an N-terminal antibody was produced that detected the full-length 63 kDa protein (CyrA-C63). Western blot analyses showed that the intracellular expression of CyrA-C63 peaked between 12 and 16 h of development, consistent with the time that cells are developing into a motile, multicellular slug. CyrA immunolocalization and CyrA-GFP showed that the protein localized to the endoplasmic reticulum, particularly its perinuclear component. CyrA-C63 secretion began shortly after the onset of starvation peaking between 8 and 16 h of development. A pharmacological analysis showed that CyrA-C63 secretion was dependent on intracellular Ca²⁺ release and active CaM, PI3K, and PLA2. CyrA-C63 bound to CaM both intra- and extracellularly and both proteins were detected in the slime sheath deposited by migrating slugs. In keeping with its purported function, CyrA-GFP over-expression enhanced cAMP-mediated chemotaxis and CyrA-C45 was detected in vinculin B (VinB)-GFP immunoprecipitates, thus providing a link between the increase in chemotaxis and a specific cytoskeletal component. Finally, DdEGFL1-FITC was detected on the membranes of cells capped with concanavalin A suggesting that a receptor exists for this peptide sequence. Together with previous studies, the data presented here suggests that CyrA is a bona fide matricellular protein in D. discoideum.