An extracellular matrix, calmodulin-binding protein from Dictyostelium with EGF-like repeats that enhance cell motility |
| |
Authors: | Suarez Andres Huber Robert J Myre Michael A O'Day Danton H |
| |
Affiliation: | a Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, Canadab Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canadac Molecular Neurogenetics Unit, Center for Human Genetic Research, Massachusetts General Hospital, Boston, MA, USA |
| |
Abstract: | CyrA is a novel cysteine-rich protein with four EGFL repeats that was isolated using the calmodulin (CaM) binding overlay technique (CaMBOT), suggesting it is a CaM-binding protein (CaMBP). The full-length 63 kDa cyrA is cleaved into two major C-terminal fragments, cyrA-C45 and cyrA-C40. A putative CaM-binding domain was detected and both CaM-agarose binding and CaM immunoprecipitation verified that cyrA-C45 and cyrA-C40 each bind to CaM in both a Ca2+-dependent and -independent manner. cyrA-C45 was present continuously throughout growth and development but was secreted at high levels during the multicellular slug stage of Dictyostelium development. At this time, cyrA localizes to the extracellular matrix (ECM). ECM purification verified the presence of cyrA-C45. An 18 amino acid peptide (DdEGFL1) from the first EGFL repeat sequence of cyrA (EGFL1) that is present in both cyrA-C45 and -C40 enhances both random cell motility and cAMP-mediated chemotaxis. Here we reveal that the dose-dependent enhancement of motility by DdEGFL1 is related to the time of cell starvation. Addition of DdEGFL1 also inhibits cyrA proteolysis. The status of cyrA as an extracellular CaMBP was further clarified by the demonstration that CaM is secreted during development. Antagonism of CaM with W7 resulted in enhanced cyrA proteolysis suggesting a functional role for extracellular CaM in protecting CaMBPs from proteolysis. cyrA is the first extracellular CaMBP identified in Dictyostelium and since it is an ECM protein with EGF-like repeats that enhance cell motility and it likely also represents the first matricellular protein identified in a lower eukaryote. |
| |
Keywords: | CaM, calmodulin CaMBOT, calmodulin overlay technique CaMBP, calmodulin-binding protein DdCaM, Dictyostelium calmodulin ECM, extracellular matrix EGF, epidermal growth factor EGFL, epidermal growth factor-like EGFR, epidermal growth factor-receptor kDa, kiloDalton PEST, proline, glutamate, serine, threonine-rich SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis Ten14, 14th epidermal growth factor-like repeat of tenascin C |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|