AprA: An autocrine, secreted factor that represses cell proliferation in Dictyostelium discoideum
Choe, Jonathan Myongwoo
Master of Arts
Dictyostelium cells secrete factors during growth and starvation. AprA (autocrine proliferation repressor), a 60 kDa protein secreted as part of a 150 kDa protein complex, functions as a cell proliferation repressor. In the present study, we expressed recombinant AprA (rAprA) in bacteria. We found that rAprA is bioactive as a proliferation repressor and that rAprA binds to live Dictyostelium cells. rAprA, when added to the growth medium of wild-type and aprA - cells, slows the proliferation of these cells; however, rAprA does not slow the proliferation of crlA - or cfaD - cells. CrlA is a putative receptor, and CfaD is a protein secreted by cells. These findings indicated that rAprA needs CrlA and CfaD to act as a proliferation repressor. However, cells lacking CrlA bound rAprA with high affinity, suggesting that CrlA may not be the receptor for AprA. Thus, AprA binds to cell surface receptors in a signal transduction pathway that involves CrlA and CfaD to negatively regulate cell proliferation.
Biochemistry; Pure sciences