Submitted on July 23, 2002
Accepted on July 25, 2003
VACM-1, a cul 5 gene, inhibits cellular growth by a mechanism that involves MAPK and p53 signaling pathways
Christa Van Dort1, Ping Zhao2, Katarina Parmelee1, Brian Capps1, Amy Poel1, Laura Listenberger1, Jennifer Kossoris1, Betsy Wasilevich1, Doug Murrey1, Paula Clare3, and Maria Burnatowska-Hledin1*
1 Biology and Chemistry, Hope College, Holland, MI, USA
2 Van Andel Research Institute, Grand Rapids, MI, USA
3 Pfizer, Kalamazoo, MI, USA
* To whom correspondence should be addressed. E-mail: hledin{at}hope.edu.
VACM-1 gene product is a 780 amino acid membrane protein that shares sequence homology with cullins, a family of genes involved in the regulation of cell cycle. However, when expressed in vitro, VACM-1 attenuates basal, vasopressin, and forskolin induced cAMP production. Mutating the PKA-dependent phosphorylation site in the VACM-1 sequence (S730AVACM-1) prevents this inhibitory effect. To further examine the biological role of VACM-1, we studied the effect of VACM-1 and S730AVACM-1 proteins on cellular proliferation and on gene expression in CHO and in cos 1 cells. Cellular proliferation of VACM-1 expressing cell lines was significantly lower when compared to the vector transfected cells, whereas it was significantly increased in S730AVACM 1 derived lines. Further, expression of VACM-1 but not S730AVACM 1 protein retarded cytokinesis and prevented MAPK phosphorylation. Screening of Human PathwayFinder-1 GEArrayTM system and subsequent Western blot analysis demonstrated that VACM-1 induces p53 mRNA and protein expression. In summary, VACM-1 inhibits cellular growth by a mechanism that involves cAMP, MAPK phosphorylation, and p53 expression.
