Inactivation of the Retinoblastoma Protein Family Can Bypass the HCF-1 Defect in tsBN67 Cell Proliferation and Cytokinesis

Abstract

Owing to a single missense mutation in the cell proliferation factor HCF-1, the temperature-sensitive tsBN67 hamster cell line arrests proliferation at nonpermissive temperatures, primarily in a G₀/G₁ state, and displays temperature-sensitive cytokinesis defects. The HCF-1 mutation in tsBN67 cells also causes a temperature-sensitive dissociation of HCF-1 from chromatin prior to cell proliferation arrest, suggesting that HCF-1-chromatin association is important for mammalian-cell proliferation. Here, we report that the simian virus 40 (SV40) early region, in particular, large T antigen (Tag), and the adenovirus oncoprotein E1A can rescue the tsBN67 cell proliferation defect at nonpermissive temperatures. The SV40 early region rescues the tsBN67 cell proliferation defect without restoring the HCF-1-chromatin association, indicating that these oncoproteins bypass a requirement for HCF-1 function. The SV40 early region also rescues the tsBN67 cytokinesis defect, suggesting that the roles of HCF-1 in cell proliferation and proper cytokinesis are intimately linked. The ability of SV40 Tag and adenovirus E1A to inactivate members of the pRb protein family—pRb, p107, and p130—is important for the bypass of HCF-1 function. These results suggest that HCF-1 regulates mammalian-cell proliferation and cytokinesis, at least in part, by either directly or indirectly opposing pRb family member function.

We thank Takeharu Nishimoto for providing the tsBN67 cell line; Eric Julien for his help with the tsBN67 _SV40e nucleation experiment; Paula Sacco-Bubulya, Andrew Samuelson, and James Pipas for providing plasmids; Richard Freiman, J. Peter Gergen, Patrick Hearing, Nouria Hernandez, Scott Lowe, Ute Moll, and William Tansey for helpful discussions; Deborah Aufiero, Martha Daddario, and Regina Whitaker for technical support; Eric Julien and Nouria Hernandez for critical readings of the manuscript; and Bruce Stillman for encouragement and support.

These studies were supported by PHS grants GM54598 and CA13106.