p600, a unique protein required for membrane morphogenesis and cell survival

doi:10.1073/pnas.0507458102

p600, a unique protein required for membrane morphogenesis and cell survival

^*Dana–Farber Cancer Institute, Harvard Medical School, Boston, MA 02115; ^§National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892; and ^‡‡Departments of Biochemistry of Cell Biology, Baylor College of Medicine, Houston, TX 77030

Communicated by C. David Allis, The Rockefeller University, New York, NY, August 26, 2005 (received for review July 20, 2005)

Abstract

In this article, we identify and characterize p600, a unique 600-kDa retinoblastoma protein- and calmodulin-binding protein. In the nucleus, p600 and retinoblastoma protein seem to act as a chromatin scaffold. In the cytoplasm, p600 and clathrin form a meshwork structure, which could contribute to cytoskeletal organization and membrane morphogenesis. Reduced expression of p600 with interference RNA abrogates integrin-mediated ruffled membrane formation and, furthermore, prevents activation of integrin-mediated survival pathways. Consequently, knockdown of p600 sensitizes cells to apoptosis induced by cell detachment. These findings provide mechanistic insight into the regulation of membrane-proximal events in tumorigenesis.

Footnotes

↵ † To whom correspondence should be addressed. E-mail: nakatani{at}mac.com.
↵ ‡ Present address: Institute of Enzyme Research, University of Tokushima, Tokushima 770-8503, Japan.
↵ ¶ Present address: School of Medicine, University of Fukui, Matsuoka, Fukui 910-1193, Japan.
↵ ∥ Present address: Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan.
↵ ** Present address: Graduate School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
↵ †† Present address: Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8575, Japan.
Author contributions: Y.N. and S.J.K. designed research; Y.N., H. Konishi, A.V., H. Kurooka, K.I., J.-i.S., T.I., J.Q., and A.M.H. performed research; and Y.N. wrote the paper.
Abbreviations: HPV, human papilloma virus; RB, retinoblastoma protein; e-RB, FLAG-epitope-tagged RB; shRNA, short hairpin RNA; FAK, focal adhesion kinase; IP3R, inositol 1,4,5-trisphosphate receptor; BPV, bovine papilloma virus.
Data deposition: The sequence reported in this paper has been deposited in the GenBank database (accession no. AF348492).
Freely available online through the PNAS open access option.