Molecular and Cellular Biochemistry

, Volume 288, Issue 1, pp 79–90

Host Cell Factor-1 and E2F4 Interact Via Multiple Determinants in Each Protein

Authors

  • Jozo Knez
    • Department of Biochemistry and Biomedical Sciences, McMaster University Medical CenterMcMaster University
  • David Piluso
    • Department of Biochemistry and Biomedical Sciences, McMaster University Medical CenterMcMaster University
  • Patricia Bilan
    • Department of Biochemistry and Biomedical Sciences, McMaster University Medical CenterMcMaster University
    • Department of Biochemistry and Biomedical Sciences, McMaster University Medical CenterMcMaster University
    • General Sciences Building (GSB)
Article

DOI: 10.1007/s11010-006-9122-x

Cite this article as:
Knez, J., Piluso, D., Bilan, P. et al. Mol Cell Biochem (2006) 288: 79. doi:10.1007/s11010-006-9122-x

Abstract

Host Cell Factor (HCF-1) is a conserved, essential protein initially identified as a co-regulator for the Herpes Simplex Virus transactivator VP16. HCF-1 is variously involved in regulating transcription, splicing, cell proliferation and cytokinesis; however, its mechanisms of action remain unknown. HCF-1 function is manifested through an increasing assortment of cellular factors that target different regions of the protein. Several HCF-1 partners target the amino-terminal kelch domain of HCF-1 (residues 1–380) via a consensus HCF-binding motif (HBM) comprising the tetrapeptide (D/E)HXY. Searches of sequence databases indicated that this motif is present in E2F1 and E2F4, two members of the E2F family of cell cycle regulators. We show here that E2F4 specifically and directly interacts with HCF-1. Mutational analysis showed E2F4 independently targets the kelch domain and the basic domain (residues 450–902) of HCF-1, both of which are required for normal cell-cycle progression via separate determinants. The HBM-containing domain of E2F4 was necessary for interaction with the kelch domain of HCF-1 but not for interaction with the basic domain. Mutations in the HCF-1 kelch domain known to block cell growth abrogated E2F4 binding to the kelch domain in the absence but not in the presence of the juxtaposed basic region. Functionally, HCF-1 co-activated E2F4/DP-1 in transient transfection assays, while E2F4 blocked HCF-1-dependent rescue of a cell line that harbors a temperature sensitive mutant of HCF-1 that causes growth arrest. Our findings show that HCF-1 and E2F4 interact via multiple determinants and suggest a linkage between E2F4 and HCF-1 cell growth pathways.

Keywords

HCF-1HCF-1 binding motif (HBM)E2F4transcriptional co-regulator

Abbreviations

HCF-1

Host Cell Factor 1

HBM

HCF-1 binding motif

AAD

acidic activation domain

HA

haemagglutinin

Rb

retinoblastoma

wt

wild-type

Copyright information

© Springer Science+Business Media, Inc. 2006