UV-damaged DNA-binding proteins are targets of CUL-4A-mediated ubiquitination and degradation. Academic Article uri icon

Overview

abstract

  • Cul-4A, which encodes a member of the cullin family subunit of ubiquitin-protein ligases, is expressed at abnormally high levels in many tumor cells. CUL-4A can physically associate with the damaged DNA-binding protein (DDB), which is composed of two subunits, p125 and p48. DDB binds specifically to UV-damaged DNA and is believed to play a role in DNA repair. We report here that CUL-4A stimulates degradation of p48 through the ubiquitin-proteasome pathway, resulting in an overall decrease in UV-damaged DNA binding activity. The R273H mutant of p48 identified from a xeroderma pigmentosium (group E) patient is not subjected to CUL-4A-mediated proteolysis, consistent with its inability to bind CUL-4A. p125 is also an unstable protein, and its ubiquitination is stimulated by CUL-4A. However, the abundance of p125 is not dramatically altered by Cul-4A overexpression. UV irradiation inhibits p125 degradation, which is temporally coupled to the UV-induced translocation of p125 from the cytoplasm into the nucleus. CUL-4A is localized primarily in the cytoplasm. These findings identify DDB subunits as the first substrates of the CUL-4A ubiquitination machinery and suggest that abnormal expression of Cul-4A results in reduced p48 levels, thus impairing the ability of DDB in lesion recognition and DNA repair in tumor cells.

publication date

  • October 22, 2001

Research

keywords

  • Cullin Proteins
  • DNA-Binding Proteins
  • Neoplasm Proteins
  • Ubiquitin
  • Ultraviolet Rays

Identity

Scopus Document Identifier

  • 0035930582

Digital Object Identifier (DOI)

  • 10.1074/jbc.M106808200

PubMed ID

  • 11673459

Additional Document Info

volume

  • 276

issue

  • 51