Mule/ARF-BP1, a BH3-only E3 ubiquitin ligase, catalyzes the polyubiquitination of Mcl-1 and regulates apoptosis.
The elimination of Mcl-1, an anti-apoptotic Bcl-2 family member, is an early and required step for DNA damage-induced apoptosis. The degradation of Mcl-1 can be blocked by proteasome inhibitors, suggesting a role for the ubiquitin proteasome pathway in apoptosis. Here, we demonstrate that Mcl-1 is ubiquinated at five lysines. Biochemical fractionation of cell extracts allowed us to identify a 482 kDa HECT-domain-containing ubiquitin ligase named Mule (Mcl-1 ubiquitin ligase E3) that is both required and sufficient for the polyubiquitination of Mcl-1. Mule also contains a region similar to the Bcl-2 homology region 3 (BH3) domain that allows Mule to specifically interact with Mcl-1. Elimination of Mule expression by RNA interference stabilizes Mcl-1 protein, resulting in an attenuation of the apoptosis induced by DNA-damage agents. Thus, Mule is a unique BH3-containing E3 ubiquitin ligase apical to Bcl-2 family proteins during DNA damage-induced apoptosis.
Howard Hughes Medical Institute and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, 75390, USA.
Qing
Q
Zhong
Wenhua
W
Gao
Fenghe
F
Du
Xiaodong
X
Wang
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020134:Catalytic Domain / Q000502:physiology; D004249:DNA Damage / Q000502:physiology; D006801:Humans; D008969:Molecular Sequence Data; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D034622:RNA Interference; D020871:RNA Stability / Q000502:physiology; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; C502830:HUWE1 protein, human; D044767:Ubiquitin-Protein Ligases