A novel C53/LZAP-interacting protein regulates stability of C53/LZAP and DDRGK domain-containing Protein 1 (DDRGK1) and modulates NF-kappaB signaling.
C53/LZAP (also named as Cdk5rap3) is a putative tumor suppressor that plays important roles in multiple cell signaling pathways, including DNA damage response and NF-kappaB signaling. Yet how its function is regulated remains largely unclear. Here we report the isolation and characterization of two novel C53/LZAP-interacting proteins, RCAD (Regulator of C53/LZAP and DDRGK1) and DDRGK1 (DDRGK domain-containing protein 1). Our co-immunoprecipitation assays confirmed their interactions, while gel filtration assay indicated that C53/LZAP and RCAD may form a large protein complex. Intriguingly, we found that RCAD knockdown led to dramatic reduction of C53/LZAP and DDRGK1 proteins. We also found that C53/LZAP and DDRGK1 became more susceptible to the proteasome-mediated degradation in RCAD knockdown cells, whereas their ubiquitination was significantly attenuated by RCAD overexpression. In addition, we found that RCAD, like C53/LZAP, also plays an important role in regulation of NF-kappaB signaling and cell invasion. Taken together, our findings strongly suggest that RCAD is a novel regulator of C53/LZAP tumor suppressor and NF-kappaB signaling.
Children's Memorial Research Center, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60614.
Jianchun
J
Wu
Children's Memorial Research Center, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60614.
Guohua
G
Lei
Children's Memorial Research Center, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60614.
Mei
M
Mei
Children's Memorial Research Center, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60614.
Yi
Y
Tang
Children's Memorial Research Center, Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60614. Electronic address: h-li2@northwestern.edu.
Honglin
H
Li
D001483:Base Sequence; D015152:Blotting, Northern; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002850:Chromatography, Gel; D017931:DNA Primers; D055785:Gene Knockdown Techniques; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008854:Microscopy, Electron; D016328:NF-kappa B / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000502:physiology*; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D025521:Tumor Suppressor Proteins
C405928:CDK5RAP3 protein, human; D018797:Cell Cycle Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D025521:Tumor Suppressor Proteins