Hyaluronan- and RNA-binding deubiquitinating enzymes of USP17 family members associated with cell viability.
BACKGROUND
Protein degradation by the ubiquitin system plays a crucial role in numerous cellular signaling pathways. Deubiquitination, a reversal of ubiquitination, has been recognized as an important regulatory step in the ubiquitin-dependent degradation pathway.


RESULTS
While identifying putative ubiquitin specific protease (USP) enzymes that contain a conserved Asp (I) domain in humans, 4 USP17 subfamily members, highly homologous to DUB-3, have been found (USP17K, USP17L, USP17M, and USP17N), from human chorionic villi. Expression analysis showed that USP17 transcripts are highly expressed in the heart, liver, and pancreas and are expressed moderately in various human cancerous cell lines. Amino acid sequence analysis revealed that they contain the highly conserved Cys, His, and Asp domains which are responsible for the deubiquitinating activity. Biochemical enzyme assays indicated that they have deubiquitinating activity. Interestingly, the sequence analysis showed that these proteins, with exception of USP17N, contain the putative hyaluronan/RNA binding motifs, and cetylpyridinium chloride (CPC)-precipitation analysis confirmed the association between these proteins and intracellular hyaluronan and RNA.


CONCLUSIONS
Here, we report that the overexpression of these proteins, with exception of USP17N, leads to apoptosis, suggesting that the hyaluronan and RNA binding motifs in these enzymes play an important role in regulating signal transduction involved in cell death.
Shin
Ju-Mi
JM
Graduate School of Life Science and Biotechnology, Cell and Gene Therapy Research Institute, Pochon CHA University, CHA General Hospital, Seoul 135-081, Korea. ju-mis@hanmail.net <ju-mis@hanmail.net>
Yoo
Kyong-Jai
KJ
Kim
Myung-Sun
MS
Kim
Dongku
D
Baek
Kwang-Hyun
KH
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000235:genetics; D015152:Blotting, Northern; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics; D002824:Chorionic Villi / Q000378:metabolism*; D003001:Cloning, Molecular; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D015870:Gene Expression / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D006820:Hyaluronic Acid / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D012313:RNA / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D064570:Ubiquitin-Specific Proteases; D014452:Ubiquitins / Q000378:metabolism
D014452:Ubiquitins; D012313:RNA; D006820:Hyaluronic Acid; D010450:Endopeptidases; D064570:Ubiquitin-Specific Proteases