A novel human BTB-kelch protein KLHL31, strongly expressed in muscle and heart, inhibits transcriptional activities of TRE and SRE.
The Bric-a-brac, Tramtrack, Broad-complex (BTB) domain is a protein-protein interaction domain that is found in many zinc finger transcription factors. BTB containing proteins play important roles in a variety of cellular functions including regulation of transcription, regulation of the cytoskeleton, protein ubiquitination, angiogenesis, and apoptosis. Here, we report the cloning and characterization of a novel human gene, KLHL31, from a human embryonic heart cDNA library. The cDNA of KLHL31 is 5743 bp long, encoding a protein product of 634 amino acids containing a BTB domain. The protein is highly conserved across different species. Western blot analysis indicates that the KLHL31 protein is abundantly expressed in both embryonic skeletal and heart tissue. In COS-7 cells, KLHL31 proteins are localized to both the nucleus and the cytoplasm. In primary cultures of nascent mouse cardiomyocytes, the majority of endogenous KLHL31 proteins are localized to the cytoplasm. KLHL31 acts as a transcription repressor when fused to GAL4 DNA-binding domain and deletion analysis indicates that the BTB domain is the main region responsible for this repression. Overexpression of KLHL31 in COS-7 cells inhibits the transcriptional activities of both the TPA-response element (TRE) and serum response element (SRE). KLHL31 also significantly reduces JNK activation leading to decreased phosphorylation and protein levels of the JNK target c-Jun in both COS-7 and Hela cells. These results suggest that KLHL31 protein may act as a new transcriptional repressor in MAPK/JNK signaling pathway to regulate cellular functions.
Yu
Weishi
W
The Center for Heart Development, Key Lab of Ministry of Education for Development Biology and Protein Chemistry, College of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, Peoples' Republic of China.
Li
Yongqing
Y
Zhou
Xijin
X
Deng
Yun
Y
Wang
Zequn
Z
Yuan
Wuzhou
W
Li
Dali
D
Zhu
Chuanbing
C
Zhao
Xueying
X
Mo
Xiaoyang
X
Huang
Wen
W
Luo
Na
N
Yan
Yan
Y
Ocorr
Karen
K
Bodmer
Rolf
R
Wang
Yuequn
Y
Wu
Xiushan
X
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D017124:Conserved Sequence; D004622:Embryo, Mammalian / Q000378:metabolism; D004789:Enzyme Activation; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D006367:HeLa Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity; D010766:Phosphorylation; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D027602:Serum Response Element / Q000235:genetics*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D000906:Antibodies; D011506:Proteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D012097:Repressor Proteins; D048031:JNK Mitogen-Activated Protein Kinases