Cloning And Functional Studies, In The Btb Gene Family Member Btbd8, Klhl7 And Klhl9

BTB domain and kelch-repeat domain are both highly conserved domains in evolution, they exist widely in nearly all organisms from yeast to human genome. The fact that there are many BTB/kelch proteins in the human genome suggests important and various roles of such proteins. Now more and more results show that BTB/kelch proteins participate in many vital cell activities, such as cytokinesis, actin cytoskeleton, cell cycle, tumorigenesis, neuronal development and the like. The fundamental roles of BTB domain lie on its ability to mediate protein interactions. Some BTB-domain containing transcription factors, such as PLZF and BCL6 play important roles in regulation of gene transcription. Recent study reveals that BTB domain can interact with Cul3 E3 ligase and take part in ubiquitin pathway. kelch proteins are considered to be a novel family of actin-binding proteins (ABPs), they can interact with actin cytoskeleton so that exert function on stability of cytoskeleton. More results demonstrate that kelch domain may have diverse functions in many signal transduction pathways. NRP/B locates in nuclear cytoskeleton. It regulates ERK/MAPK pathway and AKT pathway via regulation by p53. ENC-1 can interact with nonphosphorylated p110Rb protein and play roles in neuron cell cycle and differentiation. ENC-1 also has roles in adipocyte differentiation and colon carcinoma. Study on Mayven reveals that Mayven plays important roles in breast carcinoma, it can regulate cell cycle by activating expression of AP-1, c-jun and cyclin D.From the high quality human fetal brain library, we cloned three novel genes containing BTB domains. They are designated as BTBD8, KLHL7 and KLHL9 in agreement with HUGO nomenclature committee. KLHL7 and KLHL9 also have kelch-repeat domains in their carboxyl-terminals. Through bioinformatical analysis we showed that the cDNAs we got are full-length ones. The ORFs of BTBD8, KLHL7 and KLHL9 encode proteins of 305 amino acids, 538 amino acids and 617 amino acids, respectively. We studied expression profiles of these three genes by Northern blot, RT-PCR and In situ hybrid. The results showed that BTBD8 was strongly expressed in 8 fetal tissues while weakly in 16 adult tissues, suggesting it might play a role during development. KLHL7 was ubiquitously expressed in several tumor tissues and tumor cell lines, especially its expression was significantly upregulated in pancreatic carcinoma compared with normal pancreatic tissue. All these results suggested KLHL7 might play important roles in tumorigenesis and tumor progress. KLHL9 was also ubiquitously expressed in multiple tissues but it had...