title: Kbtbd5 is regulated by MyoD and restricted to the myogenic lineage.
abstract: BTB-BACK-Kelch (BBK) proteins play broad roles in cellular and molecular regulation. The role of BBK proteins in the skeletal muscle lineage and myogenesis remains an active area of research. Herein, we report a novel BBK gene, Kbtbd5, which we discovered and found to be restricted to the myogenic lineage. We observed that Kbtbd5 was absent in proliferating myoblasts and upregulated upon myogenic differentiation. In situ hybridization analysis revealed that Kbtbd5 was restricted to the skeletal muscle lineage during embryogenesis. We identified a conserved 1.2kb upstream region, which directs reporter expression to the developing skeletal muscle lineage. Transcriptional and mutagenesis assays demonstrated that the E-box motifs contribute to the Kbtbd5 promoter activity. We have also demonstrated the in vivo and in vitro binding between MRFs and the E-box motif in the 1.2kb promoter of the Kbtbd5 gene. Our studies have revealed that the Myod family can transactivate the 1.2kb-luc reporter through the E-box motifs. In addition, we have shown that Kbtbd5 can recruit the Cullin 3 complex in vivo. Using shRNA knockdown, our study has revealed that Kbtbd5 plays an important role in the myogenic differentiation. In summary, we have demonstrated that Kbtbd5 is the direct downstream target gene of the Myod family and regulates myogenic differentiation. Our results further support the notion that Kbtbd5 may serve as an adapter of Cul3 during myogenic differentiation.
authors.affiliation: Lillehei Heart Institute, University of Minnesota-Twin Cities, Minneapolis 55455, MN, USA.
authors.forename: Kathy M
authors.initials: KM
authors.lastname: Bowlin
authors.affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75390, TX, USA.
authors.forename: Laurence J
authors.initials: LJ
authors.lastname: Embree
authors.affiliation: Lillehei Heart Institute, University of Minnesota-Twin Cities, Minneapolis 55455, MN, USA.
authors.forename: Mary G
authors.initials: MG
authors.lastname: Garry
authors.affiliation: Lillehei Heart Institute, University of Minnesota-Twin Cities, Minneapolis 55455, MN, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Garry
authors.affiliation: Lillehei Heart Institute, University of Minnesota-Twin Cities, Minneapolis 55455, MN, USA. Electronic address: shixz@umn.edu.
authors.forename: Xiaozhong
authors.initials: X
authors.lastname: Shi
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D051379:Mice; D024510:Muscle Development / Q000235:genetics; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism; D017570:MyoD Protein / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C000593493:Kbtbd5 protein, mouse; D009124:Muscle Proteins; D017570:MyoD Protein; D014157:Transcription Factors
keywords: Cullin 3; Kbtbd5; MRF; Myogenic differentiation; Myogenic lineage