Identification and Functional Characterization of Adipogenesis-related Genes

by Wu, Yu

Abstract (Summary)
This dissertation is focused on identification and characterization of novel genes in adipogenesis from different angles. Wdnm1-like was identified as a novel 6.8 kDa adipokine secreted by adipocytes. Wdnm1-like is a differentiation-dependent gene in white and brown adipogenesis. TNF? treatment of 3T3-L1 adipocytes increases Wdnm1-like transcript level 2.4-fold and this can be attenuated by pretreatment with the p38 MAP kinase inhibitor SB203580. Ectopic overexpression of Wdnm1-like in HT1080 fibrosarcoma cells markedly increases active MMP-2 level. TSC-36 was identified as a preadipocyte gene that is highly expressed in 3T3-L1 preadipocytes and downregulated to nearly undetectable levels in 3T3-L1 adipocytes. TSC-36 is therefore a preadipokine secreted by preadipocytes. PPAR? and KLF15 downregulate TSC-36 promoter activities. TSC-36 transcript and protein levels are increased in 3T3-L1 adipocytes after TNF? treatment. In 3T3-L1 preadipocytes, TSC-36 expression is downregulated by 5-azacytidine. In a study to identify genes distinctly expressed in specific WAT depots and which may impart depot-dependent physiological functions, Boc transcript demonstrated a 12-fold enrichment in EP adipocytes. Expression of transcript for the Boc binding partner, Cdon was also assessed in adipose tissue and cell fractions thereof. We also identified a dramatic enrichment in SC adipocytes vs. EP adipocytes and in SC WAT vs. EP WAT for transcript(s) for the major urinary proteins (Mups). We established and characterized mBAP-9 which is derived from interscapular BAT of C57BL/6 mice as a new brown preadipocyte cell line. 10 adipocyte differentiation-dependent genes that are upregulated 4-fold or greater during mBAP-9 adipogenesis were identified. Two of these encoding putative hydrolases, Cmbl and Atabh were further studied. Tmem182 is a novel predicted transmembrane protein found to exhibit 45-fold upregulation in mBAP-9 adipogenesis. Further characterization of Tmem182 transcript expression revealed that Tmem182 transcript is markedly upregulated in various in vitro models of white adipogenesis. Moreover, Tmem182 transcript is also upregulated ~770-fold during the C2C12 cells myogenesis, which suggests Tmem182 may function in intracellular pathways important in both adipogenesis and myogenesis. In summary, this dissertation reveals novel genes distinctly expressed in adipocyte, preadipocyte or in specific WAT depots and also demonstrates mBAP-9 as a new brown preadipocyte cell line. This work will contribute to define a more complete picture of adipogenesis.
Bibliographical Information:


School:University of Toledo Health Science Campus

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:adipogenesis tmem182 wdnm1 like mbap 9 tsc 36 mups


Date of Publication:01/01/2008

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