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The Regulation of Adipose Triglyceride Lipase-Mediated Lipolysis in Avian Species: the Role of Comparative Gene Identification-58

Serr, Julie Marie
http://rave.ohiolink.edu/etdc/view?acc_num=osu1299517190

Abstract Details

2011, Master of Science, Ohio State University, Animal Sciences.
The mechanisms of white adipose tissue lipolysis are not yet fully understood. Increasing our knowledge of the pathways controlling hydrolysis of stored triacylglycerols may provide target genes for selective markers for breeding livestock animals, or methods to control gene function to generate leaner animals at lowered cost to producers. The United States poultry industry is of great economic importance and increased production efficiency would benefit producers and consumers alike. Many of the genes and proteins involved in adipose tissue lipolysis are highly conserved in avian and mammalian species. Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme in triacylglycerol hydrolysis. The transcriptional and post-translational regulation of ATGL has not been clearly elucidated. Comparative gene identification-58 (CGI-58) has been identified as an activator of ATGL. Avian ATGL has been recently described and CGI-58 has been identified in chickens. The studies presented here investigate CGI-58 in the chicken, turkey, and quail, and characterize its expression during development, fasting and refeeding conditions, and hormonal stimulation. The complete coding sequences of CGI-58 in the chicken, turkey, and quail and the deduced amino acid sequences are reported here. The CGI-58 protein in the chicken and quail is 343 AA in length and 344 AA in the turkey. Compared with the human and mouse, CGI-58 is highly conserved across mammalian and avian species, with complete identities at the predicted lipid binding site. Separation of chicken adipose tissue into fat cell and stromal-vascular cell fractions reveals that CGI-58 is highly expressed in mature adipocytes (P < 0.01). Expression of avian CGI-58 was observed in multiple tissues, being greatest in adipose tissues (P < 0.01), similar to ATGL. The temporal expression of CGI-58 was investigated during embryonic development and up to 33 days after hatching. The greatest CGI-58 expression occurred at post-hatch day 1 (P < 0.05), concurrent with peak ATGL expression. Avian ATGL has been shown to increase during fasting. Expression of CGI-58 was investigated in broiler chickens and quail that were fasted for 24 h and subsequently refed. Following fasting, CGI-58 mRNA expression is increased (P < 0.05) and returns to its basal expression upon refeeding, mirroring concurrent changes in ATGL expression. The direct correlation of CGI-58 expression to ATGL expression indicates a potential role for CGI-58 in activation of ATGL-mediated lipolysis in avian species. To continue our investigation of the regulation of avian lipolysis, we observed expression of ATGL and CGI-58 in response to dexamethasone exposure. Dexamethasone has been shown to elevate circulating non-esterified fatty acids and regulate ATGL expression, though the mechanism is unclear. Thirty broiler chickens received dexamethasone injections and adipose tissue was collected from 0.5 to 6 h thereafter. Expression of ATGL and CGI-58 mRNA was evaluated by quantitative Real-Time PCR. ATGL expression began to increase gradually from 2 h, peaking at 6 h (P < 0.05). Plasma concentrations of non-esterified fatty acids followed a similar pattern, being greatest at 6 h after injection (P < 0.05). Significant changes in CGI-58 mRNA were not observed, indicating that the response of ATGL expression and fatty acid release to dexamethasone may not be mediated by CGI-58. Changes in ATGL expression may occur through direct transcriptional regulation or through indirect mechanisms, such as altered insulin signaling.
Kichoon Lee, PhD (Advisor)
Pasha Lyvers-Peffer, PhD (Committee Member)
J. David Latshaw, PhD (Committee Member)
111 p.
Agriculture; Animal Sciences; Molecular Biology; Nutrition
adipose tissue; adipose triglyceride lipase; chicken; comparative gene identification-58; glucocorticoid; lipolysis

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Citations

  • Serr, J. M. (2011). The Regulation of Adipose Triglyceride Lipase-Mediated Lipolysis in Avian Species: the Role of Comparative Gene Identification-58 [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299517190

    APA Style (7th edition)

  • Serr, Julie. The Regulation of Adipose Triglyceride Lipase-Mediated Lipolysis in Avian Species: the Role of Comparative Gene Identification-58. 2011. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1299517190.

    MLA Style (8th edition)

  • Serr, Julie. "The Regulation of Adipose Triglyceride Lipase-Mediated Lipolysis in Avian Species: the Role of Comparative Gene Identification-58." Master's thesis, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299517190

    Chicago Manual of Style (17th edition)

osu1299517190
869
© 2011, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.