The global incidence of obesity is increasing at an alarming rate and this leads to a health risk that predisposes individuals to the development of diabetes and cardiovascular disease. Obesity is associated with inflammatory cell activation, insulin resistance, and vascular dysfunction. However, the mechanism that links visceral obesity to the above diseases is unclear. The hypothesis to be tested in this proposal is that obesity-induced activation of 12/15-lipoxygenase (12/15-LO) in visceral fat is necessary for local and systemic inflammatory cell activation and ensuing systemic insulin resistance and vascular dysfunction.
The first aim of this proposal is to determine the mechanism by which 12/15-LO is activated and its role in mediating inflammation, insulin resistance, and renin-angiotensin system (RAS) activation (a mediator of vascular function) using an in vitro model of 3T3-L1 adipocytes. Various obesity-related stressors, such as endoplasmic reticulum stress, high fatty acid concentrations, and angiotensin II, will be tested in adipocytes and consequent 12/15-LO induction will be measured by real-time PCR and western blotting. Furthermore, addition of the 12/15-LO siRNA and pharmacologic inhibitors will be added in the presence of these stressors to deduce the relative role of 12/15-LO in mediating consequent inflammation, insulin resistance, and RAS activation.
The second aim of the proposal will evaluate the role of 12/15-LO induction in visceral fat in mediating systemic inflammation, insulin resistance, and cardiovascular complications in vivo.
This aim will utilize a newly created adiponectin-Cre;12/15-LOFIox/Flox mouse model whereby 12/15-LO will be specifically deleted from visceral fat. These mice will be fed a standard chow diet or """"""""western"""""""" diet high in saturated fat (a diet that promotes inflammation, insulin resistance, and cardiovascular complications) for 8-10 weeks and will be compared to control mice. It is anticipated that deletion of 12/15-LO from visceral fat will reduce the ensuing inflammatory response, decrease insulin sensitivity, and prevent vascular dysfunction induced by hyperlipidemia. The proposed research will be crucial in defining how obesity is linked with diabetes and cardiovascular disease development. This information will help identify novel therapeutic targets for type 2 diabetes and cardiovascular disease prevention and intervention strategies, thereby potentially reducing the alarming increase in cardiovascular-related events.
|Cole, Banumathi K; Lieb, David C; Dobrian, Anca D et al. (2013) 12- and 15-lipoxygenases in adipose tissue inflammation. Prostaglandins Other Lipid Mediat 104-105:84-92|
|Cole, Banumathi K; Kuhn, Norine S; Green-Mitchell, Shamina M et al. (2012) 12/15-Lipoxygenase signaling in the endoplasmic reticulum stress response. Am J Physiol Endocrinol Metab 302:E654-65|
|Cole, Banumathi K; Morris, Margaret A; Grzesik, Wojciech J et al. (2012) Adipose tissue-specific deletion of 12/15-lipoxygenase protects mice from the consequences of a high-fat diet. Mediators Inflamm 2012:851798|
|Chakrabarti, Swarup K; Wen, Yeshao; Dobrian, Anca D et al. (2011) Evidence for activation of inflammatory lipoxygenase pathways in visceral adipose tissue of obese Zucker rats. Am J Physiol Endocrinol Metab 300:E175-87|