Role of Ras Oncogene and Selective Mutant on Differentionation of 3T3-L1 Preadipocytes


According to the Center for Disease Control, in the years between 2011-2014, the prevalence for obesity was 36.5%. Obesity is characterized by an increase in adipocytes. Adipocytes, also known as fat cells, store energy in the form of triglycerides which can then be released as fatty acids when energy levels are low. Adipocytes are formed through a process called adipogenesis, where cells modify their genetic environment to specifically differentiate into fat cells. Adipogenesis can be regulated by various proteins, including Ras. Ras is a proto-oncogene that codes for proteins that regulate cell growth and differentiation in several biological processes. Although extensively investigated, the specific role of Ras GTPases on differentiation of 3T3-L1 preadipocytes is not well understood. When Ras is activated, or GTP bound, it has many downstream effector proteins that can carry out selective biological processes. These effector proteins include MAP(K) kinase (i.e., Raf-1), PI3(K) kinase and Rin1. A defective hydrolysis mutant of the human-Ras (H-Ras), Ras:G12V, was used along with several selective mutations, in order to determine signaling transduction pathways responsible for fat formation in vitro. These pathwats, PI3(K) kinase and MAP(K) kinase, are responsible for Ras-dependent adipogenesis and provide relevent information on what is the potential role of H-Ras mutants. Preadipocytes were first differentiated into adipocytes by adding an induction medium, which contained both glucose and insulin. Lipid drops were then qualified by examining the accumulation of Oil red O into lipid drops. Adipocytes which had been transfected with Ras:G12V, stimulated 3T3-L1 preadipocyte differentiation with requiring induction media. The second mutation, Ras:G12V;E37G, which blocks the activation of the MAP(K) kinase pathway, inhibited preadipocyte differentiation strongly. The other Ras double mutants (Ras:G12V;S35T and V12G;C40Y) inhibited 3T3-L1 preadipocyte differentiation moderately. These results indicate that Ras plays a selective role in 3T3-L1 preadipocyte differentiation. By understanding which pathway Ras employs and how it can be manipulated, a link on how to decrease body fat production could be found. These results could lead to methods to prevent obesity and in turn, obesity related diseases such as diabetes.

C.S. was supported by NIH/NIGMS T34 GM083688. The content is solely the responsibility of the authors and does no necessarily represent the official views of the National Institutes of Health.

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2018 West Kendall Baptist Hospital Scholarly Showcase

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