Subcongenic analysis of <it>tabw2</it> obesity QTL on mouse chromosome 6

• Main Authors: Stewart Taryn P, Mao Xia, Aqqad Maha N, Uffort Deon, Dillon Kristy D, Saxton Arnold M, Kim Jung
• Format: Article
• Language: English
• Published: BMC 2012-10-01
• Series: BMC Genetics
• Online Access: http://www.biomedcentral.com/1471-2156/13/81

<p>Abstract</p> <p>Background</p> <p>We previously established a congenic mouse strain with TALLYHO/Jng (TH) donor segment on chromosome 6 in a C57BL/6 (B6) background that harbors an obesity quantitative trait locus, <it>tabw2</it>. The B6.TH-<it>tabw2</it> congenic mice developed increased adiposity that became exacerbated upon feeding a high fat-high sucrose (HFS) diet. To fine map the <it>tabw2</it>, in this study we generated and characterized subcongenic lines with smaller TH donor segments.</p> <p>Results</p> <p>We fixed four subcongenic lines, with maximum size of donor segment retained in the lines ranging from 10.8 – 92.5 Mb. For mapping, all the subcongenic mice, along with B6.TH-<it>tabw2</it> congenic and B6-homozygous control mice were fed either chow or HFS diets, and their post-mortem fat pads were weighed. Mice were also characterized for energy expenditure, respiratory exchange ratio, locomotor activity, and food intake. As previously reported, B6.TH-<it>tabw2</it> congenic mice showed a significantly larger fat mass than controls on both diets. On chow, a subcongenic line retaining the distal region of the TH donor congenic interval exhibited significantly larger fat mass than B6-homozygous controls, and comparable that to B6.TH-<it>tabw2</it> congenic mice. Two nested subcongenic lines within that region suggested that the effect of <it>tabw2</it> on obesity could be attributed to at least two subloci. On HFS diets, on the other hand, all the subcongenic mice had significantly larger fat mass than controls without genotype differences, but none of them had fat mass as large as the original congenic mice. This possibly implicates that further genetic complexity involves in the effect of <it>tabw2</it> on diet-induced obesity. Significantly reduced locomotor activity was exhibited in B6.TH-<it>tabw2</it> congenic and subcongenic mice compared to controls when animals were fed HFS diets. B6.TH-<it>tabw2</it> congenic mice, but not subcongenic mice, also had significantly increased food intake on HFS diets.</p> <p>Conclusions</p> <p>It appears that at least two subloci explaining the <it>tabw2</it> effect under chow feeding map to the distal region of the congenic interval, whereas the diet-induced obesity mediated by <it>tabw2</it> is attributed to more complex genetic mechanism.</p>