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theses

Stearoyl-CoA desaturase (SCD) is an enzyme that catalyzes the formation of monounsaturated fatty acids from saturated fatty acids. Primarily, the enzyme converts palmitoyl-CoA and stearoyl-CoA to palmitoleoyl-CoA and oleoyl-CoA, respectively. Previous studies have shown that this enzyme is transcriptionally regulated in numerous metabolically-important tissues, such as liver and adipose, in response to nutritional manipulation. However, virtually nothing is known regarding its potential expression and regulation in the intestine, the primary site of lipid absorption in the body. In this study, we aimed to identify whether SCD1 is expressed in the intestine and whether it is regulated in a manner similar to a lipogenic tissue such as liver. Age-matched male wild type C57BL/6J were fasted for 24 hours and then refed a lipogenic high-sucrose very low fat diet (HSVLF) for 16 hours, a paradigm that is known to transcriptionally activate Scd1 in the liver. Mucosal scrapings were collected from duodenum, proximal jejunum, distal jejunum, ileum and colon. Results show that this refeeding protocol increases SCD1 mRNA and protein expression in duodenum, proximal jejunum, distal jejunum, and ileum. This was also true for several other lipogenic genes, such as sterol regulatory element binding protein (Srebp-1c), acetyl-CoA carboxylase (Acc), and fatty acid synthase (Fas). SCD1 was expressed at the highest level in the ileum in comparison to duodenum and both proximal and distal sections of jejunum. Immunohistological analyses of Swiss-rolled sections of small intestine showed an increase in SCD1 protein expression after refeeding as well differential SCD1 expression along the length of the intestine, corroborating gene expression data. We conclude that SCD1 is differentially expressed throughout the intestine and is regulated through dietary manipulation.

ETD_10794

M.S.

Includes bibliographical references

doi:10.7282/t3-t727-0x82

ETD graduate

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