Project description:Niche for stem cells can profoundly influence the position and fate of stem cells in tissue homeostasis and associated disorders, however, the mechanisms underlying the maintenance of stem cell niche remain poorly understood. Here we report that fatty acid desaturation catabolized by stearoyl-coenzyme A desaturase 1 (SCD1) regulates the activity of hair follicle stem cells (HFSCs) via blocking the formation of the bulge, a niche for HFSCs. We further unraveled that the abnormal hair growth in mice with SCD1 deletion is due to its function in K14+ basal keratinocytes rather than directly affecting HFSCs. Mechanistically, SCD1 deficiency impaired the expression of integrin α6 and the formation of hemidesmosomes (HDs), and thus allowed the activation of FAK in K14+ keratinocytes. Activated FAK subsequently stimulated PI3K and promoted the differentiation and proliferation of these keratinocytes, resulting in downward extension of the outer root sheath (ORS) and the disruption of bulge formation. Interestingly, inhibition of PI3K signaling restored bulge formation and normalized HFSCs and hair growth. Supplementation of oleic acid, the product of SCD1, to SCD1-/- mice also enhanced HD numbers, normalized the niche of HFSCs, and promoted hair growth in SCD1-/- mice. Taken together, SCD1 is indispensable for hair growth through stabilizing the number of HDs and thus sustaining bulge formation for HFSC residence and periodic activity.
Project description:To help elucidate the metabolic changes in the skin that contribute to the obesity resistance and skin pathology in mice lacking Scd1, we performed microarray analysis of skin gene expression in male skin Scd1 knockout (SKO) and Scd1 flox/flox control (Lox) mice fed a standard rodent diet. We identified an extraordinary number of differentially expressed genes that support the previously documented histological observations of sebocyte atrophy, inflammation and epidermal hyperplasia in SKO mice. Additionally, transcript levels were reduced in skin of SKO mice for genes involved in fatty acid synthesis, elongation and desaturation, which may be attributed to decreased abundance of key transcription factors including SREBP1c, ChREBP and LXR?. Conversely, genes involved in cholesterol synthesis were increased, suggesting an imbalance between skin fatty acid and cholesterol synthesis. Unexpectedly, we observed a robust elevation in skin retinol, retinoic acid and retinoic acid-induced genes in SKO mice. These results highlight the importance of monounsaturated fatty acid synthesis for maintaining retinol homeostasis and point to disturbed retinol metabolism as a novel contributor to the Scd1 deficiency-induced skin pathology. We analyzed dorsal skin gene expression in non-fasted 8-9 week old male skin Scd1 knockout (SKO) mice (n=3) and Scd1flox/flox (Lox) control mice (n=3)on a C57BL/6J background using Affymetrix 430 2.0 microarrays.
Project description:To help elucidate the metabolic changes in the skin that contribute to the obesity resistance and skin pathology in mice lacking Scd1, we performed microarray analysis of skin gene expression in male skin Scd1 knockout (SKO) and Scd1 flox/flox control (Lox) mice fed a standard rodent diet. We identified an extraordinary number of differentially expressed genes that support the previously documented histological observations of sebocyte atrophy, inflammation and epidermal hyperplasia in SKO mice. Additionally, transcript levels were reduced in skin of SKO mice for genes involved in fatty acid synthesis, elongation and desaturation, which may be attributed to decreased abundance of key transcription factors including SREBP1c, ChREBP and LXRα. Conversely, genes involved in cholesterol synthesis were increased, suggesting an imbalance between skin fatty acid and cholesterol synthesis. Unexpectedly, we observed a robust elevation in skin retinol, retinoic acid and retinoic acid-induced genes in SKO mice. These results highlight the importance of monounsaturated fatty acid synthesis for maintaining retinol homeostasis and point to disturbed retinol metabolism as a novel contributor to the Scd1 deficiency-induced skin pathology.
Project description:To understand molecular mechanisms underlying the growth inhibitory ativity of Stearoyl-CoA desaturase-1 (SCD1) inhibitor, we performed microarray analysis using HCT-116 colorectal cancer cells, in which SCD1 was pharmacologically blocked or genetically ablated.
Project description:Stearoyl-CoA desaturase 1-deficient (SCD1-/-) mice have impaired monounsaturated fatty acid (MUFA) synthesis. When maintained on a very low-fat, high-carbohydrate (VLF-HC) diet, SCD1-/- mice develop severe hypercholesterolemia characterized by an increase in apolipoprotein B-containing lipoproteins and the appearance of lipoprotein-X. Additionally, high-density lipoprotein cholesterol is dramatically reduced in VLF-HC SCD1-/- mice. The concomitant presence of elevated plasma bile acids, bilirubin and aminotransferases in the VLF-HC SCD1-/- mouse are indicative of hepatic dysfunction. Supplementation of the VLF-HC diet with unsaturated fat (canola oil), but not saturated fat (coconut oil), prevents these plasma phenotypes. However, dietary oleate was not as effective as canola oil in reducing low-density lipoprotein cholesterol, signifying an additional role for dietary polyunsaturated fatty acid deficiency in the development of this phenotype. These results indicate that lack of SCD1 results in an increased requirement for dietary unsaturated fat to compensate for impaired MUFA synthesis and to prevent hypercholesterolemia and hepatic dysfunction. Keywords: repeat (genotype and diet)
Project description:Presently, there is a deficiency of effective therapies designed to target clear cell renal cell carcinoma (ccRCC), with poor prognosis resulting in patients with advanced disease. Additionally, there is a lack of molecular factors which can be remedially targeted resulting in tumor specific inhibition, and therefore current therapeutic approaches often produce adverse side effects in patients. We identified that Stearoyl-CoA desaturase 1 (SCD1) was consistently overexpressed in patient ccRCC samples, and further investigation of SCD1 as a potential molecular target for ccRCC intervention utilizing a SCD1 inhibitor (A939572) resulted in tumor specific growth inhibition and induction of cell death. In order to understand the mechanism by which the SCD1 inhibitor mediated its anti-tumor effects, we performed gene array analysis and compared expression patterns between treated and untreated samples.