Dietary protein as a potent regulator of the hyaluronan synthase gene in rat skin.

The status of hyaluronan, the major glycosaminoglycan in the skin, is regulated by many factors such as cytokines and glucocorticoids. To examine whether and how protein malnutrition affects the status of skin hyaluronan, the hyaluronan content and mRNA levels of hyaluronan synthases (has) were analyzed in the skin of rats fed on a protein-free diet or on a 12% gluten diet. When these malnourishing diets had been given for 1 week, the hyaluronan content was significantly reduced as compared with that in rats fed on a 12% casein diet. Substantial falls in the mRNA levels of rhas2 and rhas3 were also observed. The reduction of mRNAs was already evident on the second day of treatment with the malnourishing diets. These results suggest that protein malnutrition has a primary impact on the gene expression of rhass, which leads to the reduction of hyaluronan content and to disfunction of the skin.