Feeding Rats Dietary Resistant Starch Shifts the Peak of SGLT1 Gene Expression and Histone H3 Acetylation on the Gene from the Upper Jejunum toward the Ileum.

Abstract

Sodium glucose cotransporter 1 (SGLT1) participates in the incorporation of glucose from the lumen to enterocytes in the small intestine. We examined whether dietary resistant starch (RS), an autoclaved high amylose starch that is digested more slowly than regular cornstarch in the small intestine, alters SGLT1 mRNA levels along the jejunum-ileum of rats. The SGLT1 mRNA level was lower in the upper jejunum in rats fed an RS diet than in those fed a regular cornstarch diet, whereas it was higher in the lower jejunum/upper ileum. Furthermore, using chromatin immunoprecipitation (ChIP) assay, we demonstrated that histone H3 acetylation on the promoter/enhancer and transcriptional regions was reduced in the upper jejunum and elevated in the lower jejunum/upper ileum by feeding rats an RS diet. On the other hand, HNF-1 binding on the region around transcription start site of the SGLT1 gene was not altered in each jejunoileal segment by feeding rats an RS diet. Our results suggest that a shift of the expressional peak of the SGLT1 gene from the upper jejunum toward the ileum by dietary RS is associated with a change of histone H3 acetylation rather than that of HNF-1 binding on the gene.