Transcriptomic response in colon of rat with increased dietary protein content

Increase of fecal hazardous compounds and decrease of butyrate-producing bacteria has been implicated to be detrimental to colonic health during weight loss by high-protein diet in human. The question remains that whether the change of luminal microenvironment were paralleled with the alteration of colonic function in vivo.To reveal the change of gene expression involved in metabolic or immmunological process, we have employed the whole genome microarray profiling to identify differentially expressed genes in rat dietary normal protein (20% protein) or high protein (45% protein) diet. Colonic epithelium were sampled in adult male wistar rats (weighing 180-200g) fed each diet for six weeks.Each group contained six replicates.A total of 181 transcripts were significantly changed: 88 genes were up-regulated and 93 genes were down-regulated in high protein compared with normal protein rats. Transcriptome analysis identified the upregulation of chemotaxis, TNF-α signal process, antigen presentation, apoptosis, glutathione S-transferase activity and downregulation of innate immune, O-linked glycosylation of mucin, oxidative phosphorylation.Expression of ten genes, including calmodulin1,acetyl-CoA acyltransferase 2,isovaleryl-CoA dehydrogenase and occludin, were quantified in the same RNA samples by real-time PCR, validating the microarray analysis. Colonic gene expression was measured in male wistar rat (weighing 180-200g) after dietary normal protein or high protein diet for six weeks. Six replicates in each group were analyzed.