Rapid increase of fibroblast growth factor 21 under protein malnutrition and its impact on growth and lipid metabolism

ABSTRACT: Protein malnutrition promotes hepatic steatosis, decreases insulin-like growth factor (IGF)-I production, and retards growth. In order to identify new molecules involved in such changes, we conducted DNA microarray analysis for liver samples of rats fed isoenergetic low protein diet for 8 hours, and identified fibroblast growth factor 21 (Fgf21) as one of the most strongly up-regulated genes under conditions of acute protein malnutrition (P<0.05, FDR<0.001). In addition, amino acid deprivation from the culture media increased Fgf21 mRNA levels in rat liver-derived RL-34 cells (P<0.01). Thus, it was suggested that amino acid limitation directly increases Fgf21 expression. FGF21 is a polypeptide hormone that regulates glucose and lipid metabolism. Using transgenic mice, FGF21 has also been shown to promote a growth hormone-resistant state and suppress IGF-I. Therefore, to further determine whether the up-regulation of Fgf21 under protein malnutrition causes hepatic steatosis and growth retardation following decrease in IGF-I, we fed isoenergetic low protein diet to Fgf21-knockout (KO) mice. Fgf21-KO did not rescue growth retardation and reduced plasma IGF-I concentration of mice fed the low-protein diet. Meanwhile, Fgf21-KO mice showed greater epididymal white adipose tissue weight as well as hepatic triglyceride and cholesterol levels under protein malnutrition (P<0.05). Taken together, we showed that protein deprivation directly increases Fgf21 expression. However, growth retardation and decreased IGF-I were not mediated by increased FGF21 expression under protein malnutrition. Furthermore, up-regulated FGF21 rather appears to have a protective effect against obesity and hepatic steatosis in protein malnourished animals. Livers of rats from 2 groups (control (15P) or low-protain (5P) diet fed groups), total of 6 samples (3 replicates for each group) were analyzed.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Asako Takenaka 

PROVIDER: E-GEOD-64970 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress