Effect of Hyp, low phosphate diet and sex on mRNA gene expression in the mouse kidney

The renal adaptation to changing dietary phosphate levels is not well understood. The dominant Hyp mutation of the Phex gene in mice causes X-linked hypophosphatemia with low renal retention of phosphate and blocks physiologic adaptation to low phosphate diets. At P < 0.01, there were 1,711 transcripts significantly affected by genotype, 1,428 by diet and 5,601 by sex. Many renal transporters other than phosphate, as well as many novel transcripts of unknown function, were affected by the Hyp mutation. Some genes for fat metabolism and inflammation were up-regulated in Hyp kidneys. Of the genes affected by genotype and diet, only 378 were affected by both. In summary, the Hyp mutation induced changes in mRNA levels for numerous transcripts exceeding that required to alter phosphate retention. The data suggest broader physiological roles for the Phex gene unrelated to phosphate conservation. Keyword = Phex Keyword = Hyp Keyword = mouse Keyword = kidney Keyword = sex Keyword = mRNA Keyword = microarray Keyword = low phosphorus diet Keywords: disease state analysis A 2x2x2 factorial design, balanced for genotype (normal vs. Hyp), diet (control vs. low phosphate), and sex (male vs. female) was employed. Control or low phosphate diets were fed for three days to 10-week-old mice. A total of 24 samples of renal RNA were collected from 72 mice (3/array), processed to biotin-labeled cRNA, and hybridized to Affymetrix mouse MOE 430A and 430B for measurement of expression of over 45,000 transcripts.