28S-ribosomal RNA is superior to glyceraldehyde-3-phosphate dehydrogenase as a RNA reference gene in p53-deficient mice with unilateral ureteral obstruction

Although there are many kinds of reference genes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been commonly used by many researchers to assess the amount and integrity of RNA transcripts in RNA studies including Northern blot and reverse transcription real time-PCR. Although some data suggest that GAPDH could be inconstant in their situations or experiments, there is limited evidence that GAPDH expression is influenced by conditions of experiment, especially in mouse kidney model with unilateral ureteral obstruction (UUO). Therefore, the establishment of excellent reference gene according to the tissue types or conditions of experiment is a bottom line for the RNA study. Here we compared the expression of GAPDH with 28S rRNA gene by Northern blot analysis in the p53-deficient mice with UUO. We observed that GAPDH mRNA levels in ligated kidneys were significantly lower than those in contralateral kidneys, especially after postoperative day 15. In contrast, 28S rRNA levels were constant among control, ligated and contralateral kidneys. We also demonstrated that 28S rRNA signal was proportional to the amount of RNA loaded. In conclusion, these data indicate that much caution should be taken when using GAPDH as a RNA reference gene and 28S rRNA is an excellent gene for the RNA study in p53-deficient mice with UUO.