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Kidney Week

Abstract: SA-PO426

Expression and Role of TET Proteins in Fetal Kidneys of Control and Nutrient-Restricted Rat Dams

Session Information

  • Pediatric Nephrology - II
    October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1600 Pediatric Nephrology

Authors

  • Hida, Mariko, Keio University School of Medicine, Tokyo, Japan
  • Awazu, Midori, Keio University School of Medicine, Tokyo, Japan
Background

The ten-eleven translocation (TET) proteins are enzymes that oxidize 5-methylcytosine to 5-hydroxymethylcytosine and regulate DNA methylation and hydroxymethylation, which are important epigenetic modifications in fetal programming. We previously reported that inhibition of DNA methylation reduces ureteric branching and kidney growth in organ culture (ASN 2015). We also showed that kidneys of offspring of nutrient-restricted rat dams were characterized by reduction in global DNA methylation, ureteric branching, and kidney size. In the present study, we examined global DNA hydroxymethylation and the expression of TET proteins in fetal kidneys of control (CON) and nutrient-restricted (NR) rat dams. The role of TET proteins was further examined in organ culture.

Methods

NR rats were subjected to 50% food restriction throughout pregnancy. Expression of TET1, 2, and 3 was analyzed by immunoblot in the kidney of embryonic day 18 (E18). Global DNA hydroxymethylation was quantified by ELISA. In organ culture, E13 to E14 metanephroi were cultured for 2 to 3 days in the presence or absence of ascorbic acid that facilitates TET enzyme activity, or dimethyloxallyl glycine (DMOG), a small-molecule inhibitor of TET.

Results

TET1, 2, and 3 were expressed in the E18 kidney and their expression was increased in NR compared with CON. Global DNA hydroxymethylation was also increased in NR compared with CON by 1.5-fold. Metanephroi cultured with ascorbic acid 0.1 mg/mL had significantly fewer ureteric bud tips (6.5±0.3 vs 9.0±0.3 per kidney) with no difference in kidney size (6.1±0.4 vs 6.1±0.5 arbitrary units) compared with those cultured with vehicle. DMOG 1 mM, on the other hand, significantly decreased both ureteric bud tip number (3.0±0.6 vs 9.7±1.7 per kidney) and kidney size (1.1±0.1 vs 1.9±0.2 arbitrary units). The effect of DMOG was similar in metanephroi cultured from nutrient-restricted dams. Thus ureteric tip number (2.7±0.3 vs 8.0±1.2 per kidney) and kidney size (1.2±0.1 vs 1.9±0.2 arbitrary units) were significantly decreased by DMOG.

Conclusion

TET proteins are expressed in fetal kidney with increased levels in NR, which is characterized by higher global DNA hydroxymethylation. Both stimulation and inhibition of TET disturb normal kidney development. Whether TET proteins regulate kidney development through DNA methylation and or hydroxymethylation needs to be investigated.

Funding

  • Government Support - Non-U.S.