Glucocorticoid-Responsive Transcription Factor Kruppel-Like Factor 9 Regulates fkbp5 and Metabolism

Kruppel-like factor 9 (Klf9) is a feedforward regulator of glucocorticoid receptor (GR) signaling. Here we show that in zebrafish klf9 is expressed with GR-dependent oscillatory dynamics in synchrony with fkbp5, a GR target that encodes a negative feedback regulator of GR signaling. We found that fkbp5 transcript levels are elevated in klf9(-/-) mutants and that Klf9 associates with chromatin at the fkbp5 promoter, which becomes hyperacetylated in klf9(-/-) mutants, suggesting that the GR regulates fkbp5 via an incoherent feedforward loop with klf9. As both the GR and Fkbp5 are known to regulate metabolism, we asked how loss of Klf9 affects metabolic rate and gene expression. We found that klf9(-/-) mutants have a decreased oxygen consumption rate (OCR) and upregulate glycolytic genes, the promoter regions of which are enriched for potential Klf9 binding motifs. Our results suggest that Klf9 functions downstream of the GR to regulate cellular glucocorticoid responsivity and metabolic homeostasis.

Automated summary

Kruppel-like factor 9 (Klf9) is a feedforward regulator of glucocorticoid receptor (GR) signaling and is expressed in synchrony with fkbp5 in zebrafish. Loss of Klf9 results in elevated levels of fkbp5 transcript and hyperacetylation of the fkbp5 promoter, suggesting that GR regulates fkbp5 via an incoherent feedforward loop with klf9. Klf9(-/-) mutants show decreased oxygen consumption rate and upregulation of glycolytic genes, indicating a role for Klf9 in regulating metabolic rate and gene expression.