Activation of HIF-1α C-terminal transactivation domain protects against hypoxia-induced kidney injury through hexokinase 2-mediated mitophagy.

The transcription factor hypoxia-inducible factor-1α (HIF-1α), as a master regulator of adaptive responses to hypoxia, possesses two transcriptional activation domains [TAD, N-terminal (NTAD), and C-terminal (CTAD)]. Although the roles of HIF-1α NTAD in kidney diseases have been recognized, the exact effects of HIF-1α CTAD in kidney diseases are poorly understood. Here, two independent mouse models of hypoxia-induced kidney injury were established using HIF-1α CTAD knockout (HIF-1α CTAD) mice. Furthermore, hexokinase 2 (HK2) and mitophagy pathway are modulated using genetic and pharmacological methods, respectively. We demonstrated that HIF-1α CTAD aggravated kidney injury in two independent mouse models of hypoxia-induced kidney injury, including ischemia/reperfusion-induced kidney injury and unilateral ureteral obstruction-induced nephropathy. Mechanistically, we found that HIF-1α CTAD could transcriptionally regulate HK2 and subsequently ameliorate hypoxia-induced tubule injury. Furthermore, it was found that HK2 deficiency contributed to severe renal injury through mitophagy inhibition, while mitophagy activation using urolithin A could significantly protect against hypoxia-induced kidney injury in HIF-1α C-TAD mice. Our findings suggested that the HIF-1α CTAD-HK2 pathway represents a novel mechanism of kidney response to hypoxia, which provides a promising therapeutic strategy for hypoxia-induced kidney injury.