TFEB-driven lysosomal biogenesis is pivotal for PGC1α-dependent renal stress resistance

Abstract

Because injured mitochondria can accelerate cell death through the elaboration of oxidative free radicals and other mediators, it is striking that proliferator γ coactivator 1-α (PGC1α), a stimulator of increased mitochondrial abundance, protects stressed renal cells instead of potentiating injury. Here, we report that PGC1α’s induction of lysosomes via transcription factor EB (TFEB) may be pivotal for kidney protection. CRISPR and stable gene transfer showed that PGC1α-KO tubular cells were sensitized to the genotoxic stressor cisplatin, whereas Tg cells were protected. The biosensor mitochondrial-targeted Keima (mtKeima) unexpectedly revealed that cisplatin blunts mitophagy both in cells and mice. PGC1α and its downstream mediator NAD + counteracted this effect. PGC1α did not consistently affect known autophagy pathways modulated by cisplatin. Instead RNA sequencing identified coordinated regulation of lysosomal biogenesis via TFEB. This effector pathway was sufficiently important that inhibition of TFEB or lysosomes unveiled a striking harmful effect of excess PGC1α in cells and conditional mice. These results uncover an unexpected effect of cisplatin on mitophagy and PGC1α’s reliance on lysosomes for kidney protection. Finally, the data illuminate TFEB as a potentially novel target for renal tubular stress resistance.

NAD+ homeostasis in renal health and disease

“…In cultured renal tubular cells, overexpression of PGC1α protected against oxidant stress 48 . Our research group found that mice with global or tubule-specific knockout of the gene encoding PGC1α exhibited blunted recovery and worse renal injury following endotoxaemia, systemic cisplatin treatment or bilateral renal IRI compared with wild-type controls 47,49,50 . Conversely, mice with tubule-specific overexpression of PGC1α were protected against all three models of AKI 47,49,50 .…”

“…Our research group found that mice with global or tubule-specific knockout of the gene encoding PGC1α exhibited blunted recovery and worse renal injury following endotoxaemia, systemic cisplatin treatment or bilateral renal IRI compared with wild-type controls 47,49,50 . Conversely, mice with tubule-specific overexpression of PGC1α were protected against all three models of AKI 47,49,50 . The PPARGC1A locus, which encodes PGC1α, contains an evolutionarily conserved upstream open reading frame (uORF) in the 5′ untranslated region 51 .…”

Normothermic Ex-vivo Kidney Perfusion in a Porcine Auto-Transplantation Model Preserves the Expression of Key Mitochondrial Proteins: An Unbiased Proteomics Analysis

“…104 PPARGC1A is considered the master regulator of mitochondrial biogenesis, binding to a host of transcription factors (most notably PPAR-family members) to increase expression of genes that augment mitochondrial abundance, oxidative phosphorylation, and FAO. [105][106][107][108] Observations that tubular PPARGC1A can reduce the severity of AKI and accelerate functional resolution 54,57,99,109 are consistent with the high metabolic activity of PTECs. 110 Less metabolically active kidney cell types including endothelial cells 54 and podocytes 111,112 may not experience the same benefit, suggesting a cell-type specific role for PPARGC1A in the kidney.…”

“…PPAR-family members and their transcriptional co-activator PPARGC1A emerged as likely upstream regulators in our dataset, with PPARA showing increased expression at 30minutes post-reperfusion in NEVKP, and PPARA/D, RXRA/B and PPARGC1A showing significantly increased expression in NEVKP at POD3. The renoprotective effects of PPARGC1A, particularly, have been described in models of septic, 52,97 toxic, 57,98 and ischemic 54,99,100 AKI.…”

“…There were no significant differences in expression of PPAR-family transcription factors at baseline between groups (Supplemental Figure 4), however, PPARA and PPARGC1A showed increased expression in NEVKP at 30minutes post-reperfusion ( Figure 6F). PPARGC1A may mediate some of its renoprotective effects by augmenting expression of the lysosomal biogenesis regulator TFEB, 57 which was significantly increased in NEVKP at 30minutes post-reperfusion ( Figure 6F).…”