GADD45α is a direct target of TFEB and contributes to tacrolimus-induced chronic nephrotoxicity

Area of Science:

• Nephrology
• Molecular Biology
• Cellular Biology

Background:

• Tacrolimus-induced chronic nephrotoxicity (TICN) limits tacrolimus use, but its mechanism is unclear.
• Tacrolimus inhibits calcineurin, affecting T cell activation but potentially other substrates.
• Transcription factor EB (TFEB), a calcineurin substrate, is vital for cellular homeostasis.

Purpose of the Study:

• To investigate the role of TFEB in TICN.
• To identify downstream targets of TFEB involved in TICN.
• To explore TFEB and its targets as potential therapeutic interventions for TICN.

Main Methods:

• Assessed TFEB nuclear translocation and activity in mouse kidneys and HK-2 cells treated with tacrolimus.
• Utilized TFEB gain- and loss-of-function models in HK-2 cells.
• Activated TFEB via phosphorylation site mutation and agonist in a mouse model of TICN.
• Performed ChIP-Seq to identify TFEB transcriptional targets.
• Validated GADD45α as a TFEB target using ChIP and dual-luciferase reporter assays.
• Overexpressed GADD45α in vitro and in vivo to assess its protective effects.

Main Results:

• Tacrolimus inhibited TFEB nuclear translocation and activity in kidney cells and tissues.
• Modulating TFEB levels affected tacrolimus-induced cellular damage.
• TFEB activation ameliorated TICN in mice.
• Growth arrest and DNA damage-inducible 45α (GADD45α) was identified as a TFEB target gene.
• GADD45α overexpression protected against tacrolimus-induced DNA damage and kidney injury in vitro and in vivo.

Conclusions:

• Tacrolimus-induced chronic nephrotoxicity is mediated by the persistent inhibition of the TFEB/GADD45α pathway.
• Targeting the TFEB/GADD45α pathway offers a potential therapeutic strategy for mitigating TICN.