Kidney Week

Abstract: SA-PO632

Mesencephalic Astrocyte-Derived Neurotrophic Factor (MANF) Is Indispensable for Maintaining Mitochondrial Homeostasis in Uromodulin-Associated CKD

Session Information

• Genetic Kidney Diseases: Models, Mechanisms, and Therapies
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

• 1202 Genetic Diseases of the Kidneys: Non-Cystic

Authors

• Fang, Yili, Washington University in St Louis, St Louis, Missouri, United States

Yili Fang, MD, PhD

• Li, Chuang, Washington University in St Louis, St Louis, Missouri, United States

Chuang Li, PhD

• Gu, Chenjian, Washington University in St Louis, St Louis, Missouri, United States

Chenjian Gu, PhD

• Puri, Anuradhika, Washington University in St Louis, St Louis, Missouri, United States

Anuradhika Puri, PhD

• Jackrel, Meredith, Washington University in St Louis, St Louis, Missouri, United States

Meredith Jackrel, PhD

• Lindahl, Maria, Helsingin yliopisto, Helsinki, Uusimaa, Finland

Maria Lindahl, PhD

• Chen, Ying Maggie, Washington University in St Louis, St Louis, Missouri, United States

Ying Maggie Chen, MD, PhD, FASN

Background

Autosomal dominant tubulointerstitial kidney disease due to uromodulin mutations (ADTKD-UMOD), a leading hereditary kidney disease, has no targeted therapies. UMOD is expressed in the thick ascending limb (TAL) tubules, and mutant UMOD causes endoplasmic reticulum (ER) stress. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a novel ER resident molecular chaperone and ER stress-inducible secreted protein. The biological role of endogenous MANF in the regulation of mitochondrial function has not been studied.

Methods

CRISPR was utilized to generate the first Umod deletion mutation mouse model carrying Umod p.Y178-R186del, analogous to human H177-R185del, the most prevalent human mutation. To assess the function of MANF in ADTKD, tamoxifen-inducible TAL-specific MANF knockout mice were generated. Meantime, stable HEK cell line harboring WT or H177-R185del UMOD was established, and shRNA was employed to knockdown MANF in vitro. Bood urea nitrogen was monitored along the disease course. Immunoblotting, q-PCR and immunofluorescence staining were employed. Mitochondria function was assessed by electron transport chain protein expression, OROBOROS Oxygraphy system and Seahorse assay.

Results

MANF is induced in the TALs carrying the Umod deletion mutation. Genetic ablation of MANF in the mutant TALs suppresses phosphorylation of AMP-activated protein kinase (AMPK) and downstream expression of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α) and forkhead box O3 (FOXO3) in isolated primary TAL cells, resulting in impaired mitochondrial biogenesis/oxidative phosphorylation and mitophagy, respectively. The in vitroresults are in line with the in vivo findings. Consequently, MANF deficiency in TALs activates mitochondrial DNA leak-induced STING (stimulator of interferon genes) signaling and hyperinflammation, leading to accelerated renal fibrosis and kidney dysfunction in ADTKD.

Conclusion

For the first time, we discover that MANF is required to maintain mitochondrial homeostasis and acts as a critical molecular linker between ER and mitochondria homeostasis in ADTKD. The key role of MANF in mediating ER-mitochondria crosstalk may also have important implications in other protein misfolding diseases, such as Alzheimer.

Funding

• NIDDK Support