Kidney Week

Abstract: SA-PO851

Identification of β-Mannosidase (Manba) as a Key Gene for CKD

Session Information

• Molecular Mechanisms of CKD - III
  October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

• 1903 CKD (Non-Dialysis): Mechanisms

Authors

• Yang, Hongliu, West China Hospital of Sichuan University , Chengdu, SIChuan, China

Hongliu Yang,

• Qiu, Chengxiang, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Chengxiang Qiu,

• Park, Jihwan, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Jihwan Park,

• Huang, Shizheng, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Shizheng Huang,

• Susztak, Katalin, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Katalin Susztak,

Group or Team Name

• Katalin Susztak Lab

Background

Chronic kidney disease (CKD) is a complex gene-environmental disease affecting close to 10% of the population worldwide. We integrated the CKD Genome-wide association studies (GWASs) and kidney expression quantitative trait loci (eQTL) analysis results and identified the lysosomal beta-mannosidase (Manba) as a candidate gene for CKD. We found that when compared to reference allele, expression of Manba was much lower in healthy human kidney tissue samples obtained from subjects with risk alleles. We used Manba knockout mouse model to explore the functional significance of lower Manba expression and precise pathomechanism of Manba in CKD.

Methods

Genotype and gene expression data by RNA sequencing for 121 healthy human kidney tissue samples of European descent were obtained and eQTL analysis was conducted. Single cell RNA-sequencing on healthy mouse kidneys was performed to define the expression of Manba. Manba^-/- mice and age-matched WT mice were generated for experiment. CKD was studied in aging mice or following folic acid administration. Renal tubule epithelial cells (TECs) from WT and Manba^-/- mice were primary cultured and treated with fed (F), starve (S) and starve+cholorquine (S+CQ) for in vitro study.

Results

Single cell RNA-sequencing analysis of healthy mouse kidneys indicated Manba is mainly expressed in proximal tubule (PT) and principal cell (PC) of collecting duct (CD).QPCR and Western blot showed the deletion of Manba and immunohistochemical staining in human kidney and mouse kidney confirmed the location of Manba. In aging mice, Manba^-/- mice showed increased number of lysosome and increased number of vacuoles in tubule cells. In kidney fibrosis model, Manba^-/- mice demonstrated worsened renal damage after folic acid (FA) injection. In vitro study, Treatment with CQ heightened the amounts of LC3B-II in nutrientdeprived WT TECs, whereas it did not change the already elevated levels of LC3B-II in nutrient-deprived Manba^−/− cells.

Conclusion

This is the first study demonstrated the expression of Manba in mouse kidney and found that Manba deficiency induces kidney fibrosis development. Manba deficiency impair autophagy in CKD predominantly from a slower autophagosome clearance.

Funding

• NIDDK Support