The Gne M712T mouse as a model for human glomerulopathy

Area of Science:

• Nephrology
• Glycobiology
• Biochemistry

Background:

• Pathological glomerular hyposialylation is linked to unexplained glomerulopathies like IgA nephropathy.
• Minimal change nephrosis and membranous glomerulonephritis also show hyposialylation.
• Sialic acid biosynthesis is crucial for normal kidney function.

Purpose of the Study:

• To investigate the role of sialic acid biosynthesis in kidney development and function.
• To evaluate the therapeutic potential of N-acetylmannosamine (ManNAc) in a mouse model of hyposialylation-induced glomerulopathy.

Main Methods:

• Utilized a mouse model with a mutation in N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase.
• Administered ManNAc to mutant mice to assess its effect on sialylation and survival.
• Employed a lectin panel (WGA, SNA, PNA, Jacalin, HPA, VVA) to analyze glomerular glycan patterns.
• Assessed podocyte effacement, glomerular basement membrane splitting, and albuminuria.

Main Results:

• Mutant mice exhibited severe glomerulopathy and died shortly after birth due to hyposialylation.
• ManNAc treatment improved sialylation, increased survival rates, and reduced albuminuria in mutant mice.
• Lectin analysis revealed hyposialylation of O-linked glycoproteins, including nephrin and podocalyxin, in mutant mice.
• ManNAc treatment partially restored glomerular architecture and sialylation status.

Conclusions:

• Glomerular hyposialylation is a critical factor in the pathogenesis of severe glomerulopathy.
• The developed lectin panel can aid in classifying human kidney diseases based on sialylation status.
• ManNAc shows promise as a potential therapeutic agent for disorders involving glomerular hyposialylation.