O-linked β-N-acetylglucosamine modification of proteins is essential for foot process maturation and survival in podocytes

Nephrol Dial Transplant. 2017 Sep 1;32(9):1477-1487. doi: 10.1093/ndt/gfw463.

Abstract

Background: O-linked β- N -acetylglucosamine modification O-GlcNAcylation) is a post-translational modification of intracellular proteins, serving as a nutrient sensor. Growing evidence has demonstrated its physiological and pathological importance in various mammalian tissues. This study examined the physiological role of O-GlcNAcylation in podocyte function and development.

Methods: O-GlcNAc transferase (Ogt) is a critical enzyme for O-GlcNAcylation and resides on the X chromosome. To abrogate O-GlcNAcylation in podocytes, we generated congenital and tamoxifen (TM)-inducible podocyte-specific Ogt knockout mice (Podo-Ogt y/- and TM-Podo-Ogt y/- , respectively) and analyzed their renal phenotypes.

Results: Podo-Ogt y/- mice showed normal podocyte morphology at birth. However, they developed albuminuria at 8 weeks of age, increasing progressively until age 32 weeks. Glomerular sclerosis, proteinuria-related tubulointerstitial lesions and markedly altered podocyte foot processes, with decreased podocin expression, were observed histologically in 32-week-old Podo-Ogt y/- mice. Next, we induced adult-onset deletion of the Ogt gene in podocytes by TM injection in 8-week-old TM-Podo-Ogt y/- mice. In contrast to Podo-Ogt y/- mice, the induced TM-Podo-Ogt y/- mice did not develop albuminuria or podocyte damage, suggesting a need for O-GlcNAcylation to form mature foot processes after birth. To test this possibility, 3-week-old Podo-Ogt y/- mice were treated with Bis-T-23, which stimulates actin-dependent dynamin oligomerization, actin polymerization and subsequent foot process elongation in podocytes. Albuminuria and podocyte damage in 16-week-old Podo-Ogt y/- mice were prevented by Bis-T-23 treatment.

Conclusions: O-GlcNAcylation is necessary for maturation of podocyte foot processes, particularly after birth. Our study provided new insights into podocyte biology and O-GlcNAcylation.

Keywords: O-GlcNAcylation; O-linked N-acetylglucosamine transferase; foot process; podocyte.

MeSH terms

  • Acetylglucosamine / chemistry*
  • Animals
  • Female
  • Foot / physiology*
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Male
  • Membrane Proteins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • N-Acetylglucosaminyltransferases / physiology*
  • Podocytes / metabolism*
  • Protein Processing, Post-Translational*

Substances

  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • NPHS2 protein
  • N-Acetylglucosaminyltransferases
  • O-GlcNAc transferase
  • Acetylglucosamine