O-GlcNAcylation disrupts STRA6-retinol signals in kidneys of diabetes

Biochim Biophys Acta Gen Subj. 2019 Jun;1863(6):1059-1069. doi: 10.1016/j.bbagen.2019.03.014. Epub 2019 Mar 21.

Abstract

Background: O-GlcNAcylation is an important mechanism of diabetic complication. Retinoid homeostasis regulates cell-physiological functions through STRA6-retinol signaling. Therefore, we investigated whether O-GlcNAcylation disrupted STRA6-retinol signals in diabetes.

Methods: Immunoprecipitation and proximity ligation assay were used to investigate O-GlcNAcylation of STRA6-retinol signals in kidneys of db/db and ob/ob mice. Western blot and immunohistochemistry were done for STRA6/CRBP1/LRAT/RALDH1/RARs pathway, GFAT, OGT, TGFβ1 and collagen 1 level. HPLC and ELISA for retinol, retinal, and retinoic acid concentrations were performed in vivo and vitro. RBP4 binding with STRA6 was measured in vitro. To verify whether O-GlcNAcylation disrupted STRA6-retinol signals, treatment of TMG and OSMI-1, transfection of OGA and OGT, and OGT siRNA were performed in HK-2 cells.

Results: STRA6 and RALDH1 were highly O-GlcNAc-modified in glomeruli and tubules of db/db and ob/ob mice. RBP4, p-Try, p-JAK2, and p-STAT5 on STRA6 immunoprecipitate were reduced. Cellular retinol signals (CRBP1, LRAT, ADH, retinol, retinal, RA, RARα, RARγ and RXRα) remarkably decreased in kidneys of db/db, ob/ob mice and HG-cultured cells. TMG and OGT transfection induced O-GlcNAcylation of STRA6 and RALDH1, repressed RBP4-bound STRA6, and retinol signals in NG-cultured cells. OSMI-1, OGA transfection, and OGT silence reversed O-GlcNAc-modification of STRA6 and RALDH1, and rescued the decrease of retinol signals, and reversed the increase of TGFβ1 and collagen 1 in HG-treated cells.

Conclusions: O-GlcNAcylation significantly modified STRA6 and RALDH1, suppressed RBP4 binding activity, and disrupted retinol signals in the kidney of diabetes.

General significance: This study first indicates that STRA6-retinol signals were directly disrupted by O-GlcNAcylation in diabetic kidney.

Keywords: Diabetes; Diabetic nephropathy; O-GlcNAc; RALDH; RBP4; Retinol; STRA6.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acylation
  • Animals
  • Diabetes Mellitus, Experimental / metabolism*
  • Diabetes Mellitus, Experimental / pathology
  • Diabetic Nephropathies / metabolism*
  • Diabetic Nephropathies / pathology
  • Male
  • Membrane Proteins / metabolism*
  • Mice
  • Signal Transduction*
  • Vitamin A / metabolism*

Substances

  • Membrane Proteins
  • Stra6 protein, mouse
  • Vitamin A