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Acid Sphingomyelinase Gene Knockout Ameliorates Hyperhomocysteinemic Glomerular Injury in Mice Lacking Cystathionine β‐synthase
Author(s) -
Boini Krishna M,
Xia Min,
Li Cai-Xia,
Xiong Jing,
Li Pin-Lan
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.691.6
Subject(s) - podocin , acid sphingomyelinase , cystathionine beta synthase , ceramide , sphingomyelin phosphodiesterase , podocyte , knockout mouse , gene knockout , endocrinology , medicine , chemistry , sphingolipid , sphingomyelin , biology , microbiology and biotechnology , biochemistry , kidney , cysteine , gene , proteinuria , enzyme , cholesterol , apoptosis
Acid sphingomyelinase (ASM) have been implicated in the development of hyperhomocysteinemia (hHcys)‐induced glomerular oxidative stress and injury. However, it remains unknown whether genetically engineering of ASM gene produces beneficial or detrimental action on hHcys‐induced glomerular injury. The present study generated and characterized cystathionine β‐synthase (Cbs) double knockout (DKO) by cross breeding Cbs +/− and Asm +/− . Given that the homozygotes of Cbs −/− /Asm −/− DKO mice could not survive for 3 weeks. Cbs +/− , Asm −/− and Cbs +/− /Asm −/− as well as their wild type littermates were used to study the action of Asm −/− under a background of Cbs +/− with hHcys. HPLC analysis revealed that plasma Hcy level was significantly elevated in Cbs +/−/ Asm +/+ , Cbs +/− /Asm +/− , and Cbs +/− /Asm −/− mice (11.6±0.9, 11.4±0.9 and 11.8±1.0 μm) compared to their wild type littermates (4.3±0.6 μm). Cbs +/− /Asm +/+ mice had significantly increased renal Asm activity, O 2 − production and ceramide production compared to Cbs +/+ /Asm +/+ , while Cbs +/− /Asm −/− mice showed a significantly reduced hHcys‐induced renal Asm activity, O 2 − production and ceramide production. Confocal microscopy demonstrated that colocalization of podocin with ceramide was much lower in Cbs +/−/ Asm −/− mice compared to Cbs +/− /Asm +/+ mice, which was accompanied by a reduced glomerular damage index, albuminuria and proteinuria in Cbs +/− /Asm −/− mice. Immunofluorescent analyses of the podocin and desmin expression also illustrated strong podocyte damages in the glomeruli from Cbs +/− /Asm +/+ mice, but not in Cbs +/− /Asm −/− mice. In in vitro studies of podocytes, hHcys‐enhanced O 2 − production and decreased VEGF level in podocytes were substantially attenuated by prior treatment with Amitriptyline, an Asm inhibitor. In conclusion, Asm protect the podocytes and glomeruli from hHcys‐induced oxidative stress and injury (supported by NIH DK54927, HL75316).