R168H and V165X mutant podocin might induce different degrees of podocyte injury via different molecular mechanisms.
A lot of mutations of podocin, a key protein of podocyte slit diaphragm (SD), have been found both in hereditary and sporadic focal segmental glomeruloscleorosis (FSGS). Nevertheless, the mechanisms of podocyte injury induced by mutant podocins are still unclear. A compound heterozygous podocin mutation was identified in our FSGS patient, leading to a truncated (podocin (V165X)) and a missense mutant protein (podocin (R168H)), respectively. Here, it was explored whether and how both mutant podocins induce podocyte injury in the in vitro cultured podocyte cell line. Our results showed that podocin (R168H) induced more significant podocyte apoptosis and expression changes in more podocyte molecules than podocin (V165X). Podocyte injury caused by the normal localized podocin(V165X) was effectively inhibited by TRPC6 knockdown. The abnormal retention of podocin(R168H) in endoplasmic reticulum (ER) resulted in the mis-localizations of other critical SD molecules nephrin, CD2AP and TRPC6, and significantly up-regulated ER stress markers Bip/grp78, p-PERK and caspase-12. These results implicated that podocin (R168H) and podocin (V165X) induced different degrees of podocyte injury, which might be resulted from different molecular mechanisms. Our findings provided some possible clues for further exploring the pharmacological targets to the proteinuria induced by different mutant podocins.
Fan
Qingfeng
Q
Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
Zhang
Han
H
Ding
Jie
J
Liu
Shufang
S
Miao
Jing
J
Xing
Yan
Y
Yu
Zihua
Z
Guan
Na
N
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005923:Glomerulosclerosis, Focal Segmental / Q000235:genetics / Q000503:physiopathology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D009154:Mutation; D050199:Podocytes / Q000187:drug effects*; D011507:Proteinuria / Q000209:etiology*; D050052:TRPC Cation Channels / Q000378:metabolism; D000074287:TRPC6 Cation Channel
D048868:Adaptor Proteins, Signal Transducing; C114545:CD2-associated protein; D003598:Cytoskeletal Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; C000717248:Hspa5 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C407223:NPHS2 protein; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C113267:nephrin