α-Actinin-4 is involved in the process by which dexamethasone protects actin cytoskeleton stabilization from adriamycin-induced podocyte injury.
OBJECTIVE
Glucocorticoid therapy has been used in childhood nephrotic syndrome since the 1950s, where the characteristic change is effacement of the actin-rich foot process of glomerular podocytes. Recent studies have shown that glucocorticoids, in addition to their general immunosuppressive and anti-inflammatory effects, have a direct effect on podocytes, regulate some apoptotic factors, and increase the stability of actin filaments. However, the precise mechanism(s) underlying the protective effects of glucocorticoids on podocytes remain unclear. It is known that adriamycin (ADR) can induce podocyte foot process effacement and trigger massive proteinuria in rodent models. However, few reports have examined the direct role of ADR in podocyte actin rearrangement in vitro. In this study, we investigated how ADR directly induced podocyte actin cytoskeleton rearrangement and further analyzed how dexamethasone prevented such injury.


METHODS
We used confocal microscopy to assess podocyte actin rearrangement. Western blot analysis and real-time polymerase chain reaction were performed to measure the protein and mRNA levels of α-actinin-4.


RESULTS
We demonstrated that there was a time-dependent ADR-induced podocyte actin rearrangement with less than 12 h of ADR treatment in cultured podocytes. Dexamethasone could protect podocytes from ADR-induced injury and also stabilize the expression of α-actinin-4.


CONCLUSIONS
This study showed that dexamethasone had direct effects on podocytes: α-actinin-4 may be one of the potential target molecules.
Department of Nephrology and Rheumatology, Children's Hospital of Fudan University Institutes of Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Haimei
H
Liu
Xia
X
Gao
Hong
H
Xu
Chun
C
Feng
Xinyu
X
Kuang
Zengxia
Z
Li
Xiliang
X
Zha
D008841:Actin Cytoskeleton / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D000185:Actinin / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D015153:Blotting, Western; D002478:Cells, Cultured; D019610:Cytoprotection; D003907:Dexamethasone / Q000494:pharmacology*; D004317:Doxorubicin / Q000633:toxicity*; D051379:Mice; D018613:Microscopy, Confocal; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D020011:Protective Agents / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors
C491752:Actn4 protein, mouse; D000903:Antibiotics, Antineoplastic; D020011:Protective Agents; D012333:RNA, Messenger; D000185:Actinin; D003907:Dexamethasone; D004317:Doxorubicin