Document Detail


Glucocorticoids protect and enhance recovery of cultured murine podocytes via actin filament stabilization.
MedLine Citation:
PMID:  16316324     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Nephrotic syndrome is a common kidney disease in both children and adults that is characterized by dramatic structural changes in the actin-rich foot processes of glomerular podocytes. Although glucocorticoids are the primary treatment for nephrotic syndrome, neither the target cell nor mechanism of action of glucocorticoids in nephrotic syndrome is known. For the last 30 years glucocorticoids have been presumed to act by reducing the release of soluble mediators of disease by circulating lymphocytes. In contrast, we hypothesized that glucocorticoids exert their beneficial effects in nephrotic syndrome by direct action on podocytes. METHODS: Cultured murine podocytes were treated with glucocorticoids in the presence and absence of mifepristone (to inhibit glucocorticoid-induced transcriptional activation) and challenged using our previously reported in vitro model of puromycin aminonucleoside (PAN)-induced podocyte injury, as well as by direct disruption of actin filaments with latrunculin and cytochalasin. Cell viability, actin filament distribution, total polymerized actin content, and actin-regulating guanine triphosphatase (GTPase) activities were measured. RESULTS: We demonstrated that treatment of cultured murine podocytes with the glucocorticoid dexamethasone both protected and enhanced recovery from PAN-induced injury. Dexamethasone also increased total cellular polymerized actin, stabilized actin filaments against disruption by PAN, latrunculin, or cytochalasin, and induced a significant increase in the activity of the actin-regulating GTPase RhoA. CONCLUSION: These data suggest that, contrary to the current therapeutic paradigm, the beneficial effects of glucocorticoids in nephrotic syndrome may result, at least in part, from direct effects on podocytes leading to enhanced actin filament stability.
Authors:
Richard F Ransom; Nancy G Lam; Mark A Hallett; Simon J Atkinson; William E Smoyer
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Kidney international     Volume:  68     ISSN:  0085-2538     ISO Abbreviation:  Kidney Int.     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-11-30     Completed Date:  2006-02-01     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0323470     Medline TA:  Kidney Int     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2473-83     Citation Subset:  IM    
Affiliation:
Pediatric Nephrology Division, University of Michigan, Ann Arbor, MI 48109, USA. rransom@umich.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Anti-Inflammatory Agents / pharmacology*
Antibiotics, Antineoplastic / pharmacology
Bicyclo Compounds, Heterocyclic / pharmacology
Cell Line, Transformed
Cell Survival / drug effects
Cytochalasin D / pharmacology
Dexamethasone / pharmacology*
Drug Interactions
Hormone Antagonists / pharmacology
Mesangial Cells / cytology,  drug effects,  metabolism
Mice
Microfilaments / drug effects*,  metabolism
Mifepristone / pharmacology
NIH 3T3 Cells
Nucleic Acid Synthesis Inhibitors / pharmacology
Podocytes / cytology*,  drug effects*,  metabolism
Polymers / metabolism
Puromycin Aminonucleoside / pharmacology
Thiazoles / pharmacology
Thiazolidines
rho GTP-Binding Proteins / metabolism
Grant Support
ID/Acronym/Agency:
DK53194/DK/NIDDK NIH HHS; K08 DK02455-01/DK/NIDDK NIH HHS; R01 DK55602/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Anti-Inflammatory Agents; 0/Antibiotics, Antineoplastic; 0/Bicyclo Compounds, Heterocyclic; 0/Hormone Antagonists; 0/Nucleic Acid Synthesis Inhibitors; 0/Polymers; 0/Thiazoles; 0/Thiazolidines; 22144-77-0/Cytochalasin D; 50-02-2/Dexamethasone; 58-60-6/Puromycin Aminonucleoside; 76343-93-6/latrunculin A; 84371-65-3/Mifepristone; EC 3.6.5.2/rho GTP-Binding Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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