Alpha-actinin-4-mediated FSGS: an inherited kidney disease caused by an aggregated and rapidly degraded cytoskeletal protein.
PLoS Biol
; 2(6): e167, 2004 Jun.
Article
em En
| MEDLINE
| ID: mdl-15208719
ABSTRACT
Focal segmental glomerulosclerosis (FSGS) is a common pattern of renal injury, seen as both a primary disorder and as a consequence of underlying insults such as diabetes, HIV infection, and hypertension. Point mutations in the alpha-actinin-4 gene ACTN4 cause an autosomal dominant form of human FSGS. We characterized the biological effect of these mutations by biochemical assays, cell-based studies, and the development of a new mouse model. We found that a fraction of the mutant protein forms large aggregates with a high sedimentation coefficient. Localization of mutant alpha-actinin-4 in transfected and injected cells, as well as in situ glomeruli, showed aggregates of the mutant protein. Video microscopy showed the mutant alpha-actinin-4 to be markedly less dynamic than the wild-type protein. We developed a "knockin" mouse model by replacing Actn4 with a copy of the gene bearing an FSGS-associated point mutation. We used cells from these mice to show increased degradation of mutant alpha-actinin-4, mediated, at least in part, by the ubiquitin-proteasome pathway. We correlate these findings with studies of alpha-actinin-4 expression in human samples. "Knockin" mice with a disease-associated Actn4 mutation develop a phenotype similar to that observed in humans. Comparison of the phenotype in wild-type, heterozygous, and homozygous Actn4 "knockin" and "knockout" mice, together with our in vitro data, suggests that the phenotypes in mice and humans involve both gain-of-function and loss-of-function mechanisms.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Fenótipo
/
Actinina
/
Glomerulosclerose Segmentar e Focal
/
Regulação da Expressão Gênica
/
Proteínas dos Microfilamentos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2004
Tipo de documento:
Article