Journal article
Thoracic Aortic Aneurysm (TAAD)-causing Mutation in Actin Affects Formin Regulation of Polymerization
The Journal of biological chemistry, Vol.287(34), pp.28398-28408
08/17/2012
DOI: 10.1074/jbc.M112.371914
PMCID: PMC3436569
PMID: 22753406
Abstract
Background:
The biochemical mechanisms underlying α-smooth muscle actin-mediated vascular disease are unknown.
Results:
The R256H mutation in actin alters polymerization kinetics and causes misregulation by the nucleation factor, formin.
Conclusion:
Mutation-based changes in conformation affect filament stability and regulation of polymerization.
Significance:
The Arg-256 residue stabilizes the actin helix and maintains filament conformation required for formin regulation.
More than 30 mutations in
ACTA2
, which encodes α-smooth muscle actin, have been identified to cause autosomal dominant thoracic aortic aneurysm and dissection. The mutation R256H is of particular interest because it also causes patent ductus arteriosus and moyamoya disease. R256H is one of the more prevalent mutations and, based on its molecular location near the strand-strand interface in the actin filament, may affect F-actin stability. To understand the molecular ramifications of the R256H mutation, we generated
Saccharomyces cerevisiae
yeast cells expressing only R256H yeast actin as a model system. These cells displayed abnormal cytoskeletal morphology and increased sensitivity to latrunculin A. After cable disassembly induced by transient exposure to latrunculin A, mutant cells were delayed in reestablishing the actin cytoskeleton.
In vitro
, mutant actin exhibited a higher than normal critical concentration and a delayed nucleation. Consequently, we investigated regulation of mutant actin by formin, a potent facilitator of nucleation and a protein needed for normal vascular smooth muscle cell development. Mutant actin polymerization was inhibited by the FH1-FH2 fragment of the yeast formin, Bni1. This fragment strongly capped the filament rather than facilitating polymerization. Interestingly, phalloidin or the presence of wild type actin reversed the strong capping behavior of Bni1. Together, the data suggest that the R256H actin mutation alters filament conformation resulting in filament instability and misregulation by formin. These biochemical effects may contribute to abnormal histology identified in diseased arterial samples from affected patients.
Details
- Title: Subtitle
- Thoracic Aortic Aneurysm (TAAD)-causing Mutation in Actin Affects Formin Regulation of Polymerization
- Creators
- Lindsey E Malloy - From the Departments ofKuo-Kuang Wen - Biochemistry, Roy A. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242Alyson R Pierick - From the Departments ofElesa W Wedemeyer - From the Departments ofSarah E Bergeron - From the Departments ofNicole D Vanderpool - Biochemistry, Roy A. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242Melissa McKane - Biochemistry, Roy A. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242Peter A Rubenstein - Biochemistry, Roy A. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242Heather L Bartlett - From the Departments of
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.287(34), pp.28398-28408
- DOI
- 10.1074/jbc.M112.371914
- PMID
- 22753406
- PMCID
- PMC3436569
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- American Society for Biochemistry and Molecular Biology; 9650 Rockville Pike, Bethesda, MD 20814, U.S.A
- Grant note
- DC008803; UL1RR024979 / National Institutes of Health
- Alternative title
- Formin Misregulation of TAAD Mutant Actin
- Language
- English
- Date published
- 08/17/2012
- Academic Unit
- Stead Family Department of Pediatrics; Biochemistry and Molecular Biology; Internal Medicine
- Record Identifier
- 9984025282402771
Metrics
13 Record Views