Document Detail

Over-expression of alpha-actinin with a GFP fusion protein is sufficient to increase whole-cell stiffness in human osteoblasts.
MedLine Citation:
PMID:  18636329     Owner:  NLM     Status:  MEDLINE    
Osteoblasts respond to shear stress by simultaneously increasing their whole-cell stiffness and up-regulating the cytoskeletal crosslinking protein alpha-actinin. The stiffness of reconstituted cytoskeletal networks increases following the addition of alpha-actinin, but the effect of alpha-actinin on whole-cell mechanical behavior has not been investigated. The hypothesis of this study was that increasing alpha-actinin in the cytoskeleton would be sufficient to increase whole-cell stiffness. hFOB osteoblasts were transfected with a plasmid for GFP-tagged alpha-actinin, resulting in a 150% increase in the amount of alpha-actinin. The GFP-alpha-actinin fusion protein co-fractionated with the cytoskeleton and co-localized to the same regions of the cytoskeleton as endogenous alpha-actinin. Whole-cell mechanical behavior was measured by atomic force microscopy using a 25 mum diameter microsphere as an indenter. The whole-cell stiffness of cells over-expressing GFP-alpha-actinin was 60% higher than cells expressing only endogenous alpha-actinin (p < 0.002), which was within the range of mechanical behavior observed in osteoblastic cells exposed to 1 and 2 Pa of fluid shear. These results indicate that the up-regulation of alpha-actinin synthesis in osteoblasts is sufficient to alter the whole-cell mechanical behavior and highlights the potential role of alpha-actinin to reinforce cells against mechanical loads.
Wesley M Jackson; Michael J Jaasma; Andrew D Baik; Tony M Keaveny
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-07-18
Journal Detail:
Title:  Annals of biomedical engineering     Volume:  36     ISSN:  1573-9686     ISO Abbreviation:  Ann Biomed Eng     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-09-10     Completed Date:  2008-10-09     Revised Date:  2013-05-30    
Medline Journal Info:
Nlm Unique ID:  0361512     Medline TA:  Ann Biomed Eng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1605-14     Citation Subset:  IM    
Department of Mechanical Engineering, Orthopaedic Biomechanics Laboratory, University of California, 6175 Etcheverry Hall, Mailstop 1740, Berkeley, CA 94720-1740, USA.
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MeSH Terms
Actinin / biosynthesis*,  genetics
Cells, Cultured
Cytoskeleton / physiology*,  ultrastructure
Gene Expression
Green Fluorescent Proteins / biosynthesis*,  genetics
Microscopy, Atomic Force
Osteoblasts / physiology*,  ultrastructure
Recombinant Fusion Proteins / biosynthesis*,  genetics
Shear Strength
Stress, Mechanical
Reg. No./Substance:
0/Recombinant Fusion Proteins; 11003-00-2/Actinin; 147336-22-9/Green Fluorescent Proteins

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

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