Aggregation of hsp70 and hsc70 in vivo is distinct and temperature-dependent and their chaperone function is directly related to non-aggregated forms
Loading...
Date
Authors
Angelidis, C. E.
Lazaridis, I.
Pagoulatos, G. N.
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Type
Type of the conference item
Journal type
peer-reviewed
Educational material type
Conference Name
Journal name
Eur J Biochem
Book name
Book series
Book edition
Alternative title / Subtitle
Description
We used non-denaturing gradient analysis of cell extracts before and after heat treatment of the cells and showed that hsp70 and hsc70 aggregate in vivo in a temperature-dependent fashion. Their aggregation profiles were found to be clearly distinguishable and sensitive to ATP depletion. Pore exclusion limit electrophoresis showed that these two proteins are mainly found in autoaggregated forms including dimers, trimers and oligomers. The addition of denatured luciferase to the cell extracts reversed the aggregation of both proteins towards their non-aggregated forms. Immunoprecipitation and Western-blot analysis showed that the non-aggregated form is the only one bound to denatured luciferase. Our results suggest that aggregated hsp70 and hsc70 represent predominantly self-associated molecules unable to exert chaperone activity. The cochaperone hsp40 was also found to be aggregated and, on addition of denatured luciferase, its aggregation was reversed to a non-aggregated state. Immunoprecipitation analysis indicated that hsp40 forms a complex with the non-aggregated form of hsc70 and denatured luciferase. These results confirm previous in vitro studies and support the suggestion that in vivo cytosolic hsp70 and hsc70 exist mainly in an oligomer-monomer equilibrium which is dependent on the environmental temperature, the levels of ATP and the presence of denatured proteins.
Description
Keywords
Adenosine Triphosphate/metabolism, Carrier Proteins/*metabolism, HSC70 Heat-Shock Proteins, HSP40 Heat-Shock Proteins, HSP70 Heat-Shock Proteins/*metabolism, Heat-Shock Proteins/metabolism, Hot Temperature, Luciferases/metabolism, Particle Size, Protein Binding, Protein Denaturation, *Protein Folding
Subject classification
Citation
Link
http://www.ncbi.nlm.nih.gov/pubmed/9914533
http://onlinelibrary.wiley.com/store/10.1046/j.1432-1327.1999.00078.x/asset/j.1432-1327.1999.00078.x.pdf?v=1&t=h2bp453j&s=305b6f473f5bfa948e0e0f48a5ea2bb24bca8032
http://onlinelibrary.wiley.com/store/10.1046/j.1432-1327.1999.00078.x/asset/j.1432-1327.1999.00078.x.pdf?v=1&t=h2bp453j&s=305b6f473f5bfa948e0e0f48a5ea2bb24bca8032
Language
en
Publishing department/division
Advisor name
Examining committee
General Description / Additional Comments
Institution and School/Department of submitter
Πανεπιστήμιο Ιωαννίνων. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής