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Degradation of cytoskeletal proteins by the human immunodeficiency virus type 1 protease
B Höner1, R L Shoeman, P Traub
1Max-Planck-Institut für Zellbiologie, Ladenburg/Heidelberg, FRG.
Abstract:
Triton X-100-extracted human skin fibroblasts were exposed to human immunodeficiency virus type 1 protease and analysed by 2D-gel electrophoresis and immunofluorescence microscopy. Vimentin, two of the tropomyosin isoforms, a protein with M(r) approximately 90,000 and a protein with M(r) approximately 200,000 were found to be degraded. Structurally, this was accompanied by the disintegration of the vimentin filament network and the disappearance of the microfilament network. In contrast to our in vivo observations (Höner et al., 1991), prominent stress fibers and chromatin structure seemed to be rather resistant to the action of this protease.
Insights
Human immunodeficiency virus type 1 protease degrades key cytoskeletal proteins in skin fibroblasts, leading to filament network disintegration. However, stress fibers and chromatin structure showed resistance to this viral protease.
Area of Science:
- Cell Biology
- Virology
- Biochemistry
Background:
- Human immunodeficiency virus type 1 (HIV-1) protease is essential for viral maturation.
- The role of HIV-1 protease in host cell protein degradation, particularly cytoskeletal components, is not fully understood.
- Previous in vivo studies suggested resistance of certain cellular structures to HIV-1 protease.
Purpose of the Study:
- To investigate the in vitro effects of HIV-1 protease on human skin fibroblast proteins.
- To identify specific cellular proteins degraded by HIV-1 protease.
- To examine the structural consequences of protease activity on the fibroblast cytoskeleton.
Main Methods:
- Human skin fibroblasts were extracted with Triton X-100.
- Extracts were exposed to purified HIV-1 protease.
- Analysis was performed using 2D-gel electrophoresis and immunofluorescence microscopy.
Main Results:
- Vimentin, tropomyosin isoforms, and proteins of approximately 90,000 and 200,000 M(r) were degraded.
- Degradation correlated with the disintegration of the vimentin filament network.
- Microfilament network also disappeared.
- Prominent stress fibers and chromatin structure remained largely intact.
Conclusions:
- HIV-1 protease can degrade critical cytoskeletal proteins in human skin fibroblasts in vitro.
- The observed degradation leads to significant disruption of the vimentin and microfilament networks.
- Certain cellular structures, including stress fibers and chromatin, exhibit resistance to HIV-1 protease action, contrasting with some in vivo findings.