A proteomic approach towards the Hsp90-dependent ubiquitinylated proteome.
Since many Hsp90 client proteins are key players in tumour pathways, the ubiquitylation and subsequent degradation of Hsp90-substrates as a consequence of pharmacologically inhibiting Hsp90 represents an innovative approach for cancer therapy. We therefore identified Hsp90-binding proteins which accumulated as ubiquityl-tagged aggregates in the detergent insoluble fraction of HeLa cells as a consequence of simultaneously inhibiting Hsp90 and the proteasome. 2-DE followed by nanoLC-MS/MS of trypsinised protein spots provided the Hsp90-dependent ubiquitylated proteome which was finally annotated and functionally classified. The overall picture thus obtained emphasised the well-established role of Hsp90 in stabilising proteins involved in gene transcription and signal transduction. It also provided a novel Hsp90-related link to metabolic pathways as the inhibition of Hsp90 caused the ubiquitylation of a significant amount of metabolic enzymes. These findings serve to support cumulating indications which attribute Hsp90 to diverse stabilising functions beyond signal transduction and gene transcription.
Falsone
S Fabio
SF
Institute of Pharmaceutical Sciences, University of Graz, Austria.
Gesslbauer
Bernd
B
Rek
Angelika
A
Kungl
Andreas J
AJ
D015180:Electrophoresis, Gel, Two-Dimensional; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D018942:Macrolides / Q000494:pharmacology; D011485:Protein Binding; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics; D012995:Solubility; D025801:Ubiquitin / Q000378:metabolism*
D018841:HSP90 Heat-Shock Proteins; D007976:Leupeptins; D018942:Macrolides; D020543:Proteome; D025801:Ubiquitin; C035359:monorden; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde