Role of acetylation and extracellular location of heat shock protein 90alpha in tumor cell invasion.

ariel submitted, created time 5 months 3 days (cancerres.aacrjournals.org)

Heat shock protein (hsp) 90 is an ATP-dependent molecular chaperone that maintains the active conformation of client oncoproteins in cancer cells. An isoform, hsp90{alpha}, promotes extracellular maturation of matrix metalloproteinase (MMP)-2, involved in tumor invasion and metastasis.Yonghua Yang and partners have found out that reversible hyperacetylation modulates the intracellular and extracellular chaperone function of hsp90, and targeting extracellular hyperacetylated hsp90{alpha} may undermine tumor invasion and metastasis.

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Acetylation Is Indispensable for p53 Activation

kavin submitted, created time 6 months 4 days (www.cell.com)

The activation of the tumor suppressor p53 facilitates the cellular response to genotoxic stress; however, the p53 response can only be executed if its interaction with its inhibitor Mdm2 is abolished. This study identifies p53 acetylation as an indispensable event that destabilizes the p53-Mdm2 interaction and enables the p53-mediated stress response.

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Type I phosphatidylinositol-4,5-bisphosphate 4-phosphatase regulates stress-induced apoptosis

carly submitted, created time 1 year 1 month (www.pnas.org)

A recently discovered phosphatidylinositol monophosphate, phosphatidylinositol 5-phosphate (PtdIns-5-P), plays an important role in nuclear signaling by influencing p53-dependent apoptosis. It interacts with a plant homeodomain finger of inhibitor of growth protein-2, causing an increase in the acetylation and stability of p53.

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Histone H3-K56 Acetylation Is Catalyzed by Histone Chaperone-Dependent Complexes

julie submitted, created time 1 year 8 months (www.molecule.org)

"We show here that H3-K56 acetylation is catalyzed when Rtt109, a protein that lacks significant homology to known acetyltransferases, forms an active complex with either of two histone binding proteins, Asf1 or Vps75. Rtt109 binds to both these cofactors, but not to histones alone, forming enzyme complexes with kinetic parameters similar to those of known histone acetyltransferase (HAT) enzymes. "

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