Pyrrolidine dithiocarbamate and zinc inhibit proteasome-dependent proteolysis.
Proteasomes play important roles in a variety of cellular processes such as cell cycle progression, signal transduction and immune responses. Proteasome activity is important in maintaining rapid turnover of short-lived proteins, as well as preventing accumulation of misfolded or damaged proteins. Alteration in ubiquitin-proteasome function may be detrimental to its crucial role in maintaining cellular homeostasis. Here, we have found that treatment of pyrrolidine dithiocarbamate (PDTC), a zinc ionophore, resulted in the accumulation of several proteasome substrates including p53 and p21 in HeLa cells. The PDTC effect was due to an extended half-life of these proteins through the mobilization of zinc. PDTC and/or zinc also increased fluorescence intensity of Ub(G76V)-GFP fusion protein that is degraded rapidly by the ubiquitin-proteasome system. Treatment of cells with zinc induced formation of ubiquitinated inclusions in the centrosome, a histological marker of proteasome inhibition. Western blotting showed zinc-induced increase in laddering bands of polyubiquitin-conjugated proteins. In vitro study, zinc inhibited the ubiquitin-independent proteasomal degradations of p21 and alpha-synuclein. These results suggest that zinc may modulate cell functions through its action on the turnover of proteins that are susceptible to proteasome-dependent proteolysis.
Kim
Insook
I
Brain Korea 21 Project for Medical Science, Brain Research Institute, Yonsei University College of Medicine, Seoul 120-752, South Korea.
Kim
Chul Hoon
CH
Kim
Joo Hee
JH
Lee
Jinu
J
Choi
Jun Jeong
JJ
Chen
Zheng Ai
ZA
Lee
Min Goo
MG
Chung
Kwang Chul
KC
Hsu
Chung Y
CY
Ahn
Young Soo
YS
D018385:Centrosome / Q000187:drug effects / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000378:metabolism; D010447:Peptide Hydrolases / Q000187:drug effects / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000378:metabolism*; D011759:Pyrrolidines / Q000494:pharmacology*; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000378:metabolism; D051843:Synucleins; D013859:Thiocarbamates / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025801:Ubiquitin / Q000187:drug effects / Q000378:metabolism; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology*; D051844:alpha-Synuclein
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D007476:Ionophores; D009097:Multienzyme Complexes; D009419:Nerve Tissue Proteins; D011506:Proteins; D011759:Pyrrolidines; D011993:Recombinant Fusion Proteins; C497604:SNCA protein, human; D051843:Synucleins; D013859:Thiocarbamates; D016159:Tumor Suppressor Protein p53; D025801:Ubiquitin; D051844:alpha-Synuclein; C020972:pyrrolidine dithiocarbamic acid; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D015032:Zinc