Induction of apoptosis in cells expressing exogenous Hippi, a molecular partner of huntingtin-interacting protein Hip1.
To decipher the pathway of apoptosis induction downstream to caspase-8 activation by exogenous expression of Hippi, an interactor of huntingtin-interacting protein Hip1, we studied apoptosis in HeLa and Neuro2A cells expressing GFP-tagged Hippi. Nuclear fragmentation, caspase-1, caspase-8, caspase-9/caspase-6 and caspase-3 activation were increased significantly in Hippi expressing cells. Cleavage of Bid, release of cytochrome c and apoptosis inducing factor (AIF) from mitochondria were also increased in GFP-Hippi expressing cells. It was observed that caspase-1 and caspase-8 activation was earlier than caspase-3 activation and nuclear fragmentation. Expression of caspase-1, caspase-3 and caspase-7 was increased while anti-apoptotic gene Bcl-2 and mitochondrial genes ND1 and ND4 were reduced in Hippi expressing cells. Besides, the expression SDHA and SDHB, nuclear genes, subunits of mitochondrial complex II were decreased in GFP-Hippi expressing cells. Taken together, we concluded that Hippi expression induced apoptosis by releasing AIF and cytochrome c from mitochondria, activation of caspase-1 and caspase-3, and altering the expression of apoptotic genes and genes involved in mitochondrial complex I and II.
Majumder
Pritha
P
Structural Genomics Section, Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064, India.
Chattopadhyay
Biswanath
B
Mazumder
Arindam
A
Das
Pradeep
P
Bhattacharyya
Nitai P
NP
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D051033:Apoptosis Inducing Factor / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000503:physiopathology; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism; D042963:Electron Transport Complex II / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D009410:Nerve Degeneration / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics*; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D051033:Apoptosis Inducing Factor; D004268:DNA-Binding Proteins; C073368:HIP1 protein, human; C499179:IFT57 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D007506:Iron-Sulfur Proteins; C432129:Nd1 protein, mouse; D021122:Protein Subunits; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D045304:Cytochromes c; D042963:Electron Transport Complex II; C511268:SDHA protein, human; C108095:SDHB protein, human; D013385:Succinate Dehydrogenase; D020169:Caspases; D042967:Electron Transport Complex I