发信人: Marble (小石头哥哥), 信区: Biology
标 题: Re: Apoptosis---Re: Call for MCBJC dicus
发信站: The unknown SPACE (Sat Apr 5 18:17:10 2003) WWW-POST

i have just read the paper and found it is more interesting than i have
expected. they basically took a chemical screening/biochemical analysis
approach to identify novel genes that regulate the activation of caspase-3.
they found a chemical compound, namely PETCM, that could promote apoptosis,
then they fractionated protein extracts and looked for proteins that mediated
the apoptome promotion effect of PETCM; and they characterized several PHAP
genes that are tumor suppressors as well as ProT which is an oncogene. PHAPI
acts as positive regulator for apoptome formation, while ProT is an inhibitor;
and they seem to act at different steps for the apoptome formation.

so my questions are: what are the proteins that interact with PHAPI and ProT
before and after caspase activation? could this be solved by proteomics? since
PETCM releases the suppression effect from Q100 fraction, this question should
be addressed in the absence and presence of PETCM. i do not think that they
only purified one inhibitory factor as the ProT; actually they mentioned that
the PETCM effect could not be reproduced in a reconstituted system with
purified proteins, and additional factors may exist.

very interesting thing is that RNAi for ProT sensitizes HeLa cells to apotosis
after UV irradiation and this probably suggests that RNAi for oncogene in
certain circumstances may have clinical usage. it will be interesting to know
occurrence of mutations of PHAPI and ProT in diseases, particularly in cancers
with abnormal apoptosis. i do not know whether knockout animal models are
available now for these genes, but it seems a little problematic with PHAP due
to redundancy.

as for the chemical compound PETCM, does PETCM bind directly to caspase-3? if
so, what are the binding sites and stoichemistry? would it be possible to
generate missiled-PETCM that target cancerous cells to promote cell death, if
the tocixity is tolerable?

this paper applied a lot of biochemistry and a little bit of genetics. for the
future study, i think a specific structure-oriented chemical compound library
screening should be carried out in a variety of genetic background, and this
requires knowledge of the protein structure as well as key components of the
signalling pathway. and bioinformatic analysis for functional domain and
genetic/biochemical shuffeling experiments may provide invaluable information
as well. as i am very interested in applying genetic approaches to tackle such
problem, i am wondering whether RNAi for mammalian cell and functional assay
could be used to screen genes involved in the signalling pathway. (for
example, in the presence of ATP or PETCM and assay the formation of
apoptosome).

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thanks for your patience to read my blah blah blah ... hehe.







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※ 修改:·Marble 於 Apr 5 18:17:10 修改本文·[FROM: 128.118.]
※ 来源:．The unknown SPACE bbs.mit.edu．[FROM: 128.118.]