发信人: leohawk (leohawk), 信区: Biology
标 题: Re: Apoptosis---Re: Call for MCBJC dicus
发信站: The unknown SPACE (Sat Apr 5 21:45:04 2003) WWW-POST

It is an amazing paper, proof of principle of HTS methods for drug screening
and deciphering
complicated signal transduction network.

However, I don't get it when they say: "In contrast, the presense of PHAPI did
not affect ... and
increased caspase-9 was associated with apoptosome" This should be the natural
function of PHAPI, right? and did they do a timecourse? as to if add PHAPI
first, then
ProT later, will this be reversed? I probably missed something here.

and why they only tested PHAP1, I would be very interested in the other 2,
individual
function and combined function...

ProT might be involved in DNA repair from data they presented, it is probably
involved
in blocking apoptosis to give cell enough time to repair UV damaged DNA ...
hopefully
only to certain level. My wide guess is there is something inhibit ProT
function naturally
occuring in cell, only to be initiated when cell damage is beyond control...
may well
be a feedback loop of the whole caspase pathway...

one door open, release the factor that open all other doors...

only wild guess


【 在 Marble (小石头哥哥) 的大作中提到: 】
: 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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