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closeP2P-R is not a component of the miRNA processing machinery
Posted by giannako on 26 May 2010 at 11:22 GMT
According to the author the RNA binding protein, P2P-R, has been shown to bind to Dicer/TARBP2/Ago2, and thereby enhances the processing of mature miRNAs [24], [25].
This is not correct and it is based on a misunderstanding.
PACT (PKR activator) has been shown to bind to Dicer/TARBP2/Ago2 and may therefore be considered as a component of the miRNA processing machinery.
P2P-R is also known as PACT but in this case PACT stands for P53 Associated Cellular protein-Testes derived.
P2P-R has indeed been shown to promote the binding of MDM2 to the tumor suppressor p53, and thereby interferes with its ability to transactivate its target genes [26].
RE: P2P-R is not a component of the miRNA processing machinery
boomi replied to giannako on 01 Jun 2010 at 19:06 GMT
The author considers Dr. Thomas’s comments irrational/incorrect/insignificant for the following reasons:
1. Any protein (e.g. P2P-R) that is associated with the essential component (e.g. Dicer, TRBP2, and Ago) of the miRNA processing machinery is capable of altering its function.
2. It has been shown that P2P-R associates with Dicer, TRBP2, and hAgo2 proteins (microRNA processing complex present in the cytoplasm). By associating with microRNA processing complex, it increases miRNA (e.g., miR-30a-5p and miR-124a) production [24]. Evidently, reduction of P2P-R levels has been shown to reduce the mature miRNA production, suggesting that it functions as a co-factor for Dicer, TRBP2, and hAgo2 proteins or it alters the function of the protein that is required for the miRNA processing [24]. Therefore, it should be considered as a component of the miRNA processing machinery.
3. The author is aware of the fact that a number of other names, such as RBQ, RBBP6, PACT, and PRKRA, exist in the literature for P2P-R. However, it is known to the scientific community that any terminology used should be consistent throughout the manuscript. It is not encouraged to use different names for a single protein within the manuscript. Therefore, the author did not use multiple names that exist in the literature for P2P-R.
4. The author would like to point out to Dr. Thomas that PACT was cloned by his colleague [Simons et al., 1997] at the Weizmann Institute of Science for the first time.
Reference
Simons A, Melamed-Bessudo C, Wolkowicz R, Sperling J, Sperling R, Eisenbach L, Rotter V. PACT: cloning and characterization of a cellular p53 binding protein that interacts with Rb. Oncogene. 1997 Jan 16;14(2):145-55.
P2P-R is a component of the miRNA processing machinery
boomi replied to boomi on 01 Jun 2010 at 19:32 GMT
For the reasons stated above, P2P-R is a component of the miRNA processing machinery.
RE: RE: P2P-R is not a component of the miRNA processing machinery
giannako replied to boomi on 02 Jun 2010 at 10:57 GMT
The author is still under confusion.
There are TWO completely different proteins under the name PACT in the litterature.
The first one is PKR activator (Pkr ACTivator, PACT) that is a rather small protein consisting of 334 aa and that has been shown to associate with the microRNA processing complex, present in the cytoplasm (reference 24). This protein IS NOT P2P-R.
P2P-R is also known with the name PACT but in this case PACT stands for P53 Associated Cellular protein-Testes derived. P2P-R is a large nuclear matrix-associated protein consisting of 1560 aa and is not a component of the miRNA processing machinery.
This second protein was cloned indeed by Simons et al at the Weizmann Institute of Science.
The only known thing about P2P-R is that it promotes the binding of MDM2 to the tumor suppressor p53, and thereby interferes with its ability to transactivate its target genes [reference 26].