RNA Polymerase II and Psoriasis
Title: RNA Polymerase II subunit 3 is retained
in the cytoplasm by its interaction with HCR, the psoriasis vulgaris
candidate gene product.
Authors: Corbi N, et al.
Publication: J Cell Sci. 2005 Sep 15;118(Pt 18):4253-4260.
Epub 2005 Sep 1.
The authors have recently demonstrated that the expression of
alpha-like RNA polymerase II core subunit 3 (RPB3) was regulated
during the differentiation or formation of muscle cells. RPB3
was also found inside RNA polymerase II (RNAP II), and was directly
involved in contacting regulatory proteins.
In this article, the authors showed that RPB3 molecules accumulated
in the cytoplasm of cycling myogenic cells or muscle cells that
still undergo cell cycles or cellular division. Upon differentiation
or formation of muscle cells, RPB3 migrated to the cell nucleus.
Using a technique called yeast two-hybrid system, the authors
identified a novel RPB3 cytoplasmic interacting protein called
HCR. HCR was previously identified as alpha-helix coiled-coil
rod homologue, and is one of the candidate genes for psoriasis
The authors showed that in cycling muscle cells, the RPB3 protein
interact directly with HCR within the cytoplasm. When they reduced
the HCR level, the authors demonstrated that the protein act as
a docking site for RPB3 in the cytoplasm.
Editor’s Note: RNA polymerase II is a protein
that creates mRNA (messenger RNA) from the DNA sequence of a particular
gene. The mRNA copy is then used to make proteins.
The yeast two-hybrid system is a widely used technique used to
identify proteins that that bind or interact with each other.
The authors artificially reduced the HCR level by using RNA interference,
where the presence of a double-stranded RNA interferes with the
expression of a particular gene.