Ras and Rho GTPase regulation of Pol II transcription: A shortcut model revisited

ABSTRACT

Transcriptional control is critical in relaying signals mediated by Ras and Rho family small GTPases to effect gene expression. In the classical model, signaling components such as MAP kinase target sequence-specific transcription factors, which in turn recruit RNA polymerase (Pol) II holoenzyme to the promoter and activate transcription. Findings in recent years have led to the proposal of a shortcut model in which the Mediator components of the Pol II holoenzyme are regulated by signaling pathways. A very recent finding shows that an evolutionarily conserved Rho GTPase signaling pathway can directly modulate the Pol II C-terminal domain (CTD) phosphorylation by inhibiting the CTD phosphatase in yeast and Arabidopsis. This shortcut model allows direct targeting of the Pol II CTD code and thus has an advantage over the classical model in bringing about rapid, large-scale changes in gene expression.

KEYWORDS:

• CTD code
• CTD phosphatase
• Ras GTPase
• Rho GTPase
• Pol II
• shortcut model
• transcription

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Funding

Z.-L.Z. was supported by NIH grant 3S06GM008225-20S1 and NSF Grant IOS-1121551.