Quantitative proteomics of the SMAD transcription factor family reveals IPO5 as a BMP Receptor-SMAD specific importin

ABSTRACT: Gene-specific transcription factors (GSTFs) control of gene transcription by DNA binding and specific protein complex recruitment, which regulates promoter accessibility for transcription initiation by RNA polymerase II. GSTFs that are frequently mutated in colon and rectal carcinomas are Suppressor of Mothers Against Decapentaplegic 2 (SMAD2) and SMAD4, which play an important role in the TGF-β signaling pathways controlling cell fate and proliferation (ref.). The SMAD protein family is a diverse and it can be divided into three subclasses: receptor activated SMADs, inhibitory SMADs and the common SMAD4 co-activator. To study protein interactors of the SMAD protein family we generated a quantitative proteomics pipeline that allows for inducible expression of GFP-tagged SMAD proteins followed by affinity purification and MS analysis. The nuclear importin IPO5 was identified as a novel interacting protein of SMAD1. Overexpression of IPO5 shows forced BMP R-SMAD nuclear localization confirming a functional relationship between BMP but not TGF-β R-SMADs and IPO5. Finally we provide evidence that the length of the lysine stretch in the NLS is involved in importin selection.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Permanent Cell Line Cell

SUBMITTER: Harmjan Vos  

LAB HEAD: H.Th. Marc Timmers

PROVIDER: PXD004529 | Pride | 2016-10-10

REPOSITORIES: Pride