AMOTL2 interaction with TAZ causes the inhibition of surfactant proteins expression in lung cells.

BACKGROUND: TAZ (Transcriptional co-Activator with PDZ-binding motif), is a biologically potent transcriptional coactivator and functions by binding to the PPXY motif present in several transcription factors. Notably, TAZ behaves as a transducer linking cytoplasmic signaling events to transcriptional regulation in the nucleus. Several different factors regulate TAZ expression and/or function. In particular, a major regulation of TAZ activity occurs through the Hippo pathway by a phosphorylation-mediated mechanism that causes its cytoplasmic sequestration or degradation.

RESULTS: Here we demonstrate that AMOTL2 robustly co-immunoprecipitates with TAZ, and their interaction is dependent on the WW domain of TAZ and the PPXY motif in the N-terminus of AMOTL2. Furthermore, we show that AMOTL2 colocalizes with TAZ in the cytoplasm of H441 human lung cells and regulates TAZ cytoplasm-to-nucleus translocation through direct protein-protein interaction. Interestingly, the overexpression of AMOTL2 inhibits the functional cooperation between the transcription factor TTF-1 and TAZ on the Surfactant C gene promoter, as well as the expression of other known target genes of these regulatory factors.

CONCLUSIONS: Taken together, our results suggest an inhibitory role of AMOTL2 on TAZ ability to co-activate transcription and describe a different mechanism, Hippo pathway-independent, that modulates the activity of TAZ in lung cells through the interaction with Angiomotin-like 2 (AMOTL2).