Splice variant insertions in the C-terminus impairs YAP's transactivation domain

Area of Science:

• Molecular Biology
• Cell Signaling
• Transcriptional Regulation

Background:

• The yes-associated protein (YAP) is a crucial effector in the mammalian Hippo signaling pathway.
• YAP exhibits multiple alternately spliced isoforms with varied reported cellular effects.
• The impact of isoform-specific transcriptional potency on YAP function remains unquantified.

Purpose of the Study:

• To systematically compare the transcriptional potencies of different human YAP isoforms.
• To investigate how splice variant insertions in the transactivation domain affect YAP's transcriptional activity.
• To elucidate the roles of WW domains and the leucine zipper motif in YAP transcriptional regulation.

Main Methods:

• Overexpression and transcriptional reporter assays were employed.
• Full-length coding sequence constructs of YAP isoforms were utilized.
• GAL4-YAP fusion proteins assessed transactivation domain activity.

Main Results:

• Both the number of WW domains and the integrity of the leucine zipper motif influence YAP's transcriptional activity.
• Disruption of the leucine zipper motif significantly reduced transcriptional potency, more so than the absence of the second WW domain.
• GAL4-YAP fusion protein assays confirmed the critical role of the leucine zipper in transcriptional activity across multiple cell lines.

Conclusions:

• Differential transcriptional potencies among YAP isoforms allow for fine-tuning of Hippo pathway signaling.
• Experimental interpretations and future YAP research designs must consider the specific YAP isoform utilized.