JAM-A signals through the Hippo pathway to regulate intestinal epithelial proliferation

Area of Science:

• Cell Biology
• Molecular Biology
• Gastroenterology

Background:

• Junction adhesion molecule A (JAM-A) is a tight-junction protein crucial for intestinal homeostasis.
• The Hippo signaling pathway regulates cell proliferation and is essential for tissue development and maintenance.

Purpose of the Study:

• To investigate the role of JAM-A in initiating the Hippo signaling pathway.
• To elucidate the molecular mechanisms by which JAM-A influences intestinal epithelial cell (IEC) proliferation.

Main Methods:

• Interaction studies between JAM-A, NF2, and LATS1.
• Analysis of YAP activity in JAM-A-deficient and JAM-A-overexpressing IEC.
• Assessment of proliferation in response to JAM-A mutants and EVI1 expression.

Main Results:

• JAM-A interacts with NF2 and LATS1, initiating the Hippo pathway.
• JAM-A deficiency leads to increased YAP activity and proliferation in IEC.
• Overexpression of JAM-A-WT suppresses proliferation, while a dimerization-deficient mutant (JAM-A-DL1) mimics JAM-A deficiency.
• EVI1 acts downstream of YAP to promote proliferation in JAM-A-DL1 overexpressing IEC.

Conclusions:

• JAM-A functions as a cell-cell contact sensor that initiates the Hippo signaling pathway.
• JAM-A plays a critical role in regulating IEC proliferation through the Hippo-YAP axis.
• These findings offer new insights into the contribution of JAM-A to mammalian epithelial homeostasis.