Ouabain Induces Transcript Changes and Activation of RhoA/ROCK Signaling in Cultured Epithelial Cells (MDCK)

Area of Science:

• Biochemistry
• Cell Biology
• Physiology

Background:

• Ouabain, a plant-derived compound, is also endogenously produced in mammals, functioning as a hormone.
• Endogenous ouabain (10 nmol/L) influences epithelial cell polarity and intercellular junctions via cSrc and Erk1/2 signaling.
• The precise mechanisms by which ouabain affects cell-to-cell contacts remain incompletely understood.

Purpose of the Study:

• To investigate the role of RhoA and ROCK in ouabain-mediated regulation of epithelial cell-to-cell contacts.
• To identify novel signaling pathways involved in ouabain's hormonal effects on epithelial cells.

Main Methods:

• Utilized mRNA sequencing (mRNA-seq) to identify differentially expressed genes in response to ouabain.
• Employed RhoA activation assays and ROCK inhibition (using Y27 and C3) to assess signaling pathway involvement.
• Evaluated the effects of ouabain on tight junction seal and gap junctional communication.

Main Results:

• Ouabain treatment led to increased RhoA activation.
• Inhibition of RhoA and ROCK abolished ouabain's enhancement of tight junction integrity.
• Ouabain's positive effect on gap junctional communication was also abrogated by RhoA and ROCK inhibition.

Conclusions:

• Ouabain acts as a hormone to modulate epithelial cell-to-cell adhesion through the RhoA/ROCK signaling pathway.
• These findings elucidate a novel mechanism for ouabain's role in maintaining epithelial phenotype and barrier function.