Plakophilin 2 affects cell migration by modulating focal adhesion dynamics and integrin protein expression

Area of Science:

• Cell Biology
• Dermatology
• Biochemistry

Background:

• Plakophilin 2 (PKP2) is a desmosome component regulating cell-cell contacts and actin dynamics.
• Loss of PKP2 is associated with increased actin stress fibers and altered cell morphology.
• The role of PKP2 in focal adhesion dynamics and cell migration remains unclear.

Purpose of the Study:

• To investigate the role of PKP2 in regulating focal adhesion dynamics and cell migration.
• To elucidate the relationship between PKP2, RhoA signaling, and integrin expression.
• To understand PKP2's contribution to keratinocyte behavior.

Main Methods:

• Analysis of cell spreading, focal adhesion size, and stability in PKP2-deficient cells.
• Assessment of vinculin dynamics using fluorescence recovery after photobleaching (FRAP).
• Quantification of β4 and β1 integrin expression at protein and mRNA levels.
• Manipulation of RhoA pathway activity and β1 integrin levels to restore normal phenotypes.

Main Results:

• PKP2-deficient cells exhibit smaller total cell areas and larger, more stable focal adhesions.
• Vinculin recovery time is increased in PKP2-deficient cells, indicating altered focal adhesion turnover.
• PKP2 silencing leads to elevated β4 and β1 integrin expression.
• Restoration of normal focal adhesion phenotypes is achieved by inhibiting RhoA or silencing β1 integrin, but not by RhoA inhibition alone for integrin levels.

Conclusions:

• PKP2 plays a crucial role in regulating focal adhesion dynamics and cell spreading.
• PKP2 acts upstream of β1 integrin and RhoA signaling pathways.
• PKP2 integrates cell-cell and cell-substrate contact signaling in basal keratinocytes.
• These findings highlight PKP2's importance in epidermal morphogenesis, homeostasis, and reepithelialization.