The effect of differentiation induction on FAK and Src activity in live HMSCs visualized by FRET

Area of Science:

• Stem cell biology
• Molecular signaling pathways
• Tissue engineering

Background:

• Focal Adhesion Kinase (FAK) and Src signaling are crucial for cell functions like differentiation, survival, and migration.
• The precise regulation of FAK and Src activities during the initial stages of stem cell differentiation remains incompletely understood.
• Human Mesenchymal Stem Cells (HMSCs) are a key model for studying differentiation due to their multipotency.

Purpose of the Study:

• To investigate and visualize the distinct regulation of FAK and Src kinase activities at the plasma membrane of HMSCs during differentiation.
• To elucidate the specific roles of FAK and Src signaling in response to osteogenic, myoblastic, and neural induction stimuli.
• To understand the feedback mechanisms governing FAK and Src activity during stem cell fate decisions.

Main Methods:

• Utilized fluorescence resonance energy transfer (FRET)-based biosensors to monitor FAK and Src kinase activities in real-time.
• Applied FRET biosensors to the plasma membrane of human mesenchymal stem cells (HMSCs).
• Stimulated HMSCs with osteogenic, myoblastic, and neural induction reagents to observe kinase responses.

Main Results:

• Distinct regulation patterns of membrane-bound FAK and Src activities were observed across different induction types.
• Osteogenic induction led to co-up-regulation of FAK and Src with positive feedback.
• Myoblastic induction activated Src only, while neural induction transiently activated FAK then Src, followed by negative feedback on FAK.

Conclusions:

• FAK and Src activities are differentially regulated by specific differentiation cues in HMSCs, highlighting distinct signaling mechanisms for each fate.
• The findings provide novel insights into the complex interplay of FAK and Src signaling during stem cell fate determination.
• This research advances the understanding of stem cell differentiation, with implications for regenerative medicine and tissue engineering.