Ras activation by hydrostatic pressure involves GDP release and is enhanced by GAP and GEF in vitro.

Area of Science:

• Cell Biology
• Biophysics
• Biochemistry

Background:

• Hydrostatic pressure (HP) is essential for chondrocyte differentiation and growth.
• Ras signaling pathways are implicated in cellular responses to stimuli.

Purpose of the Study:

• To investigate the role of Ras activation in hydrostatic pressure-induced cellular responses.
• To determine the sensitivity of Ras and its regulators to HP using an in vitro system.

Main Methods:

• Utilized mRaichu, a FRET-based probe, to measure Ras activity under HP.
• Employed in vitro systems to assess Ras activity in the presence and absence of GAP and GEF domains.

Main Results:

• HP (28 MPa) activated Ras by 10.7% without GAP/GEF domains, evidenced by GDP dissociation.
• Low GAP domain concentration enhanced HP-induced Ras activation, while high concentrations inhibited it.
• GEF domain consistently enhanced HP-induced Ras activation across a wide concentration range.
• HP increased Ras activity even with both GEF and GAP domains present, mimicking cellular conditions.

Conclusions:

• HP-induced Ras activation is a key mechanism mediating chondrocyte differentiation and growth.
• Ras signaling is sensitive to hydrostatic pressure, modulated by its regulators (GAP, GEF).
• Findings provide insights into the molecular mechanisms of mechanotransduction in chondrocytes.