Elevated phospholipase D activity induces apoptosis in normal rat fibroblasts

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Phospholipase D (PLD) is implicated in cell transformation when co-expressed with tyrosine kinases in rat fibroblasts.
• Achieving elevated PLD expression in normal rat fibroblasts has been technically challenging.
• Understanding PLD's role in normal cells is crucial for its broader biological significance.

Purpose of the Study:

• To investigate the effects of elevated phospholipase D (PLD) expression in normal rat fibroblasts.
• To determine if PLD1 and PLD2 overexpression induces cellular changes in the absence of serum.
• To elucidate the specific apoptotic pathways activated by increased PLD activity.

Main Methods:

• Utilized transient transfection and an inducible expression system in 3Y1 rat fibroblasts.
• Overexpressed PLD1 and PLD2 to achieve elevated PLD levels.
• Assessed cell viability, caspase substrate cleavage (PARP), and cytochrome c release.

Main Results:

• Elevated expression of PLD1 or PLD2 in 3Y1 cells induced apoptosis, particularly in serum-free conditions.
• Reduced cell viability was observed with increased PLD expression.
• Evidence of mitochondrial apoptosis pathway activation, including cytochrome c release and PARP cleavage, was found.

Conclusions:

• While elevated PLD promotes transformation in tyrosine kinase-overexpressing cells, it triggers apoptosis in normal rat fibroblasts.
• Increased PLD activity sensitizes normal cells to apoptotic stimuli.
• PLD plays a differential role in cell fate determination based on cellular context.