Phagocyte cell migration is mediated by phospholipases PLD1 and PLD2

Area of Science:

• Cell Biology
• Immunology
• Biochemistry

Background:

• Leukocyte cell motility is essential for immune responses.
• The role of signaling protein phospholipase D (PLD) in leukocyte migration remains unclear.

Purpose of the Study:

• To investigate the implication of phospholipase D (PLD) isoforms in leukocyte cell motility.
• To determine the specific roles of PLD1 and PLD2 in basal and chemokine-induced migration.

Main Methods:

• Differentiated HL-60 cells were treated with small interfering RNAs (siRNAs) to deplete PLD1 expression.
• PLD1 and PLD2 overexpression constructs were used to assess their effects on cell migration.
• Lipase-inactive PLD1 mutant was employed to investigate the role of enzymatic activity.
• Chemokines (ENA-78, FMLP, IL-8) were used to stimulate cell migration.
• Immunofluorescence microscopy was utilized to examine cell polarity and F-actin polymerization.

Main Results:

• Depletion of PLD1 abolished basal chemokinesis.
• Overexpression of PLD1 enhanced chemokinesis and chemotaxis toward IL-8 and FMLP, but not ENA-78.
• PLD1's enzymatic activity was essential for chemokine-induced chemotaxis.
• Silencing PLD2 also arrested cell migration.
• ENA-78 selectively increased PLD2 activity and chemotaxis.
• PLD1 and PLD2 were associated with cell polarity and directionality.

Conclusions:

• Phospholipase D (PLD) isoforms, PLD1 and PLD2, play critical roles in leukocyte migration.
• PLD1 is differentially activated by CXCR-1, while CXCR-2 mediates PLD2 activation.
• Both PLD isoforms are involved in regulating cell polarity, adhesion, and F-actin polymerization during leukocyte migration.