A time frame permissive for Protein Kinase D2 activity to direct angiogenesis in mouse embryonic stem cells

Area of Science:

• Developmental Biology
• Cell Signaling
• Stem Cell Biology

Background:

• Protein Kinase D (PKD) isoenzymes are downstream targets of Protein Kinase Cs and phospholipase D.
• PKD isoforms are implicated in tumor cell communication, motility, metastasis, and angiogenesis.
• The specific roles of PKDs in embryonic development, vasculogenesis, and angiogenesis remain largely unknown.

Purpose of the Study:

• To investigate the role of PKD isoenzymes in germ layer segregation, vasculogenesis, and angiogenesis.
• To elucidate the function of PKD2 during early embryonic stem cell differentiation.

Main Methods:

• Utilized mouse embryonic stem cells (ESCs) for in vitro differentiation studies.
• Analyzed PKD isoenzyme expression and activation status during differentiation.
• Performed time-restricted PKD2 activation and loss-of-function experiments.
• Assessed germ layer formation, cardiovasculogenesis, and angiogenesis.
• Employed in vivo chick chorioallantoic membrane assay for angiogenic response evaluation.

Main Results:

• Mouse ESCs predominantly express PKD2 and PKD3, with minimal PKD1.
• PKD2 is specifically phosphorylated and activated during germ layer segregation.
• Time-restricted PKD2 activation impaired mesendoderm formation and cardiovasculogenesis but promoted branching angiogenesis.
• PKD2 loss-of-function favored mesendodermal differentiation over neuroectodermal differentiation.
• In vivo studies showed that timed PKD2 overexpression enhanced angiogenesis.

Conclusions:

• PKD2 exhibits novel, time-dependent functions in early cell fate determination during embryonic development.
• PKD2 is a critical regulator of germ layer segregation and subsequent differentiation pathways.
• The findings highlight a dual role for PKD2 in regulating both early developmental processes and later angiogenic events.