PDGFRα signaling regulates Srsf3 transcript binding to affect PI3K signaling and endosomal trafficking

Area of Science:

• Molecular biology
• Developmental biology
• Genetics

Background:

• Platelet-derived growth factor receptor alpha (PDGFRα) signaling is crucial for craniofacial development.
• Phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key mediator of PDGFRα signaling in skeletal development.
• Serine/arginine-rich splicing factor 3 (Srsf3) is phosphorylated by Akt downstream of PDGFRα signaling, translocating to the nucleus.

Purpose of the Study:

• To investigate the molecular mechanisms by which Srsf3 regulates craniofacial development downstream of PDGFRα signaling.
• To determine how PDGF-AA stimulation affects Srsf3 binding to RNA and its impact on alternative splicing.
• To elucidate the role of Srsf3 in PDGFRα signaling and its downstream effects on PI3K/Akt pathway.

Main Methods:

• Enhanced UV-crosslinking and immunoprecipitation (eCLIP) in mouse embryonic palatal mesenchyme (MEPM) cells.
• RNA sequencing (RNA-seq) to analyze alternative splicing changes.
• Analysis of Srsf3 binding preferences to exons and RNA motifs.

Main Results:

• PDGF-AA stimulation promotes Srsf3 binding to exons and reduces binding to CA-rich motifs.
• Srsf3 activity drives preferential inclusion of GC-rich exons with shorter introns.
• Srsf3 promotes PDGFRα retention in early endosomes, enhancing PI3K/Akt signaling.

Conclusions:

• Growth factor-mediated Srsf3 phosphorylation is a key regulatory mechanism in mammalian craniofacial development.
• Srsf3 acts as a critical node connecting PDGFRα signaling to alternative RNA splicing.
• Dysregulation of this pathway may contribute to craniofacial abnormalities.