The evolutionarily conserved PRP4K-CHMP4B/vps32 splicing circuit regulates autophagy

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• The pre-mRNA processing factor 4 kinase (PRP4K) is crucial in animal cells, but its functions are difficult to study.
• Investigating PRP4K's role requires models that allow for functional genetic interrogation.

Purpose of the Study:

• To characterize a viable knockout model of PRP4K in Dictyostelium discoideum.
• To elucidate the function of PRP4K in splicing events controlling autophagy and multicellular development.

Main Methods:

• Generation and analysis of a prp4k knockout Dictyostelium discoideum model.
• Assessment of autophagy, differentiation, and secretion pathways in knockout and wild-type cells.
• Investigation of autophagosome-lysosome fusion in both Dictyostelium and human cell lines.
• Analysis of ESCRT-III gene (CHMP4B/vps32) splicing and expression.

Main Results:

• PRP4K knockout in Dictyostelium leads to developmental defects, abnormal autophagy, and aberrant c-di-GMP secretion.
• Autophagosome-lysosome fusion is impaired in both PRP4K-deficient human cells and Dictyostelium.
• PRP4K loss causes mis-splicing and reduced expression of CHMP4B (human) and vps32 (Dictyostelium).
• Restoring CHMP4B or Vps32 expression rescues autophagosome-lysosome fusion defects.

Conclusions:

• A conserved splicing circuit involving PRP4K and CHMP4B/vps32 regulates autophagy.
• This PRP4K-CHMP4B/vps32 pathway is essential for autophagosome-lysosome fusion and is conserved across evolution.
• The study provides insights into the fundamental mechanisms of autophagy regulation.