The splicing-factor Prp40 affects dynein-dynactin function in Aspergillus nidulans

Area of Science:

• Cell Biology
• Molecular Genetics
• Cytoskeletal Dynamics

Background:

• Cytoplasmic dynein and dynactin are crucial multi-component complexes for intracellular transport.
• Factors regulating the assembly and function of dynein and dynactin remain incompletely understood.
• Prp40A is a homologue of Prp40, an essential RNA splicing factor, found in *Aspergillus nidulans*.

Purpose of the Study:

• To investigate the role of Prp40A in the function of cytoplasmic dynein and dynactin.
• To identify novel factors affecting dynein-mediated transport and cellular distribution.

Main Methods:

• Genetic screening in *Aspergillus nidulans* to identify mutations affecting early-endosome distribution.
• Analysis of *prp40A* mutants, including a hypomorphic allele (prp40A^L438*) and a deletion mutant (∆prp40A).
• Biochemical assays (pull-down) to assess protein complex interactions, specifically Arp1 and Arp11 within dynactin.
• Examination of dynein and dynactin localization at microtubule plus-ends.

Main Results:

• The prp40A^L438* mutation impairs dynein-mediated early-endosome transport and nuclear distribution, similar to ∆prp40A.
• In prp40A^L438* mutants, the frequency of dynein-mediated transport is reduced, correlating with decreased dynein and dynactin at microtubule plus-ends.
• A reduced interaction between Arp1 and Arp11 within the dynactin complex was observed in the prp40A^L438* mutant.

Conclusions:

• Prp40A homologues play a regulatory role in the assembly or function of the dynein-dynactin motor complex.
• These findings suggest a novel link between RNA splicing factors and cytoskeletal motor protein regulation.
• Further investigation into the mechanisms by which Prp40 homologues influence dynein-dynactin is warranted.