Mid-anaphase arrest in S. cerevisiae cells eliminated for the function of Cin8 and dynein

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Anaphase spindle elongation in S. cerevisiae relies on dynein and kinesin-5 motors (Cin8, Kip1).
• The synthetic lethality of Cin8 and dynein has precluded identification of combined functional loss phenotypes.
• Understanding motor protein cooperation is crucial for cell division research.

Purpose of the Study:

• To identify and characterize the anaphase arrest phenotype resulting from combined loss of dynein and Cin8 function.
• To investigate the roles of dynein and Cin8 in anaphase spindle organization and microtubule dynamics.
• To explore potential suppressors of combined motor protein defects.

Main Methods:

• Utilizing temperature-sensitive mutations (cin8-3) and gene deletions (dyn1Δ) in S. cerevisiae.
• Microscopy to observe cell cycle progression and spindle morphology at permissive and non-permissive temperatures.
• Phenotypic analysis of cells with combined dynein and Cin8 functional loss.
• Treatment with sorbitol to assess its effect on cellular defects.

Main Results:

• Cells with dyn1Δ and cin8-3 mutations arrest at mid-anaphase with a novel "two microtubule asters in one nucleus" (TAN) phenotype.
• Combined motor protein deficiency leads to perturbed and non-rigid spindle midzone morphologies.
• Sorbitol, a microtubule stabilizer, effectively corrects these spindle defects and suppresses the TAN phenotype.
• The TAN phenotype is characterized by failure to progress through the slow phase of anaphase B.

Conclusions:

• Dynein and Cin8 functionally cooperate in organizing the anaphase midzone in S. cerevisiae.
• These motor proteins significantly influence microtubule dynamics during anaphase B.
• Sorbitol's suppressive effect highlights the importance of microtubule stability in proper spindle function.
• The study elucidates novel insights into the coordinated roles of microtubule motors in cell division.