Glucose limitation andpka1deletion rescue aberrant mitotic spindle formation induced by Mal3 overexpression inSchizosaccharomyces pombe

Abstract

The cAMP-dependent protein kinase Pka1 is known as a regulator of glycogenesis, transition into meiosis, proper chromosome segregation, and stress responses in Schizosaccharomyces pombe. We demonstrated that both the cAMP/PKA pathway and glucose limitation play roles in appropriate spindle formation. Overexpression of Mal3 (1–308), an EB1 family protein, caused growth defects, increased 4C DNA content, and induced monopolar spindle formation. Overproduction of a high-affinity microtubule binding mutant (Q89R) and a recombinant protein possessing the CH and EB1 domains (1–241) both resulted in more severe phenotypes than Mal3 (1–308). Loss of functional Pka1 and glucose limitation rescued the phenotypes of Mal3-overexpressing cells, whereas deletion of Tor1 or Ssp2 did not. Growth defects and monopolar spindle formation in a kinesin-5 mutant, cut7-446, was partially rescued by pka1 deletion or glucose limitation. These findings suggest that Pka1 and glucose limitation regulate proper spindle formation in Mal3-overexpressing cells and the cut7-446 mutant.

Microtubule rescue at midzone edges promotes overlap stability and prevents spindle collapse during anaphase B

“…Ultimately, measuring microtubule dynamics in these systems will reveal their impact on microtubule sliding. Nevertheless, growth-limited sliding is widely conserved, and may contribute to spindle stability in S. pombe when microtubule dynamics are perturbed, such as during starvation ( Tanabe et al, 2020 ).…”

Transcriptome sequencing and screening of genes related to glucose availability in Schizosaccharomyces pombe by RNA-seq analysis

“…On the other hand, it is thought that the APC may be involved in enhancing genomic stability through repairing DNA damage that occurs during chromosome segregation but this process has not been fully elucidated ( Harkness, 2018 ). Recent works revealed a connection between glucose availability and kinetochore activity and bipolar spindle formation during mitosis ( Shah et al, 2019 , Tanabe et al, 2020 ). Accordingly, higher glucose levels destabilize kinetochore attachment and weaken kinetochore-microtubule binding through phosphorylation of Dam1 which is S. cerevisiae ortholog of Spc19.…”

Microtubule rescue at midzone edges promotes overlap stability and prevents spindle collapse during anaphase B

“…Ultimately, measuring microtubule dynamics in these systems will reveal their impact on microtubule sliding. Nevertheless, growth-limited sliding is widely conserved, and may contribute to spindle stability in S. pombe when microtubule dynamics are perturbed, such as during starving [71].…”