Glucose limitation and  pka1  deletion rescue aberrant mitotic spindle formation induced by Mal3 overexpression in  Schizosaccharomyces pombe .
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.
Tanabe T, Kawamukai M, Matsuo Y