Inositol is specifically involved in the sexual program of the fission yeast Schizosaccharomyces pombe

Abstract

The fission yeast Schizosaccharomyces pombe is a natural auxotroph for inositol and fails to grow in the complete absence of it. It was previously reported that a small concentration of inositol in the culture medium supports vegetative growth, but not mating and sporulation, and a tenfold of that concentration also supports mating and sporulation. The purpose of the present work was to investigate whether a moderate inositol starvation specifically affected events of the sexual program of development. A homothallic culture grown to the stationary phase in medium with a small inositol concentration was sterile but cells in the stationary phase of growth synchronously entered and completed the sexual cycle when inositol was added, without need of previous cell divisions. This suggests the involvement of inositol in a mechanism (or mechanisms) of the sexual program. The events of the program that were affected by inositol starvation were investigated. Commitment to mating and production of pheromone M were shown not to be inositol-dependent. A diploid strain homozygous at the mating-type locus and carrying a pat1-114 temperature-sensitive mutation in homozygous configuration sporulated under inositol starvation at the restrictive temperature; therefore starvation did not directly affect meiosis or sporulation. In contrast, production of pheromone P and the response of cells to pheromones were found to be inositol-dependent. The possibility that inositol or one of its derivative compounds is involved in pheromone P secretion and in pheromone signal reception is discussed.

Calnexin Regulates Apoptosis Induced by Inositol Starvation in Fission Yeast

“…The S. pombe genome does not encode an Ino1p homologue, thus sensitizing this yeast to inositol deficiency because inositol is an essential precursor [44], [45]. Moreover, S. cerevisiae strains deleted for INO1 die when inositol is absent in the culture media [46], [47], [48], [49], [50], [51]. Numerous screens performed in S. cerevisiae demonstrated that deficiencies in several pathways can lead to inositol auxotrophy, indicating that inositol biosynthesis is linked to diverse cellular processes [40], [41], [93], [94], [95], [96].…”

“…Tunicamycin treatment blocks N-glycosylation, which causes folding defects resulting in severe ER stress [118], [119]. In the case of inositol starvation, while the actual mechanism leading to apoptosis remains undefined, it is known that lack of inositol affects lipid homeostasis and signalling [46], [47], [48], [49], [50], [51], [103], [108]. These significant differences may underlie the two diverging effects observed with the mutant lumenal_Cnx1p in these two apoptotic situations.…”

“…Studies in S. pombe have shown that absence of inositol in the culture medium is lethal for this yeast, and that partial depletion provokes sexual sterility with no effects on growth [46], [47], [48], [49], [50], [51]. Although S. pombe cells die in the absence of inositol, they are able to survive longer than S. cerevisiae cells auxotroph for inositol as result of genetic manipulation ( Δino1 cells) [49].…”

Role of an Expanded Inositol Transporter Repertoire in Cryptococcus neoformans Sexual Reproduction and Virulence

“…It was reported that myo -inositol regulates the production of pheromone P and the response of cells to pheromones, but production of pheromone M is inositol independent. It is likely that inositol or one of its metabolites is involved in pheromone P secretion and pheromone signaling and thereby influences sexual reproduction (24). …”

Inositol synthesis gene is required for circadian rhythm ofDrosophila melanogastermating behavior

“…A recent study reported that Myo -inositol synthesis is involved in maintaining the period of circadian behavior in mice (Ohnishi et al, 2014). Myo -inositol may be beneficial for depressed patients (Mukai, Kishi, Matsuda, & Iwata, 2014; Zhao et al, 2015) and important for fungal sexual differentiation, reproduction and virulence (Niederberger et al, 1998; Voicu, Poitelea, Schweingruber, & Rusu, 2002). Myo -inositol is also used to increase clinical pregnancy rates in infertile men and women (Korosi, Barta, Rokob, & Torok, 2017; Regidor & Schindler, 2016).…”