SREBP pathway responds to sterols and functions as an oxygen sensor in fission yeast.

A novel mechanism of hypoxia adaptation mediated by sterol regulatory element-binding proteins (SREBPs) was characterized in Schizosaccharomyces pombe.

“Recently, a novel mechanism of hypoxia adaptation mediated by a highly conserved family of transcription factors, sterol regulatory element-binding proteins (SREBPs), was characterized in fission yeast, Schizosaccharomyces pombe [25].”

AFUA_2g01260 (srbA) is induced 5.02 fold in response to hypoxia.

“only one, AFUA_2g01260 (induced 5.02 fold in response to hypoxia), had similarity with a functionally characterized protein, Sre1 from S. pombe [25]”

In the yeasts S. pombe and C. neoformans, SREBP homologs are crucial for sterol biosynthesis, survival under hypoxic conditions, resistance to azole antifungal agents, and fungal virulence.

“In the yeasts S. pombe and C. neoformans, SREBP homologs are crucial for sterol biosynthesis, survival under hypoxic conditions, resistance to azole antifungal agents, and fungal virulence [25],[32],[33].”

C. neoformans lacks an apparent Insig homolog and the Insig homolog in S. pombe does not appear to be required for regulation of SREBP signalling.

“Interestingly, C. neoformans lacks an apparent Insig homolog and the Insig homolog in S. pombe does not appear to be required for regulation of SREBP signalling [25],[32].”

These transcriptional responses have been shown to be dependent on the presence of the azoles and/or depletion of ergosterol.

“To date, these transcriptional responses have been shown to be dependent on the presence of the azoles and/or depletion of ergosterol.”

All above lines of evidence suggest that ergosterol depletion resulted from azole stress might be a cause for the transcriptional responses by ergosterol biosynthesis genes, but some direct experimental data in other fungi are still required for making a definite conclusion.

“All above lines of evidence suggest that ergosterol depletion resulted from azole stress might be a cause for the transcriptional responses by ergosterol biosynthesis genes, but some direct experimental data in other fungi are still required for making a definite conclusion.”

Several lines of evidence suggest that ergosterol depletion might be a cause of azole-activated transcriptional responses by ergosterol biosynthesis genes.

“For azole-activated transcriptional responses by genes for ergosterol biosynthesis, several lines of evidence suggest that ergosterol depletion might be a cause.”

In S. pombe, ergosterol depletion activated the expression of ergosterol biosynthesis genes and their regulator Sre1p.

“In Schizosaccharomyces pombe, it was reported that ergosterol depletion activated the expression of ergosterol biosynthesis genes and their regulator Sre1p (Hughes et al., 2005; Porter et al., 2010).”