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FEMS Yeast Res. 2015 Dec;15(8). pii: fov095. doi: 10.1093/femsyr/fov095. Epub 2015 Oct 29.

The activity of RTA2, a downstream effector of the calcineurin pathway, is required during tunicamycin-induced ER stress response in Candida albicans.

Author information

1
Yeast Molecular Genetics Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
2
Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain.
3
Centre de Recherche en Cancérologie de Marseille, Laboratory of Integrative Structural & Chemical Biology, UMR CNRS F-7258, France.
4
Yeast Molecular Genetics Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India sneh@mail.jnu.ac.in.

Abstract

In this study, we demonstrate a novel function of a downstream effector molecule of the calcineurin pathway, RTA2 (Resistance To Aminocholesterol), in ER stress response. The deletion of RTA2 increases susceptibility to the ER stressor tunicamycin and morpholine-like drug, 7-aminocholesterol. Additionally, the expression of RTA2 is also transcriptionally induced by ergosterol biosynthesis inhibitors and cell-wall-damaging agents. As tunicamycin induces the unfolded protein response pathway (UPR) via the transcription factor, HAC1, we monitored the expression of a subset of HAC1-dependent UPR target genes in rta2Δ/Δ cells. Upon tunicamycin exposure, rta2Δ/Δ cells displayed a significantly reduced expression of UPR genes, in spite of only a moderate decrease in the HAC1 spliced mRNA levels and no change in Hac1 protein levels. Furthermore, hac1Δ/Δrta2Δ/Δ cells display an exacerbated sensitivity to tunicamycin compared to the single mutants. We propose that functional RTA2 is requisite for the regulation of Hac1p-dependent UPR target genes to maximal levels, thereby assisting survival during ER stress. Collectively, this study proposes, for the first time, existence of an interplay between the Hac1p- and calcineurin- controlled networks via a downstream effector molecule of the latter, RTA2, to facilitate survival during ER stress in Candida albicans.

KEYWORDS:

Candida albicans; ER stress; Hac1; RTA2; calcineurin; unfolded protein response

PMID:
26518191
DOI:
10.1093/femsyr/fov095
[Indexed for MEDLINE]

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