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Oxygen-dependent binding of Nro1 to the prolyl hydroxylase Ofd1 regulates SREBP degradation in yeast.

ABSTRACT: Sre1, the fission yeast sterol regulatory element-binding protein, is an ER membrane-bound transcription factor that controls adaptation to low oxygen growth. Under low oxygen, Sre1 is proteolytically cleaved and the N-terminal transcription factor domain (Sre1N) is released from the membrane and enters the nucleus to activate hypoxic gene expression. Ofd1, a prolyl 4-hydroxylase-like 2-oxoglutarate dioxygenase, controls the oxygen-dependent stability of Sre1N. In the presence of oxygen, Ofd1 accelerates the degradation of Sre1N, but under low oxygen Ofd1 is inhibited and Sre1N accumulates. To identify the regulators of Sre1N, we performed a plasmid-based screen for genes that increased Sre1N transcriptional activity. Here, we identify Nro1 (SPCC4B3.07) as a positive regulator of Sre1N stability and a direct inhibitor of Ofd1. In the absence of oxygen, Nro1 binds to the Ofd1 C-terminal degradation domain and inhibits Sre1N degradation. In the presence of oxygen, Nro1 binding to Ofd1 is disrupted, leading to rapid degradation of Sre1N. We conclude that the Ofd1 dioxygenase domain functions as an oxygen sensor that regulates binding of Nro1 to Ofd1 to control oxygen-dependent Sre1N stability.

SUBMITTER: Lee CY

PROVIDER: S-EPMC2634736 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Oxygen-dependent binding of Nro1 to the prolyl hydroxylase Ofd1 regulates SREBP degradation in yeast.

Lee Chih-Yung S CY Stewart Emerson V EV Hughes Bridget T BT Espenshade Peter J PJ

The EMBO journal 20090101 2

Sre1, the fission yeast sterol regulatory element-binding protein, is an ER membrane-bound transcription factor that controls adaptation to low oxygen growth. Under low oxygen, Sre1 is proteolytically cleaved and the N-terminal transcription factor domain (Sre1N) is released from the membrane and enters the nucleus to activate hypoxic gene expression. Ofd1, a prolyl 4-hydroxylase-like 2-oxoglutarate dioxygenase, controls the oxygen-dependent stability of Sre1N. In the presence of oxygen, Ofd1 ac ...[more]

PMID: 19158663

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Project description:The oxygen sensor PHD2 (prolyl hydroxylase domain 2) plays an important role in cell hypoxia adaptation by regulating the stability of HIF proteins (HIF1α and HIF2α) in numerous cell types including T lymphocytes. The role of oxygen sensor on immune cells, in particular on regulatory T cell (Treg) function, has not been fully elucidated. The purpose of our study was to evaluate the role of PHD2 in the regulation of Treg phenotype and function. We demonstrate herein that selective ablation of PHD2 expression in Treg (PHD2ΔTreg mice) leads to a spontaneous systemic inflammatory syndrome, as evidenced by weight loss, development of a rectal prolapse, splenomegaly, shortening of the colon and elevated expression of IFN-γ in the mesenteric lymph nodes, intestine and spleen. PHD2 deficiency in Tregs led to an increased number of activated CD4 conventional T cells expressing an effector/Th1-like phenotype. Concomitantly, the expression of innate-type cytokines such as IL1-β, IL-12p40, IL-12p35 and TNF-α was found to be elevated in peripheral (gut) tissues and spleen. PHD2ΔTreg mice also displayed an enhanced sensitivity to DSS-induced colitis and to toxoplasmosis, suggesting that PHD2-deficient Tregs do not efficiently control inflammatory response in vivo, in particular immune responses characterized by IFN-γ production. Further analysis revealed that Treg dysregulation is largely prevented in PHD2-HIF2α (PHD2-HIF2αΔTreg mice), but not in PHD2-HIF1α (PHD2-HIF1αΔTreg mice) double KOs, suggesting an important and possibly selective role of the PHD2-HIF2α axis in the control of Treg function. Finally, the transcriptomic analysis of PHD2-deficient Tregs revealed an altered expression of several chemokine receptors including CXCR3, a finding corroborated by the altered in vivo localization of PHD2-deficient Tregs in splenic tissues. Collectively, these findings uncover an important role of the PHD2-HIF2α axis in regulatory T cell positioning and trafficking.

Dataset Information

Oxygen-dependent binding of Nro1 to the prolyl hydroxylase Ofd1 regulates SREBP degradation in yeast.

Publications

Oxygen-dependent binding of Nro1 to the prolyl hydroxylase Ofd1 regulates SREBP degradation in yeast.

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