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Unfolded protein response regulates yeast Arl1p activation at late‐Golgi via phosphorylation of Arf GEF Syt1p
Author(s) -
Lee FangJen Scott,
Hsu JiaWei,
Tang PeiHua,
Wang IHao,
Liu ChiaLun,
Chen WenHui,
Tsai PeiChin,
Chen KuanYu,
Chen KuanJung,
Yu ChiaJung
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.lb77
Subject(s) - golgi apparatus , guanine nucleotide exchange factor , microbiology and biotechnology , phosphorylation , gtpase , unfolded protein response , copi , adp ribosylation factor , chemistry , biology , endoplasmic reticulum , secretory pathway
ADP‐ribosylation factor (Arf) GTPases are key regulators of membrane traffic at the Golgi complex. In yeast, Arf guanine nucleotide‐exchange factor (GEF) Syt1p activates Arl1p, which was accompanied by accumulation of golgin Imh1p at late‐Golgi, but whether and how this function of Syt1p is regulated remains unclear. Here, we report that the Ire1p‐mediated unfolded protein response (UPR) modulated Arl1p activation at the late‐Golgi. Arl1p activation was dependent on both kinase and endo‐RNase activities of Ire1p. Moreover, constitutively active Hac1p restored the Golgi localization of Arl1p and Imh1p in IRE1 ‐deleted cells. Elucidating the mechanism of Ire1p‐Hac1p axis actions, we found that it regulated phosphorylation of Syt1p, which enhances Arl1p activation, recruitment of Imh1p to the Golgi, and Syt1p interaction with Arl1p. Consistent with these findings, the induction of UPR by tunicamycin treatment increases phosphorylation of Syt1p, resulting in Arl1p activation. Thus, these findings clarify how the UPR influences the roles of Syt1p, Arl1p, and Imh1p in Golgi transport. Support or Funding Information National Science Council of Taiwan (NSC‐104‐2320‐B‐002‐048‐MY3)