TY - JOUR
T1 - Impaired IRE1α/XBP-1 pathway associated to DNA methylation might contribute to salivary gland dysfunction in Sjögren's syndrome patients
AU - Sepúlveda, Denisse
AU - Barrera, María José
AU - Castro, Isabel
AU - Aguilera, Sergio
AU - Carvajal, Patricia
AU - Lagos, Carolina
AU - González, Sergio
AU - Albornoz, Nicolá s.
AU - Bahamondes, Veró nica
AU - Quest, Andrew F.G.
AU - Urzúa, Ulises
AU - Molina, Claudio
AU - Leyton, Cecilia
AU - Hermoso, Marcela A.
AU - González, María Julieta
N1 - Funding Information:
Funding: This work was supported by Fondecyt-Chile [1160015 and 1120062 to M.J.G., S.A., C.M., S.G., I.C., 1130250 to A.F.G.Q.]; Fondecyt-Postdoctorado [3170023 to M.J.B.]; CONICYT-FONDAP Chile [15130011 to A.F.G.Q.]; CONICYT/Programa de Investigación Asociativa [ACT 1111 to A.F.G.Q.] and PhD fellowship Conicyt-Chile to D.S.
Publisher Copyright:
© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.
PY - 2018/6/1
Y1 - 2018/6/1
N2 - Objectives. Labial salivary glands (LSGs) of SS patients show alterations related to endoplasmic reticulum stress. Glandular dysfunction could be partly the consequence of an altered inositol-requiring enzyme 1α (IRE1α)/X box-binding protein 1 (XBP-1) signalling pathway of the unfolded protein response, which then regulates genes involved in biogenesis of the secretory machinery. This study aimed to determine the expression, promoter methylation and localization of the IRE1α/XBP-1 pathway components in LSGs of SS patients and also their expression induced by IFN-γ in vitro. Methods. IRE1α, XBP-1 and glucose-regulated protein 78 (GRP78) mRNA and protein levels were measured by qPCR and western blot, respectively, in LSGs of SS patients (n = 47) and control subjects (n = 37). Methylation of promoters was evaluated by methylation-sensitive high resolution melting, localization was analysed by immunofluorescence and induction of the IRE1α/XBP-1 pathway components by IFN-γ was evaluated in 3D acini. Results. A significant decrease of IRE1α, XBP-1u, XBP-1s, total XBP-1 and GRP78 mRNAs was observed in LSGs of SS patients, which was correlated with increased methylation levels of their respective promoters, and consistently the protein levels for IRE1α, XBP-1s and GRP78 were observed to decrease. IFN-γ decreased the mRNA and protein levels of XBP-1s, IRE1α and GRP78, and increased methylation of their promoters. Significant correlations were also found between IRE1α/XBP-1 pathway components and clinical parameters. Conclusion. Decreased mRNA levels for IRE1α, XBP-1 and GRP78 can be partially explained by hypermethylation of their promoters and is consistent with chronic endoplasmic reticulum stress, which may explain the glandular dysfunction observed in LSGs of SS patients. Additionally, glandular stress signals, including IFN-γ, could modulate the expression of the IRE1α/XBP-1 pathway components.
AB - Objectives. Labial salivary glands (LSGs) of SS patients show alterations related to endoplasmic reticulum stress. Glandular dysfunction could be partly the consequence of an altered inositol-requiring enzyme 1α (IRE1α)/X box-binding protein 1 (XBP-1) signalling pathway of the unfolded protein response, which then regulates genes involved in biogenesis of the secretory machinery. This study aimed to determine the expression, promoter methylation and localization of the IRE1α/XBP-1 pathway components in LSGs of SS patients and also their expression induced by IFN-γ in vitro. Methods. IRE1α, XBP-1 and glucose-regulated protein 78 (GRP78) mRNA and protein levels were measured by qPCR and western blot, respectively, in LSGs of SS patients (n = 47) and control subjects (n = 37). Methylation of promoters was evaluated by methylation-sensitive high resolution melting, localization was analysed by immunofluorescence and induction of the IRE1α/XBP-1 pathway components by IFN-γ was evaluated in 3D acini. Results. A significant decrease of IRE1α, XBP-1u, XBP-1s, total XBP-1 and GRP78 mRNAs was observed in LSGs of SS patients, which was correlated with increased methylation levels of their respective promoters, and consistently the protein levels for IRE1α, XBP-1s and GRP78 were observed to decrease. IFN-γ decreased the mRNA and protein levels of XBP-1s, IRE1α and GRP78, and increased methylation of their promoters. Significant correlations were also found between IRE1α/XBP-1 pathway components and clinical parameters. Conclusion. Decreased mRNA levels for IRE1α, XBP-1 and GRP78 can be partially explained by hypermethylation of their promoters and is consistent with chronic endoplasmic reticulum stress, which may explain the glandular dysfunction observed in LSGs of SS patients. Additionally, glandular stress signals, including IFN-γ, could modulate the expression of the IRE1α/XBP-1 pathway components.
KW - Endoplasmic reticulum stress
KW - Gene promoter methylation
KW - Glandular dysfunction
KW - IFN-γ
KW - IRE1α/XBP-1 pathway
KW - Sjögren's syndrome
KW - Unfolded protein response
UR - http://www.scopus.com/inward/record.url?scp=85048560561&partnerID=8YFLogxK
U2 - 10.1093/rheumatology/key021
DO - 10.1093/rheumatology/key021
M3 - Article
C2 - 29534223
AN - SCOPUS:85048560561
SN - 1462-0324
VL - 57
SP - 1021
EP - 1032
JO - Rheumatology (United Kingdom)
JF - Rheumatology (United Kingdom)
IS - 6
ER -