Journal of Investigative Dermatology Home

The ER Stress Sensor IRE1α Regulates the UV DNA Repair Response Through Control of Intracellular Calcium Homeostasis

Published:November 19, 2021DOI:


      The unfolded protein response is activated by UVB irradiation, but the role of a key mediator, inositol requiring enzyme 1a (IRE1α), is not clear. Here, we show that mice with an epidermal IRE1α deletion are sensitized to UV with increased apoptosis, rapid loss of UV-induced cyclopyrimidine dimer (CPD) positive keratinocytes and sloughing of the epidermis. In vitro, IRE1α deficient keratinocytes have increased UVB sensitivity, reduced CPD repair and reduced accumulation of γH2AX and p-ATR, suggesting defective the activation of nucleotide excision repair. Knockdown of XBP1 or pharmacological inhibition of the IRE1α RNase did not phenocopy IRE1α deficiency. The altered UV response was linked to elevated intracellular calcium levels and ROS, and this was due to dysregulation of the ER calcium channel inositol triphosphate receptor (InsP3R). Pharmacologic, genetic, and biochemical studies linked regulation of the Ins3PR, intracellular calcium and normal UV DNA damage response to calcium and integrin binding protein 1 (CIB1) and the IRE1α-TRAF2-ASK1 complex. These results suggest a model where IRE1α activation state drives CIB1 binding either to the InsP3R or ASK1 to regulate ER calcium efflux, ROS and DNA repair responses following UV.


      List of Abbreviations:

      ASK1 (Apoptosis signal-regulated kinase 1), ATR (Ataxia telangiectasia and Rad3-related protein), BioID (Biotin identification biotin ligase), [Ca2+]i (Intracellular calcium concentration), ELISA (Enzyme-linked immunosorbent assay), Ero1Lα (Endoplasmic reticulum oxidoreductase like protein alpha), IIF (Indirect immunofluorescence), IP (Immunoprecipitation), IRE1α (Inositol requiring enzyme 1α), JNK (c-Jun N-terminal kinase), NER (Nuclear excision repair), ROS (Reactive oxygen species), Sec24D (Protein transport protein Sec24D), SERCA (Sarco/endoplasmic reticulum Ca2+-ATPase), TRAF2 (TNF receptor-associated factor 2), XBP1 (X-box binding protein 1)
      To read this article in full you will need to make a payment
      Purchase one-time access
      Society Members (SID/ESDR), remember to log in for access.
      Subscribe to Journal of Investigative Dermatology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Assefa Z.
        • Garmyn M.
        • Bouillon R.
        • Merlevede W.
        • Vandenheede J.R.
        • Agostinis P.
        Differential stimulation of ERK and JNK activities by ultraviolet B irradiation and epidermal growth factor in human keratinocytes.
        J Invest Dermatol. 1997; 108: 886-891
        • Bankhead P.
        • Loughrey M.B.
        • Fernández J.A.
        • Dombrowski Y.
        • McArt D.G.
        • Dunne P.D.
        • et al.
        QuPath: Open source software for digital pathology image analysis.
        Sci Rep. 2017; 7: 16878
        • Blazanin N.
        • Son J.
        • Craig-Lucas A.B.
        • John C.L.
        • Breech K.J.
        • Podolsky M.A.
        • et al.
        ER stress and distinct outputs of the IRE1alpha RNase control proliferation and senescence in response to oncogenic Ras.
        Proc Natl Acad Sci U S A. 2017; 114: 9900-9905
        • Boukamp P.
        • Petrussevska R.T.
        • Breitkreutz D.
        • Hornung J.
        • Markham A.
        • Fusenig N.E.
        Normal keratinization in a spontaneously immortalized aneuploid human keratinocyte cell line.
        JCell Biol. 1988; 106: 761-771
        • Brown M.
        • Strudwick N.
        • Suwara M.
        • Sutcliffe L.K.
        • Mihai A.D.
        • Ali A.A.
        • et al.
        An initial phase of JNK activation inhibits cell death early in the endoplasmic reticulum stress response.
        J Cell Sci. 2016; 129: 2317-2328
        • Castillo K.
        • Rojas-Rivera D.
        • Lisbona F.
        • Caballero B.
        • Nassif M.
        • Court F.A.
        • et al.
        BAX inhibitor-1 regulates autophagy by controlling the IRE1alpha branch of the unfolded protein response.
        EMBO J. 2017; 36: 1640
        • Chalmers F.
        • Mogre S.
        • Son J.
        • Blazanin N.
        • Glick A.B.
        The multiple roles of the unfolded protein response regulator IRE1α in cancer.
        Mol Carcinog. 2019; 58: 1623-1630
        • Chen X.
        • Cubillos-Ruiz J.R.
        Endoplasmic reticulum stress signals in the tumour and its microenvironment.
        Nat Rev Cancer. 2021; 21: 71-88
        • Collier A.E.
        • Wek R.C.
        • Spandau D.F.
        Translational Repression Protects Human Keratinocytes from UVB-Induced Apoptosis through a Discordant eIF2 Kinase Stress Response.
        J Invest Dermatol. 2015; 135: 2502-2511
        • Corazzari M.
        • Rapino F.
        • Ciccosanti F.
        • Giglio P.
        • Antonioli M.
        • Conti B.
        • et al.
        Oncogenic BRAF induces chronic ER stress condition resulting in increased basal autophagy and apoptotic resistance of cutaneous melanoma.
        Cell Death Differ. 2015; 22: 946-958
        • Dufey E.
        • Bravo-San Pedro J.M.
        • Eggers C.
        • Gonzalez-Quiroz M.
        • Urra H.
        • Sagredo A.I.
        • et al.
        Genotoxic stress triggers the activation of IRE1alpha-dependent RNA decay to modulate the DNA damage response.
        Nat Commun. 2020; 11: 2401
        • Farrukh M.R.
        • Nissar U.A.
        • Afnan Q.
        • Rafiq R.A.
        • Sharma L.
        • Amin S.
        • et al.
        Oxidative stress mediated Ca(2+) release manifests endoplasmic reticulum stress leading to unfolded protein response in UV-B irradiated human skin cells.
        J Dermatol Sci. 2014; 75: 24-35
        • Gonzalez-Quiroz M.
        • Blondel A.
        • Sagredo A.
        • Hetz C.
        • Chevet E.
        • Pedeux R.
        When Endoplasmic Reticulum Proteostasis Meets the DNA Damage Response.
        Trends Cell Biol. 2020; 30: 881-891
        • Gumeni S.
        • Evangelakou Z.
        • Gorgoulis V.
        • Trougakos I.
        Proteome Stability as a Key Factor of Genome Integrity.
        International Journal of Molecular Sciences. 2017; 18: 2036
        • Hanasoge S.
        • Ljungman M.
        H2AX phosphorylation after UV irradiation is triggered by DNA repair intermediates and is mediated by the ATR kinase.
        Carcinogenesis. 2007; 28: 2298-2304
        • Hogan K.A.
        • Ravindran A.
        • Podolsky M.A.
        • Glick A.B.
        The TGFbeta1 pathway is required for NFkappaB dependent gene expression in mouse keratinocytes.
        Cytokine. 2013; 64: 652-659
        • Hung K.F.
        • Sidorova J.M.
        • Nghiem P.
        • Kawasumi M.
        The 6-4 photoproduct is the trigger of UV-induced replication blockage and ATR activation.
        Proc Natl Acad Sci U S A. 2020; 117: 12806-12816
        • Indra A.K.
        • Warot X.
        • Brocard J.
        • Bornert J.M.
        • Xiao J.H.
        • Chambon P.
        • et al.
        Temporally-controlled site-specific mutagenesis in the basal layer of the epidermis: comparison of the recombinase activity of the tamoxifen-inducible Cre-ER(T) and Cre-ER(T2) recombinases.
        Nucleic Acids Research. 1999; 27: 4324-4327
        • Iwawaki T.
        • Akai R.
        • Yamanaka S.
        • Kohno K.
        Function of IRE1 alpha in the placenta is essential for placental development and embryonic viability.
        ProcNatlAcadSciUSA. 2009; 106: 16657-16662
        • Kawachi Y.
        • Xu X.
        • Taguchi S.
        • Sakurai H.
        • Nakamura Y.
        • Ishii Y.
        • et al.
        Attenuation of UVB-induced sunburn reaction and oxidative DNA damage with no alterations in UVB-induced skin carcinogenesis in Nrf2 gene-deficient mice.
        J Invest Dermatol. 2008; 128: 1773-1779
        • Liu C.
        • Yan D.Y.
        • Wang C.
        • Ma Z.
        • Deng Y.
        • Liu W.
        • et al.
        IRE1 signaling pathway mediates protective autophagic response against manganese-induced neuronal apoptosis in vivo and in vitro.
        Sci Total Environ. 2020; 712: 136480
        • Madronich S.
        • de Gruijl F.R.
        Skin cancer and UV radiation.
        Nature. 1993; 366: 23
        • Masaki H.
        • Izutsu Y.
        • Yahagi S.
        • Okano Y.
        Reactive oxygen species in HaCaT keratinocytes after UVB irradiation are triggered by intracellular Ca(2+) levels.
        J Investig Dermatol Symp Proc. 2009; 14: 50-52
        • Mera K.
        • Kawahara K.
        • Tada K.
        • Kawai K.
        • Hashiguchi T.
        • Maruyama I.
        • et al.
        ER signaling is activated to protect human HaCaT keratinocytes from ER stress induced by environmental doses of UVB.
        Biochem Biophys Res Commun. 2010; 397: 350-354
        • Oslowski C.
        • Hara T.
        • O'Sullivan-Murphy B.
        • Kanekura K.
        • Lu S.
        • Hara M.
        • et al.
        Thioredoxin-Interacting Protein Mediates ER Stress-Induced β Cell Death through Initiation of the Inflammasome.
        Cell Metabolism. 2012; 16: 265-273
        • Pinton P.
        • Giorgi C.
        • Siviero R.
        • Zecchini E.
        • Rizzuto R.
        Calcium and apoptosis: ER-mitochondria Ca2+ transfer in the control of apoptosis.
        Oncogene. 2008; 27: 6407-6418
        • Ravindran A.
        • Mohammed J.
        • Gunderson A.J.
        • Cui X.
        • Glick A.B.
        Tumor-promoting role of TGFbeta1 signaling in ultraviolet B-induced skin carcinogenesis is associated with cutaneous inflammation and lymph node migration of dermal dendritic cells.
        Carcinogenesis. 2014;
        • Ray A.
        • Blevins C.
        • Wani G.
        • Wani A.A.
        ATR- and ATM-Mediated DNA Damage Response Is Dependent on Excision Repair Assembly during G1 but Not in S Phase of Cell Cycle.
        PLoS One. 2016; 11e0159344
        • Riaz T.A.
        • Junjappa R.P.
        • Handigund M.
        • Ferdous J.
        • Kim H.R.
        • Chae H.J.
        Role of Endoplasmic Reticulum Stress Sensor IRE1alpha in Cellular Physiology, Calcium, ROS Signaling, and Metaflammation.
        Cells. 2020; 9
        • Roux K.J.
        • Kim D.I.
        • Burke B.
        • May D.G.
        BioID: A Screen for Protein-Protein Interactions.
        Curr Protoc Protein Sci. 2018; 91: 19 23 1-19 23 15
        • Seo M.D.
        • Enomoto M.
        • Ishiyama N.
        • Stathopulos P.B.
        • Ikura M.
        Structural insights into endoplasmic reticulum stored calcium regulation by inositol 1,4,5-trisphosphate and ryanodine receptors.
        Biochimica et biophysica acta. 2015; 1853: 1980-1991
        • Seo S.H.
        • Kim S.E.
        • Lee S.E.
        ER stress induced by ER calcium depletion and UVB irradiation regulates tight junction barrier integrity in human keratinocytes.
        J Dermatol Sci. 2020; 98: 41-49
        • Shaj K.
        • Hutcherson R.J.
        • Kemp M.G.
        ATR Kinase Activity Limits Mutagenesis and Promotes the Clonogenic Survival of Quiescent Human Keratinocytes Exposed to UVB Radiation.
        Photochem Photobiol. 2020; 96: 105-112
        • Shiizaki S.
        • Naguro I.
        • Ichijo H.
        Activation mechanisms of ASK1 in response to various stresses and its significance in intracellular signaling.
        Advances in Biological Regulation. 2013; 53: 135-144
        • Son S.M.
        • Byun J.
        • Roh S.E.
        • Kim S.J.
        • Mook-Jung I.
        Reduced IRE1alpha mediates apoptotic cell death by disrupting calcium homeostasis via the InsP3 receptor.
        Cell Death Dis. 2014; 5: e1188
        • Tan H.Y.
        • Wang N.
        • Tsao S.W.
        • Che C.M.
        • Yuen M.F.
        • Feng Y.
        IRE1alpha inhibition by natural compound genipin on tumour associated macrophages reduces growth of hepatocellular carcinoma.
        Oncotarget. 2016; 7: 43792-43804
        • Urano F.
        • Wang X.
        • Bertolotti A.
        • Zhang Y.
        • Chung P.
        • Harding H.P.
        • et al.
        Coupling of stress in the ER to activation of JNK protein kinases by transmembrane protein kinase IRE1.
        Science. 2000; 287: 664-666
        • Wang M.
        • Kaufman R.J.
        The impact of the endoplasmic reticulum protein-folding environment on cancer development.
        Nat Rev Cancer. 2014; 14: 581-597
        • Zeng T.
        • Peng L.
        • Chao H.
        • Xi H.
        • Fu B.
        • Wang Y.
        • et al.
        IRE1alpha-TRAF2-ASK1 complex-mediated endoplasmic reticulum stress and mitochondrial dysfunction contribute to CXC195-induced apoptosis in human bladder carcinoma T24 cells.
        Biochem Biophys Res Commun. 2015; 460: 530-536