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IL-1α is a DNA damage sensor linking genotoxic stress signaling to sterile inflammation and innate immunity.

Idan C, Peleg R, Elena V, Martin T, Cicerone T, Mareike W, Lydia B, Marina F, Gerhard M, Elisa FM, Dinarello CA, Ron AN, Robert S - Sci Rep (2015)

Bottom Line: Environmental signals can be translated into chromatin changes, which alter gene expression.Thus, in addition to its role as a danger signal, which occurs when the cytokine is passively released by cell necrosis, IL-1α could directly sense DNA damage and act as signal for genotoxic stress without loss of cell integrity.Here we demonstrate localization of the cytokine to DNA-damage sites and its subsequent secretion.

View Article: PubMed Central - PubMed

Affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR 7104, INSERM U 964, Université de Strasbourg, 67404 Illkirch, France.

ABSTRACT
Environmental signals can be translated into chromatin changes, which alter gene expression. Here we report a novel concept that cells can signal chromatin damage from the nucleus back to the surrounding tissue through the cytokine interleukin-1alpha (IL-1α). Thus, in addition to its role as a danger signal, which occurs when the cytokine is passively released by cell necrosis, IL-1α could directly sense DNA damage and act as signal for genotoxic stress without loss of cell integrity. Here we demonstrate localization of the cytokine to DNA-damage sites and its subsequent secretion. Interestingly, its nucleo-cytosolic shuttling after DNA damage sensing is regulated by histone deacetylases (HDAC) and IL-1α acetylation. To demonstrate the physiological significance of this newly discovered mechanism, we used IL-1α knockout mice and show that IL-1α signaling after UV skin irradiation and DNA damage is important for triggering a sterile inflammatory cascade in vivo that contributes to efficient tissue repair and wound healing.

No MeSH data available.


Related in: MedlinePlus

IL-1α is recruited to DNA damage sites and secreted after genotoxic stress.(a) Human HT1080 fibrosarcoma and HaCaT human keratinocytes were subjected to genotoxic stresses: UV irradiation (5 mJ/cm2), 10 mM H2O2 or 50 μgr/ml Bleomycin. 16 h post exposure, hIL-1α ELISA was used to measure secreted IL-1α in cell supernatants. All experiments were performed in triplicates and data are expressed as mean ± SD. (b) Nuclear/cytoplasmic re-localization of IL-1α after DNA damage. Live cell imaging of B16 melanoma cells expressing GFP-IL-1α during treatment with 100 μM H2O2. Images were collected every 30 min for a period of 24 h. Representative images from indicated time points are shown (for full video see Supplementary Video 1, for averaged fluorescence intensities see also Supplementary Figure 1b) White scale bars, 20 μm. (c,d) Nuclear IL-1α co-localizes with γH2AX foci after genotoxic stress. (c) B16 melanoma cells expressing GFP-IL-1α were treated with Etoposide 10 µg/mL for 2 h or (d) microirradiated with femtosecond laser pulses at λ = 775 nm (see also Supplementary Videos 2 and 3). After fixation of cells, detection of GFP-IL-1α, DAPI or immunostaining of γH2AX was preformed and visualized by confocal microscopy. White scale bars, 20 μm (e) Recruitment kinetics of IL-1α to DNA damage sites. B16 melanoma cells expressing IL-1α–GFP were laser-microirradiated along a single line to induce DNA damage. Fluorescence intensity in the damaged region was measured up to 15 min from irradiaton in 1 min intervals. Data is expressed as mean ± SEM of increase in fluorescence intensity (n = 10 cells). (f) IL-1α localizes to Cyclobutane Pyrimidine Dimers (CPD) induced via laser microirradiation. B16 melanoma cells expressing GFP-IL-1α were laser irradiated and CPDs were visualized by immunostaining using specific antibodies. White scale bars, 20 μm.
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f1: IL-1α is recruited to DNA damage sites and secreted after genotoxic stress.(a) Human HT1080 fibrosarcoma and HaCaT human keratinocytes were subjected to genotoxic stresses: UV irradiation (5 mJ/cm2), 10 mM H2O2 or 50 μgr/ml Bleomycin. 16 h post exposure, hIL-1α ELISA was used to measure secreted IL-1α in cell supernatants. All experiments were performed in triplicates and data are expressed as mean ± SD. (b) Nuclear/cytoplasmic re-localization of IL-1α after DNA damage. Live cell imaging of B16 melanoma cells expressing GFP-IL-1α during treatment with 100 μM H2O2. Images were collected every 30 min for a period of 24 h. Representative images from indicated time points are shown (for full video see Supplementary Video 1, for averaged fluorescence intensities see also Supplementary Figure 1b) White scale bars, 20 μm. (c,d) Nuclear IL-1α co-localizes with γH2AX foci after genotoxic stress. (c) B16 melanoma cells expressing GFP-IL-1α were treated with Etoposide 10 µg/mL for 2 h or (d) microirradiated with femtosecond laser pulses at λ = 775 nm (see also Supplementary Videos 2 and 3). After fixation of cells, detection of GFP-IL-1α, DAPI or immunostaining of γH2AX was preformed and visualized by confocal microscopy. White scale bars, 20 μm (e) Recruitment kinetics of IL-1α to DNA damage sites. B16 melanoma cells expressing IL-1α–GFP were laser-microirradiated along a single line to induce DNA damage. Fluorescence intensity in the damaged region was measured up to 15 min from irradiaton in 1 min intervals. Data is expressed as mean ± SEM of increase in fluorescence intensity (n = 10 cells). (f) IL-1α localizes to Cyclobutane Pyrimidine Dimers (CPD) induced via laser microirradiation. B16 melanoma cells expressing GFP-IL-1α were laser irradiated and CPDs were visualized by immunostaining using specific antibodies. White scale bars, 20 μm.

Mentions: Since it had been reported that exposure to environmental factors that cause DNA damage may trigger precIL-1α secretion410 and affect the progression and severity of inflammatory diseases121415161819, we examined the possibility that IL-1α could transduce signals from the nucleus to communicate chromatin damage to the surrounding tissue. We first confirmed that DNA damage indeed induces the secretion of IL-1α precursor. We used human keratinocytes and fibroblasts containing basal levels of the precIL-1α (Supplementary Figure 1a) to monitor the secretion of IL-1α after exposure to different genotoxic agents. As previously reported1113, we detected increased levels of IL-1α in cell supernatants after exposure to various DNA damaging agents including H2O2, UV or Bleomycin (Fig. 1a). To gain insight into the intracellular dynamics of IL-1α upon DNA damage, we next used an IL-1α–EGFP expressing cell line (previously used in5) and performed time-lapse analysis upon H2O2 treatment. Within 1.5 hours after exposure of cells to sub-lethal doses of H2O2 that generate large scale DNA damage, we observed a pronounced localization of IL-1α to nuclear foci and an increase in the cytoplasmic IL-1α signal (n = 10) (Fig. 1b, Supplementary Video 1 and Supplementary Figure 1b). We next treated cells with etoposide, a drug that prevents re-ligation of the DNA strands20 and causes DNA strands breaks. Interestingly, we found that IL-1α can co-localize with phosphorylated H2A.X (γH2AX) foci that mark DNA damage sites (Fig. 1c and Supplementary Figure 1c). When DNA was damaged by laser microirradiation, IL-1α also co-localized with γH2AX foci and became enriched at these DNA lesions within 5 to 10 minutes (Fig. 1d,eSupplementary Videos 2 and 3). Furthermore, we observed localization of IL-1α at laser-induced Cyclobutane Pyrimidine Dimers (CPD), also induced by these laser pulses at λ = 775 nm (Fig. 1f).


IL-1α is a DNA damage sensor linking genotoxic stress signaling to sterile inflammation and innate immunity.

Idan C, Peleg R, Elena V, Martin T, Cicerone T, Mareike W, Lydia B, Marina F, Gerhard M, Elisa FM, Dinarello CA, Ron AN, Robert S - Sci Rep (2015)

IL-1α is recruited to DNA damage sites and secreted after genotoxic stress.(a) Human HT1080 fibrosarcoma and HaCaT human keratinocytes were subjected to genotoxic stresses: UV irradiation (5 mJ/cm2), 10 mM H2O2 or 50 μgr/ml Bleomycin. 16 h post exposure, hIL-1α ELISA was used to measure secreted IL-1α in cell supernatants. All experiments were performed in triplicates and data are expressed as mean ± SD. (b) Nuclear/cytoplasmic re-localization of IL-1α after DNA damage. Live cell imaging of B16 melanoma cells expressing GFP-IL-1α during treatment with 100 μM H2O2. Images were collected every 30 min for a period of 24 h. Representative images from indicated time points are shown (for full video see Supplementary Video 1, for averaged fluorescence intensities see also Supplementary Figure 1b) White scale bars, 20 μm. (c,d) Nuclear IL-1α co-localizes with γH2AX foci after genotoxic stress. (c) B16 melanoma cells expressing GFP-IL-1α were treated with Etoposide 10 µg/mL for 2 h or (d) microirradiated with femtosecond laser pulses at λ = 775 nm (see also Supplementary Videos 2 and 3). After fixation of cells, detection of GFP-IL-1α, DAPI or immunostaining of γH2AX was preformed and visualized by confocal microscopy. White scale bars, 20 μm (e) Recruitment kinetics of IL-1α to DNA damage sites. B16 melanoma cells expressing IL-1α–GFP were laser-microirradiated along a single line to induce DNA damage. Fluorescence intensity in the damaged region was measured up to 15 min from irradiaton in 1 min intervals. Data is expressed as mean ± SEM of increase in fluorescence intensity (n = 10 cells). (f) IL-1α localizes to Cyclobutane Pyrimidine Dimers (CPD) induced via laser microirradiation. B16 melanoma cells expressing GFP-IL-1α were laser irradiated and CPDs were visualized by immunostaining using specific antibodies. White scale bars, 20 μm.
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f1: IL-1α is recruited to DNA damage sites and secreted after genotoxic stress.(a) Human HT1080 fibrosarcoma and HaCaT human keratinocytes were subjected to genotoxic stresses: UV irradiation (5 mJ/cm2), 10 mM H2O2 or 50 μgr/ml Bleomycin. 16 h post exposure, hIL-1α ELISA was used to measure secreted IL-1α in cell supernatants. All experiments were performed in triplicates and data are expressed as mean ± SD. (b) Nuclear/cytoplasmic re-localization of IL-1α after DNA damage. Live cell imaging of B16 melanoma cells expressing GFP-IL-1α during treatment with 100 μM H2O2. Images were collected every 30 min for a period of 24 h. Representative images from indicated time points are shown (for full video see Supplementary Video 1, for averaged fluorescence intensities see also Supplementary Figure 1b) White scale bars, 20 μm. (c,d) Nuclear IL-1α co-localizes with γH2AX foci after genotoxic stress. (c) B16 melanoma cells expressing GFP-IL-1α were treated with Etoposide 10 µg/mL for 2 h or (d) microirradiated with femtosecond laser pulses at λ = 775 nm (see also Supplementary Videos 2 and 3). After fixation of cells, detection of GFP-IL-1α, DAPI or immunostaining of γH2AX was preformed and visualized by confocal microscopy. White scale bars, 20 μm (e) Recruitment kinetics of IL-1α to DNA damage sites. B16 melanoma cells expressing IL-1α–GFP were laser-microirradiated along a single line to induce DNA damage. Fluorescence intensity in the damaged region was measured up to 15 min from irradiaton in 1 min intervals. Data is expressed as mean ± SEM of increase in fluorescence intensity (n = 10 cells). (f) IL-1α localizes to Cyclobutane Pyrimidine Dimers (CPD) induced via laser microirradiation. B16 melanoma cells expressing GFP-IL-1α were laser irradiated and CPDs were visualized by immunostaining using specific antibodies. White scale bars, 20 μm.
Mentions: Since it had been reported that exposure to environmental factors that cause DNA damage may trigger precIL-1α secretion410 and affect the progression and severity of inflammatory diseases121415161819, we examined the possibility that IL-1α could transduce signals from the nucleus to communicate chromatin damage to the surrounding tissue. We first confirmed that DNA damage indeed induces the secretion of IL-1α precursor. We used human keratinocytes and fibroblasts containing basal levels of the precIL-1α (Supplementary Figure 1a) to monitor the secretion of IL-1α after exposure to different genotoxic agents. As previously reported1113, we detected increased levels of IL-1α in cell supernatants after exposure to various DNA damaging agents including H2O2, UV or Bleomycin (Fig. 1a). To gain insight into the intracellular dynamics of IL-1α upon DNA damage, we next used an IL-1α–EGFP expressing cell line (previously used in5) and performed time-lapse analysis upon H2O2 treatment. Within 1.5 hours after exposure of cells to sub-lethal doses of H2O2 that generate large scale DNA damage, we observed a pronounced localization of IL-1α to nuclear foci and an increase in the cytoplasmic IL-1α signal (n = 10) (Fig. 1b, Supplementary Video 1 and Supplementary Figure 1b). We next treated cells with etoposide, a drug that prevents re-ligation of the DNA strands20 and causes DNA strands breaks. Interestingly, we found that IL-1α can co-localize with phosphorylated H2A.X (γH2AX) foci that mark DNA damage sites (Fig. 1c and Supplementary Figure 1c). When DNA was damaged by laser microirradiation, IL-1α also co-localized with γH2AX foci and became enriched at these DNA lesions within 5 to 10 minutes (Fig. 1d,eSupplementary Videos 2 and 3). Furthermore, we observed localization of IL-1α at laser-induced Cyclobutane Pyrimidine Dimers (CPD), also induced by these laser pulses at λ = 775 nm (Fig. 1f).

Bottom Line: Environmental signals can be translated into chromatin changes, which alter gene expression.Thus, in addition to its role as a danger signal, which occurs when the cytokine is passively released by cell necrosis, IL-1α could directly sense DNA damage and act as signal for genotoxic stress without loss of cell integrity.Here we demonstrate localization of the cytokine to DNA-damage sites and its subsequent secretion.

View Article: PubMed Central - PubMed

Affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR 7104, INSERM U 964, Université de Strasbourg, 67404 Illkirch, France.

ABSTRACT
Environmental signals can be translated into chromatin changes, which alter gene expression. Here we report a novel concept that cells can signal chromatin damage from the nucleus back to the surrounding tissue through the cytokine interleukin-1alpha (IL-1α). Thus, in addition to its role as a danger signal, which occurs when the cytokine is passively released by cell necrosis, IL-1α could directly sense DNA damage and act as signal for genotoxic stress without loss of cell integrity. Here we demonstrate localization of the cytokine to DNA-damage sites and its subsequent secretion. Interestingly, its nucleo-cytosolic shuttling after DNA damage sensing is regulated by histone deacetylases (HDAC) and IL-1α acetylation. To demonstrate the physiological significance of this newly discovered mechanism, we used IL-1α knockout mice and show that IL-1α signaling after UV skin irradiation and DNA damage is important for triggering a sterile inflammatory cascade in vivo that contributes to efficient tissue repair and wound healing.

No MeSH data available.


Related in: MedlinePlus