Interferon-γ induces senescence in normal human melanocytes

PLoS One. 2014 Mar 28;9(3):e93232. doi: 10.1371/journal.pone.0093232. eCollection 2014.

Abstract

Background: Interferon-γ (IFN-γ) plays an important role in the proceedings of vitiligo through recruiting lymphocytes to the lesional skin. However, the potential effects of IFN-γ on skin melanocytes and the subsequent contribution to the vitiligo pathogenesis are still unclear.

Objective: To investigate the effects of IFN-γ on viability and cellular functions of melanocytes.

Methods: Primary human melanocytes were treated with IFN-γ. Cell viability, apoptosis, cell cycle melanin content and intracellular reactive oxygen species (ROS) level were measured. mRNA expression was examined by real-time PCR. The release of interleukin 6 (IL-6) and heat shock protein 70 (HSP-70) was monitored by ELISA. β-galactosidase staining was utilized to evaluate melanocyte senescence.

Results: Persistent IFN-γ treatment induced viability loss, apoptosis, cell cycle arrest and senescence in melanocytes. Melanocyte senescence was characterized as the changes in pigmentation and morphology, as well as the increase of β-galactosidase activity. Increase of p21Cip1/Waf1 protein was evident in melanocytes after IFN-γ treatment. IFN-γ induction of senescence was attenuated by siRNAs against p21, Janus kinase 2 (JAK2) or signal transducer and activator of transcription 1 (STAT1), but not by JAK1 siRNA nor by p53 inhibitor pifithrin-α. IFN-γ treatment increased the accumulation of intracellular ROS in melanocytes, while ROS scavenger N-acetyl cysteine (NAC) effectively inhibited IFN-γ induced p21 expression and melanocyte senescence. IL-6 and HSP-70 release was significantly induced by IFN-γ treatment, which was largely inhibited by NAC. The increase of IL-6 and HSP-70 release could also be observed in senescent melanocytes.

Conclusion: IFN-γ can induce senescence in melanocytes and consequently enhance their immuno-competency, leading to a vitiligo-prone milieu.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine / pharmacology
  • Aging / drug effects
  • Aging / metabolism*
  • Aging / physiology*
  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Cell Cycle / drug effects
  • Cell Cycle Checkpoints / drug effects
  • Cells, Cultured
  • Cellular Senescence / drug effects
  • Cellular Senescence / physiology*
  • Cyclin-Dependent Kinase Inhibitor p16 / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Humans
  • Interferon-gamma / metabolism*
  • Interleukin-6 / metabolism
  • Iron-Binding Proteins / metabolism
  • Janus Kinase 1 / metabolism
  • Janus Kinase 2 / metabolism
  • Melanocytes / drug effects
  • Melanocytes / metabolism*
  • Melanocytes / physiology*
  • Phosphorylation / drug effects
  • Reactive Oxygen Species / metabolism
  • STAT1 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Tumor Suppressor Protein p53 / metabolism
  • beta-Galactosidase / metabolism

Substances

  • Cyclin-Dependent Kinase Inhibitor p16
  • Cyclin-Dependent Kinase Inhibitor p21
  • Interleukin-6
  • Iron-Binding Proteins
  • Reactive Oxygen Species
  • STAT1 Transcription Factor
  • Tumor Suppressor Protein p53
  • iron-binding seminal plasma antigen
  • Interferon-gamma
  • JAK2 protein, human
  • Janus Kinase 1
  • Janus Kinase 2
  • beta-Galactosidase
  • Acetylcysteine

Grants and funding

This research was supported by grants from the Natural Science Foundation of Zhejiang, China (grant no. LY13H110001 and Z2100973), the National Natural Science Foundation of China (grant no. 81071294 and 81271758), and the Co-construction Project of Ministry of Health and Zhejiang Province (grant no. WKJ2012-2-036). This research was also supported by the National key clinical specialty construction project of China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.