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Regulation of expression and trafficking of perforin-2 by LPS and TNF-α

Peng Xiong1, Motoaki Shiratsuchi1, Takamitsu Matsushima1

  • 1Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.

Cellular Immunology
|July 15, 2017
PubMed

Insights

Human macrophages express two forms of perforin-2, a protein crucial for controlling bacteria. These isoforms, membrane-bound perforin-2a and secretory perforin-2b, play distinct roles in immune defense.

Area of Science:

  • Immunology
  • Cell Biology

Background:

  • Perforin-2 is essential for bacterial control and constitutively expressed in macrophages.
  • Macrophages are key immune cells involved in host defense against pathogens.

Purpose of the Study:

  • To investigate the isoforms of perforin-2 expressed in human macrophages.
  • To determine the subcellular localization and regulation of these perforin-2 isoforms.
  • To elucidate the functional roles of perforin-2 isoforms in macrophage-mediated immune responses.

Main Methods:

  • Immunofluorescence microscopy to assess subcellular localization.
  • Western blotting to detect protein expression.
  • NF-κB pathway analysis.
  • Stimulation with lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-α).

Main Results:

  • Two perforin-2 isoforms, perforin-2a (full-length) and perforin-2b (splice variant), were identified in human macrophages.
  • Perforin-2a localized to endosome-like vesicles via its transmembrane domain, while perforin-2b, lacking this domain, did not.
  • Pro-inflammatory stimuli (LPS, TNF-α) induced perforin-2a expression via NF-κB, promoting vesicle fusion with lysosomes.
  • LPS stimulation led to the secretion of perforin-2b.

Conclusions:

  • Human macrophages express distinct membrane-bound (perforin-2a) and secretory (perforin-2b) isoforms of perforin-2.
  • These isoforms exhibit differential subcellular localization and regulation.
  • Perforin-2 isoforms likely play critical, distinct roles in macrophage immune defense against bacterial infections.
Keywords:
Endosome-like vesicleMACPF domainMacrophageMpeg1Transmembrane domain

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