Lipoapoptosis induced by saturated free fatty acids stimulates monocyte migration

a novel role for Pannexin1 in liver cells

Feng Xiao, Shar L. Waldrop, Steve F. Bronk, Gregory J. Gores, Laurie S. Davis, Gordan Kilic

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Recruitment of monocytes in the liver is a key pathogenic feature of hepatic inflammation in nonalcoholic steatohepatitis (NASH), but the mechanisms involved are poorly understood. Here, we studied migration of human monocytes in response to supernatants obtained from liver cells after inducing lipoapoptosis with saturated free fatty acids (FFA). Lipoapoptotic supernatants stimulated monocyte migration with the magnitude similar to a monocyte chemoattractant protein, CCL2 (MCP-1). Inhibition of c-Jun NH<inf>2</inf>-terminal kinase (JNK) in liver cells with SP600125 blocked migration of monocytes in a dose-dependent manner, indicating that JNK stimulates release of chemoattractants in lipoapoptosis. Notably, treatment of supernatants with Apyrase to remove ATP potently inhibited migration of THP-1 monocytes and partially blocked migration of primary human monocytes. Inhibition of the CCL2 receptor (CCR2) on THP-1 monocytes with RS102895, a specific CCR2 inhibitor, did not block migration induced by lipoapoptotic supernatants. Consistent with these findings, lipoapoptosis stimulated pathophysiological extracellular ATP (eATP) release that increased supernatant eATP concentration from 5 to ~60 nM. Importantly, inhibition of Panx1 expression in liver cells with short hairpin RNA (shRNA) decreased supernatant eATP concentration and inhibited monocyte migration, indicating that monocyte migration is mediated in part by Panx1-dependent eATP release. Moreover, JNK inhibition decreased supernatant eATP concentration and inhibited Pannexin1 activation, as determined by YoPro-1 uptake in liver cells in a dose-dependent manner. These results suggest that JNK regulates activation of Panx1 channels, and provide evidence that Pannexin1-dependent pathophysiological eATP release in lipoapoptosis is capable of stimulating migration of human monocytes, and may participate in the recruitment of monocytes in chronic liver injury induced by saturated FFA.

Original languageEnglish (US)
Pages (from-to)347-359
Number of pages13
JournalPurinergic Signalling
Volume11
Issue number3
DOIs
StatePublished - Jun 9 2015

Fingerprint

Nonesterified Fatty Acids
Monocytes
Fatty Acids
Liver
Adenosine Triphosphate
JNK Mitogen-Activated Protein Kinases
Monocyte Chemoattractant Proteins
CCR2 Receptors
Apyrase
Chemotactic Factors
Small Interfering RNA
Inflammation
Wounds and Injuries

Keywords

  • JNK
  • Monocyte migration
  • Pannexin1
  • Pathophysiological ATP release

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology
  • Cellular and Molecular Neuroscience

Cite this

Lipoapoptosis induced by saturated free fatty acids stimulates monocyte migration : a novel role for Pannexin1 in liver cells. / Xiao, Feng; Waldrop, Shar L.; Bronk, Steve F.; Gores, Gregory J.; Davis, Laurie S.; Kilic, Gordan.

In: Purinergic Signalling, Vol. 11, No. 3, 09.06.2015, p. 347-359.

Research output: Contribution to journalArticle

Xiao, Feng ; Waldrop, Shar L. ; Bronk, Steve F. ; Gores, Gregory J. ; Davis, Laurie S. ; Kilic, Gordan. / Lipoapoptosis induced by saturated free fatty acids stimulates monocyte migration : a novel role for Pannexin1 in liver cells. In: Purinergic Signalling. 2015 ; Vol. 11, No. 3. pp. 347-359.
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abstract = "Recruitment of monocytes in the liver is a key pathogenic feature of hepatic inflammation in nonalcoholic steatohepatitis (NASH), but the mechanisms involved are poorly understood. Here, we studied migration of human monocytes in response to supernatants obtained from liver cells after inducing lipoapoptosis with saturated free fatty acids (FFA). Lipoapoptotic supernatants stimulated monocyte migration with the magnitude similar to a monocyte chemoattractant protein, CCL2 (MCP-1). Inhibition of c-Jun NH2-terminal kinase (JNK) in liver cells with SP600125 blocked migration of monocytes in a dose-dependent manner, indicating that JNK stimulates release of chemoattractants in lipoapoptosis. Notably, treatment of supernatants with Apyrase to remove ATP potently inhibited migration of THP-1 monocytes and partially blocked migration of primary human monocytes. Inhibition of the CCL2 receptor (CCR2) on THP-1 monocytes with RS102895, a specific CCR2 inhibitor, did not block migration induced by lipoapoptotic supernatants. Consistent with these findings, lipoapoptosis stimulated pathophysiological extracellular ATP (eATP) release that increased supernatant eATP concentration from 5 to ~60 nM. Importantly, inhibition of Panx1 expression in liver cells with short hairpin RNA (shRNA) decreased supernatant eATP concentration and inhibited monocyte migration, indicating that monocyte migration is mediated in part by Panx1-dependent eATP release. Moreover, JNK inhibition decreased supernatant eATP concentration and inhibited Pannexin1 activation, as determined by YoPro-1 uptake in liver cells in a dose-dependent manner. These results suggest that JNK regulates activation of Panx1 channels, and provide evidence that Pannexin1-dependent pathophysiological eATP release in lipoapoptosis is capable of stimulating migration of human monocytes, and may participate in the recruitment of monocytes in chronic liver injury induced by saturated FFA.",
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