Dataset Information

PHF11 expression and cellular distribution is regulated by the Toll-Like Receptor 3 Ligand Polyinosinic:Polycytidylic Acid in HaCaT keratinocytes.

ABSTRACT:

Background

Inflammatory skin diseases such as atopic dermatitis and psoriasis represent a complex interaction between the skin and infiltrating immune cells, resulting in damage to the skin barrier and increased inflammation. Polymorphisms in PHF11 have been associated with dermatitis and allergy and PHF11 regulates the transcription of T-cell cytokines as well as class switching to IgE in activated B-cells. The importance of skin barrier homeostasis in the context of inflammatory skin diseases, together with reports identifying PHF11 as an interferon-induced gene, have led us to examine its role in the innate immune response of keratinocytes.

Results

We developed a cell culture model that allowed us to analyze the effects of the double-stranded RNA analogue poly(I:C) on a confluent cell monolayer immediately after a 24-h treatment, as well as three days after withdrawal of treatment. Immediately after treatment with poly(I:C), PHF11, IL8, and interferon-dependent ISG15 RNA expression was increased. This was accompanied by nuclear localization of PHF11 as well the tight junction protein claudin-1. Knock-down of PHF11 resulted in increased interleukin-8 expression and secretion immediately following treatment with poly(I:C), as well as changes in the cellular distribution of membrane-bound and increased nuclear claudin-1 that was observed up to 3 days after the withdrawal of poly(I:C). This was associated with lower cell density and a decrease in the number of cells in the G1 phase of the cell cycle.

Conclusions

In addition to a role for PHF11 in lymphocyte gene expression, we have now shown that PHF11 was part of the keratinocyte innate immune response by poly(I:C). As knock-down of PHF11 was associated with increased expression of the pro-inflammatory chemokine IL-8 and changes in the cellular distribution of claudin-1, a change normally associated with increased proliferation and migration, we suggest that PHF11 may contribute to epidermal recovery following infection or other damage.

SUBMITTER: Muscat P

PROVIDER: S-EPMC4647448 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Although there is strong evidence that ligand activation of peroxisome proliferator-activated receptor (PPAR)-beta/delta induces terminal differentiation and attenuates cell growth, some studies suggest that PPARbeta/delta actually enhances cell proliferation. For example, it was suggested recently that retinoic acid (RA) is a ligand for PPARbeta/delta and potentiates cell proliferation by activating PPARbeta/delta. The present study examined the effect of ligand activation of PPARbeta/delta on cell proliferation, cell cycle kinetics, and target gene expression in human HaCaT keratinocytes using two highly specific PPARbeta/delta ligands [4-[[[2-[3-fluoro-4-(trifluoromethyl)phenyl]-4-methyl-5-thiazolyl]methyl]thio]-2-methylphenoxy acetic acid (GW0742) and 2-methyl-4-((4-methyl-2-(4-trifluoromethylphenyl)-1,3-thiazol-5-yl)-methylsulfanyl)phenoxy-acetic acid (GW501516)] and RA. Both PPARbeta/delta ligands and RA inhibited cell proliferation of HaCaT keratinocytes. GW0742 and GW501516 increased expression of known PPARbeta/delta target genes, whereas RA did not; RA increased the expression of known retinoic acid receptor/retinoid X receptor target genes, whereas GW0742 did not affect these genes. GW0742, GW501516, and RA did not modulate the expression of 3-phosphoinositide-dependent protein kinase or alter protein kinase B phosphorylation. GW0742 and RA increased annexin V staining as quantitatively determined by flow cytometry. The effects of GW0742 and RA were also examined in wild-type and PPARbeta/delta-null primary mouse keratinocytes to determine the specific role of PPARbeta/delta in modulating cell growth. Although inhibition of keratinocyte proliferation by GW0742 was PPARbeta/delta-dependent, inhibition of cell proliferation by RA occurred in both genotypes. Results from these studies demonstrate that ligand activation of PPARbeta/delta inhibits keratinocyte proliferation through PPARbeta/delta-dependent mechanisms. In contrast, the observed inhibition of cell proliferation in mouse and human keratinocytes by RA is mediated by PPARbeta/delta-independent mechanisms and is inconsistent with the notion that RA potentiates cell proliferation by activating PPARbeta/delta.