Ghrelin Represses Thymic Stromal Lymphopoietin Gene Expression through Activation of Glucocorticoid Receptor and Protein Kinase C Delta in Inflamed Skin Keratinocytes.

Ghrelin, a peptide hormone secreted from enteroendocrine cells of the gastrointestinal tract, has anti-inflammatory activity in skin diseases, including dermatitis and psoriasis. However, the molecular mechanism underlying the beneficial effect of ghrelin on skin inflammation is not clear. In this study, we found that ghrelin alleviates atopic dermatitis (AD)-phenotypes through suppression of thymic stromal lymphopoietin (TSLP) gene activation. Knockdown or antagonist treatment of growth hormone secretagogue receptor 1a (GHSR1a), the receptor for ghrelin, suppressed ghrelin-induced alleviation of AD-like phenotypes and suppression of TSLP gene activation. We further found that ghrelin induces activation of the glucocorticoid receptor (GR), leading to the binding of GR with histone deacetylase 3 (HDAC3) and nuclear receptor corepressor (NCoR) NCoR corepressor to negative glucocorticoid response element (nGRE) on the TSLP gene promoter. In addition, ghrelin-induced protein kinase C δ (PKCδ)-mediated phosphorylation of p300 at serine 89 (S89), which decreased the acetylation and DNA binding activity of nuclear factor- κB (NF-κB) p65 to the TSLP gene promoter. Knockdown of PKCδ abolished ghrelin-induced suppression of TSLP gene activation. Our study suggests that ghrelin may help to reduce skin inflammation through GR and PKCδ-p300-NF-κB-mediated suppression of TSLP gene activation.

An Accelerated Wound-Healing Surgical Suture Engineered with an Extracellular Matrix.

A suture is a ubiquitous medical device to hold wounded tissues together and support the healing process after surgery. Surgical sutures, having incomplete biocompatibility, often cause unwanted infections or serious secondary trauma to soft or fragile tissue. In this research, UV/ozone (UVO) irradiation or polystyrene sulfonate acid (PSS) dip-coating is used to achieve a fibronectin (FN)-coated absorbable suture system, in which the negatively charged moieties produced on the suture cause fibronectin to change from a soluble plasma form into a fibrous form, mimicking the actions of cellular fibronectin upon binding. The fibrous fibronectin coated on the suture can be exploited as an engineered interface to improve cellular migration and adhesion in the region around the wounded tissue while preventing the binding of infectious bacteria, thereby facilitating wound healing. Furthermore, the FN-coated suture is found to be associated with a lower friction between the suture and the wounded tissue, thus minimizing the occurrence of secondary wounds during surgery. It is believed that this surface modification can be universally applied to most kinds of sutures currently in use, implying that it may be a novel way to develop a highly effective and safer suture system for clinical applications.

Caffeoyl-Prolyl-Histidine Amide Inhibits Fyn and Alleviates Atopic Dermatitis-Like Phenotypes via Suppression of NF-κB Activation.

Caffeic acid (CA) is produced from a variety of plants and has diverse biological functions, including anti-inflammation activity. It has been recently demonstrated that caffeoyl-prolyl-histidine amide (CA-PH), which is CA conjugated with proline-histidine dipeptide, relieves atopic dermatitis (AD)-like phenotypes in mouse. In this study, we investigated the molecular mechanism underlying CA-PH-mediated alleviation of AD-like phenotypes using cell line and AD mouse models. We confirmed that CA-PH suppresses AD-like phenotypes, such as increased epidermal thickening, infiltration of mast cells, and dysregulated gene expression of cytokines. CA-PH suppressed up-regulation of cytokine expression through inhibition of nuclear translocation of NF-κB. Using a CA-PH affinity pull-down assay, we found that CA-PH binds to Fyn. In silico molecular docking and enzyme kinetic studies revealed that CA-PH binds to the ATP binding site and inhibits Fyn competitively with ATP. CA-PH further suppressed spleen tyrosine kinase (SYK)/inhibitor of nuclear factor kappa B kinase (IKK)/inhibitor of nuclear factor kappa B (IκB) signaling, which is required for nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation. In addition, chronic application of CA-PH, in contrast with that of glucocorticoids, did not induce up-regulation of regulated in development and DNA damage response 1 (REDD1), reduction of mammalian target of rapamycin (mTOR) signaling, or skin atrophy. Thus, our study suggests that CA-PH treatment may help to reduce skin inflammation via down-regulation of NF-κB activation, and Fyn may be a new therapeutic target of inflammatory skin diseases, such as AD.

SFMBT2-Mediated Infiltration of Preadipocytes and TAMs in Prostate Cancer.

Infiltration of diverse cell types into tumor microenvironment plays a critical role in cancer progression including metastasis. We previously reported that SFMBT2 (Scm-like with four mbt domains 2) regulates the expression of matrix metalloproteinases (MMPs) and migration and invasion of cancer cells in prostate cancer. Here we investigated whether the down-regulation of SFMBT2 regulates the infiltration of preadipocytes and tumor-associated macrophages (TAMs) in prostate cancer. We found that the down-regulation of SFMBT2 promotes the infiltration of preadipocytes and TAMs through up-regulation of CXCL8, CCL2, CXCL10, and CCL20 expression in prostate cancer. Expression of CXCL8, CCL2, CXCL10, and CCL20 was also elevated in prostate cancer patients having a higher Gleason score (≥8), which had substantially lower SFMBT2 expression. We also found that the up-regulation of CXCL8, CCL2, CXCL10, and CCL20 expression is dependent on NF-κB activation in prostate cancer cells expressing a low level of SFMBT2. Moreover, increased IL-6 from infiltrated preadipocytes and TAMs promoted migration and invasion of prostate cancer cells expressing a low level of SFMBT2. Our study may suggest that SFMBT2 a critical regulator for the infiltration of preadipocytes and TAMs into the prostate tumor microenvironment. Thus, the regulation of SFMBT2 may provide a new therapeutic strategy to inhibit prostate cancer metastasis, and SFMBT2 could be used as a potential biomarker in prostate cancer metastasis.

Activation of Aryl Hydrocarbon Receptor Negatively Regulates Thymic Stromal Lymphopoietin Gene Expression via Protein Kinase Cδ-p300-NF-κB Pathway in Keratinocytes under Inflammatory Conditions.

Epithelial-derived thymic stromal lymphopoietin (TSLP) plays an important role in pathogenesis in several types of dermatitis. Recently, the anti-inflammatory effects of aryl hydrocarbon receptor (AhR) have been reported in inflamed skin. In this study, keratinocytes were stimulated with tumor necrosis factor-α or flagellin in combination with AhR ligands or antagonist. TSLP gene expression and recruitment of transcriptional regulator to TSLP gene promoter were determined. The effects of AhR activation were also studied in DNFB-induced dermatitis model. We found that AhR activation suppressed upregulation of TSLP expression in keratinocytes treated with tumor necrosis factor-α or flagellin. In addition, AhR activation induced protein kinase Cδ-mediated phosphorylation of p300 at serine 89, leading to decreased acetylation and DNA binding activity of NF-κB p65 to the TSLP gene promoter. We also found that AhR activation alleviates dermatitis induced by DNFB treatment. Protein kinase Cδ depletion by small interfering RNA abolished the beneficial effect of AhR activation on dermatitis. Our study suggests that AhR activation may help to reduce inflammation in the dermatitis via downregulation of TSLP expression.

JMJD3 and NF-κB-dependent activation of Notch1 gene is required for keratinocyte migration during skin wound healing.

It has been shown that epigenetic regulation plays an important role in skin wound healing. We previously found that histone H3K27me3 demethylase JMJD3 regulates inflammation and cell migration in keratinocyte wound healing. In this study, we identified Notch1 as a direct target of JMJD3 and NF-κB in wounded keratinocytes using in vitro cell and in vivo animal models. We found that Notch1 is up-regulated in the wound edge and its expression is dependent on JMJD3 and NF-κB in wounded keratinocytes. We also found that Notch1 activates the expression of RhoU and PLAU gene, which are critical regulators of cell migration. Consistently, depletion or inactivation of Notch1 resulted in decreased filopodia formation, increased focal adhesion and actin stress fiber, leading to reduced keratinocyte migration and skin wound healing. Thus, our findings provide the molecular mechanism involving JMJD3/NF-κB-Notch pathway in keratinocyte wound healing.

Role of type II protein arginine methyltransferase 5 in the regulation of Circadian Per1 gene.

Circadian clocks are the endogenous oscillators that regulate rhythmic physiological and behavioral changes to correspond to daily light-dark cycles. Molecular dissections have revealed that transcriptional feedback loops of the circadian clock genes drive the molecular oscillation, in which PER/CRY complexes inhibit the transcriptional activity of the CLOCK/BMAL1 heterodimer to constitute a negative feedback loop. In this study, we identified the type II protein arginine methyltransferase 5 (PRMT5) as an interacting molecule of CRY1. Although the Prmt5 gene was constitutively expressed, increased interaction of PRMT5 with CRY1 was observed when the Per1 gene was repressed both in synchronized mouse liver and NIH3T3 cells. Moreover, rhythmic recruitment of PRMT5 and CRY1 to the Per1 gene promoter was found to be associated with an increased level of histone H4R3 dimethylation and Per1 gene repression. Consistently, decreased histone H4R3 dimethylation and altered rhythmic Per1 gene expression were observed in Prmt5-depleted cells. Taken together, these findings provide an insight into the link between histone arginine methylation by PRMT5 and transcriptional regulation of the circadian Per1 gene.