KGF promotes integrin alpha5 expression through CCAAT/enhancer-binding protein-beta

Primer on fibroblast growth factor 7 (FGF 7)

Fibroblast growth factor 7 (FGF7), also known as keratinocyte growth factor (KGF), is an important member of the FGF family that is mainly expressed by cells of mesenchymal origin while affecting specifically epithelial cells. Thus, FGF7 is widely expressed in diverse tissues, especially in urinary system, gastrointestinal tract (GI-tract), respiratory system, skin, and reproductive system. By interacting specifically with FGFR2-IIIb, FGF7 activates several downstream signal pathways, including Ras, PI3K-Akt, and PLCs. Previous studies of FGF7 mutants also have implicated its roles in various biological processes including development of essential organs and tissue homeostasis in adults. Moreover, more publications have reported that FGF7 and/or FGF7/FGFR2-IIIb-associated signaling pathway are involved in the progression of various heritable or acquired human diseases: heritable conditions like autosomal dominant polycystic kidney disease (ADPKD) and non-syndromic cleft lip and palate (NS CLP), where it promotes cyst formation and affects craniofacial development, respectively; acquired non-malignant diseases such as chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), mucositis, osteoarticular disorders, and metabolic diseases, where it influences inflammation, repair, and metabolic control; and tumorigenesis and malignant diseases, including benign prostatic hyperplasia (BPH), prostate cancer, gastric cancer, and ovarian cancer, where it enhances cell proliferation, invasion, and chemotherapy resistance. Targeting FGF7 pathways holds therapeutic potential for managing these conditions, underscoring the need for further research to explore its clinical applications. Having more insights into the function and underlying molecular mechanisms of FGF7 is warranted to facilitate the development of effective treatments in the future. Here, we discuss FGF7 genomic structure, signal pathway, expression pattern during embryonic development and in adult organs and mutants along with phenotypes, as well as associated diseases.

Effect of Taspine hydrochloride on the repair of rat skin wounds by regulating keratinocyte growth factor signal

To explore the regulation of keratinocyte growth factor (KGF) in the process of repairing rat skin wounds by taspine hydrochloride (TA/HCl), 45 male Sprague-Dawley (SD) rats were purchased and divided into an experimental group, a dimethyl sulfoxide (DMSO) control group, and a basic fibroblast growth factor (bFGF) control group, each with 15 only. A back trauma model was innovatively adopted to prevent rats from biting and contaminating. The wound healing time and healing rate of the rat, and the Hydroxyproline (Hyp) and KGF expressions were observed. Morphological changes of wound tissue and the number of capillaries were observed after hematoxylin-eosin (HE) staining. The results showed that wound healing rate of experimental group and bFGF group was significantly higher than that of DMSO group (P < 0.05) after 2–15 days, and wound healing time of experimental group was 18 days, which was significantly lower than that of the DMSO group (P < 0.05). Expression levels of Hyp and KGF in the granulation tissue of rats in the experimental group were much higher than those in the DMSO control group after trauma (P < 0.05). In early stage of wound tissue repair, the number of new capillaries formed in experimental group was significantly higher than that in DMSO control group (P < 0.05). In summary, this study innovatively focused on KGF. The mechanism of TA/HCL promoting rat skin wound healing was closely related to KGF.

Downregulation of miR-205 in migrating epithelial tongue facilitates skin wound re-epithelialization by derepressing ITGA5

Keratinocyte migration is essential for re-epithelialization during skin wound healing, but the molecular mechanisms regulating this cellular response remain to be completely clarified. Here we show that keratinocyte-specific miR-205 is significantly downregulated in the leading edge of the migrating epithelial tongue after skin injury in mice. In HaCaT keratinocytes, miR-205 could be downregulated by TGF-β1 stimulation. And similar to the effect of TGF-β1, miR-205 knockdown could promote keratinocyte migration in wound scratch model in vitro. Furthermore, topical inhibition of miR-205 by administrating Pluronic gel containing antagomir-205 could accelerate re-epithelialization in mouse skin wound model in vivo. Moreover, we identified integrin alpha 5 (ITGA5) as one key functional miR-205 target in the re-epithelialization process and epidermal downregulation of miR-205 may desilence ITGA5 to promote keratinocyte migration. And knockdown of ITGA5 would abolish the pro-migratory effects of miR-205 inhibition in vitro. What's more, we found dysregulation of miR-205 and its target ITGA5 in epidermis of clinical chronic wound samples with persistence of high level miR-205 and absence of ITGA5. Our findings indicate that downregulation of miR-205 in the leading migrating keratinocytes is critical for re-epithelialization and miR-205 may be a potential therapeutic target for chronic wounds.

Palifermin for the protection and regeneration of epithelial tissues following injury: new findings in basic research and pre-clinical models

Keratinocyte growth factor (KGF) is a paracrine-acting epithelial mitogen produced by cells of mesenchymal origin, that plays an important role in protecting and repairing epithelial tissues. Pre-clinical data initially demonstrated that a recombinant truncated KGF (palifermin) could reduce gastrointestinal injury and mortality resulting from a variety of toxic exposures. Furthermore, the use of palifermin in patients with hematological malignancies reduced the incidence and duration of severe oral mucositis experienced after intensive chemoradiotherapy. Based upon these findings, as well as the observation that KGF receptors are expressed in many, if not all, epithelial tissues, pre-clinical studies have been conducted to determine the efficacy of palifermin in protecting different epithelial tissues from toxic injury in an attempt to model various clinical situations in which it might prove to be of benefit in limiting tissue damage. In this article, we review these studies to provide the pre-clinical background for clinical trials that are described in the accompanying article and the rationale for additional clinical applications of palifermin.

Nanog reverses the effects of organismal aging on mesenchymal stem cell proliferation and myogenic differentiation potential

Although the therapeutic potential of mesenchymal stem cells (MSCs) is widely accepted, loss of cell function due to donor aging or culture senescence are major limiting factors hampering their clinical application. Our laboratory recently showed that MSCs originating from older donors suffer from limited proliferative capacity and significantly reduced myogenic differentiation potential. This is a major concern, as the patients most likely to suffer from cardiovascular disease are elderly. Here we tested the hypothesis that a single pluripotency-associated transcription factor, namely Nanog, may reverse the proliferation and differentiation potential of bone marrow-derived MSC (BM-MSC) from adult donors. Microarray analysis showed that adult (a)BM-MSC expressing Nanog clustered close to Nanog-expressing neonatal cells. Nanog markedly upregulated genes involved in cell cycle, DNA replication, and DNA damage repair and enhanced the proliferation rate and clonogenic capacity of aBM-MSC. Notably, Nanog reversed the myogenic differentiation potential and restored the contractile function of aBM-MSC to a similar level as that of neonatal (n)BM-MSC. The effect of Nanog on contractility was mediated--at least in part--through activation of the TGF-β pathway by diffusible factors secreted in the conditioned medium of Nanog-expressing BM-MSC. Overall, our results suggest that Nanog may be used to overcome the effects of organismal aging on aBM-MSC, thereby increasing the potential of MSC from aged donors for cellular therapy and tissue regeneration.

P2Y(2) receptor expression is regulated by C/EBPβ during inflammation in intestinal epithelial cells

Inflammatory bowel diseases are characterized by relapses and remission periods during which numerous factors, including stress factors and nucleotides, are mobilized to re-establish intestinal mucosal homeostasis. We have previously found that expression of the P2Y(2) nucleotide receptor is increased in colonic tissue isolated from inflammatory bowel disease patients as well as in a mouse model of colitis, and that P2Y(2) transcription is regulated in part by nuclear factor κB (NF-κB) p65. Transcription factor DNA-binding site analysis identified three potential CCAAT/enhancer-binding protein β (C/EBPβ) binding sites in the P2Y(2) proximal promoter. We then assessed the role of C/EBP transcription factors in the regulation of P2Y(2) in intestinal epithelial cells (IECs). We identified a region between -229 and -220 bp upstream of the transcription initiation site as a DNA-binding site for C/EBPβ, by electrophoretic mobility and supershift assays. Mutagenesis of this site decreased C/EBPβ-dependent P2Y(2) expression, as assessed by luciferase assays. In vivo, C/EBPβ as well as P2Y(2) expression was increased in colonic IECs isolated from mice with dextran sulfate sodium-induced acute colitis. In contrast, P2Y(2) expression was decreased in C/EBPβ-deficient mice treated with dextran sulfate sodium. Although C/EBPβ was sufficient to induce P2Y(2) transcription, the effect of C/EBPβ and NF-κB p65 on receptor transcription was synergistic. Chromatin immunoprecipitation assays revealed that both proteins simultaneously bind to the P2Y(2) promoter. Thus, we have identified C/EBPβ as a novel regulator of P2Y(2) expression.

Herpes simplex virus type 2 infection of human epithelial cells induces CXCL9 expression and CD4+ T cell migration via activation of p38-CCAAT/enhancer-binding protein-β pathway

Recruitment of CD4(+) T cells to infection areas after HSV-2 infection may be one of the mechanisms that account for increased HIV-1 sexual transmission. Lymphocytes recruited by chemokine CXCL9 are known to be important in control of HSV-2 infection in mice, although the underlying mechanism remains to be addressed. Based on our observation that CXCL9 expression is augmented in the cervical mucus of HSV-2-positive women, in this study we demonstrate that HSV-2 infection directly induces CXCL9 expression in primary cervical epithelial cells and cell lines, the principal targets of HSV-2, at both mRNA and protein levels. Further studies reveal that the induction of CXCL9 expression by HSV-2 is dependent upon a binding site for C/EBP-β within CXCL9 promoter sequence. Furthermore, CXCL9 expression is promoted at the transcriptional level through phosphorylating C/EBP-β via p38 MAPK pathway, leading to binding of C/EBP-β to the CXCL9 promoter. Chemotaxis assays indicate that upregulation of CXCL9 expression at the protein level by HSV-2 infection enhances the migration of PBLs and CD4(+) T cells, whereas neutralization of CXCL9 or inhibition of p38-C/EBP-β pathway can significantly decrease the migration. Our data together demonstrate that HSV-2 induces CXCL9 expression in human cervical epithelial cells by activation of p38-C/EBP-β pathway through promoting the binding of C/EBP-β to CXCL9 promoter, which may recruit activated CD4(+) T cells to mucosal HSV-2 infection sites and potentially increase the risk of HIV-1 sexual transmission.

Membrane-bound and exosomal metastasis-associated C4.4A promotes migration by associating with the α(6)β(4) integrin and MT1-MMP

Metastasis-associated C4.4A, which becomes upregulated during wound healing and, in some tumors, during tumor progression, is known to be frequently associated with hypoxia. With the function of C4.4A still unknown, we explored the impact of hypoxia on C4.4A expression and functional activity. Metastatic rat and human tumor lines upregulate C4.4A expression when cultured in the presence of CoCl(2). Although hypoxia-inducible factor 1α (HIF-1α) becomes upregulated concomitantly, HIF-1α did not induce C4.4A transcription. Instead, hypoxia-induced C4.4A up-regulation promoted in vivo and in vitro wound healing, where increased migration on the C4.4A ligands laminin-111 and -332 was observed after a transient period of pronounced binding. Increased migration was accompanied by C4.4A associating with α(6)β(4), MT1-MMP1, and TACE and by laminin fragmentation. Hypoxia also promoted the release of C4.4A in exosomes and TACE-mediated C4.4A shedding. The association of C4.4A with α(6)β(4) and MT1-MMP1 was maintained in exosomes and exosomal α(6)β(4)- and MT1-MMP1-associated C4.4A but not shed C4.4A sufficient for laminin degradation. Hypoxia-induced recruitment of α(6)β(4) toward raft-located C4.4A, MT1-MMP, and TACE allows for a shift from adhesion to motility, which is supported by laminin degradation. These findings provide the first explanation for the C4.4A contribution to wound healing and metastasis.

Ordered and disordered proteins as nanomaterial building blocks

Proteins possess a number of attractive properties that have contributed to their recent emergence as nanoscale building blocks for biomaterials and bioinspired materials. For instance, the amino acid sequence of a protein can be precisely controlled and manipulated via recombinant DNA technology, and proteins can be biosynthesized with very high purity and virtually perfect monodispersity. Most importantly, protein-based biomaterials offer the possibility of technologically harnessing the vast array of functions that these biopolymers serve in nature. In this review, we discuss recent progress in the field of protein-based biomaterials, with an overall theme of relating protein structure to material properties. We begin by discussing materials based on proteins that have well-defined three-dimensional structures, focusing specifically on elastin- and silk-like peptides. We then explore the newer field of materials based on intrinsically disordered proteins, using nucleoporin and neurofilament proteins as case studies. A key theme throughout the review is that specific environmental stimuli can trigger protein conformational changes, which in turn can alter macroscopic material properties and function.

ZEB2 upregulates integrin α5 expression through cooperation with Sp1 to induce invasion during epithelial-mesenchymal transition of human cancer cells

Epithelial-mesenchymal transition (EMT) is a process implicated in tumor invasion, metastasis, embryonic development and wound healing. ZEB2 is a transcription factor involved in EMT that represses E-cadherin transcription. Although E-cadherin downregulation is a major event during EMT and tumor progression, E-cadherin reduction is probably not sufficient for full invasiveness. The mechanisms by which E-cadherin transcriptional repressors induce mesenchymal genes during EMT remain largely unknown. Here, we investigated the role of ZEB2 in the induction of integrin α5 during cancer EMT and its underlying mechanism. In human cancer cells, ZEB2 was found to directly upregulate integrin α5 transcription in a manner that is independent of the regulation of E-cadherin expression. Conversely, depletion of ZEB2 by small interfering RNA suppressed integrin α5 expression, leading to reduced invasion. Suppression of integrin α5 inhibited cancer cell invasion, suggesting an important role for integrin α5 in cancer progression. Furthermore, ZEB2 was found to activate the integrin α5 and vimentin promoters by interacting with and activating the transcription factor Sp1, suggesting that cooperation between ZEB2 and Sp1 represents a novel mechanism of mesenchymal gene activation during EMT. These findings increase our understanding of the pathways beyond E-cadherin reduction that regulate mesenchymal gene expression during EMT and cancer progression.

Connective tissue growth factor acts as a therapeutic agent and predictor for peritoneal carcinomatosis of colorectal cancer

PURPOSE

Here, we aimed to investigate the role of connective tissue growth factor (CTGF) in peritoneal carcinomatosis (PC) associated with colorectal cancer (CRC) and to characterize the underlying mechanism of CTGF mediating adhesion.

EXPERIMENTAL DESIGN

A cohort of 136 CRC patient specimens was analyzed in this study. CRC cell lines were used for in vitro adhesion assay and in vivo peritoneal dissemination experiment. Recombinant CTGF protein treatment, transfection of CTGF expression plasmids, and knockdown of CTGF expression in CRC cells were utilized to evaluate the integrin α5, which served as a target of CTGF in inhibiting peritoneal seeding.

RESULTS

The analysis of CRC tissues revealed an inverse correlation between CTGF expression and prevalence of PC. Lower CTGF level in CRC patients was associated with higher peritoneal recurrence rate after surgery. Inducing CTGF expression in cancer cells resulted in decreased incidence of PC and increased rate of mice survival. The mice received intraperitoneal injection of recombinant CTGF protein simultaneously with cancer cells or following tumor formation; in both cases, peritoneal tumor dissemination was found to be effectively inhibited in the mouse model. Functional assay revealed that CTGF significantly decreased the CRC cell adhesion ability, and integrin α5 was confirmed by reverse transcriptase PCR and functional blocking assay as a downstream effector in the CTGF-mediated inhibition of CRC cell adhesion.

CONCLUSIONS

CTGF acts as a molecular predictor of PC and could be a potential therapeutic target for the chemoprevention and treatment of PC in CRC patients.

Self-assembling elastin-like peptides growth factor chimeric nanoparticles for the treatment of chronic wounds

Chronic wounds are associated with poor epidermal and dermal remodeling. Previous work has shown the efficacy of keratinocyte growth factor (KGF) in reepithelialization and elastin in dermal wound healing. Here we demonstrate the fabrication of a fusion protein comprising of elastin-like peptides and KGF. This fusion protein retains the performance characteristics of KGF and elastin as evidenced by its enhancement of keratinocyte and fibroblast proliferation. It also preserved the characteristic elastin-like peptides inverse phase transitioning allowing the recombinant protein to be expressed in bacterial hosts (such as Escherichia coli) and purified rapidly and easily using inverse temperature cycling. The fusion protein self-assembled into nanoparticles at physiological temperatures. When applied to full thickness, wounds in Lepr(db) diabetic mice these particles enhanced reepithelialization and granulation, by 2- and 3-fold respectively, when compared to the controls. The data strongly suggests that these self-assembled nanoparticles may be beneficial in the treatment of chronic wounds resulting from diabetes or other underlying circulatory conditions.

Differentiation associated changes in gene expression profiles of interstitial cystitis and control urothelial cells

PURPOSE

We evaluated gene expression profiles after inducing differentiation in cultured interstitial cystitis and control urothelial cells.

MATERIALS AND METHODS

Bladder biopsies were taken from patients with interstitial cystitis and controls, that is women undergoing surgery for stress incontinence. Primary cultures were grown in keratinocyte growth medium with supplements. To induce differentiation in some plates the medium was changed to Dulbecco's modified Eagle's minimal essential medium-F12 (Media Tech, Herndon, Virginia) with supplements. RNA was analyzed with Affymetrix(R) chips. Three patients with nonulcerative interstitial cystitis were compared with 3 controls.

RESULTS

After inducing differentiation 302 genes with a described function were altered at least 3-fold in interstitial cystitis and control cells (p <0.01). Functions of the 162 up-regulated genes included cell adhesion (eg claudins, occludin and cingulin), urothelial differentiation, the retinoic acid pathway and keratinocyte differentiation (eg skin cornified envelope components). The 140 down-regulated transcripts included genes associated with basal urothelium (eg p63, integrins beta4, alpha5 and alpha6, basonuclin 1 and extracellular matrix components), vimentin, metallothioneins, and members of the Wnt and Notch pathways. When comparing interstitial cystitis control cells after differentiation, only 7 genes with a described function were altered at least 3-fold (p <0.01). PI3, SERPINB4, CYP2C8, EFEMP2 and SEPP1 were decreased, and AKR1C2 and MKNK1 were increased in interstitial cystitis cases.

CONCLUSIONS

Differentiation associated changes occurred in interstitial cystitis and control cells. Comparing interstitial cystitis vs control cases revealed few differences. This study may have included patients with interstitial cystitis and minimal urothelial deficiency, and/or we may have selected cells that were most robust in culture. Also, the abnormal urothelium in interstitial cystitis cases may be due to post-translational changes and/or to the bladder environment.