Epigallocatechin-3-gallate inhibits lysophosphatidic acid-stimulated connective tissue growth factor via JNK and Smad3 suppression in human gingival fibroblasts

JNK Signaling as a Key Modulator of Soft Connective Tissue Physiology, Pathology, and Healing

In healthy individuals, the healing of soft tissues such as skin after pathological insult or post injury follows a relatively predictable and defined series of cell and molecular processes to restore tissue architecture and function(s). Healing progresses through the phases of hemostasis, inflammation, proliferation, remodeling, and concomitant with re-epithelialization restores barrier function. Soft tissue healing is achieved through the spatiotemporal interplay of multiple different cell types including neutrophils, monocytes/macrophages, fibroblasts, endothelial cells/pericytes, and keratinocytes. Expressed in most cell types, c-Jun N-terminal kinases (JNK) are signaling molecules associated with the regulation of several cellular processes involved in soft tissue wound healing and in response to cellular stress. A member of the mitogen-activated protein kinase family (MAPK), JNKs have been implicated in the regulation of inflammatory cell phenotype, as well as fibroblast, stem/progenitor cell, and epithelial cell biology. In this review, we discuss our understanding of JNKs in the regulation of cell behaviors related to tissue injury, pathology, and wound healing of soft tissues. Using models as diverse as Drosophila, mice, rats, as well as human tissues, research is now defining important, but sometimes conflicting roles for JNKs in the regulation of multiple molecular processes in multiple different cell types central to wound healing processes. In this review, we focus specifically on the role of JNKs in the regulation of cell behavior in the healing of skin, cornea, tendon, gingiva, and dental pulp tissues. We conclude that while parallels can be drawn between some JNK activities and the control of cell behavior in healing, the roles of JNK can also be very specific modes of action depending on the tissue and the phase of healing.

Biological approaches for hypertrophic scars

Scar formation is usually the pathological consequence of skin trauma. And hypertrophic scars (HSs) frequently occur in people after being injured deeply. HSs are unusually considered as the result of tissue contraction and excessive extracellular matrix component deposition. Myofibroblasts, as the effector cells, mainly differentiated from fibroblasts, play the crucial role in the pathophysiology of HSs. A number of growth factors, inflammatory cytokines involved in the process of HS occurrence. Currently, with in-depth exploration and clinical research of HSs, various creative and effective treatments budded. In here, we summarize the progress in the molecular mechanism of HSs, and review the available biotherapeutic methods for their pathophysiological characteristics. Additionally, we further prospected that the comprehensive therapy may be more suitable for HS treatment.

Mycobacterium tuberculosis induces connective tissue growth factor expression through the TLR2-JNK-AP-1 pathway in human lung fibroblasts

Mycobacterium tuberculosis (M.tb) infection in lung causes pulmonary fibrosis, which leads to the irreversible reduction of pulmonary function. Fibrotic protein connective tissue growth factor (CTGF) expression has been confirmed to play a crucial role in lung fibrosis. However, the underlying signal pathway and effect of M.tb on CTGF expression in human lung fibroblasts are unclear. Our results revaled that M.tb caused time- and concentration-dependent increases in CTGF expression in human lung fibroblasts. A mechanistic investigation revealed that M.tb induced CTGF expression through TLR2 but not TLR4. The promoter activity assay indicated that M.tb-induced CTGF activity was mainly controlled by the promoter region at -747 to -184 bp, which contained signal transducer and activator of transcription 3 and activator protein 1 (AP-1) binding sites. Moreover, curcumin (AP-1 inhibitor) restrained M.tb-induced CTGF expression. M.tb also induced increases in AP-1 luciferase activity and DNA binding activity of c-Jun and c-Fos on the CTGF promoter. Furthermore, the knockdown of c-Jun by small interfering RNA attenuated M.tb-induced CTGF expression and AP-1 luciferase activity. A JNK inhibitor (SP600125) and a JNK dominant-negative mutant suppressed M.tb-induced CTGF expression. We also discovered that M.tb could induce the phosphorylation of JNK and c-Jun. Furthermore, SP600125 inhibited M.tb-induced c-Jun phosphorylation and AP-1- luciferase activity. M.tb-induced fibronectin expression was inhibited by anti-CTGF antibody. These results demonstrate that M.tb is activated through TLR2 to induce JNK activation, further increasing the DNA binding activity of c-Jun and c-Fos and finally inducing CTGF expression and extracellular matrix production.-Lee, H.-S., Hua, H.-S., Wang, C.-H., Yu, M.-C., Chen, B.-C., Lin, C.-H. Mycobacterium tuberculosis induces connective tissue growth factor expression through the TLR2-JNK-AP-1 pathway in human lung fibroblasts.

Lysophosphatidic acid induces integrin β6 expression in human oral squamous cell carcinomas cells via LPAR1 coupling to Gαi and downstream SMAD3 and ETS-1 activation

Integrin β6 (ITGB6), an epithelial-specific integrin, is upregulated in oral squamous cell carcinomas (OSCC) and is associated with progression and metastasis of OSCC. Lysophosphatidic acid (LPA), an important bioactive phospholipid present in saliva, has also been related to OSCC cell migration and invasiveness. LPA exerts its biological effects through signal transduction pathways that ultimately regulate gene expression. However, it is unclear whether LPA signaling is involved in ITGB6 upregulation in OSCC. Therefore, the aim of the current study was to investigate the role of LPA in the regulation of ITGB6 expression in OSCC cells, and to delineate the molecular signaling pathways involved. Using SAS and HSC-3 OSCC cell lines, we found that LPA increases ITGB6 mRNA expression without affecting mRNA stability, suggesting that LPA acts by regulating ITGB6 gene transcription. In addition, we show that LPA stimulation increases phosphorylation and binding of the transcription factors SMAD3 and ETS-1 to the ITGB6 promoter resulting in ITGB6 active transcription. Finally, we demonstrate that LPA-induced ITGB6 expression is mediated via the LPA receptors 1 (LPAR1) coupling to Gα_i. Our findings provide insights into the molecular mechanism underlying ITGB6 overexpression in OSCC and may have important implications for therapeutic purposes.

MEKK1, JNK, and SMAD3 mediate CXCL12-stimulated connective tissue growth factor expression in human lung fibroblasts

Background

In idiopathic pulmonary fibrosis, the interaction of CXCL12 and CXC receptor 4 (CXCR4) plays a critical role in lung fibrosis. Connective tissue growth factor (CTGF) overexpression underlies the development of pulmonary fibrosis. Our previous report showed that the Rac1-dependent extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and activator protein (AP)-1 pathways are involved in CXCL12-generated CTGF expression in human lung fibroblasts (WI-38). In present study, we additionally inspected the involvement of mitogen-activated protein kinase kinase kinase 1 (MEKK1)/JNK-dependent SMAD3 in CXCL12-triggered CTGF expression in WI-38 cells.

Methods

WI-38 cells were stimulated with CXCL12 in the absence or presence of specific inhibitors or small interfering RNAs (siRNAs). CTGF expression and signaling transduction molecules were assessed by Western blot, luciferase activity assay, or ChIP assay.

Results

CXCL-12-induced CTGF expression was attenuated by SIS3 (a SMAD3 inhibitor) and SMAD3 siRNA, but not by SB431542 (an activin receptor-like kinase 5, ALK5, inhibitor). CXCL12-stimulated CTGF expression was also attenuated by MEKK1 siRNA. Treatment of cells with CXCL12 caused an increase in SMAD3 phosphorylation at Ser208, translocation to nuclei, SMAD3-luciferase activity, and recruitment of SMAD3 to the CTGF promoter. Stimulation of cells with CXCL12 resulted in increase in JNK phosphorylation at Thr183/Tyr185 and MEKK1 phosphorylation at Thr261. Moreover, CXCL12-mediated SMAD3 phosphorylation or SMAD3-luciferase activity was inhibited by MEKK1 siRNA or SP600125. Finally, CXCL12-mediated JNK phosphorylation was attenuated by MEKK1 siRNA.

Conclusion

In conclusion, results of this study suggest that CXCL12 activates the MEKK1/JNK signaling pathway, which in turn initiates SMAD3 phosphorylation, its translocation to nuclei, and recruitment of SMAD3 to the CTGF promoter, which ultimately induces CTGF expression in human lung fibroblasts.

The evidence for natural therapeutics as potential anti-scarring agents in burn-related scarring

Though survival rate following severe thermal injuries has improved, the incidence and treatment of scarring have not improved at the same speed. This review discusses the formation of scars and in particular the formation of hypertrophic scars. Further, though there is as yet no gold standard treatment for the prevention or treatment of scarring, a brief overview is included. A number of natural therapeutics have shown beneficial effects both in vivo and in vitro with the potential of becoming clinical therapeutics in the future. These natural therapeutics include both plant-based products such as resveratrol, quercetin and epigallocatechin gallate as examples and includes the non-plant-based therapeutic honey. The review also includes potential mechanism of action for the therapeutics, any recorded adverse events and current administration of the therapeutics used. This review discusses a number of potential 'treatments' that may reduce or even prevent scarring particularly hypertrophic scarring, which is associated with thermal injuries without compromising wound repair.

Cyclosporine A induces connective tissue growth factor expression in human gingival fibroblasts: suppression by epigallocatechin-3-gallate

BACKGROUND/PURPOSE

Transforming growth factor-β (TGF-β) plays an important role in the pathogenesis of cyclosporine A (CsA)-induced gingival overgrowth (GO). Connective tissue growth factor (CTGF/CCN2) acts as a cofactor with TGF-β to induce the maximal profibrotic effects of TGF-β. We investigated the effects of CsA on CCN2 expression in human gingival fibroblasts (HGFs) and the potential chemopreventive agent for CsA-induced GO.

METHODS

Western blot analyses were used to examine the signaling pathways of CsA-induced CCN2 expression in HGFs and whether epigallocatechin-3-gallate (EGCG), curcumin, or lovastatin can inhibit CsA-induced CCN2 expression.

RESULTS

CsA significantly stimulated CCN2 synthesis in HGFs. This effect can be inhibited by c-Jun NH(2)-terminal kinase (JNK) and Smad3 inhibitors but not by TGF-β neutralizing antibody and TGF-β type I receptor inhibitor. Furthermore, EGCG completely blocked CsA-induced CCN2 expression.

CONCLUSION

CsA-induced CCN2 protein expression is mediated through JNK and Smad signaling. CsA may contribute to the pathogenesis of GO through upregulation of CCN2 expression in HGFs. EGCG could be an adjuvant for the prevention of CsA-induced GO.