Identification of a new class of activators of the Hippo pathway with antitumor activity in vitro and in vivo

The Hippo pathway is a key regulator of tissue growth, organ size, and tumorigenesis. Activating the Hippo pathway by gene editing or pharmaceutical intervention has been proven to be a new therapeutic strategy for treatment of the Hippo pathway-dependent cancers. To now, a number of compounds that directly target the downstream effector proteins of Hippo pathway, including YAP and TEADs, have been disclosed, but very few Hippo pathway activators are reported. Here, we discovered a new class of Hippo pathway activator, YL-602, which inhibited CTGF expression in cells irrespective of cell density and the presence of serum. Mechanistically, YL-602 activates the Hippo pathway via MST1/2, which is different from known activators of Hippo pathway. In vitro, YL-602 significantly induced tumor cell apoptosis and inhibited colony formation of tumor cells. In vivo, oral administration of YL-602 substantially suppressed the growth of cancer cells by activation of Hippo pathway. Overall, YL-602 could be a promising lead compound, and deserves further investigation for its mechanism of action and therapeutic applications.

The regulatory effect of electroacupuncture on endometrial M1-type macrophages in rats with intrauterine adhesions

OBJECTIVES

To observe the effect of electroacupuncture(EA) on endometrial fibrosis and M1-type macrophages in rats with intrauterine adhesions(IUA), so as to explore the possible mechanism of EA in the treatment of IUA.

METHODS

Fifteen female SD rats were randomly divided into blank group, model group and EA group, with 5 rats in each group. The IUA rat model was established by double damage method using mechanical scraping combined with lipopolysaccharide infection. Rats in the EA group were treated with acupuncture at "Guanyuan"(CV4), and EA at bilateral "Zusanli"(ST36) and "Sanyinjiao"(SP6)for 20 minutes each time, once a day, for 3 consecutive cycles of estrus. Five rats in each group were sampled during the estrous period, and the endometrial morphology, endometrial thickness and the number of blood vessels and glands were observed after HE staining. The fibrotic area of the uterus was observed after Masson staining. The positive expressions of Runt-related transcription factor(RUNX1), transforming growth factor-β1(TGF-β1), connective tissue growth factor(CTGF), α-smooth muscle actin(α-SMA), collagen type I(Col-Ⅰ), cluster of differentiation 86(CD86), interleukin-1β(IL-1β), and tumor necrosis factor-α(TNF-α) in endometrial tissue were detected by immunohistochemistry. Western blot was used to detect relative protein expressions of RUNX1, TGF-β1, α-SMA, CD86, and TNF receptor 2 (TNFR2), and real-time fluorescence quantitative PCR was used to detect mRNA expressions of RUNX1, TGF-β1, α-SMA, CD86, and TNF-α in the endometrium.

RESULTS

During the estrous phase, the endometrial layer in the model group was damaged, with reduced folds, disordered arrangement of epithelial cells, loose fibrous connective tissue, significant narrowing and adhesions in the uterine cavity, interstitial congestion, edema, and a significant infiltration of inflammatory cells with sparse glands. While uterine tissue structure of the EA group was basically intact, resembling a normal uterus, with more newly formed glands and a small amount of inflammatory cell infiltration. In comparison with the blank group, the endometrial thickness, the number of blood vessels, and the number of glands were significantly decreased(P<0.001) in the model group, while the ratio of uterine fibrosis area, the positive expressions of RUNX1, TGF-β1, CTGF, α-SMA, Col-Ⅰ, CD86, IL-1β, and TNF-α, the protein relative expressions of RUNX1, TGF-β1, α-SMA, CD86 and TNFR2, and the mRNA relative expression levels of RUNX1, TGF-β1, α-SMA, CD86 and TNF-α in the endometrium were significantly increased (P<0.001, P<0.01). Compared to the model group, the endometrial thickness, the number of blood vessels, and the number of glands were significantly increased(P<0.01, P<0.05) in the EA group, while the ratio of uterine fibrosis area, the positive expressions of RUNX1, TGF-β1, CTGF, α-SMA, Col-Ⅰ, CD86, IL-1β and TNF-α in the endometrial tissue, the protein expressions of RUNX1, TGF-β1, α-SMA, CD86 and TNFR2, and the mRNA relative expressions of RUNX1, TGF-β1, α-SMA, CD86 and TNF-α in the endometrium were significantly decreased (P<0.001, P<0.01, P<0.05).

CONCLUSIONS

EA can improve endometrial fibrosis in IUA rats, which may be related to its function in decreasing the level of endometrial M1-type macrophages and the secretion of related inflammatory factors.

The Role of Collagen VIII in the Aging Mouse Kidney

The gradual loss of kidney function due to increasing age is accompanied by structural changes such as fibrosis of the tissue. The underlying molecular mechanisms are complex, but not yet fully understood. Non-fibrillar collagen type VIII (COL8) could be a potential factor in the fibrosis processes of the aging kidney. A pathophysiological significance of COL8 has already been demonstrated in the context of diabetic kidney disease, with studies showing that it directly influences both the development and progression of renal fibrosis occurring. The aim of this study was to investigate whether COL8 impacts age-related micro-anatomical and functional changes in a mouse model. The kidneys of wild-type (Col8-wt) and COL8-knockout (Col8-ko) mice of different age and sex were characterized with regard to the expression of molecular fibrosis markers, the development of nephrosclerosis and renal function. The age-dependent regulation of COL8 mRNA expression in the wild-type revealed sex-dependent effects that were not observed with collagen IV (COL4). Histochemical staining and protein analysis of profibrotic cytokines TGF-β1 (transforming growth factor) and CTGF (connective tissue growth factor) in mouse kidneys showed significant age effects as well as interactions of the factors age, sex and Col8 genotype. There were also significant age and Col8 genotype effects in the renal function data analyzed by urinary cystatin C. In summary, the present study shows, for the first time, that COL8 is regulated in an age- and sex-dependent manner in the mouse kidney and that the expression of COL8 influences the severity of age-induced renal fibrosis and function.

Connective tissue growth factor enhances TGF-β1-induced osteogenic differentiation via activation of p38 MAPK in mesenchymal stem cells

OBJECTIVES

Cellular differentiation is based on the effects of various growth factors. Transforming growth factor (TGF)-β1 plays a pivotal role in inducing osteogenic differentiation of mesenchymal stem cells (MSCs). In this study, we investigated the influence of connective tissue growth factor (CTGF), known to function synergistically with TGF-β1, on osteogenic differentiation in MSCs.

METHODS

UE7T-13 cells were treated with TGF-β1 and/or CTGF. Subsequently, protein levels of intracellular signaling pathway molecules were determined through western blot analysis. The mRNA expression levels of osteogenic differentiation markers were investigated using reverse transcription-quantitative polymerase chain reaction. Bone matrix mineralization was evaluated through alizarin red staining.

RESULTS

Co-treatment with TGF-β1 and CTGF resulted in the suppression of TGF-β1-induced phosphorylation of extracellular signal-regulated kinase 1/2, an intracellular signaling pathway molecule in MSCs, while significantly enhancing the phosphorylation of p38 mitogen-activated protein kinase (MAPK). In MSCs, co-treatment with CTGF and TGF-β1 led to increased expression levels of alkaline phosphatase and type I collagen, markers of osteogenic differentiation induced by TGF-β1. Osteopontin expression was observed only after TGF-β1 and CTGF co-treatment. Notably, bone sialoprotein and osteocalcin were significantly upregulated by treatment with CTGF alone. Furthermore, CTGF enhanced the TGF-β1-induced mineralization in MSCs, with complete suppression observed after treatment with a p38 MAPK inhibitor.

CONCLUSIONS

CTGF enhances TGF-β1-induced osteogenic differentiation and subsequent mineralization in MSCs by predominantly activating the p38 MAPK-dependent pathway.

MCPIP1 Inhibits Hepatic Stellate Cell Activation in Autocrine and Paracrine Manners, Preventing Liver Fibrosis

BACKGROUND & AIMS

Hepatic fibrosis is characterized by enhanced deposition of extracellular matrix (ECM), which results from the wound healing response to chronic, repeated injury of any etiology. Upon injury, hepatic stellate cells (HSCs) activate and secrete ECM proteins, forming scar tissue, which leads to liver dysfunction. Monocyte-chemoattractant protein-induced protein 1 (MCPIP1) possesses anti-inflammatory activity, and its overexpression reduces liver injury in septic mice. In addition, mice with liver-specific deletion of Zc3h12a develop features of primary biliary cholangitis. In this study, we investigated the role of MCPIP1 in liver fibrosis and HSC activation.

METHODS

We analyzed MCPIP1 levels in patients' fibrotic livers and hepatic cells isolated from fibrotic murine livers. In vitro experiments were conducted on primary HSCs, cholangiocytes, hepatocytes, and LX-2 cells with MCPIP1 overexpression or silencing.

RESULTS

MCPIP1 levels are induced in patients' fibrotic livers compared with their nonfibrotic counterparts. Murine models of fibrosis revealed that its level is increased in HSCs and hepatocytes. Moreover, hepatocytes with Mcpip1 deletion trigger HSC activation via the release of connective tissue growth factor. Overexpression of MCPIP1 in LX-2 cells inhibits their activation through the regulation of TGFB1 expression, and this phenotype is reversed upon MCPIP1 silencing.

CONCLUSIONS

We demonstrated that MCPIP1 is induced in human fibrotic livers and regulates the activation of HSCs in both autocrine and paracrine manners. Our results indicate that MCPIP1 could have a potential role in the development of liver fibrosis.

CTGF regulates mineralization in human mature chondrocyte by controlling Pit-1 and modulating ANK via the BMP/Smad signalling

OBJECTIVE

Connective tissue growth factor (CTGF) exhibits potent proliferative, differentiated, and mineralizing effects, and is believed to be contribute to cartilage mineralization in Osteoarthritis (OA). However, the underlying mechanism of chondrocyte mineralization induced by CTGF remains obscure. As a key regulator of mineral responses, type III phosphate transporter 1 (Pit-1) has been associated with the pathogenesis of articular mineralization. Therefore, the primary objective of this study was to investigate whether CTGF influences the development of mature chondrocyte mineralization and the underlying mechanisms governing such mineralization.

METHODS

The effect of Connective tissue growth factor (CTGF) on human C-28/I2 chondrocytes were investigated. The chondrocytes were treated with CTGF or related inhibitors, and transfected with Overexpression and siRNA transfection of Type III Phosphate Transporter 1(Pit-1). Subsequently, the cells were subjected to Alizarin red S staining, PiPer Phosphate Assay Kit, Alkaline Phosphatase Diethanolamine Activity Kit, ELISA, RT-PCR or Western blot analysis.

RESULTS

Stimulation with Connective tissue growth factor (CTGF) significantly upregulated the expression of the Type III Phosphate Transporter 1(Pit-1) and mineralization levels in chondrocytes through activation of α5β1 integrin and BMP/Samd1/5/8 signaling pathways. Furthermore, treatment with overexpressed Pit-1 markedly increased the expression of Multipass Transmembrane Ankylosis (ANK) transporter in the cells. The inhibitory effect of CTGF receptor blockade using α5β1 Integrin blocking antibody was demonstrated by significantly suppressed the expression of Pit-1 and ANK transporter, as well as chondrocyte mineralization.

CONCLUSIONS

Our data indicate that Connective tissue growth factor (CTGF) plays a critical role inchondrocyte mineralization, which is dependent on the expression of the Type III Phosphate Transporter 1(Pit-1) and Multipass Transmembrane Ankylosis (ANK) transporter. Consequently, inhibition of CTGF activity may represent a novel therapeutic approach for the management of Osteoarthritis (OA).

Aerobic exercise protects MI heart through miR-133a-3p downregulation of connective tissue growth factor

OBJECTIVE

To investigate the effect of aerobic exercise intervention to inhibit cardiomyocyte apoptosis and thus improve cardiac function in myocardial infarction (MI) mice by regulating CTGF expression through miR-133a-3p.

METHODS

Male C57/BL6 mice, 7-8 weeks old, were randomly divided into sham-operated group (S group), sham-operated +aerobic exercise group (SE group), myocardial infarction group (MI group) and MI + aerobic exercise group (ME group). The mice were anesthetized the day after training and cardiac function was assessed by cardiac echocardiography. Myocardial collagen volume fraction (CVF%) was analyzed by Masson staining. Myocardial CTGF, Bax and Bcl-2 were detected by Western blotting, and myocardial miR-133a-3p was measured by RT-qPCR.

RESULTS

Compared with the S group, miR-133a-3p, Bcl-2 and EF were significantly decreased and CTGF, Bax, Bax/ Bcl-2, Caspase 3, Cleaved Caspase-3, LVIDd, LVIDs and CVF were significantly increased in the MI group. Compared with the MI group, miR-133a-3p, Bcl-2 and EF were significantly increased, cardiac function was significantly improved, and CTGF, Bax, Bax/ Bcl-2, Caspase 3, Cleaved Caspase-3, LVIDd, LVIDs and CVF were significantly decreased in ME group. The miR-133a-3p was significantly lower and CTGF was significantly higher in the H2O2 intervention group compared with the control group of H9C2 rat cardiomyocytes. miR-133a-3p was significantly higher and CTGF was significantly lower in the AICAR intervention group compared to the H2O2 intervention group. Compared with the control group of H9C2 rat cardiomyocytes, CTGF, Bax and Bax/Bcl-2 were significantly increased and Bcl-2 was significantly decreased in the miR-133a-3p inhibitor intervention group; CTGF, Bax and Bax/Bcl-2 were significantly decreased and Bcl-2 was significantly upregulated in the miR-133a-3p mimics intervention group.

CONCLUSION

Aerobic exercise down-regulated CTGF expression in MI mouse myocardium through miR-133a-3p, thereby inhibiting cardiomyocyte apoptosis and improving cardiac function.

Unraveling Connective Tissue Growth Factor as a Therapeutic Target and Assessing Kahweol as a Potential Drug Candidate in Triple-Negative Breast Cancer Treatment

Triple-negative breast cancer (TNBC) is characterized by aggressive behavior and limited treatment options, necessitating the identification of novel therapeutic targets. In this study, we investigated the clinical significance of connective tissue growth factor (CTGF) as a prognostic marker and explored the potential therapeutic effects of kahweol, a coffee diterpene molecule, in TNBC treatment. Initially, through a survival analysis on breast cancer patients from The Cancer Genome Atlas (TCGA) database, we found that CTGF exhibited significant prognostic effects exclusively in TNBC patients. To gain mechanistic insights, we performed the functional annotation and gene set enrichment analyses, revealing the involvement of CTGF in migratory pathways relevant to TNBC treatment. Subsequently, in vitro experiments using MDA-MB 231 cells, a representative TNBC cell line, demonstrated that recombinant CTGF (rCTGF) administration enhanced cell motility, whereas CTGF knockdown using CTGF siRNA resulted in reduced motility. Notably, rCTGF restored kahweol-reduced cell motility, providing compelling evidence for the role of CTGF in mediating kahweol's effects. At the molecular level, kahweol downregulated the protein expression of CTGF as well as critical signaling molecules, such as p-ERK, p-P38, p-PI3K/AKT, and p-FAK, associated with cell motility. In summary, our findings propose CTGF as a potential prognostic marker for guiding TNBC treatment and suggest kahweol as a promising antitumor compound capable of regulating CTGF expression to suppress cell motility in TNBC. These insights hold promise for the development of targeted therapies and improved clinical outcomes for TNBC patients.

miR-584-5p Inhibits Osteosarcoma Progression by Targeting Connective Tissue Growth Factor

Background: miR-584-5p is a critical regulator in the progression of multiple cancers. However, its specific role and downstream targets in osteosarcoma are unclear. This research investigated the roles and underlying mechanisms of miR-769-5p and the Hippo pathway in osteosarcoma cells. Materials and Methods: RT-qPCR, CCK-8 and EdU and colony formation, wound-healing and transwell chamber, flow cytometry, and Western blot assay detected the expression of miR-584-5p and CTGF, cell proliferation, migration, invasion apoptosis and protein expression. Result: Their study illuminated that miR-584-5p overexpression repressed osteosarcoma cell migration/invasion and proliferation and facilitated apoptosis. Mechanistically, miR-584-5p targets negatively regulated connective tissue growth factor (CTGF). miR-584-5p inhibited osteosarcoma cell metastasis by regulating CTGF. In addition, miR-584-5p inactivated the Hippo pathway through CTGF in osteosarcoma. Conclusion: miR-584-5p inhibits osteosarcoma cell proliferation, migration, and invasion and promotes apoptosis by targeting CTGF, indicating that miR-584-5p acts as a promising diagnostic and predictive biomarker for osteosarcoma.

CTGF promotes the repair and regeneration of alveoli after acute lung injury by promoting the proliferation of subpopulation of AEC2s

BACKGROUND

Functional alveolar regeneration is essential for the restoration of normal lung homeostasis after acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Lung is a relatively quiescent organ and a variety of stem cells are recruited to participate in lung repair and regeneration after lung tissue injury. However, there is still no effective method for promoting the proliferation of endogenous lung stem cells to promote repair and regeneration.

METHODS

Using protein mass spectrometry analysis, we analyzed the microenvironment after acute lung injury. RNA sequencing and image cytometry were used in the alveolar epithelial type 2 cells (AEC2s) subgroup identification. Then we used Sftpc+AEC2 lineage tracking mice and purified AEC2s to further elucidate the molecular mechanism by which CTGF regulates AEC2s proliferation both in vitro and in vivo. Bronchoalveolar lavage fluid (BALF) from thirty ARDS patients who underwent bronchoalveolar lavage was collected for the analysis of the correlation between the expressing of Krt5 in BALF and patients' prognosis.

RESULTS

Here, we elucidate that AEC2s are the main facultative stem cells of the distal lung after ALI and ARDS. The increase of connective tissue growth factor (CTGF) in the microenvironment after ALI promoted the proliferation of AEC2s subpopulations. Proliferated AEC2s rapidly expanded and differentiated into alveolar epithelial type 1 cells (AEC1s) in the regeneration after ALI. CTGF initiates the phosphorylation of LRP6 by promoting the interaction between Krt5 and LRP6 of AEC2s, thus activating the Wnt signaling pathway, which is the molecular mechanism of CTGF promoting the proliferation of AEC2s subpopulation.

CONCLUSIONS

Our study verifies that CTGF promotes the repair and regeneration of alveoli after acute lung injury by promoting the proliferation of AEC2s subpopulation.

SPARC accelerates biliary tract cancer progression through CTGF-mediated tumor-stroma interactions: SPARC as a prognostic marker of survival after neoadjuvant therapy

PURPOSE

In biliary tract cancer (BTC), malignancy is strongest at the invasion front. To improve the BTC prognosis, the invasion front should be controlled. We evaluated tumor-stroma crosstalk at the tumor center and at the invasion front of BTC lesions. We investigated the expression of SPARC, a marker of cancer-associated fibroblasts, and determined its ability to predict BTC prognosis after neoadjuvant chemoradiotherapy (NAC-RT).

METHODS

We performed immunohistochemistry to evaluate SPARC expression in resected specimens from patients that underwent BTC surgery. We established highly invasive (HI) clones in two BTC cell lines (NOZ, CCLP1), and performed mRNA microarrays to compare gene expression in parental and HI cells.

RESULTS

Among 92 specimens, stromal SPARC expression was higher at the invasion front than at the lesion center (p = 0.014). Among 50 specimens from patients treated with surgery alone, high stromal SPARC expression at the invasion front was associated with a poor prognosis (recurrence-free survival: p = 0.033; overall survival: p = 0.017). Coculturing fibroblasts with NOZ-HI cells upregulated fibroblast SPARC expression. mRNA microarrays showed that connective tissue growth factor (CTGF) was upregulated in NOZ-HI and CCLP1-HI cells. A CTGF knockdown suppressed cell invasion in NOZ-HI cells. Exogeneous CTGF upregulated SPARC expression in fibroblasts. SPARC expression at the invasion front was significantly lower after NAC-RT, compared to surgery alone (p = 0.003).

CONCLUSION

CTGF was associated with tumor-stroma crosstalk in BTC. CTGF activated stromal SPARC expression, which promoted tumor progression, particularly at the invasion front. SPARC expression at the invasion front after NAC-RT may serve as a prognosis predictor.

Context-dependent effects of CCN2 on β-cell mass expansion and indicators of cell stress in the setting of acute and chronic stress

Stimulation of functional β-cell mass expansion can be beneficial for the treatment of type 2 diabetes. Our group has previously demonstrated that the matricellular protein CCN2 can induce β-cell mass expansion during embryogenesis, and postnatally during pregnancy and after 50% β-cell injury. The mechanism by which CCN2 stimulates β-cell mass expansion is unknown. However, CCN2 does not induce β-cell proliferation in the setting of euglycemic and optimal functional β-cell mass. We thus hypothesized that β-cell stress is required for responsiveness to CCN2 treatment. In this study, a doxycycline-inducible β-cell-specific CCN2 transgenic mouse model was utilized to evaluate the effects of CCN2 on β-cell stress in the setting of acute (thapsigargin treatment ex vivo) or chronic [high-fat diet or leptin receptor haploinsufficiency (db/+) in vivo] cellular stress. CCN2 induction during 1 wk or 10 wk of high-fat diet or in db/+ mice had no effect on markers of β-cell stress. However, CCN2 induction did result in a significant increase in β-cell mass over high-fat diet alone when animals were fed high-fat diet for 10 wk, a duration known to induce insulin resistance. CCN2 induction in isolated islets treated with thapsigargin ex vivo resulted in upregulation of the gene encoding the Nrf2 transcription factor, a master regulator of antioxidant genes, suggesting that CCN2 further activates this pathway in the presence of cell stress. These studies indicate that the potential of CCN2 to induce β-cell mass expansion is context-dependent and that the presence of β-cell stress does not ensure β-cell proliferation in response to CCN2.NEW & NOTEWORTHY CCN2 promotes β-cell mass expansion in settings of suboptimal β-cell mass. Here, we demonstrate that the ability of CCN2 to induce β-cell mass expansion in the setting of β-cell stress is context-dependent. Our results suggest that β-cell stress is necessary but insufficient for CCN2 to increase β-cell proliferation and mass. Furthermore, we found that CCN2 promotes upregulation of a key antioxidant transcription factor, suggesting that modulation of β-cell oxidative stress contributes to the actions of CCN2.

Long noncoding RNA AI662270 promotes kidney fibrosis through enhancing METTL3-mediated m6 A modification of CTGF mRNA

The sustained release of profibrotic cytokines, mainly transforming growth factor-β (TGF-β), leads to the occurrence of kidney fibrosis and chronic kidney disease (CKD). Connective tissue growth factor (CTGF) appears to be an alternative target to TGF-β for antifibrotic therapy in CKD. In this study, we found that long noncoding RNA AI662270 was significantly increased in various renal fibrosis models. In vivo, ectopic expression of AI662270 alone was sufficient to activate interstitial fibroblasts and drive kidney fibrosis, whereas inhibition of AI662270 blocked the activation of interstitial fibroblasts and ameliorated kidney fibrosis in various murine models. Mechanistic studies revealed that overexpression of AI662270 significantly increased CTGF product, which was required for the role of AI662270 in driving kidney fibrosis. Furthermore, AI662270 binds to the CTGF promoter and directly interacts with METTL3, the methyltransferase of RNA N6 -methyladenosine (m6 A) modification. Functionally, AI662270-mediated recruitment of METTL3 increased the m6 A methylation of CTGF mRNA and consequently enhanced CTGF mRNA stability. In conclusion, our results support that AI662270 promotes CTGF expression at the posttranscriptional stage by recruiting METTL3 to the CTGF promoter and depositing m6 A modifications on the nascent mRNA, thereby, uncovering a novel regulatory mechanism of CTGF in the pathogenesis of kidney fibrosis.

Lipophilic Statins Inhibit YAP Nuclear Localization, Coactivator Activity, and Migration in Response to Ligation of HLA Class I Molecules in Endothelial Cells: Role of YAP Multisite Phosphorylation

Solid-organ transplant recipients exhibiting HLA donor-specific Abs are at risk for graft loss due to chronic Ab-mediated rejection. HLA Abs bind HLA molecules expressed on the surface of endothelial cells (ECs) and induce intracellular signaling pathways, including the activation of the transcriptional coactivator yes-associated protein (YAP). In this study, we examined the impact of lipid-lowering drugs of the statin family on YAP localization, multisite phosphorylation, and transcriptional activity in human ECs. Exposure of sparse cultures of ECs to cerivastatin or simvastatin induced striking relocalization of YAP from the nucleus to the cytoplasm and inhibited the expression of the YAP/TEA domain DNA-binding transcription factor-regulated genes connective tissue growth factor and cysteine-rich angiogenic inducer 61. In dense cultures of ECs, statins prevented YAP nuclear import and expression of connective tissue growth factor and cysteine-rich angiogenic inducer 61 stimulated by the mAb W6/32 that binds HLA class I. Exposure of ECs to either cerivastatin or simvastatin completely blocked the migration of ECs stimulated by ligation of HLA class I. Exogenously supplied mevalonic acid or geranylgeraniol reversed the inhibitory effects of statins on YAP localization either in low-density ECs or high-density ECs challenged with W6/32. Mechanistically, cerivastatin increased the phosphorylation of YAP at Ser127, blunted the assembly of actin stress fiber, and inhibited YAP phosphorylation at Tyr357 in ECs. Using mutant YAP, we substantiated that YAP phosphorylation at Tyr357 is critical for YAP activation. Collectively, our results indicate that statins restrain YAP activity in EC models, thus providing a plausible mechanism underlying their beneficial effects in solid-organ transplant recipients.

MicroRNA-19 upregulation attenuates cardiac fibrosis via targeting connective tissue growth factor

BACKGROUND

Previous studies have shown the role of microRNA (miR)-19 in aging-related heart failure. The present study aimed to verify the effects of miR-19 on cardiac fibrosis and its target.

METHODS

Cardiac fibrosis was induced by myocardial infarction (MI)-induced heart failure and angiotensin (Ang) II-treated rats in vivo, and was induced in Ang II-treated cardiac fibroblasts (CFs) in vitro.

RESULTS

The expression of miR-19 was reduced in the heart tissue of MI and Ang II-treated rats, and Ang II-treated CFs. The impaired cardiac function in rats was repaired after miR-19 administration. The levels of collagen I, collagen III and transforming growth factor-beta (TGF-β) increased in the heart tissue of MI and Ang II-treated rats, and Ang II-treated CFs. These increases were reversed by miR-19 agomiR. Moreover, the bioinformatic analysis and luciferase reporter assays demonstrated that connective tissue growth factor (CTGF) was a direct target of miR-19. MiR-19 treatment inhibited CTGF expression in CFs, while CTGF overexpression inhibited miR-19 agomiR to attenuate the Ang II-induced increases of collagen I and collagen III in CFs. The increases of p-ERK, p-JNK and p-p38 in the CFs induced by Ang II were repressed by miR-19 agomiR.

CONCLUSIONS

Upregulating miR-19 can improve cardiac function and attenuate cardiac fibrosis by inhibiting the CTGF and MAPK pathways.

Metabolic regulation of the proteasome under hypoxia by Poldip2 controls fibrotic signaling in vascular smooth muscle cells

The polymerase delta interacting protein 2 (Poldip2) is a nuclear-encoded mitochondrial protein required for oxidative metabolism. Under hypoxia, Poldip2 expression is repressed by an unknown mechanism. Therefore, low levels of Poldip2 are required to maintain glycolytic metabolism. The Cellular Communication Network Factor 2 (CCN2, Connective tissue growth factor, CTGF) is a profibrogenic molecule highly expressed in cancer and vascular inflammation in advanced atherosclerosis. Because CCN2 is upregulated under hypoxia and is associated with glycolytic metabolism, we hypothesize that Poldip2 downregulation is responsible for the upregulation of profibrotic signaling under hypoxia. Here, we report that Poldip2 is repressed under hypoxia by a mechanism that requires the activation of the enhancer of zeste homolog 2 repressive complex (EZH2) downstream from the Cyclin-Dependent Kinase 2 (CDK2). Importantly, we found that Poldip2 repression is required for CCN2 expression downstream of metabolic inhibition of the ubiquitin-proteasome system (UPS)-dependent stabilization of the serum response factor. Pharmacological or gene expression inhibition of CDK2 under hypoxia reverses Poldip2 downregulation, the inhibition of the UPS, and the expression of CCN2, collagen, and fibronectin. Thus, our findings connect cell cycle regulation and proteasome activity to mitochondrial function and fibrotic responses under hypoxia.

Analyses of the Posttranscriptional Regulation of CCN Genes: Approach to Multiple Steps of CCN2 Gene Expression

Cells generally control the concentration of mRNA via transcriptional and posttranscriptional regulation, so the separate contributions of synthesis and degradation (decay) cannot be discriminated by the quantification of mRNA. To elucidate the contribution of posttranscriptional regulation, all experimental procedures for the analysis of the total transcript level, transcriptional induction, degradation of the target mRNA, and inhibition of mRNA translation are performed either individually or in combination. From our experience, measurement of the steady-state levels of mRNA using quantitative real-time polymerase chain reaction is an essential first step in quantifying the ccn2 gene expression. Subsequently, the effect of transcription rates should be assessed by reporter assays of the ccn2 promoter and nuclear run-on assays. The stability of ccn2 mRNAs is then evaluated in the presence of a metabolic inhibitor actinomycin D, followed by mRNA degradation assays in vitro. Finally, repression of ccn2 mRNA translation can be estimated by comparing the expression of mRNA and protein changes. We herein report the strategic methods used in a series of analyses to elucidate the possible involvement of the posttranscriptional regulatory mechanism of the ccn2 gene and show how this approach can, in theory, be used to elucidate the posttranscriptional regulation of other genes belonging to the CCN family.

Imaging Analysis of Neurotrophic Effects by CCN2 Protein in Neuronal Precursor Cells Derived from Human-Induced Pluripotent Stem Cells

Human-induced pluripotent stem cells (hiPSCs) are useful tools to examine human neuronal maturation processes. In this chapter, we describe the maturation of human neuronal precursor cells derived from hiPSCs by cellular communication network family member 2, also known as connective tissue growth factor. We describe the (1) preparation of feeder cells for undifferentiated culture of hiPSCs, (2) undifferentiated culture of hiPSCs, (3) induction of neuronal precursor cells from hiPSCs, (4) maturation of neuronal precursor cells from hiPSCs, (5) immunofluorescent staining of neuronal cells from hiPSCs, and (6) immunofluorescence analysis.

Using the Bleomycin-Induced Model of Fibrosis to Study the Contribution of CCN Proteins to Scleroderma Fibrosis

Approximately 45% of the deaths in the developed world result from conditions with a fibrotic component. Although no specific, focused anti-fibrotic therapies have been approved for clinical use, a long-standing concept is that targeting CCN proteins may be useful to treat fibrosis. Herein, we summarize current data supporting the concept that targeting CCN2 may be a viable anti-fibrotic approach to treat scleroderma. Testing this hypothesis has been made possible by using a mouse model of inflammation-driven skin and lung fibrosis.

Ccn2a-FGFR1-SHH signaling is necessary for intervertebral disc homeostasis and regeneration in adult zebrafish

Intervertebral disc (IVD) degeneration is the primary cause of back pain in humans. However, the cellular and molecular pathogenesis of IVD degeneration is poorly understood. This study shows that zebrafish IVDs possess distinct and non-overlapping zones of cell proliferation and cell death. We find that, in zebrafish, cellular communication network factor 2a (ccn2a) is expressed in notochord and IVDs. Although IVD development appears normal in ccn2a mutants, the adult mutant IVDs exhibit decreased cell proliferation and increased cell death leading to IVD degeneration. Moreover, Ccn2a overexpression promotes regeneration through accelerating cell proliferation and suppressing cell death in wild-type aged IVDs. Mechanistically, Ccn2a maintains IVD homeostasis and promotes IVD regeneration by enhancing outer annulus fibrosus cell proliferation and suppressing nucleus pulposus cell death through augmenting FGFR1-SHH signaling. These findings reveal that Ccn2a plays a central role in IVD homeostasis and regeneration, which could be exploited for therapeutic intervention in degenerated human discs.

MALAT1-miR-30c-5p-CTGF/ATG5 axis regulates silica-induced experimental silicosis by mediating EMT in alveolar epithelial cells

Epithelial-mesenchymal transdifferentiation of alveolar type Ⅱ epithelial cells is a vital source of pulmonary myofibroblasts, and myofibroblasts formation is recognized as an important phase in the pathological process of silicosis. miR-30c-5p has been determined to be relevant in the activation of the epithelial-mesenchymal transition (EMT) in numerous disease processes. However, elucidating the role played by miR-30c-5p in the silicosis-associated EMT process remains a great challenge. In this work, based on the establishment of mouse silicosis and A549 cells EMT models, miR-30c-5p was interfered with in vivo and in vitro models to reveal its effects on EMT and autophagy. Moreover, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), connective tissue growth factor (CTGF), autophagy-related gene 5 (ATG5), and autophagy were further interfered with in the A549 cells models to uncover the possible molecular mechanism through which miR-30c-5p inhibits silicosis associated EMT. The results demonstrated the targeted binding of miR-30c-5p to CTGF, ATG5, and MALAT1, and showed that miR-30c-5p could prevent EMT in lung epithelial cells by acting on CTGF and ATG5-associated autophagy, thereby inhibiting the silicosis fibrosis process. Furthermore, we also found that lncRNA MALAT1 might competitively absorb miR-30c-5p and affect the EMT of lung epithelial cells. In a word, interfering with miR-30c-5p and its related molecules (MALAT1, CTGF, and ATG5-associated autophagy) may provide a reference point for the application of silicosis intervention-related targets.

Regulation of CCN2 and Its Bioactivity by Advanced Glycation End Products

Advanced glycation end products (AGEs) have been implicated in the tissue fibrosis and extracellular matrix (ECM) expansion in organ complications of diabetes mellitus and in other diseases. CCN2, also known as cellular communication factor 2 and earlier as connective tissue growth factor, is a matrix-associated protein that acts as a pro-fibrotic cytokine to cause fibrosis in tissues in many diseases. We were the first to report that AGEs regulate CCN2, which itself can then affect ECM synthesis. In this chapter, we describe the methods of preparation of soluble AGEs and matrix-bound AGEs that can be used to study AGE effect on CCN2 and ECM expansion.

Transfection, Spinfection, Exofection, and Luciferase Assays for Analysis of CCN Genes Expression Mechanism

Cell communication network factor 2 (CCN2), also known as connective tissue growth factor (CTGF), is protein inducible in response to TGFβ/Smad signal or the transcriptional activity of matrix metalloproteinase 3 (MMP3). We discovered that MMP3 in exosomes is transferable to recipient cells and then translocates into cell nuclei to transactivate the CCN2/CTGF gene. Exosomes and liposomes enable molecular transfection to recipient cells in vitro and in vivo. These small vesicles are surrounded by lipid membranes and carry proteins, RNA, DNA, and small chemicals. Here we define the exosome-based transfection as "exofection." In addition, spinfection increases the efficiencies of transfection, exofection, and viral infection, thus being compatible with various molecular transfer protocols. Here, we provide protocols, tips, and practical examples of transfection, spinfection, exofection, fluorescence microscopy, and luciferase assays to analyze the CCNs gene expression mechanisms.

Analysis of Chemotactic Property of CCN2/CTGF in Intramembranous Osteogenesis

Chemotaxis is a directed migration of cells in response to a gradient of extracellular molecules called chemoattractants. Development, growth, remodeling, and fracture healing of bones are advanced through intramembranous osteogenesis. Chemotaxis of preosteoblasts toward future bone formation sites observed in the early stage of intramembranous osteogenesis is a critical cellular process for normal bone formation. However, molecular biological mechanisms of the chemotaxis of preosteoblasts are not fully understood. We have recently clarified, for the first time, the critical role of the cellular communication network factor 2 (CCN2)/connective tissue growth factor (CTGF)-integrin α5-Ras axis for chemotaxis of preosteoblasts during new bone formation through intramembranous osteogenesis. In this chapter, we describe in detail the procedures of the in vivo and in vitro assays to investigate the chemotactic property of CCN2/CTGF and its underlying molecular biological mechanisms during intramembranous osteogenesis.

Adriamycin-Induced Podocyte Injury Disrupts the YAP-TEAD1 Axis and Downregulates Cyr61 and CTGF Expression

The most severe forms of kidney diseases are often associated with irreversible damage to the glomerular podocytes, the highly specialized epithelial cells that encase glomerular capillaries and regulate the removal of toxins and waste from the blood. Several studies revealed significant changes to podocyte cytoskeletal structure during disease onset, suggesting possible roles of cellular mechanosensing in podocyte responses to injury. Still, this topic remains underexplored partly due to the lack of appropriate in vitro models that closely recapitulate human podocyte biology. Here, we leveraged our previously established method for the derivation of mature podocytes from human induced pluripotent stem cells (hiPSCs) to help uncover the roles of yes-associated protein (YAP), a transcriptional coactivator and mechanosensor, in podocyte injury response. We found that while the total expression levels of YAP remain relatively unchanged during Adriamycin (ADR)-induced podocyte injury, the YAP target genes connective tissue growth factor (CTGF) and cysteine-rich angiogenic inducer 61 (Cyr61) are significantly downregulated. Intriguingly, TEAD1 is significantly downregulated in podocytes injured with ADR. By examining multiple independent modes of cellular injury, we found that CTGF and Cyr61 expression are downregulated only when podocytes were exposed to molecules known to disrupt the cell's mechanical integrity or cytoskeletal structure. To our knowledge, this is the first report that the YAP-TEAD1 signaling axis is disrupted when stem cell-derived human podocytes experience biomechanical injury. Together, these results could help improve the understanding of kidney disease mechanisms and highlight CTGF and Cyr61 as potential therapeutic targets or biomarkers for patient stratification.

[Unsaturated fatty acid of Actinidia chinesis planch seed oil protects against pulmonary fibrosis by inhibiting collagen synthesis via down-regulating connective tissue growth factor (CTGF) expression in rats]

Objective To observe the role of connective tissue growth factor (CTGF) and collagen synthesis in anti-pulmonary fibrosis (PF) by Kiwi fruit essence(unsaturated fatty acid of actinidia chinesis planch seed oil)in rats. Methods Sixty male SD rats were randomly divided into control group, model group, Kiwi fruit essence (60, 120, 240 mg/kg) treatment groups, and 5 mg/kg prednisone acetate group, with 10 animals in each group. Rats in control group were intratracheally administered with 9 g/L sodium chloride solution, and animals in other groups were intratracheally administered with bleomycin A5 to establish PF model. From the second day on, rats in the latter 4 groups were intragastrically treated with Kiwi fruit essence of 60, 120 and 240 mg/kg and prednisone acetate of 5 mg/kg, respectively. Rats in control and model groups were treated with 9 g/L sodium chloride solution once a day. All rats were sacrificed on day 28, and then pulmonary tissues were removed. The extent of PF lesions were evaluated using HE and Masson staining. The contents of hydroxyproline (HYP) were measured by a commercial kit. The mRNA expressions of CTGF and α-smooth muscle actin (α-SMA) in pulmonary tissues was detected by quantitative real-time PCR. The protein expressions of CTGF, α-SMA, collagen type 1 (Col1) and Col3 were measured by Western blotting. The protein levels of CTGF were analyzed using immunohistochemical staining. Results Compared with the model group, the alveolitis and PF extent in 60, 120, 240 mg/kg Kiwi fruit essence treatment groups as well as 5 mg/kg prednisone acetate group were significantly alleviated, and the content of HYP and the expression of CTGF, α-SMA, Col1 and Col3 decreased. The changes of above indicators were dose-dependent among the (60, 120, 240) mg/kg Kiwi fruit essence treatment groups. Moreover, the above indicators were found higher in (60, 120) mg/kg Kiwi fruit essence treatment groups than those in 5 mg/kg prednisone acetate group, which, however, showed no significantly difference between 240 mg/kg Kiwi fruit essence treatment group and 5 mg/kg prednisone acetate group. Conclusion Kiwi fruit essence down-regulates CTGF expression and decreases the levels of α-SMA, leading to inhibition of Col1 and Col3 synthesis and alleviation of PF.

Hepatocyte-Specific Smad4 Deficiency Alleviates Liver Fibrosis via the p38/p65 Pathway

Liver fibrosis is a wound-healing response caused by the abnormal accumulation of extracellular matrix, which is produced by activated hepatic stellate cells (HSCs). Most studies have focused on the activated HSCs themselves in liver fibrosis, and whether hepatocytes can modulate the process of fibrosis is still unclear. Sma mothers against decapentaplegic homologue 4 (Smad4) is a key intracellular transcription mediator of transforming growth factor-β (TGF-β) during the development and progression of liver fibrosis. However, the role of hepatocyte Smad4 in the development of fibrosis is poorly elucidated. Here, to explore the functional role of hepatocyte Smad4 and the molecular mechanism in liver fibrosis, a CCl₄-induced liver fibrosis model was established in mice with hepatocyte-specific Smad4 deletion (Smad4^Δhep). We found that hepatocyte-specific Smad4 deficiency reduced liver inflammation and fibrosis, alleviated epithelial-mesenchymal transition, and inhibited hepatocyte proliferation and migration. Molecularly, Smad4 deletion in hepatocytes suppressed the expression of inhibitor of differentiation 1 (ID1) and the secretion of connective tissue growth factor (CTGF) of hepatocytes, which subsequently activated the p38 and p65 signaling pathways of HSCs in an epidermal growth factor receptor-dependent manner. Taken together, our results clearly demonstrate that the Smad4 expression in hepatocytes plays an important role in promoting liver fibrosis and could therefore be a promising target for future anti-fibrotic therapy.

trans-Chalcone inhibits transforming growth factor-β1 and connective tissue growth factor-dependent collagen expression in the heart of high-fat diet-fed rats

Objective: Non-alcoholic fatty liver disease (NAFLD) is one of the main risk factors for cardiovascular mortality and morbidity. This study, for the first time, explored the effects of trans-chalcone on cardiac expressions of myocardial fibrosis-related genes, including transforming growth factor -β1 (TGF-β1), connective tissue growth factor (CTGF/CCN2), and collagen type I.Materials and methods: Twenty-eight rats were randomly divided into four groups: control, received 10% tween 80; chalcone, received trans-chalcone; HFD, received high-fat diet (HFD) and 10% tween 80; HFD + chalcone, received HFD and trans-chalcone, by once-daily gavage for 6 weeks. Finally, cardiac expression levels of TGF-β1, CTGF, and collagen type I were determined.Results: HFD feeding increased mRNA levels of collagen type I, TGF-β1, and CTGF in the heart of rats. However, trans-chalcone inhibited HFD-induced changes.Conclusions: trans-Chalcone can act as a cardioprotective compound by inhibiting TGF-β1 and CTGF-dependent stimulation of collagen type I synthesis in the heart of HFD-fed rats.

STAT3 is Activated by CTGF-mediated Tumor-stroma Cross Talk to Promote HCC Progression

BACKGROUND & AIMS

Signal transducer and activator of transcription 3 (STAT3) is known as a pro-oncogenic transcription factor. Regarding liver carcinogenesis, however, it remains controversial whether activated STAT3 is pro- or anti-tumorigenic. This study aimed to clarify the significance and mechanism of STAT3 activation in hepatocellular carcinoma (HCC).

METHODS

Hepatocyte-specific Kras-mutant mice (Alb-Cre Kras^LSL-G12D/+; Kras^G12D mice) were used as a liver cancer model. Cell lines of hepatoma and stromal cells including stellate cells, macrophages, T cells, and endothelial cells were used for culture. Surgically resected 12 HCCs were used for human analysis.

RESULTS

Tumors in Kras^G12D mice showed up-regulation of phosphorylated STAT3 (p-STAT3), together with interleukin (IL)-6 family cytokines, STAT3 target genes, and connective tissue growth factor (CTGF). Hepatocyte-specific STAT3 knockout (Alb-Cre Kras^LSL-G12D/+ STAT3^fl/fl) downregulated p-STAT3 and CTGF and suppressed tumor progression. In coculture with stromal cells, proliferation, and expression of p-STAT3 and CTGF, were enhanced in hepatoma cells via gp130/STAT3 signaling. Meanwhile, hepatoma cells produced CTGF to stimulate integrin/nuclear factor kappa B signaling and up-regulate IL-6 family cytokines from stromal cells, which could in turn activate gp130/STAT3 signaling in hepatoma cells. In Kras^G12D mice, hepatocyte-specific CTGF knockout (Alb-Cre Kras^LSL-G12D/+ CTGF^fl/fl) downregulated p-STAT3, CTGF, and IL-6 family cytokines, and suppressed tumor progression. In human HCC, single cell RNA sequence showed CTGF and IL-6 family cytokine expression in tumor cells and stromal cells, respectively. CTGF expression was positively correlated with that of IL-6 family cytokines and STAT3 target genes in The Cancer Genome Atlas.

CONCLUSIONS

STAT3 is activated by CTGF-mediated tumor-stroma crosstalk to promote HCC progression. STAT3-CTGF positive feedback loop could be a therapeutic target.

Mechanosensitive expression of the mesenchymal subtype marker connective tissue growth factor in glioblastoma

Mechanical forces created by the extracellular environment regulate biochemical signals that modulate the inter-related cellular phenotypes of morphology, proliferation, and migration. A stiff microenvironment induces glioblastoma (GBM) cells to develop prominent actin stress fibres, take on a spread morphology and adopt trapezoid shapes, when cultured in 2D, which are phenotypes characteristic of a mesenchymal cell program. The mesenchymal subtype is the most aggressive among the molecular GBM subtypes. Recurrent GBM have been reported to transition to mesenchymal. We therefore sought to test the hypothesis that stiffer microenvironments-such as those found in different brain anatomical structures and induced following treatment-contribute to the expression of markers characterising the mesenchymal subtype. We cultured primary patient-derived cell lines that reflect the three common GBM subtypes (mesenchymal, proneural and classical) on polyacrylamide (PA) hydrogels with controlled stiffnesses spanning the healthy and pathological tissue range. We then assessed the canonical mesenchymal markers Connective Tissue Growth Factor (CTGF) and yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) expression, via immunofluorescence. Replating techniques and drug-mediated manipulation of the actin cytoskeleton were utilised to ascertain the response of the cells to differing mechanical environments. We demonstrate that CTGF is induced rapidly following adhesion to a rigid substrate and is independent of actin filament formation. Collectively, our data suggest that microenvironmental rigidity can stimulate expression of mesenchymal-associated molecules in GBM.

Connective tissue growth factor-targeting DNA aptamer suppresses pannus formation as diagnostics and therapeutics for rheumatoid arthritis

Connective tissue growth factor (CTGF) has been recently acknowledged as an ideal biomarker in the early disease course, participating in the pathogenesis of pannus formation in rheumatoid arthritis (RA). However, existing approaches for the detection of or antagonist targeting CTGF are either lacking or unsatisfactory in the diagnosis and treatment of RA. To address this, we synthesized and screened high-affinity single-stranded DNA aptamers targeting CTGF through a protein-based SELEX procedure. The structurally optimized variant AptW2-1-39-PEG was characterized thoroughly for its high-affinity (KD 7.86 nM), sensitivity (minimum protein binding concentration, 2 ng), specificity (negative binding to other biomarkers of RA), and stability (viability-maintaining duration in human serum, 48 h) properties using various biochemical and biophysical assays. Importantly, we showed the antiproliferative and antiangiogenic activities of the aptamers obtained using functional experiments and further verified the therapeutic effect of the aptamers on joint injury and inflammatory response in collagen-induced arthritis (CIA) mice, thus advancing this study into actual therapeutic application. Furthermore, we revealed that the binding within AptW2-1-39-PEG/CTGF was mediated by the thrombospondin 1 (TSP1) domain of CTGF using robust bioinformatics tools together with immunofluorescence. In conclusion, our results revealed a novel aptamer that holds promise as an additive or alternative approach for CTGF-targeting diagnostics and therapeutics for RA.

Molecular and Genetic Interactions between CCN2 and CCN3 behind Their Yin-Yang Collaboration

Cellular communication network factor (CCN) 2 and 3 are the members of the CCN family that conduct the harmonized development of a variety of tissues and organs under interaction with multiple biomolecules in the microenvironment. Despite their striking structural similarities, these two members show contrastive molecular functions as well as temporospatial emergence in living tissues. Typically, CCN2 promotes cell growth, whereas CCN3 restrains it. Where CCN2 is produced, CCN3 disappears. Nevertheless, these two proteins collaborate together to execute their mission in a yin–yang fashion. The apparent functional counteractions of CCN2 and CCN3 can be ascribed to their direct molecular interaction and interference over the cofactors that are shared by the two. Recent studies have revealed the mutual negative regulation systems between CCN2 and CCN3. Moreover, the simultaneous and bidirectional regulatory system of CCN2 and CCN3 is also being clarified. It is of particular note that these regulations were found to be closely associated with glycolysis, a fundamental procedure of energy metabolism. Here, the molecular interplay and metabolic gene regulation that enable the yin–yang collaboration of CCN2 and CCN3 typically found in cartilage development/regeneration and fibrosis are described.

Connective tissue growth factor mediates bone morphogenetic protein 2-induced increase in hyaluronan production in luteinized human granulosa cells

BACKGROUND

Hyaluronan is the main component of the cumulus-oocyte complex (COC) matrix, and it maintains the basic structure of the COC during ovulation. As a member of the transforming growth factor β (TGF-β) superfamily, bone morphogenetic protein 2 (BMP2) has been identified as a critical regulator of mammalian folliculogenesis and ovulation. However, whether BMP2 can regulate the production of hyaluronan in human granulosa cells has never been elucidated.

METHODS

In the present study, we investigated the effect of BMP2 on the production of hyaluronan and the underlying molecular mechanism using both immortalized (SVOG) and primary human granulosa-lutein (hGL) cells. The expression of three hyaluronan synthases (including HAS1, HAS2 and HAS3) were examined following cell incubation with BMP2 at different concentrations. The concentrations of the hyaluronan cell culture medium were determined by enzyme-linked immunosorbent assay (ELISA). The TGF-β type I receptor inhibitors (dorsomorphin and DMH-1) and small interfering RNAs targeting ALK2, ALK3, ALK6 and SMAD4 were used to investigate the involvement of TGF-β type I receptor and SMAD-dependent pathway.

RESULTS

Our results showed that BMP2 treatment significantly increased the production of hyaluronan by upregulating the expression of hyaluronan synthase 2 (HAS2). In addition, BMP2 upregulates the expression of connective tissue growth factor (CTGF), which subsequently mediates the BMP2-induced increases in HAS2 expression and hyaluronan production because overexpression of CTGF enhances, whereas knockdown of CTGF reverses, these effects. Notably, using kinase inhibitor- and siRNA-mediated knockdown approaches, we demonstrated that the inductive effect of BMP2 on the upregulation of CTGF is mediated by the ALK2/ALK3-mediated SMAD-dependent signaling pathway.

CONCLUSIONS

Our findings provide new insight into the molecular mechanism by which BMP2 promotes the production of hyaluronan in human granulosa cells.

Connective tissue growth factor expression hints at aggressive nature of colorectal cancer

BACKGROUND

Connective tissue growth factor (CTGF) is a mediator of transforming growth factor-beta signaling and plays a key role in connective tissue remodeling, inflammatory processes and fibrosis in various illnesses including cancer.

AIM

To investigate the role of CTGF in colorectal cancer (CRC) progression and to compare the CTGF expression with different clinicopathological parameters.

METHODS

Real-time polymerase chain reaction, immunohistochemistry and Western blotting was performed to evaluate the CTGF expression and the results were statistically analyzed against the clinicopathological variables of patient data using STATA software version 16.

RESULTS

CTGF expression levels in tumor specimens were significantly higher than their paired normal specimens. The higher protein expression levels showed a significant association with smoking, staging, tumor grade, invasion depth, necrosis of tumor tissue, and both lymphovascular and perineural invasion. As per the cox regression model and classification tree analysis, tumor-node-metastasis stage and perineural invasion were important predictors for CTGF expression and prognosis of CRC patients. Survival analysis indicated that CTGF overexpression was associated with poorer overall and disease-free survival.

CONCLUSION

Expression of CTGF was increased in CRC and was linked with poor overall and disease-free survival of CRC patients. These findings support prior observations and thus CTGF may be a possible prognostic marker in CRC.

Esomeprazole alleviates fibrosis in systemic sclerosis by modulating AhR/Smad2/3 signaling

Systemic sclerosis (SSc) is a connective tissue disease with the involvement of complex signaling pathways, such as TGF-β/Smad2/3. SSc can lead to severe multiple organ fibrosis, but no effective therapy is currently available because of its unclear pathogenesis. Exploring new treatments is the focus of recent research on SSc. Recent studies have implied a potential antifibrotic role of esomeprazole (ESO), but with currently unidentified mechanisms. Signaling of AhR, a ligand-dependent transcription factor, has been described as a key controller of fibrosis, tumorigenesis, and immune balance. Recently, it has been reported that ESO may be an exogenous agonist of AhR signaling, while no previous study has revealed the effects of ESO on SSc and its underlying mechanisms. In this study, we demonstrate that ESO suppresses the migration of SSc dermal fibroblasts, downregulates profibrotic markers, including COLIA1, α-SMA CTGF and MMP1, and limits collagen production potentially via the activation of AhR signaling. More importantly, ESO could block Smad2/3 phosphorylation concurrently with the reduction in collagen via AhR signaling. Moreover, our results from the bleomycin (BLM)-induced SSc model in skin and lung shows that ESO ameliorates fibrosis in vivo, which in keeping with our in vitro results. We conclude that ESO is a potential therapeutic drug for SSc fibrosis.

CCN2 participates in overload-induced skeletal muscle hypertrophy

The regulation of skeletal muscle growth following pro-hypertrophic stimuli requires a coordinated response by different cell types that leads to extracellular matrix (ECM) remodeling and increases in muscle cross-sectional area. Indeed, matricellular proteins serve a key role as communication vehicles that facilitate the propagation of signaling stimuli required for muscle adaptation to environmental challenges. We found that the matricellular protein cellular communication network factor 2 (CCN2), also known as connective tissue growth factor (CTGF), is induced during a time course of overload-driven skeletal muscle hypertrophy in mice. To elucidate the role of CCN2 in mediating the hypertrophic response, we utilized genetically engineered mouse models for myofiber-specific CCN2 gain- and loss-of-function and then examined their response to mechanical stimuli through muscle overload. Interestingly, myofiber-specific deletion of CCN2 blunted muscle's hypertrophic response to overload without interfering with ECM deposition. On the other hand, when in excess through transgenic CCN2 overexpression, CCN2 was efficient in promoting overload-induced aberrant ECM accumulation without affecting myofiber growth. Altogether, our genetic approaches highlighted independent ECM and myofiber stress adaptation responses, and positioned CCN2 as a central mediator of both. Mechanistically, CCN2 acts by regulating focal adhesion kinase (FAK) mediated transduction of overload-induced extracellular signals, including interleukin 6 (IL6), and their regulatory impact on global protein synthesis in skeletal muscle. Overall, our study highlights the contribution of muscle-derived extracellular matrix factor CCN2 for proper hypertrophic muscle growth.

Endothelial cell-derived pro-fibrotic factors increase TGF-β1 expression by smooth muscle cells in response to cycles of hypoxia-hyperoxia

BACKGROUND

The vascular pathology of peripheral artery disease (PAD) encompasses abnormal microvascular architecture and fibrosis in response to ischemia-reperfusion (I/R) cycles. We aimed to investigate the mechanisms by which pathological changes in the microvasculature direct fibrosis in the context of I/R.

METHODS

Primary human aortic endothelial cells (ECs) were cultured under cycles of normoxia-hypoxia (NH) or normoxia-hypoxia-hyperoxia (NHH) to mimic I/R. Primary human aortic smooth muscle cells (SMCs) were cultured and treated with media from the ECs.

FINDINGS

The mRNA and protein expression of the pro-fibrotic factors platelet derived growth factor (PDGF)-BB and connective tissue growth factor (CTGF) were significantly upregulated in ECs undergoing NH or NHH cycles. Treatment of SMCs with media from ECs undergoing NH or NHH cycles led to significant increases in TGF-β1, TGF-β pathway signaling intermediates, and collagen expression. Addition of neutralizing antibodies against PDGF-BB and CTGF to the media blunted the increases in TGF-β1 and collagen expression. Treatment of SMCs with PAD patient-derived serum also led to increased TGF-β1 levels.

INTERPRETATION

In an in-vitro model of I/R, which recapitulates the pathophysiology of PAD, increased secretion of PDGF-BB and CTGF by ECs was shown to be predominantly driving TGF-β1-mediated expression by SMCs. These cell culture experiments help elucidate the mechanism and interaction between ECs and SMCs in microvascular fibrosis associated with I/R. Thus, targeting these pro-fibrotic factors may be an effective strategy to combat fibrosis in response to cycles of I/R.

FUNDING

National Institute on Aging at the National Institutes of Health grant number R01AG064420.

RESEARCH IN CONTEXT

Evidence before this study: Previous studies in gastrocnemius biopsies from peripheral artery disease (PAD) patients showed that transforming growth factor beta 1 (TGF-β1), the most potent inducer of pathological fibrosis, is increased in the vasculature of PAD patients and correlated with collagen deposition. However, the exact cellular source of TGF-β1 remained unclear. Added value of this study: Exposing cells to cycles of normoxia-hypoxia-hyperoxia (NHH) resulted in pathological changes that are consistent with human PAD. This supports the idea that the use of NHH may be a reliable, novel in vitro model of PAD useful for studying associated pathophysiological mechanisms. Furthermore, pro-fibrotic factors (PDGF-BB and CTGF) released from endothelial cells were shown to induce a fibrotic phenotype in smooth muscle cells. This suggests a potential interaction between these cell types in the microvasculature that drives increased TGF-β1 expression and collagen deposition. Thus, targeting these pro-fibrotic factors may be an effective strategy to combat fibrosis in response to cycles of ischemia-reperfusion.

Genome-wide chromatin contacts of super-enhancer-associated lncRNA identify LINC01013 as a regulator of fibrosis in the aortic valve

Calcific aortic valve disease (CAVD) is characterized by a fibrocalcific process. The regulatory mechanisms that drive the fibrotic response in the aortic valve (AV) are poorly understood. Long noncoding RNAs derived from super-enhancers (lncRNA-SE) control gene expression and cell fate. Herein, multidimensional profiling including chromatin immunoprecipitation and sequencing, transposase-accessible chromatin sequencing, genome-wide 3D chromatin contacts of enhancer-promoter identified LINC01013 as an overexpressed lncRNA-SE during CAVD. LINC01013 is within a loop anchor, which has contact with the promoter of CCN2 (CTGF) located at ~180 kb upstream. Investigation showed that LINC01013 acts as a decoy factor for the negative transcription elongation factor E (NELF-E), whereby it controls the expression of CCN2. LINC01013-CCN2 is part of a transforming growth factor beta 1 (TGFB1) network and exerts a control over fibrogenesis. These findings illustrate a novel mechanism whereby a dysregulated lncRNA-SE controls, through a looping process, the expression of CCN2 and fibrogenesis of the AV.

Calcific aortic valve disease is the most common heart valve disorder characterized by a thickening of the aortic valve resulting from fibrotic and calcific processes. Because the aortic valve replacement is currently the only therapeutic option, the identification of key molecular processes that control the progression of the disease could lead to the development of novel noninvasive therapies. Growing evidence suggests that long noncoding RNAs (lncRNAs) fine tune gene expression in health and disease states. By using a multidimensional profiling including genome-wide 3D enhancer-promoter looping data, we identified LINC01013, a lncRNA, as a regulator of fibrogenesis. Specifically, we found that LINC01013 is located in a cluster of distant enhancers (super-enhancer) in aortic valve interstitial cells and has significant long-range looping with the promoter of CCN2, a gene that orchestrates fibrogenesis. We discovered that LINC01013 is acting as a decoy factor for a negative transcription elongation factor, whereby it controls the transcription of CCN2. In turn, higher expression of LINC01013 during calcific aortic valve disease promoted the expression of CCN2 and a fibrogenic program. These findings provide evidence that LINC01013 is a key regulator of fibrogenesis in CAVD.

PGE2 and Thrombin Induce Myofibroblast Transdifferentiation via Activin A and CTGF in Endometrial Stromal Cells

Endometriosis is characterized by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal hemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, menstruation-related factors, PGE2 and thrombin (P/T), a PAR1 agonist induced epithelial-mesenchymal transition (EMT) of endometrial cells under hypoxia. However, the molecular mechanisms by which P/T induce development of endometriosis have not been fully characterized. To investigate the effects of P/T, RNA extracted from endometrial stromal cells (ESCs) treated with P/T were subjected to RNA sequence analysis, and identified activin A, FOS, and GATA2 as upregulated genes. Activin A increased the expression of connective tissue growth factor (CTGF) and mesenchymal marker genes in ESCs. CTGF induced the expression of fibrosis marker type I collagen, fibronectin, and α-smooth muscle actin (αSMA), indicating fibroblast to myofibroblast transdifferentiation (FMT) of ESCs. In addition, activin A, FOS, GATA2, CTGF, and αSMA were localized in endometriosis lesions. Taken together, our data show that P/T induces changes resembling EMT and FMT in ectopic ESCs derived from retrograde menstruation, and that these are associated with fibrotic changes in the lesions. Pharmacological means that block P/T-induced activin A and CTGF signaling may be strategies to inhibit fibrosis in endometriotic lesions.

Ghrelin ameliorates cardiac fibrosis after myocardial infarction by regulating the Nrf2/NADPH/ROS pathway

To evaluate the role of ghrelin in cardiac fibrosis after myocardial infarction (MI) and to investigate the underlying mechanisms of ghrelin-regulated Nrf2/NADPH/ROS pathway-mediated cardioprotection, the profile of Nrf2, fibrosis markers, and oxidative stress markers were characterized in a rat model of MI and Angiotensin II (Ang II)-stimulated cardiac fibroblasts (CFs). The effects of ghrelin on cardiac function, fibrosis and oxidative stress were investigated after MI in vivo. The role of ghrelin in CF migration and proliferation was evaluated in Ang II-stimulated CFs in vitro. Inhibition of ghrelin receptors using the antagonist, d-Lys3-GHRP-6, in addition to ghrelin was employed in MI and CFs to investigate the direct effect of ghrelin on cardiac fibrosis. Loss function of Nrf2 in CFs was performed to investigate the effect of ghrelin-regulated Nrf2 on oxidative stress and cardiac fibrosis. Ghrelin improved the post-MI cardiac function and reduced cardiac fibrosis. This phenotype is associated with the upregulation of Nrf2 and downregulation of fibrotic proteins, NADPH oxidase and ROS production. In line with in vivo findings, ghrelin attenuated Ang II-stimulated CF migration, proliferation, and oxidative stress in vitro. Inhibition of the ghrelin receptor or knockdown of Nrf2 abolished the beneficial effects of ghrelin on MI or Ang II-stimulated cardiac fibroblasts. In conclusion, ghrelin ameliorates post-MI and Ang II-induced cardiac fibrosis by activating Nrf2, which in turn inhibits the NADPH/ROS pathway.

Effect of Pirfenidone on TGF-β1-Induced Myofibroblast Differentiation and Extracellular Matrix Homeostasis of Human Orbital Fibroblasts in Graves' Ophthalmopathy

Pirfenidone is a pyridinone derivative that has been shown to inhibit fibrosis in animal models and in patients with idiopathic pulmonary fibrosis. Its effect on orbital fibroblasts remains poorly understood. We investigated the in vitro effect of pirfenidone in transforming growth factor-β1 (TGF-β1)-induced myofibroblast transdifferentiation and extracellular matrix (ECM) homeostasis in primary cultured orbital fibroblasts from patients with Graves' ophthalmopathy (GO). The expression of fibrotic proteins, including α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), fibronectin, and collagen type I, was determined by Western blots. The activities of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) responsible for the ECM homeostasis were examined. After pretreating the GO orbital fibroblasts with pirfenidone (250, 500, and 750 μg/mL, respectively) for one hour followed by TGF-β1 for another 24 h, the expression of α-SMA, CTGF, fibronectin, and collagen type I decreased in a dose-dependent manner. Pretreating the GO orbital fibroblasts with pirfenidone not only abolished TGF-β1-induced TIMP-1 expression but recovered the MMP-2/-9 activities. Notably, pirfenidone inhibited TGF-β1-induced phosphorylation of p38 and c-Jun N-terminal kinase (JNK), the critical mediators in the TGF-β1 pathways. These findings suggest that pirfenidone modulates TGF-β1-mediated myofibroblast differentiation and ECM homeostasis by attenuating downstream signaling of TGF-β1.

MicroRNA-26 regulates the expression of CTGF after exposure to ionizing radiation

Radiation-induced fibrosis (RIF) is a serious complication that occurs after irradiation and which is caused by the deposition of extracellular matrix (ECM) proteins such as collagen. However, the underlying mechanisms, including the expression of the cytokines, that promote the RIF process, are not yet fully understood. MicroRNAs (miRNAs) have recently been suggested to act as post-transcriptional repressors for many genes; however, their role in the process of RIF remains to be elucidated. Our previous study showed that ionizing radiation increased the type I collagen expression through the activation of transforming growth factor (TGF)-β, while miR-29 repressed this increase. This study aimed to investigate the mechanisms by which the expression of connective tissue growth factor (CTGF), a downstream mediator of TGF-β, is controlled by miRNAs post-transcriptionally after exposure to ionizing radiation. The expression of CTGF in NIH-3T3 cells and mouse embryonic fibroblasts was increased by ionizing radiation. However, this increase was suppressed with a specific inhibitor of TGF-β receptor. Among the predictable miRNAs that target the CTGF gene, the expression of miR-26a was downregulated after exposure to ionizing radiation and this regulation was negatively mediated by TGF-β signaling. miR-26a negatively regulated the CTGF expression at the post-transcriptional level; however, ionizing radiation suppressed this negative regulation. In addition, the overexpression of miR-26a inhibited the expression of CTGF and type I collagen after irradiation. In conclusion, miR-26a modulates the expression of CTGF via TGF-β signaling in irradiated fibroblasts. The results suggest the potential application of miR-26a in the treatment of RIF.

Molecular laterality encodes stress susceptibility in the medial prefrontal cortex

Functional lateralization of the prefrontal cortex has been implicated in stress and emotional disorders, yet underlying gene expression changes remains unknown. Here, we report molecular signatures lateralized by chronic social defeats between the two medial prefrontal cortices (mPFCs). Stressed mice show 526 asymmetrically expressed genes between the mPFCs. This cortical asymmetry selectively occurs in stressed mice with depressed social activity, but not in resilient mice with normal behavior. We have isolated highly asymmetric genes including connective tissue growth factor (CTGF), a molecule that modulates wound healing at the periphery. Knockdown of CTGF gene in the right mPFC by shRNA led to a stress-resistant behavioral phenotype. Overexpression of CTGF in the right mPFC using viral transduction induces social avoidance while the left mPFC thereof prevent stress-induced social avoidance. Our study provides a molecular window into the mechanism of stress-induced socioemotional disorders, which can pave the way for new interventions by targeting cortical asymmetry.

Influence of TGFBR2, TGFB3, DNMT1, and DNMT3A Knockdowns on CTGF, TGFBR2, and DNMT3A in Neonatal and Adult Human Dermal Fibroblasts Cell Lines

Dermal fibroblasts are responsible for the production of the extracellular matrix that undergoes significant changes during the skin aging process. These changes are partially controlled by the TGF-β signaling, which regulates tissue homeostasis dependently on several genes, including CTGF and DNA methyltransferases. To investigate the potential differences in the regulation of the TGF-β signaling and related molecular pathways at distinct developmental stages, we silenced the expression of TGFB1, TGFB3, TGFBR2, CTGF, DNMT1, and DNMT3A in the neonatal (HDF-N) and adult (HDF-A) human dermal fibroblasts using the RNAi method. Through Western blot, we analyzed the effects of the knockdowns of these genes on the level of the CTGF, TGFBR2, and DNMT3A proteins in both cell lines. In the in vitro assays, we observed that CTGF level was decreased after knockdown of DNMT1 in HDF-N but not in HDF-A. Similarly, the level of DNMT3A was decreased only in HDF-N after silencing of TGFBR2, TGFB3, or DNMT1. TGFBR2 level was lower in HDF-N after knockdown of TGFB3, DNMT1, or DNMT3A, but it was higher in HDF-A after TGFB1 silencing. The reduction of TGFBR2 after silencing of DNMT3A and vice versa in neonatal cells only suggests the developmental stage-specific interactions between these two genes. However, additional studies are needed to explain the dependencies between analyzed proteins.

Selective deletion of connective tissue growth factor attenuates experimentally-induced pulmonary fibrosis and pulmonary arterial hypertension

Connective tissue growth factor (CTGF, CCN2) is a matricellular protein which plays key roles in normal mammalian development and in tissue homeostasis and repair. In pathological conditions, dysregulated CCN2 has been associated with cancer, cardiovascular disease, and tissue fibrosis. In this study, genetic manipulation of the CCN2 gene was employed to investigate the role of CCN2 expression in vitro and in experimentally-induced models of pulmonary fibrosis and pulmonary arterial hypertension (PAH). Knocking down CCN2 using siRNA reduced expression of pro-fibrotic markers (fibronectin p < 0.01, collagen type I p < 0.05, α-SMA p < 0.0001, TIMP-1 p < 0.05 and IL-6 p < 0.05) in TGF-β-treated lung fibroblasts derived from systemic sclerosis patients. In vivo studies were performed in mice using a conditional gene deletion strategy targeting CCN2 in a fibroblast-specific and time-dependent manner in two models of lung disease. CCN2 deletion significantly reduced pulmonary interstitial scarring and fibrosis following bleomycin-instillation, as assessed by fibrotic scores (wildtype bleomycin 3.733 ± 0.2667 vs CCN2 knockout (KO) bleomycin 4.917 ± 0.3436, p < 0.05) and micro-CT. In the well-established chronic hypoxia/Sugen model of pulmonary hypertension, CCN2 gene deletion resulted in a significant decrease in pulmonary vessel remodelling, less right ventricular hypertrophy and a reduction in the haemodynamic measurements characteristic of PAH (RVSP and RV/LV + S were significantly reduced (p < 0.05) in CCN2 KO compared to WT mice in hypoxic/SU5416 conditions). These results support a prominent role for CCN2 in pulmonary fibrosis and in vessel remodelling associated with PAH. Therefore, therapeutics aimed at blocking CCN2 function are likely to benefit several forms of severe lung disease.

Connective tissue growth factor promotes retinal pigment epithelium mesenchymal transition via the PI3K/AKT signaling pathway

Proliferative vitreoretinopathy (PVR) is a disease leading to the formation of contractile preretinal membranes (PRMs) and is one of the leading causes of blindness. Connective tissue growth factor (CTGF) has been identified as a possible key determinant of progressive tissue fibrosis and excessive scarring. Therefore, the present study investigated the role and mechanism of action of CTGF in PVR. Immunohistochemical staining was performed to detect the expression of CTGF, fibronectin and collagen type III in PRMs from patients with PVR. The effects and mechanisms of recombinant human CTGF and its upstream regulator, TGF‑β1, on epithelial‑mesenchymal transition (EMT) and the synthesis of extracellular matrix (ECM) by retinal pigment epithelium (RPE) cells were investigated using reverse transcription‑quantitative PCR, western blotting and a [3H]proline incorporation assay. The data indicated that CTGF, fibronectin and collagen type III were highly expressed in PRMs. In vitro, CTGF significantly decreased the expression of the epithelial markers ZO‑1 and E‑cadherin and increased that of the mesenchymal markers fibronectin, N‑cadherin and α‑smooth muscle actin in a concentration‑dependent manner. Furthermore, the expression of the ECM protein collagen type III was upregulated by CTGF. However, the trends in expression for the above‑mentioned markers were reversed after knocking down CTGF. The incorporation of [3H]proline into RPE cells was also increased by CTGF. In addition, 8‑Bromoadenosine cAMP inhibited CTGF‑stimulated collagen synthesis and transient transfection of RPE cells with a CTGF antisense oligonucleotide inhibited TGF‑β1‑induced collagen synthesis. The phosphorylation of PI3K and AKT in RPE cells was promoted by CTGF and TGF‑β1 and the latter promoted the expression of CTGF. The results of the present study indicated that CTGF may promote EMT and ECM synthesis in PVR via the PI3K/AKT signaling pathway and suggested that targeting CTGF signaling may have a therapeutic or preventative effect on PVR.

Inhibition of fibroblast growth factor-inducible 14 attenuates experimental tubulointerstitial fibrosis and profibrotic factor expression of proximal tubular epithelial cells

BACKGROUND AND AIM

As a proinflammatory cytokine, tumor necrosis factor-like weak inducer of apoptosis (TWEAK) participates in the progression of renal fibrosis by binding to its receptor, fibroblast growth factor-inducible 14 (Fn14). However, the effect of Fn14 inhibition on tubular epithelial cell-mediated tubulointerstitial fibrosis remains unclear. This study aimed to elucidate the role of TWEAK/Fn14 interaction in the development of experimental tubulointerstitial fibrosis as well as the protective effect of Fn14 knockdown on proximal tubular epithelial cells.

METHODS

A murine model of unilateral ureteral obstruction was constructed in both wild-type and Fn14-deficient BALB/c mice, followed by observation of the tubulointerstitial pathologies.

RESULTS

Fn14 deficiency ameliorated the pathological changes, including inflammatory cell infiltration and cell proliferation, accompanied by reduced production of profibrotic factors and extracellular matrix deposition. In vitro experiments showed that TWEAK dose-dependently enhanced the expression of collagen I, fibronectin, and α-smooth muscle actin in proximal tubular epithelial cells. Interestingly, TWEAK also upregulated the expression levels of Notch1/Jagged1. Fn14 knockdown and Notch1/Jagged1 inhibition also mitigated the effect of TWEAK on these cells.

CONCLUSIONS

In conclusion, TWEAK/Fn14 signals contributed to tubulointerstitial fibrosis by acting on proximal tubular epithelial cells. Fn14 inhibition might be a therapeutic strategy for protecting against renal interstitial fibrosis.

The relationship between miRNA-26b and connective tissue growth factor in rat models of aortic banding and debanding

BACKGROUND/AIMS

Connective tissue growth factor (CTGF) is a profibrotic factor implicated in pressure overload-mediated myocardial fibrosis. In this study, we determined the role of predicted CTGF-targeting microRNAs (miRNAs) in rat models of aortic stenosis and reverse cardiac remodeling.

METHODS

Minimally invasive ascending aortic banding was performed in 24 7-week-old male Sprague-Dawley rats, which were divided into three groups. The banding group consisted of eight rats that were sacrificed immediately after 6 weeks of aortic constriction. The debanding group underwent aortic constriction for 4 weeks and was sacrificed 2 weeks after band removal. The third group underwent sham surgery. We investigated the expression of CTGF, transforming growth factor-β1 (TGFβ1), and matrix metalloproteinase-2 using ELISA and examined miRNA-26b, miRNA-133a, and miRNA-19b as predicted CTGF-targeting miRNAs based on miRNA databases in 24-hour TGFβ-stimulated and TGFβ- washed fibroblasts and myocardial tissues from all subjects.

RESULTS

CTGF was elevated in 24-hour TGFβ-stimulated fibroblasts and decreased in 24-hour TGFβ-washed fibroblasts. miRNA-26b was significantly increased in TGFβ-washed fibroblasts compared with control and TGFβ-stimulated fibroblasts (p < 0.05). CTGF expression was significantly higher in the banding group than that in the sham and debanding groups. The relative expression levels of miRNA-26b were higher in the debanding group than in the banding group.

CONCLUSION

The results of our study using models of aortic banding and debanding suggested that miRNA-26b was significantly increased after aortic debanding. The in vitro model yielded the same results: miRNA-26b was upregulated after removal of TGFβ from fibroblasts.

[TGF-β1/ERK/CTGF pathway involved in effect of acupuncture on exercise-induced skeletal muscle fibrosis]

OBJECTIVE

To observe the changes of the skeletal muscle fibrosis and changes of transforming growth factor-β1(TGF-β1)/ extracellular signal-regulated kinase (ERK) / connective tissue growth factor (CTGF)pathway in rats after long-term eccentric exercise and acupuncture intervention, so as to explore the mechanism of acupuncture in regulating exercise-induced skeletal muscle fibrosis.

METHODS

A total of 30 male SD rats were randomly divided into normal control, exercise and acupuncture group, with 10 rats in each group. The rat model of skeletal muscle fibrosis was established by eccentric exercise for 3 weeks. After exercise trained every time, the rats of the acupuncture group received acupuncture stimulation by holding the acupuncture needle to obliquely and longitudinally penetrate the ventral part of triceps of the lower leg along its lateral side, followed by retaining the needle for 2 min. Changes of the collagen fibers in each group was observed by scanning electron microscope. The expressions of Collagen Ⅰ, TGF-β1, phosphated (p)-ERK/ERK and CTGF proteins were detected by Western blot.

RESULTS

After 3 weeks of eccentric exercise and acupuncture, the fibrosis and deposition of collagen fibers in the exercise group were significantly higher than that in the normal control group,the degree of fibrosis in the acupuncture group was significantly lower than that in the exercise group. Compared with the normal control group, the expression levels of Collagen Ⅰ, TGF-β1, CTGF and p-ERK/ERK in the exercise group was significantly higher (P<0.01，P<0.05). After EA interventions, the increased levels of the above indicators were significantly reversed (P<0.05，P<0.01) apart from p-ERK/ERK which had a downward trend, but the difference was not statistically significant.

CONCLUSION

The accumulation of chronic sports injury can lead to the deposition of collagen fibers in skeletal muscle, which leads to the fibrosis of skeletal muscle. Acupuncture can inhibit skeletal muscle fibrosis via down-regulating TGF-β1/ERK/CTGF signaling pathway.

Possibility for Transcriptional Targeting of Cancer-Associated Fibroblasts-Limitations and Opportunities

Cancer-associated fibroblasts (CAF) are attractive therapeutic targets in the tumor microenvironment. The possibility of using CAFs as a source of therapeutic molecules is a challenging approach in gene therapy. This requires transcriptional targeting of transgene expression by cis-regulatory elements (CRE). Little is known about which CREs can provide selective transgene expression in CAFs. We hypothesized that the promoters of FAP, CXCL12, IGFBP2, CTGF, JAG1, SNAI1, and SPARC genes, the expression of whose is increased in CAFs, could be used for transcriptional targeting. Analysis of the transcription of the corresponding genes revealed that unique transcription in model CAFs was characteristic for the CXCL12 and FAP genes. However, none of the promoters in luciferase reporter constructs show selective activity in these fibroblasts. The CTGF, IGFBP2, JAG1, and SPARC promoters can provide higher transgene expression in fibroblasts than in cancer cells, but the nonspecific viral promoters CMV, SV40, and the recently studied universal PCNA promoter have the same features. The patterns of changes in activity of various promoters relative to each other observed for human cell lines were similar to the patterns of activity for the same promoters both in vivo and in vitro in mouse models. Our results reveal restrictions and features for CAF transcriptional targeting.