Molecular mechanism of triptolide in myocardial fibrosis through the Wnt/β-catenin signaling pathway

Objective. Myocardial fibrosis (MF) is a common manifestation of end-stage cardiovascular diseases. Triptolide (TP) provides protection against cardiovascular diseases. This study was to explore the functional mechanism of TP in MF rats via the Wnt/β-catenin pathway. Methods. The MF rat model was established via subcutaneous injection of isoproterenol (ISO) and treated with low/medium/high doses of TP (L-TP/M-TP/H-TP) or Wnt agonist BML-284. Cardiac function was examined by echocardiography. Pathological changes of myocardial tissues were observed by HE and Masson staining. Col-I/Col-III/Vimentin/α-SMA levels were detected by immunohistochemistry, RT-qPCR, and Western blot. Collagen volume fraction content was measured. Expression levels of the Wnt/β-catenin pathway-related proteins (β-catenin/c-myc/Cyclin D1) were detected by Western blot. Rat cardiac fibroblasts were utilized for in vitro validation experiments. Results. MF rats had enlarged left ventricle, decreased systolic and diastolic function and cardiac dysfunction, elevated collagen fiber distribution, collagen volume fraction and hydroxyproline content. Levels of Col-I/Col-III/Vimentin/α-SMA, and protein levels of β-catenin/c-myc/Cyclin D1 were increased in MF rats. The Wnt/β-catenin pathway was activated in the myocardial tissues of MF rats. TP treatment alleviated impairments of cardiac function and myocardial tissuepathological injury, decreased collagen fibers, collagen volume fraction, Col-I, Col-III, α-SMA and Vimentin levels, HYP content, inhibited Wnt/β-catenin pathway, with H-TP showing the most significant effects. Wnt agonist BML-284 antagonized the inhibitive effect of TP on MF. TP inhibited the Wnt/β-catenin pathway to repress the proliferation and differentiation of mouse cardiac fibroblasts in vitro. Conclusions. TP was found to ameliorate ISO-induced MF in rats by inhibiting the Wnt/β-catenin pathway.

[Different calcium ion concentrations affect epithelial mesenchymal transformation of human peritoneal mesothelial cells via endoplasmic reticulum stress]

OBJECTIVE

To study the effects of different calcium ion concentrations on epithelial mesenchymal transformation (EMT) of human peritoneal mesothelial cell (HPMC) via endoplasmic reticulum stress (ERS).

METHODS

HPMC cell line HMrSV5 was cultured in vitro and treated in groups. The cells in the control group, high calcium group 1, and high calcium group 2 were treated with medium containing calcium ion concentrations of 1.25, 1.75, and 2.25 mmol/L, respectively. The solvent control group was treated with medium containing 1.25 mmol/L physiological calcium ion concentration and 0.1% dimethyl sulfoxide (DMSO), the high calcium+solvent group was treated with medium containing 2.25 mmol/L calcium ion concentration and 0.1% DMSO, the high calcium+4-phenylbutyric acid (4-PBA) group was treated with medium containing 2.25 mmol/L calcium ion concentration and 1 mmol/L ERS inhibitor 4-PBA, and each group was treated for 48 hours. Morphological changes of cells in each group were observed under light microscope. The expressions of epithelial cell phenotype marker zonula occluden-1 (ZO-1) and mesenchymal cell phenotype marker α-smooth muscle actin (α-SMA) in the cells were observed by immunofluorescence staining. The expressions of EMT marker genes E-cadherin, ZO-1, α-SMA and Vimentin were detected by fluorescence quantitative polymerase chain reaction (PCR). The expressions of ERS marker proteins phosphorylated protein kinase R-like endoplasmic reticulum kinase (p-PERK), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), transcription activating factor 4 (ATF4) and C/EBP homologous protein (CHOP) were detected by Western blotting.

RESULTS

Compared with the control group, the morphology of HMrSV5 cells became slender and fibrotic, the fluorescence intensity of ZO-1 increased, and the fluorescence intensity of α-SMA decreased in high calcium 1 and high calcium 2 groups, indicating that the cells transformed from epithelial cells to mesenchyme cells. The mRNA expressions of E-cadherin and ZO-1 were significantly decreased, while the mRNA expressions of α-SMA and Vimentin and the protein expressions of p-PERK, p-eIF2α, ATF4 and CHOP were significantly increased, moreover, the expressions of the above marker genes or proteins in the high calcium 2 group was more obvious than those in the high calcium 1 group [E-cadherin mRNA (2-ΔΔCt): 0.53±0.05 vs. 0.75±0.09, ZO-1 mRNA (2-ΔΔCt): 0.42±0.06 vs. 0.69±0.06, α-SMA mRNA (2-ΔΔCt): 1.81±0.16 vs. 1.32±0.14, Vimentin mRNA (2-ΔΔCt): 2.05±0.22 vs. 1.48±0.16, p-PERK protein (p-PERK/β-actin): 0.81±0.09 vs. 0.59±0.06, p-eIF2α protein (p-eIF2α/β-actin): 0.87±0.10 vs. 0.50±0.06, ATF4 protein (ATF4/β-actin): 0.93±0.10 vs. 0.72±0.06, CHOP protein (CHOP/β-actin): 0.79±0.09 vs. 0.46±0.04, all P < 0.05]. Compared with the solvent control group, the morphological changes of cells, the expressions of EMT marker genes and ERS marker proteins after high calcium ion concentration of 2.25 mmol/L were consistent with those in the high calcium 2 group than control group. Compared with the high calcium+solvent group, the cell morphology recovered the characteristics of polygonal and pebble-like epithelial cells in the high calcium+4-PBA group, the fluorescence intensity of ZO-1 increased, the fluorescence intensity of α-SMA decreased, and the mRNA expressions of E-cadherin and ZO-1 in the cells were significantly increased [E-cadherin mRNA (2-ΔΔCt): 0.86±0.09 vs. 0.57±0.04, ZO-1 mRNA (2-ΔΔCt): 0.81±0.06 vs. 0.48±0.05, both P < 0.05], the mRNA expressions of α-SMA and Vimentin and the protein expressions of p-PERK, p-eIF2α, ATF4 and CHOP were significantly decreased [α-SMA mRNA (2-ΔΔCt): 1.21±0.13 vs. 1.77±0.15, Vimentin mRNA (2-ΔΔCt): 1.30±0.14 vs. 1.94±0.20, p-PERK protein (p-PERK/β-actin): 0.38±0.04 vs. 0.92±0.11, p-eIF2α protein (p-eIF2α/β-actin): 0.34±0.05 vs. 1.05±0.13, ATF4 protein (ATF4/β-actin): 0.57±0.06 vs. 0.97±0.11, CHOP protein (CHOP/β-actin): 0.51±0.04 vs. 0.90±0.12, all P < 0.05].

CONCLUSIONS

High calcium ion concentrations of 1.75 mmol/L and 2.25 mmol/L promote EMT of HPMC via activating ERS.

Impairment of Assembly of the Vimentin Intermediate Filaments Leads to Suppression of Formation and Maturation of Focal Contacts and Alteration of the Type of Cellular Protrusions

Cell migration is largely determined by the type of protrusions formed by the cell. Mesenchymal migration is accomplished by formation of lamellipodia and/or filopodia, while amoeboid migration is based on bleb formation. Changing of migrational conditions can lead to alteration in the character of cell movement. For example, inhibition of the Arp2/3-dependent actin polymerization by the CK-666 inhibitor leads to transition from mesenchymal to amoeboid motility mode. Ability of the cells to switch from one type of motility to another is called migratory plasticity. Cellular mechanisms regulating migratory plasticity are poorly understood. One of the factors determining the possibility of migratory plasticity may be the presence and/or organization of vimentin intermediate filaments (VIFs). To investigate whether organization of the VIF network affects the ability of fibroblasts to form membrane blebs, we used rat embryo fibroblasts REF52 with normal VIF organization, fibroblasts with vimentin knockout (REF-/-), and fibroblasts with mutation inhibiting assembly of the full-length VIFs (REF117). Blebs formation was induced by treatment of cells with CK-666. Vimentin knockout did not lead to statistically significant increase in the number of cells with blebs. The fibroblasts with short fragments of vimentin demonstrate the significant increase in number of cells forming blebs both spontaneously and in the presence of CK-666. Disruption of the VIF organization did not lead to the significant changes in the microtubules network or the level of myosin light chain phosphorylation, but caused significant reduction in the focal contact system. The most pronounced and statistically significant decrease in both size and number of focal adhesions were observed in the REF117 cells. We believe that regulation of the membrane blebbing by VIFs is mediated by their effect on the focal adhesion system. Analysis of migration of fibroblasts with different organization of VIFs in a three-dimensional collagen gel showed that organization of VIFs determines the type of cell protrusions, which, in turn, determines the character of cell movement. A novel role of VIFs as a regulator of membrane blebbing, essential for manifestation of the migratory plasticity, is shown.

[Aumolertinib inhibits proliferation, invasion and migration and promotes apoptosis of neuroblastoma cells by downregulating MMP2 and MMP9 expression]

OBJECTIVE

To investigate the effects of aumolertinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), on biological behaviors of neuroblastoma SH-SY5Y cells.

METHODS

CCK-8 assay, colony-forming assay, Transwell assay and flow cytometry were used to assess the effects of 2, 4 and 8 μmol/L aumolertinib on proliferation, survival, migration, invasion and apoptosis of SH-SY5Y cells, and the changes in ultrastructure of the cells were observed using transmission electron microscopy. The protein expressions of Bax, Bcl-2, E-cadherin, vimentin, MMP2, and MMP9 in the treated cells were detected using Western blotting. A nude mouse model bearing subcutaneous SH-SY5Y cell xenograft were treated with aumolertinib (15 mg/kg) or cyclophosphamide (20 mg/kg), and the tumor volume and body mass changes was measured. HE staining was used to observe adverse effects of the treatment on the heart, liver, spleen, lungs and kidneys.

RESULTS

Aumolertinib significantly inhibited the proliferation and viability of SH-SY5Y cells (P<0.05) with IC50 of 5.004, 3.728 and 3.228 µmol/L at 24, 48 and 72 h, respectively. Aumolertinib treatment induced obvious apoptosis of the cells, which showed characteristic morphological changes of apoptosis under transmission electron microscope. The treatment also inhibited the invasion and migration abilities of SH-SY5Y cells (P<0.01), up-regulated the expression levels of E-cadherin and Bax and lowered the expression levels of Bcl-2, vimentin, MMP2 and MMP9 (P<0.05). In the nude mouse models, treatment with aumolertinib effectively inhibited the growth of neuroblastoma without causing significant toxicity to the vital organs.

CONCLUSION

Aumolertinib inhibits proliferation, survival, invasion and migration and induces apoptosis in SH-SY5Y cells by downregulating MMP2 and MMP9 expression.

Circular RNA circARPC1B functions as a stabilisation enhancer of Vimentin to prevent high cholesterol-induced articular cartilage degeneration

BACKGROUND

Osteoarthritis (OA) is a prevalent and debilitating condition, that is, directly associated with cholesterol metabolism. Nevertheless, the molecular mechanisms of OA remain largely unknown, and the role of cholesterol in this process has not been thoroughly investigated. This study aimed to investigate the role of a novel circular RNA, circARPC1B in the relationship between cholesterol and OA progression.

METHODS

We measured total cholesterol (TC) levels in the synovial fluid of patients with or without OA to determine the diagnostic role of cholesterol in OA. The effects of cholesterol were explored in human and mouse chondrocytes in vitro. An in vivo OA model was also established in mice fed a high-cholesterol diet (HCD) to explore the role of cholesterol in OA. RNAseq analysis was used to study the influence of cholesterol on circRNAs in chondrocytes. The role of circARPC1B in the OA development was verified through circARPC1B overexpression and knockdown. Additionally, RNA pulldown assays and RNA binding protein immunoprecipitation were used to determine the interaction between circARPC1B and Vimentin. CircARPC1B adeno-associated virus (AAV) was used to determine the role of circARPC1B in cholesterol-induced OA.

RESULTS

TC levels in synovial fluid of OA patients were found to be elevated and exhibited high sensitivity and specificity as predictors of OA diagnosis. Moreover, elevated cholesterol accelerated OA progression. CircARPC1B was downregulated in chondrocytes treated with cholesterol and played a crucial role in preserving the extracellular matrix (ECM). Mechanistically, circARPC1B is competitively bound to the E3 ligase synoviolin 1 (SYVN1) binding site on Vimentin, inhibiting the proteasomal degradation of Vimentin. Furthermore, circARPC1B AAV infection alleviates Vimentin degradation and OA progression caused by high cholesterol.

CONCLUSIONS

These findings indicate that the cholesterol-circARPC1B-Vimentin axis plays a crucial role in OA progression, and circARPC1B gene therapy has the opportunity to provide a potential therapeutic approach for OA.

Effect of emodin combined with cisplatin on the invasion and migration of HepG2 hepatoma cells

Cisplatin is the leading chemotherapy agent for advanced liver cancer. However, the resistance to cisplatin in liver cancer reduces its efficacy. A potential strategy to increase its effectiveness and reduce toxicity is to combine cisplatin with 1,3,8-trihydroxy-6-methylanthraquinone (emodin). In this study, we examined the effects of emodin combined with cisplatin on the invasion and migration of HepG2 cells and analyzed the role of emodin. The effects of cisplatin, emodin and their combination were assessed in HepG2 cells. Proliferation, invasion and migration of HepG2 cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), scar and Transwell assays. The gelatinase spectrum and an ELISA detected the expression of matrix metallopeptidase 2 (MMP-2) and matrix metallopeptidase 9 (MMP-9). The expression of E-cadherin and vimentin was detected by immunofluorescence and Western blots. Emodin inhibited cell invasion and migration in HepG2 hepatoma cells, increased E-cadherin expression, decreased vimentin, MMP-2, and MMP-9 expression. The combination of emodin and cisplatin-induced a more significant effect in a dose-dependent manner. In this study, we found that emodin inhibited hepatocellular carcinoma (HCC) metastasis. Compared with either cisplatin or emodin alone, the combination of both showed a more significant synergistic effect. Emodin can enhance the sensitivity of HepG2 HCC cells to cisplatin by inhibiting epithelial-mesenchymal transition, and thus, play a role in preventing recurrence and metastasis in HCC.

CircRNA7632 down-regulation alleviates endothelial cell dysfunction in Kawasaki disease via regulating IL-33 expression

Kawasaki disease (KD) is a form of idiopathic vasculitis frequently accompanied by coronary artery lesions, which involves endothelial dysfunction. Recent studies have demonstrated that circular RNAs (circRNAs) are implicated in many cardiovascular diseases. However, few studies have examined the role of circRNAs on endothelial dysfunction in KD. In this study, we investigated the role of circ7632 on endothelial-mesenchymal transition (EndoMT) in KD and then explored the underlying mechanism. Children diagnosed with KD and age-matched healthy controls (HC) were included. Sera samples were collected. Primary human umbilical vein endothelial cells (HUVECs) were obtained and incubated with 15% HC and KD serum for 48 h. The mRNA and protein expression of mesenchymal markers vimentin and α-smooth muscle actin (α-SMA) and endothelial marker zonula occludens-1 (ZO-1) in HUVECs transfected with plasmid-circ7632 and si-circ7632 were detected by RT-qPCR and Western blot analysis. CCK8, scratch test, and migration test were performed to examine the effect of circ7632 on the cell proliferation and migration. The circ7632 level was higher in HUVECs treated by KD serum than in HUVECs treated with HC serum. Overexpression of circ7632 significantly increased vimentin and α-SMA expression, decreased ZO-1 expression, and also decreased cell proliferation. Down-regulation of circ7632 expression got the opposite results. RNA-seq analysis, and confirmatory experiment displayed that down-regulation of circ7632 decreased IL-33 expression, and IL-33 silencing mitigated KD serum-mediated EndoMT. Our study revealed that circ7632 level was elevated in KD serum-treated HUVECs. Circ7632 down-regulation could alleviate EndoMT likely through decreasing IL-33 expression. The circ7632 may become a potential therapeutic target for KD.

Ephedrine alleviates bleomycin-induced pulmonary fibrosis by inhibiting epithelial-mesenchymal transition and restraining NF-κB signaling

Pulmonary fibrosis is a lethal and progressive pulmonary disorder in human beings. Ephedrine is a compound isolated from Ephedra and plays a regulatory role in inflammatory response. This study focused on the anti-pulmonary fibrosis effect of ephedrine and its potential molecular mechanism. After a mouse model of pulmonary fibrosis was established through bleomycin (BLM) induction, the survival percentage, body weight, and pulmonary index were measured. Hematoxylin-eosin staining and Masson's trichrome staining for lung tissues were performed to observe the pathological alterations. The viability of lung epithelial BEAS-2B cells, intracellular production of reactive oxygen species, and the levels of pro-inflammatory cytokines were examined by cell counting kit-8 assays, 2',7'-dichlorofluorescein diacetate (DCF-DA) staining, and enzyme-linked immunosorbent assay, respectively. Immunofluorescence staining was performed to determine E-cadherin and vimentin expression after BLM or ephedrine treatment. The mRNA and protein levels of cytokeratin-8, E-cadherin, α-SMA, and vimentin were subjected to quantitative polymerase chain reaction and immunoblotting. Experimental results revealed that ephedrine treatment rescued the repressive impact of BLM on BEAS-2B cell viability, and ephedrine inhibited BLM-induced overproduction of reactive oxygen species and inflammatory response in BEAS-2B cells. Additionally, ephedrine suppressed epithelial-mesenchymal transition (EMT) process stimulated by BLM treatment, as demonstrated by the reduced α-SMA and vimentin levels together with the increased cytokeratin-8 and E-cadherin levels in BLM + Ephedrine group. In addition, ephedrine inhibited NF-κB and activated Nrf-2 signaling in BLM-treated BEAS-2B cells. Moreover, ephedrine ameliorated pulmonary fibrosis in BLM-induced mice and improved the survival of model mice. In conclusion, ephedrine attenuates BLM-evoked pulmonary fibrosis by repressing EMT process via blocking NF-κB signaling and activating Nrf-2 signaling, suggesting that ephedrine might become a potential anti-pulmonary fibrosis agent in the future.

Extracellular vesicles improve diastolic function and substructure in normal and high-fat diet models of chronic myocardial ischemia

OBJECTIVE

The burden of mortality and morbidity of cardiovascular disease is in part due to substantial fibrosis accelerated by coexisting risk factors. This study aims to evaluate the effect of extracellular vesicle therapy on diastolic function and myocardial fibrosis in the setting of chronic myocardial ischemia with and without a high-fat diet.

METHODS

Forty male Yorkshire swine were administered a normal or high-fat diet. At 11 weeks of age, they underwent placement of an ameroid constrictor on their left circumflex coronary artery. Both dietary groups then received either intramyocardial injection of vehicle saline as controls or extracellular vesicles as treatment into the ischemic territory (normal diet control, n = 8; high-fat diet controls, n = 11) or extracellular vesicles (normal diet extracellular vesicles, n = 9; high-fat diet extracellular vesicles, n = 12). Five weeks later, hemodynamic parameters, histology, and selected protein expression were evaluated.

RESULTS

Extracellular vesicles reduced end-diastolic pressure volume relationship (P = .002), perivascular collagen density (P = .031), calcium mineralization (P = .026), and cardiomyocyte diameter (P < .0001), and upregulated osteopontin (P = .0046) and mechanistic target of rapamycin (P = .021). An interaction between extracellular vesicles and diet was observed in the vimentin area (P = .044) and fraction of myofibroblast markers to total vimentin (P = .049). Significant changes across diet were found with reductions in muscle fiber area (P = .026), tumor necrosis factor α (P = .0002), NADPH oxidase 2 and 4 (P = .0036, P = .008), superoxide dismutase 1 (P = .034), and phosphorylated glycogen synthase kinase 3β (P = .020).

CONCLUSIONS

Extracellular vesicle therapy improved the myocardium's ability to relax and is likely due to structural improvements at the extracellular matrix and cellular levels.

Anti-EMT and anti-fibrosis effects of protocatechuic aldehyde in renal proximal tubular cells and the unilateral ureteral obstruction animal model

CONTEXT

Protocatechuic aldehyde (PCA) is a natural product that has various benefits for fibrosis.

OBJECTIVE

This study evaluated the effects of PCA on renal fibrosis.

MATERIALS AND METHODS

Epithelial-mesenchymal transition (EMT) was induced by 20 ng/mL transforming growth factor-β1 (TGF-β1), followed by treatment with 1 and 5 μM PCA, in the rat renal proximal tubular cell line NRK-52E. Cell viability, protein expression, and scratch wound-healing assays were conducted. Sprague-Dawley (SD) rats underwent unilateral ureteral obstruction (UUO) surgery for renal fibrosis indication and were treated with 50 and 100 mg/kg PCA for 14 days.

RESULTS

The IC₅₀ of PCA was appropriately 13.75 ± 1.91 μM in NRK-52E cells, and no significant difference at concentrations less than 5 μM. PCA ameliorated TGF-β1-induced EMT, such as enhanced E-cadherin and decreased vimentin. Fibrotic markers collagen IV and α-smooth muscle actin (α-SMA) increased in TGF-β1-induced NRK-52E. Moreover, PCA reduced TGF-β1-induced migration in the wound-healing assay. Analysis of rat kidneys indicated that PCA reduced UUO-induced hydronephrosis (control: 15.11 ± 1.00%; UUO: 39.89 ± 1.91%; UUO + PCA50: 18.37 ± 1.61%; UUO + PCA100: 17.67 ± 1.39%). Protein level demonstrated that PCA not only decreased vimentin expression and enhanced E-cadherin expression, but inhibited UUO-induced collagen IV and α-SMA upregulation, indicating that it could mitigate EMT in a rat model of UUO-induced renal fibrosis.

DISCUSSION AND CONCLUSIONS

This study suggested that PCA decreases TGF-β1-induced fibrosis and EMT in vitro and in vivo. These findings demonstrate pharmacological effects of PCA and might be a potential strategy for the prevention of organ fibrosis in clinics.

BDE-209 and TCDD enhance metastatic characteristics of melanoma cells after chronic exposure

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) and BDE-209 (decabromodiphenyl ether) are persistent organic pollutants (POPs) produced by industrial activities and associated with several diseases. TCDD is a known human carcinogen, but few studies investigated about the effects of exposure to both compounds, i.e., whether BDE-209 and TCDD can render tumor cells more aggressive and metastatic. In the current study we investigated if the exposure of B16-F1 and B16-F10 melanoma murine cells to environmental relevant concentrations of TCDD and BDE-209 at 24 h and 15-day exposure modulates the expression of genes related to metastasis, making the cells more aggressive. Both pollutants did not affect cell viability but lead to increase of cell proliferation, including the upregulation of vimentin, MMP2, MMP9, MMP14 and PGK1 gene expression and downregulation of E-cadherin, TIMP2, TIMP3 and RECK, strongly suggesting changes in cell phenotypes defined as epithelial to mesenchymal transition (EMT) in BDE-209 and TCDD-exposed cells. Foremost, increased expression of metalloproteinases and decreased expression of their inhibitors made B16-F1 cells similar the more aggressive B16-F10 cell line. Also, the higher secretion of extracellular vesicles by cells after acute exposure to BDE-209 could be related with the phenotype changes. These results are a strong indication of the potential of BDE-209 and TCDD to modulate cell phenotype, leading to a more aggressive profile.

[Protective effect of active vitamin D on liver fibrosis induced by sodium arsenite in SD rats]

OBJECTIVE

To explore the protective effect of active vitamin D(VD) on liver fibrosis injury induced by sodium arsenite(NaAsO_2) in SD rats.

METHODS

Eighteen healthy newly weaned SD rats, half male and half female, were randomly divided into Control group(gavaged with 10 mL/kg normal saline), NaAsO_2-treated group(gavaged with 10 mg/kg NaAsO_2), Active VD(calcitriol) intervention group(gavaged with 10 mg/kg NaAsO_2 and 1.0 μg/kg calcitriol was given by gavage along with NaAsO_2 administration after 12 weeks), all rats were administered 6 days a week for 36 weeks and weighed every week. Enzyme-linked immunosorbent(ELISA) was used to detect the secretion levels of 25(OH)D_3 and hyaluronic acid(HA), laminin(LN), type Ⅲ pre-collagen amino-terminal peptide(PⅢNP), type Ⅳ collagen(COL-Ⅳ) in the serum of rats in each group; HE staining was used to observe the basic pathological changes of liver tissues in each group, Masson and Sirius Red staining were used to observe the fibrosis and collagen deposition of liver tissues in each group; Western Blot was used to detected the protein levels of fibrosis-related markers α-smooth actin(α-SMA), transforming growth factor-β1(TGF-β1) and Vimentin in each group.

RESULTS

After 36 weeks of NaAsO_2 exposure, the weight of rats was significantly decreased compared with the control group, and the weight of female rats after calcitriol intervention was significantly increased compared with NaAsO_2-treated group(P&lt;0.05). The result of liver coefficient showed increasing in NaAsO_2-treated group compared with the control group, while decreasing in calcitriol intervention group compared with NaAsO_2-treated group, and the difference was statistically significant in female rats. ELISA assay showed that compared with the control group((550.21±29.16) ng/L), the serum level of 25(OH)D_3 in NaAsO_2-treated group((436.82±74.37) ng/L) was significantly decreased(P&lt;0.05), while the serum level of 25(OH)D_3 was significantly higher in calcitriol intervention group than that of NaAsO_2-treated group(P&lt;0.05). HE staining found that, compared with the control group, the liver tissue of rats in NaAsO_2-treated group showed abnormal morphology, the liver tissue was structurally disordered, false lobules and fat vacuoles were also increased. Masson and Sirius Red staining also revealed abnormal hepatic lobule structure, enlarged and deformed portal area and abundant collagen fiber deposition in NaAsO_2-treated group. Further analysis showed that the positive staining area of collagen deposition in liver tissue of rats exposed to NaAsO_2 increased significantly compared with the control group(P&lt;0.05). Those above changes in calcitriol intervention group were significantly alleviated compared with NaAsO_2-treated group(P&lt;0.05). Western Blot analysis showed that the protein levels of α-SMA, TGF-β1 and Vimentin were obviously higher in NaAsO_2-treated group(1.12±0.21, 1.12±0.26, 1.31±0.15) than that in the control group(0.57±0.10, 0.64±0.13, 0.72±0.16)(P&lt;0.05). In addition, the serum levels of HA, LN, PⅢNP and COL-Ⅳ in rats exposed to NaAsO_(2 )((87.92±9.67), (89.04±11.91), (12.09±2.97) and(19.86±3.40)ng/mL) were also higher than those in control group. After calcitriol intervention, the protein levels of α-SMA, TGF-β1 and Vimentin(0.68±0.16, 0.85±0.21, 0.84±0.09) in liver tissue and the serum levels of HA, LN, PⅢNP and COL-Ⅳ((54.29±7.23), (55.56±9.43), (6.49±1.08), (10.15±1.99) ng/mL) were significantly lower than those of NaAsO_2-treated group(P&lt;0.05).

CONCLUSION

Calcitriol can effectively alleviate liver fibrosis injury caused by long-term NaAsO_2 exposure in SD rats.

PEG2-Induced Pyroptosis Regulates the Expression of HMGB1 and Promotes hEM15A Migration in Endometriosis

Endometriosis (EMS) is a common gynecological disease. Prostaglandin E2 (PGE2), which induces chronic pelvic inflammation and cell pyroptosis, a form of programmed cell death based on inflammasome activation, are involved in EMS, but the extent of their involvement and roles remain unclear. The present study aimed to evaluate PGE2-induced pyroptosis in EMS and the influence of PGE2 in EMS progression. Using western blotting, it was found that the expressions of PGE2 and pyroptosis-related proteins (NLRP3, cleaved caspase-1, interleukin (IL)-1β and IL-18) were higher in EMS tissues than in normal endometrial tissues. The levels of PGE2, IL-1β, and IL-18 in the serum of patients with EMS and cell culture fluids were also detected. Using the transwell assay, we verified that PGE2 promoted hEM15A migration via the NLRP3/caspase-1 pyroptotic pathway, and PGE2-induced pyroptosis upregulated the expressions of high mobility group box 1 (HMGB1), E-cadherin, and vimentin. Immunohistochemistry analysis confirmed that PGE2-induced pyroptosis contributed to EMS invasion. These results suggest that PGE2-induced pyroptosis affects the progression of EMS by changing the migration ability of pyroptotic cells and upregulating the expression of HMGB1, E-cadherin, and vimentin. Our findings provide crucial evidence for new treatment pathways and use of anti-inflammatory drugs in EMS.

Cobalt Chloride-induced Hypoxia Can Lead SKBR3 and HEK293T Cell Lines toward Epithelial-mesenchymal Transition

Hypoxia is a common characteristic of the tumor microenvironment. In response to hypoxia, expression of the hypoxia-inducible factor (HIF) can lead to activation of downstream molecular events such as epithelial-mesenchymal transition (EMT), invasion, and angiogenesis. In this study, CoCl2 was used to simulate hypoxia in SKBR3 and HEK293T cell lines to investigate whether this treatment can induce hypoxia-associated EMT and invasion in the studied cells. SKBR3 and HEK293T cells were treated with different concentrations of CoCl2 at different exposure times and their viability was analyzed. To confirm successful hypoxia induction, the expression levels of HIF1α and vascular endothelial growth factor A (VEGFA) mRNA were assessed. Additionally, the expression of EMT-associated markers including snail, E-cadherin, N-cadherin, and vimentin, as well as invasion-related genes including matrix metalloproteinase-2 (MMP2) and MMP9 was measured. We found that cell viability in CoCl2-treated cells was concentration-dependent and was not affected at low doses. While the expression of HIF and VEGFA genes was upregulated following hypoxia induction. E-cadherin expression was significantly downregulated in HEK293T cells; while, N-cadherin and snail were upregulated in both cell lines. Moreover, an increment of MMP expression was only observed in SKBR3 cells. Taken together, the findings indicated that CoCl2 can mimic hypoxia in both cell lines, but EMT was triggered in SKBR3 cells more effectively than in HEK293T cells, and invasion was only stimulated in SKBR3 cells. In conclusion, SKBR3 cancer cells can be used as an EMT model to better understand its control and manipulation mechanisms and to investigate new therapeutic targets for the suppression of tumor metastasis.

The Efficacy of Atelocollagen to Inhibit Fibrotic Proliferation in Tenon Tissue: In vitro Study

INTRODUCTION

The aim of the study was to evaluate the safety and efficacy of atelocollagen in preventing the fibrotic change of human tenon tissue induced by transforming growth factor β1 (TGFβ1).

METHODS

Primary cultured human Tenon's fibroblasts (HTFs) were incubated with TGFβ1 alone and with various concentrations of atelocollagen, respectively. Cell viability was measured by Cell Counting Kit-8 (CCK-8). The mRNA levels of α-smooth muscle actin (α-SMA), vimentin, fibronectin, zonular occludens scaffolding protein (ZO-1), cellular communication network factor 2 (CCN2), and interleukin 6 (IL-6) were measured by quantitative reverse transcription polymerase chain reaction, Western blot, and immunofluorescence analysis. Wound healing assay and collagen contraction assay were additionally evaluated for identifying the inhibitory effect of atelocollagen in HTFs. To elucidate the mechanism by which atelocollagen affects HTF proliferation, the phospho-extracellular-signal-regulated kinases (pERK)/total-extracellular-signal-regulated kinases (tERK), phospho-focal adhesion kinase (pFAK)/total-focal adhesion kinase (tFAK), and pSmad3/tSmad3 protein expression ratios were measured by Western blot.

RESULTS

The safety of atelocollagen in HTF was identified by CCK-8 analysis. The expression of α-SMA and vimentin in HTFs treated with 0.023% and 0.046% atelocollagen significantly decreased at both mRNA and protein levels, while that of ZO-1 in 0.046% atelocollagen increased compared with TGFβ1-treated cells. The protein expression of fibronectin, CCN2, and IL-6 in HTFs treated with 0.023% and 0.046% atelocollagen significantly decreased. The immunofluorescence microscopy of α-SMA and ZO-1 showed results similar to those of the Western blot. In the wound-scratch assays, cell migration was significantly attenuated in HTFs treated with 0.005% atelocollagen. Atelocollagen at 0.005, 0.011, and 0.023% significantly inhibited the gel contraction induced by TGFβ1 at both 24 h and 48 h. The increase in pERK/tERK and pSmad3/tSmad3 protein expression ratios in TGFβ1-treated HTFs significantly decreased after treatment with 0.023 and 0.046% atelocollagen.

CONCLUSION

Since atelocollagen gel effectively suppresses the proliferation of HTFs in TGFβ1-induced transdifferentiation, it may be a potential therapeutic agent in glaucoma surgery.

Nickel nanoparticles induce epithelial-mesenchymal transition in human bronchial epithelial cells via the HIF-1α/HDAC3 pathway

We and others have previously demonstrated that exposure to nickel nanoparticles (Nano-Ni) caused fibrogenic and carcinogenic effects; however, the underlying mechanisms are still not fully understood. This study aimed to investigate the effects of Nano-Ni on epithelial-mesenchymal transition (EMT) in human bronchial epithelial cells (BEAS-2B) and its underlying mechanisms since EMT is involved in both cancer pathogenesis and tissue fibrosis. Our results showed that exposure to Nano-Ni, compared to the control Nano-TiO2, caused a remarkable decrease in the expression of E-cadherin and an increase in the expression of vimentin and α-SMA, indicating an inducible role of Nano-Ni in EMT development in human bronchial epithelial cells. HIF-1α nuclear accumulation, HDAC3 upregulation, and decreased histone acetylation were also observed in the cells exposed to Nano-Ni, but not in those exposed to Nano-TiO2. Pretreatment of the cells with a specific HIF-1α inhibitor, CAY10585, or HIF-1α-specific siRNA transfection prior to Nano-Ni exposure resulted in the restoration of E-cadherin and abolished Nano-Ni-induced upregulation of vimentin and α-SMA, suggesting a crucial role of HIF-1α in Nano-Ni-induced EMT development. CAY10585 pretreatment also attenuated the HDAC3 upregulation and increased histone acetylation. Inhibition of HDAC3 with specific siRNA significantly restrained Nano-Ni-induced reduction in histone acetylation and restored EMT-related protein expression to near control levels. In summary, our findings suggest that exposure to Nano-Ni promotes the development of EMT in human bronchial epithelial cells by decreasing histone acetylation through HIF-1α-mediated HDAC3 upregulation. Our findings may provide information for further understanding of the molecular mechanisms of Nano-Ni-induced fibrosis and carcinogenesis.

Forkhead box A2 transcriptionally activates hsa-let-7 g to inhibit hypoxia-induced epithelial-mesenchymal transition by targeting c14orf28 in colorectal cancer

BACKGROUND AND STUDY AIMS

This study aimed to investigate the effect of Forkhead Box A2 (FOXA2) on migration, invasion, and epithelial-mesenchymal transition (EMT) of colorectal cancer (CRC) cells in hypoxia and explore its related molecular mechanisms.

PATIENTS AND METHODS

A cellular hypoxia model was established, and the FOXA2 overexpression vector was transfected into SW480 and HCT116 cells. Cell apoptosis, migration, and invasion were examined by flow cytometry, scratch test, and transwell-invasion assay. Next, the hsa-let-7 g gene expression was detected by quantitative reverse transcription-polymerase chain reaction. Relative protein levels of HIF-1, FOXA2, c14orf28, E-cadherin, N-cadherin, and Vimentin were detected by western blot.

RESULTS

Hypoxia-exposed CRC cells showed a significantly increased cell apoptosis rate, as well as enhanced cell invasion and migration abilities compared with the cells in normoxia. FOXA2 overexpression induced apoptosis and inhibited hypoxia-exposed CRC cell migration and invasion. Additionally, FOXA2 overexpression led to the significantly increased hsa-let-7 g and E-cadherin expression, as well as the decreased c14orf28, N-cadherin, and Vimentin expression in hypoxic CRC cells.

CONCLUSIONS

This study demonstrated that FOXA2 could affect the apoptosis, migration, invasion, and EMT of CRC cells under hypoxia conditions. FOXA2 transcriptionally activates hsa-let-7 g to inhibit hypoxia-induced EMT by targeting c14orf28.

The effect of neuropilin-1 silencing on the transforming growth factor-β1-mediated epithelial-mesenchymal transition of colon cancer SW480 cells and its effect on the proliferation and migration of colon cancer cells

This study aimed to investigate the effect of neuropilin-1 (NRP-1) silencing on epithelial-mesenchymal transformation (EMT) mediated by transforming growth factor-β1 (TGF-β1) and on the proliferation and migration of colon cancer SW480 cells. After transfection of small interfering ribonucleic acid (siRNA)-NRP-1 into colon cancer SW480 cells, the messenger RNA (mRNA) and protein expression levels of NRP-1 were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Four EMT models were induced using 0, 2, 5, and 10 ng/mL TGF-β1, respectively. Cell proliferation was detected using Cell Counting Kit-8, and the protein levels of EMT markers E-cadherin and vimentin were detected using Western blot. EMT was induced in the transfected SW480 cells using TGF-β1, after which four groups were created: a negative control group (siRNA-Ncontrol), a transfection group (siRNA-NRP-1), an induction group (TGF-β1), and a transfection + induction group (siRNA-NRP-1+TGF-β1). Western blot was then used to detect the expression of E-cadherin and vimentin, and cell proliferation and migration were detected using cell counting kit-8 (CCK-8) and scratch assay. After transfection with siRNA-NRP-1, the mRNA and protein expression levels of SW480 cells were significantly decreased (P<0.05). After 48 hours of induction with 10 ng/mL TGF-β1, cell proliferation was obvious, E-cadherin expression decreased, and vimentin expression significantly increased (P<0.05), indicating that EMT had been successfully induced compared with the induction group, the transfection + induction group had significantly increased E-cadherin expression after corresponding treatments (including transfection and induction alone) (P<0.05), and the proliferation and migration of colon cancer cells decreased (P<0.05). In conclusion: silencing, NRP-1 in colon cancer SW480 cells can partially reverse TGF-β1-mediated EMT, reduce the proliferation activity of colon cancer cells, and slow their migration ability. Therefore, NRP-1 may become a new target for the treatment of colon cancer.

Potential therapeutic effects of hAMSCs secretome on Panc1 pancreatic cancer cells through downregulation of SgK269, E-cadherin, vimentin, and snail expression

Pancreatic cancer is one of the leading causes of death from cancer worldwide. The current treatment options for pancreatic cancer are unsuccessful and thereby, finding novel and more effective therapeutic strategies is urgently required. Stem cells-based therapies are currently believed to be a potential promising option in cancer therapy. Herein, we are interested in evaluating the therapeutic effects of human amniotic mesenchymal stromal cells (hAMSCs) secretome on tumor growth suppression and EMT inhibition in Panc1 pancreatic cancer cells using 2D and 3D cell culture models. For this purpose, we employed a co-culture system using 6-well Transwell plates with a pore diameter of 0.4 μm. After 72 h treatment of Panc1 cancer cells with hAMSCs, the expression of c-Src, EGFR, SgK269, E-cadherin, Vimentin, Snail transcriptional factor, Bax, Bcl2, and caspase 3 was analyzed by quantitative real-time PCR (qRT-PCR) and Western blot methods. Our results showed significant reduction in tumor cell growth and motility through downregulation of c-Src, EGFR, SgK269, E-cadherin, Vimentin, and Snail transcriptional factor expression in Panc1 pancreatic cancer cells. The induction of cellular apoptosis was also found. Our finding supports the idea that the secretome from hAMSCS has therapeutic effects on cancer cells.

Chronic Leptin Treatment Induces Epithelial-Mesenchymal Transition in MCF10A Mammary Epithelial Cells

Leptin is a cytokine-like hormone that functions as a link between obesity and breast cancer (BC). Leptin treatment induces Epithelial to Mesenchymal Transition (EMT) in BC cell lines. In non-tumoral breast epithelial MCF10A cells, acute leptin treatment induces partial EMT. However, the effect of chronic leptin treatment on EMT in non-tumorigenic breast cells has not been fully explored. This study aimed to evaluate the effect of chronic leptin treatment on the induction of EMT in MCF10A cells. We found that chronic leptin treatment induces a switch from an epithelial to a mesenchymal morphology, partial loss of E-cadherin and gain of vimentin expression. Immunolocalization experiments showed a partial loss of E-cadherin at cell junctions and increased cytoplasmic localization of vimentin in leptin-treated cells. Moreover, chronic leptin treatment increased collective cell migration and invasion. Furthermore, when cultured in non-adherent conditions leptin treated cells exhibited reduced cell aggregation, increased survival, and decreased apoptosis, which correlates with increased FAK and AKT phosphorylation. Finally, bioinformatic analysis in two publicly available RNAseq datasets from normal breast tissue shows that high levels of leptin mRNA correlate positively with the expression of mesenchymal markers, and negatively with epithelial markers. Thus, our results demonstrate that chronic leptin treatment induces EMT in non-tumorigenic MCF10A cells and suggest that high leptin expression in normal breast tissue may induce EMT and contribute to increased risk of breast cancer.

Exogenous Vimentin Supplementation Transiently Affects Early Steps during HPV16 Pseudovirus Infection

Understanding and modulating the early steps in oncogenic Human Papillomavirus (HPV) infection has great cancer-preventative potential, as this virus is the etiological agent of virtually all cervical cancer cases and is associated with many other anogenital and oropharyngeal cancers. Previous work from our laboratory has identified cell-surface-expressed vimentin as a novel HPV16 pseudovirus (HPV16-PsVs)-binding molecule modulating its infectious potential. To further explore its mode of inhibiting HPV16-PsVs internalisation, we supplemented it with exogenous recombinant human vimentin and show that only the globular form of the molecule (as opposed to the filamentous form) inhibited HPV16-PsVs internalisation in vitro. Further, this inhibitory effect was only transient and not sustained over prolonged incubation times, as demonstrated in vitro and in vivo, possibly due to full-entry molecule engagement by the virions once saturation levels have been reached. The vimentin-mediated delay of HPV16-PsVs internalisation could be narrowed down to affecting multiple steps during the virus’ interaction with the host cell and was found to affect both heparan sulphate proteoglycan (HSPG) binding as well as the subsequent entry receptor complex engagement. Interestingly, decreased pseudovirus internalisation (but not infection) in the presence of vimentin was also demonstrated for oncogenic HPV types 18, 31 and 45. Together, these data demonstrate the potential of vimentin as a modulator of HPV infection which can be used as a tool to study early mechanisms in infectious internalisation. However, further refinement is needed with regard to vimentin’s stabilisation and formulation before its development as an alternative prophylactic means.

The vimentin rod domain blocks P-selectin-P-selectin glycoprotein ligand 1 interactions to attenuate leukocyte adhesion to inflamed endothelium

Acute inflammation begins with leukocyte P-selectin glycoprotein ligand-1 (PSGL-1) binding to P-selectin on inflamed endothelium and platelets. In pathologic conditions, this process may contribute to secondary organ damage, like sepsis-induced liver injury. Therefore, developing novel therapies to attenuate inflammation may be beneficial. We previously reported that recombinant human vimentin (rhVim) binds P-selectin to block leukocyte adhesion to endothelium and platelets. In this study, we used SPOT-peptide arrays to identify the rod domain as the active region within rhVim that interacts with P-selectin. Indeed, recombinant human rod domain of vimentin (rhRod) binds to P-selectin with high affinity, with in silico modeling suggesting that rhRod binds P-selectin at or near the PSGL-1 binding site. Using bio-layer interferometry, rhRod decreases PSGL-1 binding to immobilized P-selectin, corroborating the in silico data. Under parallel-plate flow, rhRod blocks leukocyte adhesion to fibrin(ogen)-captured platelets, P-selectin/Fc-coated channels, and IL-1β/IL-4-co-stimulated human umbilical vein endothelial cells. Finally, using intravital microscopy in endotoxemic C57Bl/6 mice, rhRod co-localizes with P-selectin in the hepatic sinusoids and decreases neutrophil adhesion to hepatic sinusoids. These data suggest a potential role for rhRod in attenuating inflammation through directly blocking P-selectin-PSGL-1 interactions.

[Effect of vimentin on activation of NLRP3 inflammasome in the brain of mice with EV71 infection]

OBJECTIVE

To explore whether vimentin (VIM) mediates the activation of inflammasome in mice with EV71 infection in the central nervous system.

METHODS

Forty VIM knockout mice (VIM^-/-, 3 to 5 days old) were randomly divided into control group and infection group. The infection group was intraperitoneally injected with EV71 (10⁸ TCID₅₀), while the control group was injected with PBS (10 µL); another 40 wild-type mice (WT, 3 to 5 days old) were grouped in the same manner. The general conditions of mice were observed each day. Western blotting, ELISA, and RT-PCR were used to measure the levels of IL-1β and casepase-1 in the brain or cerebrospinal fluid. The pathological changes in the cerebella and brain were observed using immunohistochemistry.

RESULTS

Compared with the control group, the VIM^-/- mice infected with EV71 showed no significant changes in NLRP3, IL-1β or caspase-1 expression. The WT mice infected with EV71 showed obviously increased NLRP3, IL-1β, and caspase-1 expressions in the central nervous system. The neurons of infected VIM^-/- mice exhibited milder cell damage than the those in WT mice.

CONCLUSION

VIM mediates the activation of inflammasome and promotes brain inflammation and neuronal damage in mice with EV71 infection in the central nervous system.

[Transforming growth factor beta1 regulation of epithelial-mesenchymal transition in esophagus squamous cell carcinoma]

OBJECTIVE

To study the functional role of transforming growth factor beta1(TGFbeta1) in the regulation of epithelial-mesenchymal transition (EMT) and the effect of TGFbeta1-ASODN blockage of EMT in esophagus squamous cell carcinoma.

METHODS

Esophageal squamous cell carcinoma cell line EC9706 was transfected with chemically synthesized TGFbeta1-ASODN. RT-PCR, immunohistochemistry and flow cytometry were used to detect the protein and mRNA expressions of TGF-beta1, E-cadherin and vimentin before and after the transfection. Morphological changes were documented and scarification test was used to detect the migration potential of EC9706 before and after the transfection.

RESULTS

After TGFbeta1-ASODN transfection, mRNA (0.25 +/- 0.07) and protein (35.07% +/- 1.42%) expressions of TGFbeta1 in EC9706 were significantly lower than those before transfection (mRNA: 0.43 +/- 0.09; protein: 43.57% +/- 1.77%, chi(2) = 13.847 and chi(2) = 84.120, P < 0.05). The mRNA (0.38 +/- 0.09) and protein (17.13% +/- 1.45%) expressions of E-cadherin were significantly higher than those before transfection (0.22 +/- 0.06; 12.53% +/- 1.31%, chi(2) = 0.160 and chi(2) = 40.008, P < 0.05) and the mRNA (0.73 +/- 0.07) and protein (14.15% +/- 1.46%) expressions of vimentin were significantly lower than those (0.89 +/- 0.09; 17.97% +/- 1.42%) before transfection (chi(2) = 0.160 and chi(2) = 21.103, P < 0.05). Scarification test showed that after transfection, the mobility of EC9706 was significantly inhibited and its migration length (0.45 +/- 0.05) was significantly shorter than that before the transfection (0.81 +/- 0.11, chi(2) = 16.854, P < 0.05).

CONCLUSIONS

TGFbeta1 may contribute to EMT in esophageal squamous cell carcinoma. TGFbeta1-ASODN leads to an over-expression of E-cadherin and a down-regulation of vimentin, along with the morphological alterations and migration inhibition, indicating that a blockage of TGFbeta1 suppresses EMT in esophagus squamous cell carcinoma.

Improvement of Anselme's adhesion model for evaluating human osteoblast response to peptide-grafted titanium surfaces

Investigations on the relationships between the properties of biomaterial surfaces and cell adhesion/proliferation processes have recently gained increasing interest. To describe the behaviour of cells adhering and proliferating over different types of (and/or differently treated) substrates, some mathematical models have been also suggested in literature; these models consider both the dependence of cell adhesion/proliferation over time, and the influence of substrate morphology in allowing (or even hampering) cell attachment. Major developments in the biochemical functionalization of the materials used for the production of endosseous devices have been achieved; the ability of the so-called "biomimetic" surfaces to promote cell adhesion, thus favoring the osseointegration process, is already well acknowledged. The aim of this study was to formulate a mathematical model for osteoblast adhesion, mediated by an adhesion peptide (sequence 351-359 mapped on the Human Vitronectin Protein) covalently grafted to a titanium-based surface. To assure a highly homogenous orientation of the peptide to cells, the "specific functionalization" strategy was properly designed. Enzymatic detachment assays allowed comparing osteoblast behaviour over three differently treated titanium substrates (i.e., oxidized, silanized, and peptide-grafted), thus determining how and how much the bioactive peptide can improve the strength of cell adhesion. The results confirmed the capacity of the peptide to increase cell adhesion and adhesion strength; moreover, the role of the peptide was described by a mathematical equation characterizing cells behaviour.

Humoral immunity to vimentin is associated with cardiac allograft injury in nonhuman primates

Immunity to autologous protein has not previously been described following nonhuman primate cardiac transplant. Native hearts and cardiac allografts from cynomolgus monkeys were assessed by immunohistology for vimentin, a highly conserved intermediate filament protein. IgM and IgG to vimentin were measured in serial sera from untreated (n = 4) or cyclosporine (CsA)-treated (n = 8, 2 with ATG) cardiac allograft recipients, and in groups treated with anti-CD154 antibody with (n = 6) or without ATG (n = 28). IgM or IgG reactive with vimentin was elaborated within 30 days with unmodified acute rejection (3/4) or in CsA-treated animals (5/6). CD154 blockade did not prevent anti-vimentin IgM (14/28) but tended to delay the IgG response during therapy (anti-CD154: 8/28, p = 0.10 vs. CsA; anti-CD154+ATG: 2/6). CAV and alloantibody were seen in 25 of 26 animals with grafts surviving over 30 days, including seven animals without increasing anti-vimentin antibody. Anti-vimentin antibodies and vascular complement deposition were found in rejected hearts. Acute and chronic alloimmunity disrupt modulation of autoreactivity to vimentin through pathways, which are resistant to CsA, but may be partially regulated by CD154.

The autoimmune response to vimentin after renal transplantation in nonhuman primates is immunosuppression dependent

BACKGROUND

Chronic allograft nephropathy (CAN) is a common late complication of kidney transplantation. Antibodies to both human leukocyte antigen and nonhuman leukocyte antigen antigens have been implicated in the development of this condition. Here we investigated the presence of antivimentin antibodies in nonhuman primate recipients of kidney allografts as a possible predictor of CAN and the effects of immunosuppression.

METHODS

Thirty seven rhesus monkeys received a kidney allograft to study the potency of several different immunosuppressive regimens (conventional immunosuppression, n=19, vs. costimulatory blockade, n=18). Monkeys were tested for antivimentin antibody by enzyme-linked immunosorbent assay and for anti-donor antibody by staining donor spleen cells with recipient serum. The appearance of antibodies was correlated with the graft pathology in biopsy and necropsy material.

RESULTS

Antivimentin antibodies were found in 31 of 37 animals, whereas only 15 of 32 animals made anti-donor antibodies. Conventional immunosuppression did not prevent antivimentin antibody formation. Costimulation blockade, in particular blocking CD40 and CD86, significantly delayed or prevented antivimentin antibody formation, but did not prevent CAN. Antivimentin antibodies were not significantly associated with development of CAN.

CONCLUSIONS

We postulate that vimentin acts as an autoantigen after renal transplantation; it elicits an autoimmune response that is not regulated by cyclosporine. This autoimmune response may be part of the complex immunologic events occurring posttransplantation and may contribute to the development of CAN, but cannot be considered as a major cause of CAN because this condition also develops without antivimentin antibodies.

Protein levels of α1-tubulin, protein disulfide isomerase, tropomyosins and vimentin are regulated by the tuberous sclerosis gene products

Tuberous sclerosis (TSC) is an autosomal dominant tumour suppressor gene syndrome affecting about 1 in 6000 individuals. It is characterized by mental retardation and epilepsy. A variety of tumours characteristically occur in different organs of TSC patients. Typically, highly epileptogenic dysplastic lesions (tubers) composed of abnormal shaped neurones can be detected in the cerebral cortex. Two tumour suppressor genes have been shown to be responsible for this disease: TSC1, encoding hamartin, and TSC2, encoding tuberin. In this study we performed a proteomic approach of two-dimensional gel electrophoresis with subsequent mass spectrometrical identification of protein spots after ectopic overexpression of human TSC1 or TSC2. We found the protein levels of alpha1-tubulin, protein disulfide isomerase, tropomyosin 3 and 5 and vimentin to be regulated by the two tuberous sclerosis gene products. The here presented findings suggest that deregulation of the control of these target proteins might contribute to the development of tumours in tuberous sclerosis patients. These data provide important new insights into the molecular development of this disease especially since alpha1-tubulin, protein disulfide isomerase and certain tropomyosins have also been implicated in the regulation of neuronal differentiation.

The N-Terminal Domain of Vimentin Alters Bladder Permeability

PURPOSE

We assessed the effect of the vimentin amino terminal polypeptide (NT1) on barrier function of rabbit bladder epithelium.

MATERIALS AND METHODS

The effect of NT1 on the properties of rabbit bladder epithelium were studied using Ussing chambers and electrophysiological methods.

RESULTS

NT1 increased transepithelial conductance (Gt) in a voltage dependent manner. At a transepithelial voltage (Vt) of -70 mV (serosal solution ground) the addition of NT1 to mucosal solution did not result in a change in Gt. When Vt was clamped to 0 mV, there was a time dependent increase in Gt. The increase in Gt was reversed by clamping Vt back to -70 mV or by removing NT1 from the mucosal bath at 0 mV. The polypeptide acts primarily at the apical membrane with a conductance increase that is concentration dependent. Induced conductance is nonselective for small monovalent cations and anions. The ability of NT1 to increase membrane conductance was decreased in the presence of bath calcium.

CONCLUSIONS

The data suggest that the amino terminus of vimentin can interact with the plasma membrane of bladder epithelium and increase ion permeability in a voltage dependent manner.

Caspase-resistant vimentin suppresses apoptosis after photodynamic treatment with a silicon phthalocyanine in Jurkat cells

Oxidative stress, such as photodynamic therapy, is an apoptosis inducer. Apoptosis, as well as photosensitization, have been associated with disruption of the cytoskeletal network. The purpose of the present study was to assess the role of vimentin, a major cytoskeletal protein, in apoptosis after photodynamic treatment (PDT) with the silicon phthalocyanine Pc 4 in human Jurkat T cells. Here we show for the first time that photosensitization with Pc 4 initiates vimentin cleavage and that this event precedes poly(ADP-ribose) polymerase (PARP) degradation. Similar findings were obtained in the presence of C2-ceramide, an inducer of oxidative stress and apoptosis. In the presence of benzyloxycarbonyl-Val-Ala-Asp(O-methyl)-fluoromethylketone, a pan-caspase inhibitor, Pc 4-PDT-induced vimentin and PARP cleavage were abolished. In Jurkat cells transfected with a caspase-resistant vimentin apoptosis was partly suppressed and delayed post-Pc 4-PDT. We suggest that the full-length vimentin confers resistance to nuclear apoptosis after PDT with Pc 4.

Amino-terminal polypeptides of vimentin are responsible for the changes in nuclear architecture associated with human immunodeficiency virus type 1 protease activity in tissue culture cells

Electron microscopy of human skin fibroblasts syringe-loaded with human immunodeficiency virus type 1 protease (HIV-1 PR) revealed several effects on nuclear architecture. The most dramatic is a change from a spherical nuclear morphology to one with multiple lobes or deep invaginations. The nuclear matrix collapses or remains only as a peripheral rudiment, with individual elements thicker than in control cells. Chromatin organization and distribution is also perturbed. Attempts to identify a major nuclear protein whose cleavage by the protease might be responsible for these alterations were unsuccessful. Similar changes were observed in SW 13 T3 M [vimentin(+)] cells, whereas no changes were observed in SW 13 [vimentin(-)] cells after microinjection of protease. Treatment of SW 13 [vimentin(-)] cells, preinjected with vimentin to establish an intermediate filament network, with HIV-1 PR resulted in alterations in chromatin staining and distribution, but not in nuclear shape. These same changes were produced in SW 13 [vimentin(-)] cells after the injection of a mixture of vimentin peptides, produced by the cleavage of vimentin to completion by HIV-1 PR in vitro. Similar experiments with 16 purified peptides derived from wild-type or mutant vimentin proteins and five synthetic peptides demonstrated that exclusively N-terminal peptides were capable of altering chromatin distribution. Furthermore, two separate regions of the N-terminal head domain are primarily responsible for perturbing nuclear architecture. The ability of HIV-1 to affect nuclear organization via the liberation of vimentin peptides may play an important role in HIV-1-associated cytopathogenesis and carcinogenesis.

Perinuclear localization and insulin responsiveness of GLUT4 requires cytoskeletal integrity in 3T3-L1 adipocytes

The GLUT4 glucose transporter resides mostly in perinuclear membranes in unstimulated 3T3-L1 adipocytes and is acutely translocated to the cell surface in response to insulin. Using a novel method to purify intracellular GLUT4-enriched membranes, we identified by mass spectrometry the intermediate filament protein vimentin and the microtubule protein alpha-tubulin as components of these membranes. Immunoelectron microscopy of the GLUT4-containing membranes also revealed their association with these cytoskeletal proteins. Disruption of intermediate filaments and microtubules in 3T3-L1 adipocytes by microinjection of a vimentin-derived peptide of the helix initiation 1A domain caused marked dispersion of perinuclear GLUT4 to peripheral regions of the cells. Inhibition of the microtubule-based motor dynein by brief cytoplasmic acidification of cultured adipocytes also dispersed perinuclear GLUT4 and inhibited insulin-stimulated GLUT4 translocation to the cell surface. Insulin sensitivity was restored as GLUT4 was again concentrated near the nucleus upon recovery of cells in physiological buffer. These data suggest that GLUT4 trafficking to perinuclear membranes of cultured adipocytes is directed by dynein and is required for optimal GLUT4 regulation by insulin.

The response of distant uninvolved psoriatic skin to standardised injury is not different from that in normal skin

The epidermis of uninvolved psoriatic skin is characterised by a slight hyperproliferation and an increase in inflammatory parameters, whereas no differentiation abnormalities are seen. Data with respect to the response of distant uninvolved psoriatic skin to standardised injury are not uniform. In this study, a recently developed multiparameter flow cytometric assay was used to compare the response to tape stripping of uninvolved psoriatic and normal skin. With this method, a parameter for proliferation, differentiation and inflammation was measured simultaneously. Concerning these parameters, no statistically significant differences were found between uninvolved psoriatic skin and normal skin. The mechanism that underlies hyperproliferation in distant uninvolved psoriatic skin does not indicate an intrinsic abnormality in keratinocytes. Inflammatory signals might play a role in this process.

Assembly properties of amino- and carboxyl-terminally truncated neurofilament NF-H proteins with NF-L and NF-M in the presence and absence of vimentin

To understand the assembly characteristics of the high-molecular-weight neurofilament protein (NF-H), carboxyl- and amino-terminally deleted NF-H proteins were examined by transiently cotransfecting mutant NF-H constructs with the other neurofilament triplet proteins, low- and middle-molecular-weight neurofilament protein (NF-L and NF-M, respectively), in the presence or absence of cytoplasmic vimentin. The results confirm that NF-H can coassemble with vimentin and NF-L but not with NF-M into filamentous networks. Deletions from the amino-terminus show that the N-terminal head is necessary for the coassembly of NF-H with vimentin, NF-L, or NF-M/vimentin. However, headless NF-H or NF-H from which the head and a part of the rod is removed can still incorporate into an NF-L/vimentin network. Deletion of the carboxyl-terminal tail of NF-H shows that this region is not essential for coassembly with vimentin but is important for coassembly with NF-L into an extensive filamentous network. Carboxyl-terminal deletion into the alpha-helical rod results in a dominant-negative mutant, which disrupts all the intermediate filament networks. These results indicate that NF-L is the preferred partner of NF-H over vimentin and NF-M, the head region of NF-H is important for the formation of NF-L/NF-H filaments, and the tail region of NF-H is important to form an extensive network of NF-L/NF-H filaments.

Astrocytes in kindling: relevance to epileptogenesis

Astrogliosis is a prominent feature of epileptic foci, and may play a causal role in the development of seizures and the persistance of seizure disorders. We have studied morphological changes in astrocytes with respect to the evolution of seizures using the kindling model of epilepsy. Kindling-induced seizures result in a prominent hypertrophy of astrocytes that is accompanied by a reorganization of astrocytic cytoskeleton. The change in the morphology of astrocytes appears to be seizure-intensity dependent, occurs early in the kindling process, and persists for weeks following the last seizure. In addition to hypertrophy, we have observed an increase in proliferation of astrocytes in hippocampus, amygdala and piriform cortex, but no change in the expression of connexin-43 following kindling. Significantly, induction of a localized astrocyte hypertrophy prior to initiation of kindling does not result in seizures and does not facilitate kindling. Altogether these data suggest that 'gliosis' is an adaptive response to seizures.

The function of intermediate filaments in cell shape and cytoskeletal integrity

This study describes the development and use of a specific method for disassembling intermediate filament (IF) networks in living cells. It takes advantage of the disruptive effects of mimetic peptides derived from the amino acid sequence of the helix initiation 1A domain of IF protein chains. The results demonstrate that at 1:1 molar ratios, these peptides disassemble vimentin IF into small oligomeric complexes and monomers within 30 min at room temperature in vitro. Upon microinjection into cultured fibroblasts, these same peptides induce the rapid disassembly of IF networks. The disassembly process is accompanied by a dramatic alteration in cell shape and the destabilization of microtubule and actin-stress fiber networks. These changes in cell shape and IF assembly states are reversible. The results are discussed with respect to the roles of IF in cell shape and the maintenance of the integrity and mechanical properties of the cytoplasm, as well as the stability of the other major cytoskeletal systems.

Pathways of glycosphingolipid biosynthesis in SW13 cells in the presence and absence of vimentin intermediate filaments

We reported previously that the incorporation of sugars into glycosphingolipids (GSL) is diminished in SW13 cells that lack a vimentin intermediate filament (IF) network (vim-) compared to vim+ cells. To further analyze the nature of this abnormality, we double-labeled cells with 3H-serine and 14C-sugars. There was no difference between vim+ and vim- cells in the incorporation of serine into GSL, although the usual difference in sugar incorporation was observed. This indicated that the defect in vim- cells was not in the incorporation of sugars into ceramide synthesized de novo by acylation of sphinganine (pathway 1). Sugars can also be incorporated into ceramide synthesized from sphingosine that is derived from catabolism of sphingolipids (pathway 2), and into GSL that recycle through the Golgi apparatus from endosomes (pathway 3). The amount of galactose and glucosamine incorporated into GSL in these three pathways was analyzed by the use of two inhibitors of sphingolipid biosynthesis. beta-Chloroalanine inhibits the de novo synthesis of sphinganine (pathway 1), and fumonisin B1 inhibits the acylation of sphinganine and sphingosine (pathways 1 and 2). We were surprised to observe that in both vim+ and vim- cells only 20-40% of sugar incorporation into GSL took place in pathway 1, and 60-80% of sugar incorporation took place in the recycling pathways. Moreover, in contrast to larger GSL, GlcCer was not synthesized in pathway 3. Our observations indicate that vimentin IF facilitate the recycling of GSL and sphingosine, and that the differences between vim+ and vim- cells are predominantly in pathways 2 and 3. Furthermore, although it is generally believed that virtually all GSL are synthesized in the de novo pathway, these data indicate that the recycling pathways predominate in the incorporation of sugars into GSL in SW13 cells.

Free calcium and calpain I activity

Activation of purified calpain I proceeds through a Ca(2+)-induced autolysis from the 80 kDa catalytic subunit to a 76 kDa form via an intermediate 78 kDa form, and from a 30 kDa form to a 18 kDa form as the result of two autocatalytic processes (intra and intermolecular). The minimum Ca2+ requirements for autolysis and proteolysis have been determined by physico-chemical and electrophoretic methods in the presence or absence of a digestible substrate. According to our results the activation process needs less free Ca2+ than the proteolysis of a digestible substrate, which means that proteolysis is really subsequent to activation. For very low Ca2+ levels, a digestible substrate does not initiate the calpain I activation process. In the presence of phospholipid vesicles, such as PI, PS or a mixture of PI (20%), PS (20%) and PC (60%), the apparent kinetic constants of activation are greatly increased without any change in the initial velocity of the substrate proteolysis. Thus, enzyme activation and substrate proteolysis are observed as independent phenomena. These results obtained from experiments using low free Ca2+ concentrations enable us to propose a hypothesis for the mechanism of regulation by which the enzyme could be activated in the living cell.

Growth-associated gene expression is not constant in cells traversing G-1 after exiting mitosis

Analysis of gene expression following stimulation of growth-arrested cells has been the main approach for identification of growth-associated genes. Since the activation of these gene sequences is dependent on both the stimulatory agent and the state of quiescence of the cell, the activation and role of the same genes may be entirely different in non-growth arrested, actively proliferating cells. We have addressed the question of growth-associated gene expression during active growth by analyzing gene expression during G-1 of cells which have just exited mitosis without first leaving the cell cycle. We were able to isolate, by a non-inductive, drug free system, a population of highly synchronized Swiss 3T3 cells within mitosis (greater than 90%) in numbers sufficient to determine the pattern of expression of a large number of representative growth-associated genes. Our results show that after replating the mitotic cells into conditioned medium: (1) growth-associated gene expression is not constant during G-1 of actively proliferating cells, and (2) while a number of genes (e.g., JE, c-myc, ODC, p53, and histone) exhibited patterns of expression similar to that reported in the quiescent systems, others (e.g., nur-77, vimentin, calcyclin) exhibited patterns which were completely different. From these results, we can begin to construct a temporal map of G-1 progression during active growth.

Properties of erythrocyte membrane binding and autolytic activation of calcium-activated neutral protease

The binding of a calcium-activated neutral protease (CANP) with high calcium sensitivity (muCANP) to erythrocyte membranes and its subsequent autolytic activation on the membranes were analyzed by an immunoblot technique. In the presence of calcium ions, muCANP bound to the erythrocyte membranes as a heterodimer of 79- and 28-kDa subunits and was converted quickly on the membranes to an active form with a 76-kDa large subunit. The active form was then released from the membranes to the soluble fraction. These sequential reactions, however, were not specific to inside-out vesicles, but occurred also, except for some Ca2+-independent binding, on right side-out vesicles. A rapid degradation of some membrane proteins was observed after binding of muCANP to the membranes. The binding of muCANP to erythrocyte membranes was inhibited by substrates and the endogenous CANP inhibitor, which is also a suicide substrate. These results strongly suggest that muCANP binds to membranes by recognition of membrane proteins as substrates and not at a special site for activation. Thus, a possible mechanism for muCANP activation on membranes is that muCANP first binds to substrates on membranes, is activated, and then degrades the substrates to deform the membrane structures.

Effect of parathyroid hormone and forskolin on cytoskeletal protein synthesis in cultured mouse osteoblastic cells

Parathyroid hormone (PTH) has been shown to cause transient cell shape changes in bone cells. We have examined the effects of parathyroid hormone and forskolin on the organization and expression of cytoskeletal proteins in cultured mouse endosteal osteoblastic cells. Analysis of [35S]methionine-labeled cytoskeletal proteins isolated on two-dimensional gel electrophoresis showed that PTH treatment (24 h) stimulated the de novo biosynthesis of actin, vimentin and tubulins in confluent cells, whereas forskolin had a minor effect despite a huge stimulation of cAMP production. This PTH-induced stimulation was associated with cell respreading following a mild and transitory cell retraction. PTH increased the synthesis of monomeric subunits of actin and beta-tubulins in subconfluent bone cells, whereas both monomeric and polymeric levels of beta-tubulins were increased in confluent osteoblasts. Under conditions reducing cell spreading, osteoblastic cells had initially high levels of unpolymerized subunits. In these poorly spread cells, parathyroid hormone or forskolin had no effect on the de novo synthesis of cytoskeletal proteins despite a marked elevation in intracellular cAMP levels. It is concluded that PTH affects the biosynthesis of cytoskeletal proteins in osteoblastic cells and that cAMP production does not seem to be directly involved. In addition, the effect of PTH is modulated by cell spreading and by the initial pool of cytoskeletal subunits.

Binding of two desmin derivatives to the plasma membrane and the nuclear envelope of avian erythrocytes: evidence for a conserved site-specificity in intermediate filament-membrane interactions

Using solution binding assays, we found that a 45-kDa fragment of desmin, lacking 67 residues from the N terminus, could specifically associate with avian erythrocyte nuclear envelopes but not with plasma membranes from the same cells. It was also observed that a 50-kDa desmin peptide, missing 27 C-terminal residues, retained the ability to bind to both membrane preparations. Displacement experiments with an excess of purified vimentin suggested that the two desmin derivatives were interacting with a previously identified vimentin receptor at the nuclear envelope, the protein lamin B [Georgatos, S. & Blobel, G. (1987) J. Cell Biol. 105, 117-127]. Additional analysis by affinity chromatography confirmed this conclusion. Employing an overlay assay, we demonstrated that the 50-kDa fragment, but not the 45-kDa desmin peptide, was capable of interacting with the plasma membrane polypeptide ankyrin (a known vimentin attachment site), as was intact vimentin. Conversely, the nuclear envelope protein lamin B was recognized by both fragments but not by a chymotryptic peptide composed solely of the helical rod domain of desmin. These data imply that the lamin B-binding site on desmin resides within the 21 residues following its helical rod domain, whereas the ankyrin-associating region is localized within its N-terminal head domain, exactly as in the case of vimentin.