The p27 protein plays a critical role in cell cycle arrest. Our previous studies have demonstrated that recombinant P40 protein from Schistosoma japonicum (rSjP40) could induce G1 phase arrest of cell cycle. We, therefore, attempted to observe the effect of rSjP40 on p27 promoter activity in LX-2 cells and to explore its potential mechanisms in this study. Using both Western blot and dual-luciferase reporter assay, we demonstrated that rSjP40 could enhance the expression of p27 in LX-2 cells. Results obtained using truncated fragments of p27 promoter showed that rSjP40 increased p27 promoter activity in LX-2 cells, mainly via some transcription factors that bind to the -1740/-873 region of p27 promoter. Further studies confirmed that the enhancement of p27 promoter activity induced by rSjP40 was related to E2F1 in LX-2 cells. Transfection of siRNA of E2F1 could also restore the effect of rSjP40 on expression of p27 and partially on α-SMA. Therefore, our study provided further insights into the mechanism by which rSjP40 induces LX-2 cell cycle arrest at G1 phase and inhibits HSC activation. Our results provide basis for future study of the blocking effect of rSjP40 in liver fibrosis.

Schistosomiasis is characterized by egg deposition, granulomatous inflammatory reaction and then subsequent hepatic fibrosis formation. Activated HSCs are regarded as the main effector cells in the progression of liver fibrosis and induction of senescence in hepatic stellate cells (HSCs) is vital to the reversion of hepatic fibrosis. Our previous work has showed that S. japonicum egg antigen p40 (Sjp40) could promote HSCs senescence via a STAT3/p53/p21 mechanism. In this paper, the major aim was to explore whether there are other signaling pathways in the process of Sjp40-induced HSCs aging and the underlying effect of SKP2/P27 signal pathway in this procedure. We observed the Sjp40-induced decrease of α-SMA and the senescence of LX-2 cells, and Sjp40 could upregulate P27 and downregulate the protein level of SKP2. The senescence induced by Sjp40 might be reversed in LX-2 cells that treated with P27-specific siRNA or with SKP2-special over-expression plasmid. In addition, we also demonstrated that the decreased expression of P-Rb and α-SMA induced by Sjp40 were partly restored by SKP2-overexpression. These data suggest that Sjp40 might inhibit HSCs activation by promoting cellular senescence via SKP2/P27 signaling pathway, which put forward novel mechanism in the treatment of liver fibrosis.

In the process of hepatic fibrosis, hepatic stellate cells (HSCs) can be activated by many inflammatory cytokines. The transforming growth factor-β1 (TGF-β1) is one of the main profibrogenic mediators. Recently, some studies have also shown that microRNAs (miRNAs) play essential roles in the progress of liver fibrosis by being involved in the differentiation, fat metabolism and ECM production of HSCs.

Activation of hepatic stellate cells is the dominant pathogenic event during the process of liver fibrosis. Bone morphogenic protein (BMP)-7 has recently been identified as an anti-fibrotic factor and leads to phosphorylation of Smad1/5/8 in activated hepatic stellate cells. Its expression can be upregulated by the transcriptional activator, Y-Box protein-1 (YB1). Previous studies have found that the recombinant Schistosoma japonicum protein p40 (rSjp40) can inhibit the activation of hepatic stellate cells, and based on this evidence we attempted to investigate whether or not BMP-7 is involved in rSjp40's inhibition.

YB1 is a negative regulator in liver fibrosis. We wondered whether SJYB1, a homologous protein of YB1 from Schistosoma japonicum, has an effect on liver fibrosis in vitro. Recombinant SJYB1 (rSJYB1) protein was expressed in a bacterial system and purified by Ni-NTA His·Bind Resin. A human hepatic stellate cell line, the LX-2 cell line, was cultured and treated with rSJYB1. The role of rSJYB1 on LX-2 cells was then analysed by Western blot and luciferase assay. We succeeded in expressing and purifying SJYB1 in a bacterial system and the purified rSJYB1 could be recognized by S japonicum-infected rabbit sera. Western bolt analysis showed that rSJYB1 inhibited the expression of collagen type I, but had little effect on α-smooth muscle actin (α-SMA). Further analysis revealed that rSJYB1 inhibited the activity of collagen α1 (I) (COL1A1) promoter and functioned at -1592/-1176 region of COL1A1 promoter. Our data demonstrate that rSJYB1-mediated anti-fibrotic activity involves inhibiting the activity of COL1A1 promoter and subsequently suppressing the expression of collagen type I in hepatic stellate cells.

Liver fibrosis was viewed as a reversible process. The activation of hepatic stellate cells (HSCs) is a key event in the process of liver fibrosis. The induction of senescence of HSCs would accelerate the clearance of the activated HSCs. Previously, we demonstrated that soluble egg antigens (SEA) of Schistosoma japonicum promoted the senescence of HSCs via STAT3/P53/P21 pathway. In this paper, our study was aimed to explore whether there are other signaling pathways in the process of SEA-induced HSCs aging and the underlying effect of SKP2/P27 signal on senescent HSCs.

Liver fibrosis is characterized by the activation of hepatic stellate cells (HSCs). Recent findings suggest that senescence of activated HSCs might limit the development of liver fibrosis. Based on previously observed anti-fibrotic effects of soluble egg antigens from Schistosoma japonicum in vitro, we hypothesized that SEA might play a crucial role in alleviating liver fibrosis through promoting senescence of activated HSCs. We show here that SEA inhibited expression of α-SMA and pro-collagen I and promoted senescence of activated HSCs in vitro. In addition, SEA induced an increased expression of P-p53 and p21. Knockdown of p53 inhibited the expression of p21 and failed to induce senescence of activated-HSCs. Phosphorylated STAT3 was elevated upon SEA stimulation, while loss of STAT3 decreased the level of p53 and senescence of HSCs. Results from immunoprecipitation analysis demonstrated that SOCS3 might be involved in the SEA-induced senescence in HSCs through its interaction with p53. This study demonstrates the potential capacity of SEA in restricting liver fibrosis through promoting senescence in HSCs. Furthermore, a novel STAT3-p53-p21 pathway might participate in the observed SEA-mediated senescence of HSCs. Our results suggest that SEA might carry potential therapeutic effects of restraining liver fibrosis through promoting senescence.

Liver fibrosis is a serious disease that is characterized by the excess deposition of extracellular matrix (ECM) components. Activated hepatic stellate cells (HSCs) are a major source of ECM and serve as a key regulator in liver fibrogenesis. Inactivation of HSCs is essential for liver fibrotic regression. The present study explores the underlying mechanisms of Schistosoma japonicum egg antigen p40 (Sjp40) promoting senescence in HSCs and antifibrosis. For the first time we report that Sjp40 inhibits the activation and proliferation of an immortalized human HSC line (LX-2 cells) and promotes cellular senescence and cell cycle arrest. Sjp40 through action on the STAT3/p53/p21 pathway triggered cellular senescence, while knockdown of p53 or STAT3 partly restored cell senescence. In addition, Sjp40-induced cellular senescence caused LX-2 cells to be more sensitive to a human NK cell line (YT cells). Together these findings provide novel insights into the mechanism of antifibrosis and may have implications for the development of antifibrosis therapies.

Activation of hepatic stellate cells (HSCs) is the central event of the evolution of hepatic fibrosis. Schistosomiasis is one of the pathogenic factors which could induce hepatic fibrosis. Previous studies have shown that recombinant Schistosoma japonicum egg antigen P40 (rSjP40) can inhibit the activation and proliferation of HSCs. MicroRNA-155 is one of the multifunctional noncoding RNA, which is involved in a series of important biological processes including cell development, proliferation, differentiation and apoptosis. Here, we try to observe the role of microRNA-155 in rSjP40-inhibited HSC activation and explore its potential mechanisms. We found that microRNA-155 was raised in rSjP40-treated HSCs, and further studies have shown that rSjP40 enhanced microRNA-155 expression by inhibiting STAT5 transcription. Up-regulated microRNA-155 can down-regulate the expression of FOXO3a and then participate in rSjP40-inhibited expression of α-smooth muscle actin (α-SMA) and collagen I. Furthermore, we observed microRNA-155 inhibitor could partially restore the down-regulation of FOXO3a, α-SMA and collagen I expression in LX-2 cells induced by rSjP40. Therefore, our research provides further insight into the mechanism by which rSjP40 could inhibit HSC activation via miR-155.

The induction of hepatic stellate cell (HSC) apoptosis has potential as a potent strategy to diminish the progression of liver fibrosis. Previous studies have demonstrated the ability of soluble egg antigens (SEA) from schistosomes to inhibit HSC activation and to induce apoptosis in vitro. In this study, we aimed to explore the mechanism of SEA-induced apoptosis in HSCs.

The activation of hepatic stellate cells (HSCs) is a key event in schistosome-induced liver fibrosis. Previous studies have shown that soluble egg antigens and the recombinant P40 protein from Schistosoma japonicum eggs inhibit HSC activation. In the present study, we observed the direct effect of the S. japonicum recombinant (r)SjE16 protein on HSCs.

Apoptosis-related protein in the TGF-β signaling pathway (ARTS) is an unusual mitochondrial Septin-like protein which functions as a tumor suppressor. There are various splice variants derived from the human Septin4 gene, one of which is ARTS, also known as Septin4_i2. Unlike other Septin4 members, ARTS can induce apoptosis in many cells, however, the underlying molecular mechanism for the transcriptional regulation of ARTS has yet to be deciphered. In this study, we attempted to analyze the promoter region of ARTS in cultured HEK-293T and LX-2 cells with the purpose of elucidating the underlying transcriptional mechanisms driving ARTS expression. We effectively demonstrated that the -824 to -5 bp region of the ARTS promoter was essential for ARTS transcription and identified four putative specificity protein 1 (Sp1) binding sites within this core promoter region. ChIP analysis showed that Sp1 protein could bind to two of these sites (-735/-718 and -173/-157) and mutation of each Sp1 binding site led to a significant decrease in ARTS promoter activity. In conclusion, all the results indicated that the Sp1 transcription factor could contribute to ARTS gene transcription. The underlying molecular events of the specific promoter of ARTS could also be used to explain why ARTS is selectively silenced during some human diseases. This would provide basis for further study on the function of ARTS on cell apoptosis.

Liver fibrosis is a severe disease characterized by excessive deposition of extracellular matrix (ECM) components in the liver. Activated hepatic stellate cells (HSCs) are a major source of ECM and a key regulator of liver fibrosis. Collagen type I alpha I (COL1A1) is one of the main components of ECM and is a major component in fibrotic tissues. Previously, we demonstrated that soluble egg antigen from Schistosoma japonicum could inhibit the expression of COL1A1 in activated HSCs. In addition, studies have found that Ets proto-oncogene 1 (Ets-1) suppresses the production of ECM by down-regulating matrix related genes such as COL1A1 induced by transforming growth factor β, and ultimately inhibits liver fibrosis. In this study, the major aim was to investigate the effect and mechanism of Ets-1 on inhibiting COL1A1 gene promoter activity in HSCs by recombinant Schistosoma japonicum protein P40 (rSjP40). We observed the rSjP40 inhibited the expression of COL1A1 by inhibiting the activity of the COL1A1 promoter, and the core region of rSjP40 acting on COL1A1 promoter was located at -1,722/-1,592. In addition, we also demonstrated that rSjP40 could promote the expression of Ets-1, and Ets-1 has a negative regulation effect on the COL1A1 promoter in human LX-2 cells. These data suggest that rSjP40 might inhibit the activity of COL1A1 promoter and inhibit the activation of HSCs by increasing the expression of transcription factor Ets-1, which will provide a new experimental basis for the prevention and treatment of liver fibrosis.