Journal of Cellular Immunology
ISSN: 2689-2812

Commentary - Journal of Cellular Immunology (2020) Volume 2, Issue 3

A novel therapeutic strategy for antifibrotic based on a new gene NS5ATP9

Jing Zhao1,2, Jun Cheng1,2,3,*

1Peking University Ditan Teaching Hospital, Beijing 100015, China

2Institiute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University/Beijing Key Laboratory of Emerging Infectious Diseases, Beijing 100015, China

3Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing 100191, China

*Corresponding Author:
Jun Cheng
E-mail: chengj0817@sina.cn

Received date: February 12, 2020; Accepted date: April 07, 2020

Citation: Zhao J, Cheng J. A Novel Therapeutic Strategy for Antifibrotic Based on a New Gene NS5ATP9. J Cell Immunol. 2020; 2(3): 94-101.

Copyright: © 2020 Zhao J, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Abstract

In this article, we introduced a screening of anti-fibrotic drugs focused on new genes. More precisely, we screened and cloned 127 new genes, reporting on a potential target gene and two promising drugs for fibrosis. Among 127 genes, hepatitis C virus nonstructural protein 5A transactivated protein 9 (NS5ATP9), which expression is significantly upregulated by tenofovir disoproxil fumarate (TDF)/tenofovir alafenamide fumarate (TAF), suppresses hepatic stellate cells (HSCs) and HFL1 cells (lung fibroblasts) activation. Therefore, we reported NS5ATP9 as a potential therapeutic target, and TDF/TAF as a new promising therapeutic strategy in fibrosis. These results elucidate mechanisms of disease and translate molecular techniques into clinical treatment.


Discovery of 127 New Genes and the Main Achievements

By the suppression of subtractive hybridization (SSH) and yeast-two hybrid system, 127 new genes were screened, cloned, and registered at GenBank (Table 1) [1,2]. These new genes which were found in the liver have been demonstrated to be closely related to liver diseases such as viral hepatitis, liver fibrosis, fatty liver, and hepatocellular carcinoma (HCC) (Figure 1).

Serial numberGene nameRegistration number (GenBank)
1NS5ATP1AF529362
2NS5ATP2AF529363
3NS5ATP3AF529364
4NS5ATP4AF529365
5NS5ATP5AF529366
6NS5ATP6AF529367
7NS5ATP7AF529368
8NS5ATP8AF529369
9NS5ATP9AF529370
10NS5ATP10AK000514
11NS5ATP11AK091427
12DNAPTP1TPADQ414820
13NS5ATP13AY820769
14NS5BBP1BC020596
15MBP1DQ307498
16XTP1AF488828
17XTP2AF488829
18XTP3AF490252
19XTP4AF490253
20XTP5AF490254
21XTP6AF490255
22XTP7AF490256
23XTP8AF490257
24XTP9AF490258
25XTP10NM_001326303
26X-30AY280722
27C1AY555145
28C2AF530058
29C12AF529371
30E2BP1AY459290
31E2BP2AF529373
32E2BP3DQ294736
33E2BP4AF189768
34EBP1AF529372
35EBP2AF529373
36EBP3AF530058
37EBP4AY134474
38EBP19AF529373
39EBP36AY189820
40HCBP1AF359506
41HCBP6AY032594
42HCBP12AF395068
43HCTP4AY734680
44NS3BPAF435951
45NS3TP1AY116969
46NS3TP2AY116970
47NS3TP6XM_017004595
48PreS1BP1AY535000
49PS2BP1AF497566
50SBP1AY281252
51TAHCCP1AY038359
52TAHCCP2AY039043
53TTP1AF407672
54XBP-1AF529374
55LRRP1AY358788
56PS1TP1AY646229
57PS1TP2AY426673
58PS1TP3AY426674
59PS1TP4AY427952
60PS1TP5TP1ABF61801
61PS1TP6AY444749
62PS2TP1AY561706
63PS2TP2AY561707
64PS2TP3AY561704
65PS2TP4AY561705
66CSTP1AY553877
67PS1TP3BP1DQ910907
68NS5ATP13TP1AY459295
69NS5ATP13TP2AY459296
70HBeAgTPAY423624
71PFAAP1AF530059
72PFAAP2AF530060
73PFAAP3AF530061
74PFAAP4AF530062
75PFAAP5AF530063
76FBP2AY553876
77FBP1AY553875
78NS5ATP5BP1AY459291
79HCTP4BPAY390431
80NS5ATP1BP16AY390430
81NS5ABP37AF543840
82XTP3TPBAY453410
83XTP3TPAAY453409
84DNAPTP1AY450389
85DNAPTP2AY450390
86DNAPTP3AY450391
87DNAPTP4AY450392
88DNAPTP5AY450393
89DNAPTP6AY450394
90PPS22-1AY498718
91NS3TP2TPAY425618
92NS5ATP6TP1AY339614
93NS5ATP6TP2AY339615
94HuALRAF146394
95P7TP3AY820138
96P7TP2AY819648
97AsTP3AY744367
98AsTP2AY744366
99FTP2AY740522
100AsTPAY720898
101AsTP1AY605064
102XTP13AY631401
103NS5ATP4ADQ908899
104NS5ATP4ABP1DQ630520
105PS1TP5AY427953
106XTP3TPATP1DQ457058
107FTP1AY605045
108XTP12AY598792
109PS1TP5BP1DQ471327
110P7TP1AY596776
111NS3TP6BP2AC097504
112NS3TP6BP3AC023785
113TTG1DQ323046
114XTP11AY740520
115DNAPTP1BP1DQ414819
116DNAPTP1TPDQ451688
117HBEBP2BPADQ499597
118HBEBP2BPBDQ499598
119HBEBP2BPCDQ499599
120NS2TPAY605046
121NS4ATP1AY740521
122NS4ATP2AY846876
123TTG1ADQ529299
124PS1TP2BP1DQ787424
125HCBP12BPADQ499468
126XTP3TPATP2DQ457059
127NS3TP6BP1AC124014

Table 1: 127 new genes.

For several decades, our group was committed to studying of these 127 new genes, providing a new research perspective for liver diseases. Hepatitis C virus core protein-binding protein 6 (HCBP6) upregulates sterol regulatory element-binding protein 1c (SREBP1c) expression by binding to the C/EBPβ-binding site in the SREBP1c promoter [3] and then modulating intracellular triglyceride homeostasis [4]. Hepatitis C virus nonstructural protein 5A trans-activated protein 6 (NS5ATP6) regulates the intracellular triglyceride level via fibroblast growth factor 21 (FGF21), and independently of sirtuin1 (SIRT1) and SREBP1 [5]. HCV promotes the profibrogenic effect of HCV NS5A-transactivated protein 13 (NS5ATP13), by transforming growth factor β1/Sekelsky mothers against decapentaplegic homolog 3 (TGFβ1/Smad3) and nuclear factor κB (NF-κB) signal pathways. Moreover, as a pro-fibrogenic factor, NS5ATP13 expression is down-regulated by CX-4945, a CK2 specific inhibitor [6]. Besides, NS5ATP13 promotes the proliferation and migration of HepG2 cells (human hepatoblastoma HepG2 cell line). Also, oxymatrine (OMT) may inhibit liver cancer progression by downregulating NS5ATP13 expression [7]. Hepatitis C virus nonstructural protein 5A-associated binding protein 37 (NS5ABP37) inhibits cancer cell proliferation and promotes its apoptosis, by altering SREBP-dependent lipogenesis and cholesterogenesis and inducing oxidative stress and endoplasmic reticulum stress [8]. In HCC, hepatitis B virus X Ag-transactivated protein 8 (XTP8) acts as a valuable prognostic predictor by forming a positive feedback loop with FOXM1 oncogene [9]. Hepatitis C virus p7 trans-regulated protein 3 (p7TP3), the direct target gene of miR-182-5p, inhibits HCC by suppressing migration, invasion, adhesion, proliferation and cell cycle progression of liver cancer cell via Wnt/β- catenin signaling pathway, which suggests that p7TP3 might be a new promising tumor suppressor [10]. HBX protein trans-activate gene (XTP4) suppresses apoptosis of HepG2 by up-regulating Bcl-2 and Bax expression [11], and promotes the migration and invasion of HepG2 via regulation of epithelial-mesenchymal transition (EMT) related molecules E-cadherin and N-cadherin [12]. HBV PS1 trans-activator protein 2 (PS1TP2) inhibits apoptosis of HepG2 via the mitochondrial pathway, and promotes proliferation via adenosine 5-monophosphate-activated protein kinase (AMPK) pathway [13]. Besides, NS5ATP9 is a new gene that has been widely recognized in various fields over recent years.

For several decades, our group was committed to studying of these 127 new genes, providing a new research perspective for liver diseases. Hepatitis C virus core protein-binding protein 6 (HCBP6) upregulates sterol regulatory element-binding protein 1c (SREBP1c) expression by binding to the C/EBPβ-binding site in the SREBP1c promoter [3] and then modulating intracellular triglyceride homeostasis [4]. Hepatitis C virus nonstructural protein 5A trans-activated protein 6 (NS5ATP6) regulates the intracellular triglyceride level via fibroblast growth factor 21 (FGF21), and independently of sirtuin1 (SIRT1) and SREBP1 [5]. HCV promotes the profibrogenic effect of HCV NS5A-transactivated protein 13 (NS5ATP13), by transforming growth factor β1/Sekelsky mothers against decapentaplegic homolog 3 (TGFβ1/Smad3) and nuclear factor κB (NF-κB) signal pathways. Moreover, as a pro-fibrogenic factor, NS5ATP13 expression is down-regulated by CX-4945, a CK2 specific inhibitor [6]. Besides, NS5ATP13 promotes the proliferation and migration of HepG2 cells (human hepatoblastoma HepG2 cell line). Also, oxymatrine (OMT) may inhibit liver cancer progression by downregulating NS5ATP13 expression [7]. Hepatitis C virus nonstructural protein 5A-associated binding protein 37 (NS5ABP37) inhibits cancer cell proliferation and promotes its apoptosis, by altering SREBP-dependent lipogenesis and cholesterogenesis and inducing oxidative stress and endoplasmic reticulum stress [8]. In HCC, hepatitis B virus X Ag-transactivated protein 8 (XTP8) acts as a valuable prognostic predictor by forming a positive feedback loop with FOXM1 oncogene [9]. Hepatitis C virus p7 trans-regulated protein 3 (p7TP3), the direct target gene of miR-182-5p, inhibits HCC by suppressing migration, invasion, adhesion, proliferation and cell cycle progression of liver cancer cell via Wnt/β- catenin signaling pathway, which suggests that p7TP3 might be a new promising tumor suppressor [10]. HBX protein trans-activate gene (XTP4) suppresses apoptosis of HepG2 by up-regulating Bcl-2 and Bax expression [11], and promotes the migration and invasion of HepG2 via regulation of epithelial-mesenchymal transition (EMT) related molecules E-cadherin and N-cadherin [12]. HBV PS1 trans-activator protein 2 (PS1TP2) inhibits apoptosis of HepG2 via the mitochondrial pathway, and promotes proliferation via adenosine 5-monophosphate-activated protein kinase (AMPK) pathway [13]. Besides, NS5ATP9 is a new gene that has been widely recognized in various fields over recent years.

NS5ATP9

NS5ATP9 genomic DNA, which is located on human chromosome 15q22.1, encodes a protein with 111 amino acid residues [14]. It is also known as KIAA0101, OEACT-1, P15PAF, L5, PCNA-associated factor (PAF), and is registered in GenBank under the AF529370 registration number. NS5ATP9 participates in many physiological functions, such as cartilage formation [15], DNA damage repair [16], cell cycle regulation [17], the maturation and development of hematopoietic stem/progenitor cells [18], and so on. In addition, different kinds of tumor development are associated with uncontrolled expression of NS5ATP9, including HCC [19], breast cancer [20], thyroid carcinoma [21], and non-small cell lung cancer [22].

Endogenous NS5ATP9 expression is overexpressed in CCl4-induced liver fibrosis mouse models and TGFβ1- treated hepatic stellate cells (HSCs) [23]. In LX2 cells (human HSC cell line), NS5ATP9 directly binds to Smad3 and inhibits its phosphorylation, which induces [24]. Besides, compared with wild type mice, NS5ATP9 the suppression of the TGFβ1/Smad3 signal pathway deficiency results in significantly higher levels of ECM deposition, indicating that NS5ATP9 attenuates liver fibrosis in vivo and in vitro [23]. In lung fibroblasts, NS5ATP9 suppresses its activation via the TGFβ1/ Smad3 signal pathway [25]. These studies confirmed that NS5ATP9 inhibits liver fibrosis and lung fibrosis.

Drugs Screening

Given that NS5ATP9 is a potential therapeutic target for liver fibrosis and lung fibrosis, drugs or small molecule compounds targeted at NS5ATP9 are expected to treat fibrosis. In primary vaginal epithelial cells, expression of NS5ATP9 in mRNA level is up-regulated after cells are stimulated by TDF for 1 or 7 days [26]. Therefore, we hypothesized that TDF and its pro-drug, TAF, may promote regression of fibrosis via up-regulated NS5ATP9.

In vivo, TAF inhibits both CCl4-induced liver fibrosis and bleomycin-induced pulmonary fibrosis, while TAF inhibits activation of HSCs and lung fibroblasts in vitro [23,25]. Previous studies have also shown that TDF/ TAF inhibit liver fibrosis by inhibiting TGFβ1/Smad3 and NF-κB/NLRP3 inflammasome signaling pathways activation and regulating the differentiation, activation, and proliferation of HSCs [23].

Consistent with previous findings [14], TDF/TAF upregulate NS5ATP9 expression both in the liver and in the lung. By using dual-luciferase reporter assays, we showed that NS5ATP9 promoter activity was upregulated by TDF and TAF. Therefore, TDF/TAF could prevent progression and promote the reversion of fibrosis by upregulating the expression of NS5ATP9.

Conclusions and Perspectives

In summary, our study proposed a novel role of TDF/ TAF in fibrosis progression through assembling TGFβ1/ Smad3 and NF-κB/NLRP3 inflammasome signaling pathways via upregulating the expression of NS5ATP9, thus defining NS5ATP9 as a potential therapeutic target and TDF/TAF as novel drugs for fibrosis.

Challenges

Fibrosis is defined as the accumulation of extracellular matrix (ECM) in specific organs. TDF/TAF inhibits liver fibrosis and lung fibrosis in mouse models. However, to elucidate the role of TDF/TAF in clinic, we asked the following questions: 1. Do the results from mouse experiments translate to human liver fibrosis and lung fibrosis? So results in a large, prospective, double-blind study are needed [27]. 2. Do TDF and TAF inhibit fibrosis in other organs or fibrosis due to other causes, such as bile duct ligation (BDL)-induced liver fibrosis [28]? 3. When used to treat different organ fibrosis, what is the optimal time and dosages of TDF/TAF? This means that the pharmacokinetics of TDF and TAF in liver fibrosis are indispensable [29]. 4. New insight into liver fibrosis therapy is that the intercellular crosstalk between HSCs and those “responded” cells (such as hepatic macrophages and natural killer/natural killer T cells) has been a critical event involved in HSC activation and fibrogenesis [30]. We propose that TDF and TAF inhibit NF-κB/NLRP3 inflammasome in mice [17]. However, how TDF and TAF affect the inflammation and immune system is not completely solved.

Opportunities

Compared with other novel treatment strategies, such as low-energy extracorporeal shock waves [31], hyperbranched lipoid-based lipid nanoparticles [32], acetyl-CoA carboxylase [33], as marketed drugs, adverse reactions to TDF/TAF can be effectively followed up with broad physician support, and an adequate number of patients. In addition, the cooperation of multiple clinical departments could fill the gap related to TDF/TAF in the treatment of fibrosis affecting other organs.

Acknowledgments

This study was supported by the National Key Research and Development Program of China (No. 2017YFC0908100/2017YFC0908104), the National Natural Science Foundation of China (No. 81670547), the Beijing Municipal Administration of Hospitals (XMLX201711 to JC), the Beijing Municipal Administration of Hospitals’ Ascent Plan (DFL20151701), and the National Science and Technology Major Project (No. 2015ZX10004801-001-002, No. 2017ZX10302201- 005-004 and No. 2017ZX10202202-005-008). Support was also provided by the Program of Beijing Advanced Innovation Center for Big Data-Based Precision Medicine and the Beijing Key Laboratory of Emerging Infectious Diseases, Beijing, China.

References