Avian leukosis virus subgroup J promotes cell proliferation and cell cycle progression through miR-221 by targeting CDKN1B

PMAIP1 promotes J subgroup avian leukosis virus replication by regulating mitochondrial function

Avian leukosis virus Subgroup J (ALV-J) exhibits high morbidity and pathogenicity, affecting approximately 20% of poultry farms. It induces neoplastic diseases and immunosuppression. Phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1), a proapoptotic mitochondrial protein in the B-cell lymphoma-2 (Bcl-2) family, plays a role in apoptosis in cancer cells. However, the connection between the PMAIP1 gene and ALV-J pathogenicity remains unexplored. This study investigates the potential impact of the PMAIP1 gene on ALV-J replication and its regulatory mechanisms. Initially, we examined PMAIP1 expression using quantitative real-time PCR (qRT-PCR) in vitro and in vivo. Furthermore, we manipulated PMAIP1 expression in chicken fibroblast cells (DF-1) and assessed its effects on ALV-J infection through qRT-PCR, immunofluorescence assay (IFA), and western blotting (WB). Our findings reveal a significant down-regulation of PMAIP1 in the spleen, lung, and kidney, coupled with an up-regulation in the bursa and liver of ALV-J infected chickens compared to uninfected ones. Additionally, DF-1 cells infected with ALV-J displayed a notable up-regulation of PMAIP1 at 6, 12, 24, 48, 74, and 108 h. Over-expression of PMAIP1 enhanced ALV-J replication, interferon expression, and proinflammatory factors. Conversely, interference led to contrasting results. Furthermore, we observed that PMAIP1 promotes virus replication by modulating mitochondrial function. In conclusion, the PMAIP1 gene facilitates virus replication by regulating mitochondrial function, thereby enriching our understanding of mitochondria-related genes and their involvement in ALV-J infection, offering valuable insights for avian leukosis disease resistance strategies.

A pan-cancer analysis for the oncogenic role of cyclin-dependent kinase inhibitor 1B in human cancers

BACKGROUND

Human health and life are threatened by cancer with high morbidity and mortality worldwide. In many experiments, CDKN1B level is associated with cancer risk, Nevertheless, no pan-cancer analysis has been conducted on CDKN1B in human cancers.

METHODS

With the help of bioinformatics, a pan-cancer analysis was conducted on the expression levels of CDKN1B in cancer tissues and adjacent tissues from the TCGA, CPTAC and GEO databases. The CDKN1B expression levels in tumor patients was further validated using immunohistochemistry (IHC) and quantitative real-time PCR.

RESULTS

In the study, we first investigated the cancer-related roles of CDKN1B's in 40 tumors with malignancy. The CDKN1B gene encodes the p27^Kip1 protein, which can block the production cyclin-dependent kinase (CDK), which is obviously related to the function and survival of cancer cells and alters the prognosis of cancer patients. Furthermore, CDKN1B function requires both protein processing and RNA metabolism. Additionally, the elevated expression of the CDKN1B gene and protein was validated in several cancer tissues from the patients.

CONCLUSIONS

These results showed that the levels of CDKN1B were considerably different in a number of cancer tissues, offering a potential future target for cancer therapy.

J Subgroup Avian Leukosis Virus Strain Promotes Cell Proliferation by Negatively Regulating 14-3-3σ Expressions in Chicken Fibroblast Cells

This study focuses on clarifying the regulation of chicken 14-3-3σ protein on the fibrous histiocyte proliferation caused by ALV-J-SD1005 strain infection. DF-1 cells were inoculated with 10² TCID₅₀ of ALV-J-SD1005 strain; the cell proliferation viability was dramatically increased and 14-3-3σ expressions were dramatically decreased within 48 h after inoculation. Chicken 14-3-3σ over-expression could significantly decrease the cell proliferation and the ratio of S-phase cells, but increase the ratio of G2/M-phase cells in ALV-J-infected DF-1 cells; by contrast, chicken 14-3-3σ knockdown expression could cause the opposite effects. Additionally, chicken 14-3-3σ over-expression could also dramatically down-regulate the expressions of CDK2/CDC2, but up-regulate p53 expressions in the DF-1 cells; in contrast, the knockdown expression could significantly increase the expressions of CDK2/CDC2 and decrease p53 expressions. It can be concluded that chicken 14-3-3σ can inhibit cell proliferation and cell cycle by regulating CDK2/CDC2/p53 expressions in ALV-J-infected DF1 cells. ALV-J-SD1005 strain can promote cell proliferation by reducing 14-3-3σ expressions. This study helps to clarify the forming mechanism of acute fibrosarcoma induced by ALV-J infection.

Avian Leucosis Virus-Host Interaction: The Involvement of Host Factors in Viral Replication

Avian leukosis virus (ALV) causes various diseases associated with tumor formation and decreased fertility. Moreover, ALV induces severe immunosuppression, increasing susceptibility to other microbial infections and the risk of failure in subsequent vaccination against other diseases. There is growing evidence showing the interaction between ALV and the host. In this review, we will survey the present knowledge of the involvement of host factors in the important molecular events during ALV infection and discuss the futuristic perspectives from this angle.

gga-miR-200b-3p promotes avian leukosis virus subgroup J replication via targeting dual-specificity phosphatase 1

MicroRNAs (miRNAs) involved host-virus interaction, affecting the replication or pathogenesis of several viruses. Although avian leukosis virus subgroup J (ALV-J) has been one of the most studied avian viruses, the effects of various host miRNAs on ALV-J infection and its underlying molecular mechanisms are still unclear. Here, we reported that gga-miR-200b-3p acts as a positive host factor enhancing ALV-J replication. We found that gga-miR-200b-3p was increased in response to ALV-J infection in host cells, and that gga-miR-200b-3p effectively enhanced ALV-J replication via targeting host protein dual-specificity phosphatase 1 (DUSP1). Collectively, these findings highlight a crucial role of gga-miR-200b-3p in ALV-J replication.

DF-1 cells prevent MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis

Mycoplasma gallisepticum (MG) is a major poultry pathogen that can induce Chronic Respiratory Disease (CRD) in chickens, causing serious economic losses in the poultry industry worldwide. Increasing evidence suggests that microRNAs (miRNAs) act as a vital role in resisting microbial pathogenesis and maintaining cellular mechanism. Our previous miRNAs sequencing data showed gga-miR-24-3p expression level was significantly increased in MG-infected chicken lungs. The aim of this study is to reveal the cellular mechanism behind the MG-HS infection. We found that gga-miR-24-3p was significantly upregulated and Ras-related protein-B (RAP1B) was downregulated in chicken fibroblast cells (DF-1) with MG infection. Dual luciferase reporting assay and rescue assay confirmed that RAP1B was the target gene of gga-miR-24-3p. Meanwhile, overexpressed gga-miR-24-3p increased the levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), and significantly inhibited cell proliferation as well as promoted MG-infected DF-1 cell apoptosis, whereas inhibition of gga-miR-24-3p had the opposite effect. More importantly, the results of overexpression and knockdown of target gene RAP1B demonstrated that the presence of RAP1B promoted cell proliferation and it saved the reduced or increased cell proliferation caused by overexpression or inhibition of gga-miR-24-3p. Furthermore, the overexpression of gga-miR-24-3p could significantly inhibit the expression of MG-HS adhesion protein. Taken together, these findings demonstrate that DF-1 cells can resist MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis, which provides a new mechanism of resistance to MG infection in vitro.

Mutual regulation between chicken telomerase reverse transcriptase and the Wnt/β-catenin signalling pathway inhibits apoptosis and promotes the replication of ALV-J in LMH cells

This study aimed to explore the mutual regulation between chicken telomerase reverse transcriptase (chTERT) and the Wnt/β-catenin signalling pathway and its effects on cell growth and avian leukosis virus subgroup J (ALV-J) replication in LMH cells. First, LMH cells stably overexpressing the chTERT gene (LMH-chTERT cells) and corresponding control cells (LMH-NC cells) were successfully constructed with a lentiviral vector expression system. The results showed that chTERT upregulated the expression of β-catenin, Cyclin D1, TCF4 and c-Myc. chTERT expression level and telomerase activity were increased when cells were treated with LiCl. When the cells were treated with ICG001 or IWP-2, the activity of the Wnt/β-catenin signalling pathway was significantly inhibited, and chTERT expression and telomerase activity were also inhibited. However, when the β-catenin gene was knocked down by small interfering RNA (siRNA), the changes in chTERT expression and telomerase activity were consistent with those in cells treated with ICG001 or IWP-2. These results indicated that chTERT and the Wnt/β-catenin signalling pathway can be mutually regulated. Subsequently, we found that chTERT not only shortened the cell cycle to promote proliferation but also inhibited apoptosis by downregulating the expression of Caspase 3, Caspase 9 and BAX; upregulating BCL-2 and BCL-X expression; and promoting autophagy. Moreover, chTERT significantly enhanced the migration ability of LMH cells, upregulated the protein and mRNA expression of ALV-J and increased the virus titre. ALV-J replication promoted chTERT expression and telomerase activity.

gga-miR-148a-5p-Targeting PDPK1 Inhibits Proliferation and Cell Cycle Progression of Avain Leukosis Virus Subgroup J (ALV-J)-Infected Cells

Avian leukosis virus subgroup J disease (ALV-J) is a contagious and immunosuppressive avian disease caused by ALV-J virus. Although miRNA participate in various biological processes of tumors, little is known about the potential role of miRNA in ALV-J. Our previous miRNA and RNA sequencing data showed that the expression of gga-miR-148a-5p was significantly different in ALV-J-infected chicken spleens compared with non-infected chickens. The aim of this study was to investigate the functional roles of gga-miR-148a-5p and identify downstream targets regulated by gga-miR-148a-5p in ALV-J-infected chickens. We found that the expression of gga-miR-148a-5p was significantly downregulated during ALV-J infection of chicken embryo fibroblasts (CEF). Dual luciferase reporter assays demonstrated that PDPK1 is a direct target gene of gga-miR-148a-5p. In vitro, overexpression of gga-miR-148a-5p significantly promoted ALV-J-infected CEF cell proliferation, included cell cycle, whereas inhibition of gga-miR-148a-5p had an opposite effect. Inhibition of PDPK1 promoted the proliferation of ALV-J-infected cells but had no effect on the activity of NF-κB. Together, these results suggested that gga-miR-148a-5p targets PDPK1 to inhibit the proliferation and cell cycle of ALV-J-infected CEF cells. Our study provides a new understanding for the tumor mechanism of ALV-J infection.

Epigenetic Regulation by Non-Coding RNAs in the Avian Immune System

The identified non-coding RNAs (ncRNAs) include circular RNAs, long non-coding RNAs, microRNAs, ribosomal RNAs, small interfering RNAs, small nuclear RNAs, piwi-interacting RNAs, and transfer RNAs, etc. Among them, long non-coding RNAs, circular RNAs, and microRNAs are regulatory RNAs that have different functional mechanisms and were extensively participated in various biological processes. Numerous research studies have found that circular RNAs, long non-coding RNAs, and microRNAs played their important roles in avian immune system during the infection of parasites, virus, or bacterium. Here, we specifically review and expand this knowledge with current advances of circular RNAs, long non-coding RNAs, and microRNAs in the regulation of different avian diseases and discuss their functional mechanisms in response to avian diseases.

Understanding the cross-talk between host and virus in poultry from the perspectives of microRNA

In poultry, viral infections (e.g., Marek's disease virus, avian leukosis virus, influenza A virus, and so on) can cause devastating mortality and economic losses. Because viruses are solely dependent on host cells to propagate, they alter the host intracellular microenvironment. Thus, understanding the virus-host interaction is important for antiviral immunity and drug development in the poultry industry. MicroRNAs are crucial posttranscriptional regulators of gene expression in a wide spectrum of biological processes, including viral infection. Recently, microRNAs have been identified as key players in virus-host interactions. In this review, we will discuss the intricacies involved in the virus-host cross-talk mediated by host and viral microRNAs in poultry (i.e., chicken and ducks), as well as recent trends and challenges in this field. These findings may provide some insights into the rapidly developing area of research regarding viral pathogenesis and antiviral immunity in poultry production.

The Roles of MicroRNAs (miRNAs) in Avian Response to Viral Infection and Pathogenesis of Avian Immunosuppressive Diseases

MicroRNAs (miRNAs) are a class of non-coding small RNAs that play important roles in the regulation of various biological processes including cell development and differentiation, apoptosis, tumorigenesis, immunoregulation and viral infections. Avian immunosuppressive diseases refer to those avian diseases caused by pathogens that target and damage the immune organs or cells of the host, increasing susceptibility to other microbial infections and the risk of failure in subsequent vaccination against other diseases. As such, once a disease with an immunosuppressive feature occurs in flocks, it would be difficult for the stakeholders to have an optimal economic income. Infectious bursal disease (IBD), avian leukemia (AL), Marek’s disease (MD), chicken infectious anemia (CIA), reticuloendotheliosis (RE) and avian reovirus infection are on the top list of commonly-seen avian diseases with a feature of immunosuppression, posing an unmeasurable threat to the poultry industry across the globe. Understanding the pathogenesis of avian immunosuppressive disease is the basis for disease prevention and control. miRNAs have been shown to be involved in host response to pathogenic infections in chickens, including regulation of immunity, tumorigenesis, cell proliferation and viral replication. Here we summarize current knowledge on the roles of miRNAs in avian response to viral infection and pathogenesis of avian immunosuppressive diseases, in particular, MD, AL, IBD and RE.

Multiple functions of p27 in cell cycle, apoptosis, epigenetic modification and transcriptional regulation for the control of cell growth: A double-edged sword protein

The cell cycle is controlled by precise mechanisms to prevent malignancies such as cancer, and the cell needs these tight and advanced controls. Cyclin dependent kinase inhibitor p27 (also known as KIP₁) is a factor that inhibits the progression of the cell cycle by using specific molecular mechanisms. The inhibitory effect of p27 on the cell cycle is mediated by CDKs inhibition. Other important functions of p27 include cell proliferation, cell differentiation and apoptosis. Post- translational modification of p27 by phosphorylation and ubiquitination respectively regulates interaction between p27 and cyclin/CDK complex and degradation of p27. In this review, we focus on the multiple function of p27 in cell cycle regulation, apoptosis, epigenetic modifications and post- translational modification, and briefly discuss the mechanisms and factors that have important roles in p27 functions.