An unscheduled switch to endocycles induces a reversible senescent arrest that impairs growth of the Drosophila wing disc.

A programmed developmental switch to G / S endocycles results in tissue growth through an increase in cell size. Unscheduled, induced endocycling cells (iECs) promote wound healing but also contribute to cancer. Much remains unknown, however, about how these iECs affect tissue growth. Using the D. melanogaster wing disc as model, we find that populations of iECs initially increase in size but then subsequently undergo a heterogenous arrest that causes severe tissue undergrowth. iECs acquired DNA damage and activated a Jun N-terminal kinase (JNK) pathway, but, unlike other stressed cells, were apoptosis-resistant and not eliminated from the epithelium. Instead, iECs entered a JNK-dependent and reversible senescent-like arrest. Senescent iECs promoted division of diploid neighbors, but this compensatory proliferation did not rescue tissue growth. Our study has uncovered unique attributes of iECs and their effects on tissue growth that have important implications for understanding their roles in wound healing and cancer.

Characterization of c-Jun N-terminal kinase (JNK) gene reveals involvement of immune defense against Vibrio splendidus infection in Apostichopus japonicus.

The c-Jun N-terminal kinase (JNK) constitutes an evolutionarily conserved family of serine/threonine protein kinases, pivotal in regulating various physiological processes in vertebrates, encompassing apoptosis and antibacterial immunity. Nevertheless, the involvement of JNK in the innate immune response remains largely unexplored in pathogen-induced echinoderms. We isolated and characterized the JNK gene from Apostichopus japonicus (AjJNK) in our investigation. The full-length cDNA sequences of AjJNK spanned 1806 bp, comprising a 1299 bp open reading frame (ORF) encoding 432 amino acids, a 274 bp 5'-untranslated region (UTR), and a 233 bp 3'-UTR. Structural analysis revealed the presence of a classical S_TKc domain (37-335 amino acids) within AjJNK and contains several putative immune-related transcription factor-binding sites, including Elk-1, NF-κB, AP-1, and STAT5. Spatial expression analysis indicated ubiquitous expression of AjJNK across all examined tissues, with the highest expression noted in coelomocytes. The mRNA, protein, and phosphorylation levels of AjJNK were obviously induced in coelomocytes upon V. splendidus challenge and lipopolysaccharide stimulation. Immunofluorescence analysis demonstrated predominant cytoplasmic localization of AjJNK in coelomocytes with subsequent nuclear translocation following the V. splendidus challenge in vivo. Moreover, siRNA-mediated knockdown of AjJNK led to a significant increase in intracellular bacterial load, as well as elevated levels of Ajcaspase 3 and coelomocyte apoptosis post V. splendidus infection. Furthermore, the phosphorylation levels of AjJNK inhibited by its specific inhibitor SP600125 and also significantly suppressed the expression of Ajcaspase 3 and coelomocyte apoptosis during pathogen infection. Collectively, these data underscored the pivotal role of AjJNK in immune defense, specifically in the regulation of coelomocyte apoptosis in V. splendidus-challenged A. japonicus.

The Drosophila tumor necrosis factor Eiger promotes Myc supercompetition independent of canonical Jun N-terminal kinase signaling.

Numerous factors have been implicated in the cell-cell interactions that lead to elimination of cells via cell competition, a context-dependent process of cell selection in somatic tissues that is based on comparisons of cellular fitness. Here, we use a series of genetic tests in Drosophila to explore the relative contribution of the pleiotropic cytokine tumor necrosis factor α (TNFα) in Myc-mediated cell competition (also known as Myc supercompetition or Myc cell competition). We find that the sole Drosophila TNF, Eiger (Egr), its receptor Grindelwald (Grnd/TNF receptor), and the adaptor proteins Traf4 and Traf6 are required to eliminate wild-type "loser" cells during Myc cell competition. Although typically the interaction between Egr and Grnd leads to cell death by activating the intracellular Jun N-terminal kinase (JNK) stress signaling pathway, our experiments reveal that many components of canonical JNK signaling are dispensable for cell death in Myc cell competition, including the JNKKK Tak1, the JNKK Hemipterous and the JNK Basket. Our results suggest that Egr/Grnd signaling participates in Myc cell competition but functions in a role that is largely independent of the JNK signaling pathway.

Dendrobine Ameliorates Glucocorticoid-Induced Osteoporosis by Promoting Osteogenesis through JNK/p38 MAPK Pathway Activation and GR Nuclear Translocation Inhibition.

Glucocorticoid-induced osteoporosis (GIOP) is the common reason for secondary osteoporosis. Dendrobine (DEN) is the major biologically active component of Dendrobium officinale with anti-inflammatory and antiaging properties. Whether DEN could alleviate osteogenic inhibition in GIOP rats is still unknown. The influence on osteogenic function caused by DEN on dexamethasone-treated bone marrow mesenchymal stem cells and rats was observed. The in vitro results showed that DEN reversed the inhibition of osteogenic differentiation by dexamethasone. Moreover, DEN supplementation attenuated dexamethasone-induced bone loss in vivo. DEN activated JNK and p38 MAPK pathways and restrained GR nuclear translocation, which could be prevented by the JNK (SP600125) or p38 (SB203580) pathway inhibitor. This study verified that DEN alleviated dexamethasone-induced nuclear translocation of GR, and inhibition of osteogenesis via JNK and p38 pathways, laying the foundation for DEN as a therapeutic agent for GIOP.

Vitamin C inactivates c-Jun N-terminal kinase to stabilize heart and neural crest derivatives expressed 1 (Hand1) in regulating placentation and maintenance of pregnancy.

Vitamin C (VC) serves as a pivotal nutrient for anti-oxidation process, metabolic responses, and stem cell differentiation. However, its precise contribution to placenta development and gestation remains obscure. Here, we demonstrated that physiological levels of VC act to stabilize Hand1, a key bHLH transcription factor vital for the development trajectory of trophoblast giant cell (TGC) lineages, thereby promoting the differentiation of trophoblast stem cells into TGC. Specifically, VC administration inactivated c-Jun N-terminal kinase (JNK) signaling, which directly phosphorylates Hand1 at Ser48, triggering the proteasomal degradation of Hand1. Conversely, a loss-of-function mutation at Ser48 on Hand1 not only significantly diminished both intrinsic and VC-induced stabilization of Hand1 but also underscored the indispensability of this residue. Noteworthy, the insufficiency of VC led to severe defects in the differentiation of diverse TGC subtypes and the formation of labyrinth's vascular network in rodent placentas, resulting in failure of maintenance of pregnancy. Importantly, VC deficiency, lentiviral knockdown of JNK or overexpression of Hand1 mutants in trophectoderm substantially affected the differentiation of primary and secondary TGC in E8.5 mouse placentas. Thus, these findings uncover the significance of JNK inactivation and consequential stabilization of Hand1 as a hitherto uncharacterized mechanism controlling VC-mediated placentation and perhaps maintenance of pregnancy.

Crosstalk of MAP3K1 and EGFR signaling mediates gene-environment interactions that block developmental tissue closure.

Aberrant regulation of signal transduction pathways can adversely derail biological processes for tissue development. One such process is the embryonic eyelid closure that is dependent on the mitogen-activated protein kinase kinase kinase 1 (MAP3K1). Map3k1 KO in mice results in defective eyelid closure and an autosomal recessive eye-open at birth phenotype. We have shown that in utero exposure to dioxin, a persistent environmental toxicant, induces the same eye defect in Map3k1+/- heterozygous but not WT pups. Here, we explore the mechanisms of the Map3k1 (gene) and dioxin (environment) interactions (GxE) underlying defective eyelid closure. We show that, acting through the aryl hydrocarbon receptor, dioxin activates epidermal growth factor receptor signaling, which in turn depresses MAP3K1-dependent Jun N-terminal kinase (JNK) activity. The dioxin-mediated JNK repression is moderate but is exacerbated by Map3k1 heterozygosity. Therefore, dioxin exposed Map3k1+/- embryonic eyelids have a marked reduction of JNK activity, accelerated differentiation and impeded polarization in the epithelial cells. Knocking out Ahr or Egfr in eyelid epithelium attenuates the open-eye defects in dioxin-treated Map3k1+/- pups, whereas knockout of Jnk1 and S1pr that encodes the sphigosin-1-phosphate (S1P) receptors upstream of the MAP3K1-JNK pathway potentiates the dioxin toxicity. Our novel findings show that the crosstalk of aryl hydrocarbon receptor, epidermal growth factor receptor, and S1P-MAP3K1-JNK pathways determines the outcome of dioxin exposure. Thus, gene mutations targeting these pathways are potential risk factors for the toxicity of environmental chemicals.

Tip60-FOXO regulates JNK signaling mediated apoptosis in Drosophila.

The JNK signaling pathway plays crucial roles in various physiological processes, including cell proliferation, differentiation, migration, apoptosis, and stress response. Dysregulation of this pathway is closely linked to the onset and progression of numerous major diseases, such as developmental defects and tumors. Identifying and characterizing novel components of the JNK signaling pathway to enhance and refine its network hold significant scientific and clinical importance for the prevention and treatment of associated cancers. This study utilized the model organism Drosophila and employed multidisciplinary approaches encompassing genetics, developmental biology, biochemistry, and molecular biology to investigate the interplay between Tip60 and the JNK signaling pathway, and elucidated its regulatory mechanisms. Our findings suggest that loss of Tip60 acetyltransferase activity results in JNK signaling pathway activation and subsequent induction of JNK-dependent apoptosis. Genetic epistasis analysis reveals that Tip60 acts downstream of JNK, paralleling with the transcription factor FOXO. The biochemical results confirm that Tip60 can bind to FOXO and acetylate it. Introduction of human Tip60 into Drosophila effectively mitigates apoptosis induced by JNK signaling activation, underscoring conserved regulatory role of Tip60 in the JNK signaling pathway from Drosophila to humans. This study further enhances our understanding of the regulatory network of the JNK signaling pathway. By revealing the role and mechanism of Tip60 in JNK-dependent apoptosis, it unveils new insights and potential therapeutic avenues for preventing and treating associated cancers.

Perfluorooctane sulfonate-induced Sertoli cell injury through c-Jun N-terminal kinase: a study by RNA-Seq.

Per- and polyfluoroalkyl substances (PFASs) are a family of "forever chemicals" including perfluorooctane sulfonate (PFOS). These toxic chemicals do not break down in the environment or in our bodies. In the human body, PFOS and perfluoroctanoic acid (PFOA) have a half-life (T1/2) of about 4-5 yr so low daily consumption of these chemicals can accumulate in the human body to a harmful level over a long period. Although the use of PFOS in consumer products was banned in the United States in 2022/2023, this forever chemical remains detectable in our tap water and food products. Every American tested has a high level of PFAS in their blood (https://cleanwater.org/pfas-forever-chemicals). In this report, we used a Sertoli cell blood-testis barrier (BTB) model with primary Sertoli cells cultured in vitro with an established functional tight junction (TJ)-permeability barrier that mimicked the BTB in vivo. Treatment of Sertoli cells with PFOS was found to perturb the TJ-barrier, which was the result of cytoskeletal disruption across the cell cytoplasm, disrupting actin and microtubule polymerization. These changes thus affected the proper localization of BTB-associated proteins at the BTB. Using RNA-Seq transcriptome profiling, bioinformatics analysis, and pertinent biochemical and cell biology techniques, it was discovered that PFOS -induced Sertoli cell toxicity through the c-Jun N-terminal kinase (JNK; also known as stress-activated protein kinase, SAPK) and its phosphorylated/active form p-JNK signaling pathway. More importantly, KB-R7943 mesylate (KB), a JNK/p-JNK activator, was capable of blocking PFOS-induced Sertoli cell injury, supporting the notion that PFOS-induced cell injury can possibly be therapeutically managed.NEW & NOTEWORTHY PFOS induces Sertoli cell injury, including disruption of the 1) blood-testis barrier function and 2) cytoskeletal organization, which, in turn, impedes male reproductive function. These changes are mediated by JNK/p-JNK signaling pathway. However, the use of KB-R7943, a JNK/p-JNK activator was capable of blocking PFOS-induced Sertoli cell injury, supporting the possibility of therapeutically managing PFOS-induced reproductive dysfunction.

[Ginsenoside Rg_1 ameliorates OGD/R-induced PC12 cell injury by inhibiting autography via IRE1-JNK-CHOP pathway].

This study investigated the protective effect of ginsenoside Rg_1(GRg_1) on oxygen and glucose deprivation/reoxygenation(OGD/R)-injured rat adrenal pheochromocytoma(PC12) cells and whether the underlying mechanism was related to the regulation of inositol-requiring enzyme 1(IRE1)-c-Jun N-terminal kinase(JNK)-C/EBP homologous protein(CHOP) signaling pathway. An OGD/R model was established in PC12 cells, and PC12 cells were randomly classified into control, model, OGD/R+GRg_1(0.1, 1, 10 µmol·L~(-1)), OGD/R+GRg_1+rapamycin(autophagy agonist), OGD/R+GRg_1+3-methyladenine(3-MA,autophagy inhibitor), OGD/R+GRg_1+tunicamycin(endoplasmic reticulum stress agonist), OGD/R+GRg_1+4-phenylbutyric acid(4-PBA, endoplasmic reticulum stress inhibitor), and OGD/R+GRg_1+3,5-dibromosalicylaldehyde(DBSA, IRE1 inhibitor) groups. Except the control group, the other groups were subjected to OGD/R treatment, i.e., oxygen and glucose deprivation for 6 h followed by reoxygenation for 6 h. Cell viability was detected by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide(MTT) assay. Apoptosis was detected by Hoechst 33342 staining, and the fluorescence intensity of autophagosomes by the monodansylcadaverine(MDC) assay. Western blot was employed to determine the expression of autophagy-related proteins(Beclin1, LC3-Ⅱ, and p62) and the pathway-related proteins [IRE1, p-IRE1, JNK, p-JNK, glucose-regulated protein 78(GRP78), and CHOP]. The results showed that GRg_1 dose-dependently increased the viability of PC12 cells and down-regulated the expression of Beclin1, LC3-Ⅱ, p-IRE1, p-JNK, GRP78, and CHOP, compared with the model group. Furthermore, GRg_1 decreased the apoptosis rate and MDC fluorescence intensity and up-regulated the expression of p62 protein. Compared with the OGD/R+GRg_1(10 µmol·L~(-1)) group, OGD/R+GRg_1+rapamycin and OGD/R+GRg_1+tunicamycin groups showed increased apoptosis rate and MDC fluorescence intensity, up-regulated protein levels of Beclin1, LC3-Ⅱ, p-IRE1, p-JNK, GRP78, and CHOP, decreased relative cell survival rate, and down-regulated protein level of p62. The 3-MA, 4-PBA, and DBSA groups exerted the opposite effects. Taken together, GRg_1 may ameliorate OGD/R-induced PC12 cell injury by inhibiting autophagy via the IRE1-JNK-CHOP pathway.

Deoxynivalenol leads to endoplasmic reticulum stress-mediated apoptosis via the IRE1/JNK/CHOP pathways in porcine embryos.

The cytotoxic mycotoxin deoxynivalenol (DON) reportedly has adverse effects on oocyte maturation and embryonic development in pigs. Recently, the interplay between cell apoptosis and endoplasmic reticulum (ER) stress has garnered increasing attention in embryogenesis. However, the involvement of the inositol-requiring enzyme 1 (IRE1)/c-jun N-terminal kinase (JNK)/C/EBP homologous protein (CHOP) pathways of unfolded protein response (UPR) signaling in DON-induced apoptosis in porcine embryos remains unknown. In this study, we revealed that exposure to DON (0.25 µM) substantially decreased cell viability until the blastocyst stage in porcine embryos, concomitant with initiation of cell apoptosis through the IRE1/JNK/CHOP pathways in response to ER stress. Quantitative PCR confirmed that UPR signaling-related transcription factors were upregulated in DON-treated porcine blastocysts. Western blot analysis showed that IRE1/JNK/CHOP signaling was activated in DON-exposed porcine embryos, indicating that ER stress-associated apoptosis was instigated. The ER stress inhibitor tauroursodeoxycholic acid protected against DON-induced ER stress in porcine embryos, indicating that the toxic effects of DON on early developmental competence of porcine embryos can be prevented. In conclusion, DON exposure impairs the developmental ability of porcine embryos by inducing ER stress-mediated apoptosis via IRE1/JNK/CHOP signaling.

Lycopene Alleviates Endoplasmic Reticulum Stress in Steatohepatitis through Inhibition of the ASK1-JNK Signaling Pathway.

Lycopene has been proven to alleviate nonalcoholic steatohepatitis (NASH), but the precise mechanisms are inadequately elucidated. In this study, we found a previously unknown regulatory effect of lycopene on the apoptosis signal-regulating kinase 1 (ASK1) signaling pathway in both in vivo and in vitro models. Lycopene supplementation (3 and 6 mg/kg/day) exhibited a significant reduction in lipid accumulation, inflammation, and fibrosis of the liver in mice fed with a high-fat/high-cholesterol diet or a methionine-choline-deficient diet. RNA sequencing uncovered that the mitogen-activated protein kinases signaling pathway, which is closely associated with inflammation and endoplasmic reticulum (ER) stress, was significantly downregulated by lycopene. Furthermore, we found lycopene ameliorated ER swelling and decreased the expression levels of ER stress markers (i.e., immunoglobulin heavy chain binding protein, C/EBP homologous protein, and X-box binding protein 1s). Especially, the inositol-requiring enzyme 1α involved in the ASK1 phosphorylation was inhibited by lycopene, resulting in the decline of the subsequent c-Jun N-terminal kinase (JNK) signaling cascade. ASK1 inhibitor DQOP-1 eliminated the lycopene-induced inhibition of the ASK1-JNK pathway in oleic acid and palmitic acid-induced HepG2 cells. Molecular docking further indicated hydrophobic interactions between lycopene and ASK1. Collectively, our research indicates that lycopene can alleviate ER stress and attenuate inflammation cascades and lipid accumulation by inhibiting the ASK1-JNK pathway.

Genetic deletion of c-Jun amino-terminal kinase 3 (JNK3) modestly increases disease severity in a mouse model of multiple sclerosis.

The c-Jun amino terminal kinases (JNKs) regulate transcription, and studies suggest they contribute to neuropathology in the EAE model of MS. To examine the role of the JNK3 isoform, we compared EAE in JNK3 null mice to wild type (WT) littermates. Although disease severity was similar in female mice, in male JNK3 null mice the day of onset and time to reach 100% incidence occurred sooner, and disease severity was increased. While glial activation in spinal cord was similar, white matter lesions were increased in JNK3 null mice. These results suggest JNK3 normally limits EAE disease in a sex-dependent manner.

c-Jun N-terminal kinase activation contributes to improving low temperature tolerance via regulating apoptosis in the Pacific white shrimp Penaeus vannamei.

Temperature is an essential environmental factor for the survival of aquatic animals. Low temperature stress can induce mitochondria to produce excessive ROS and free radicals, and destroy homeostasis. c-Jun N-terminal kinase (JNK) is involved in regulating various physiological processes, including inflammatory responses, cell cycle, reproduction, and apoptosis. Here, we investigated the mechanism of ROS/JNK pathway under low temperature stress both in vitro and in vivo. In this study, transcriptome analysis revealed that apoptosis, autophagy, calcium channel, and antioxidant were involved in the mediation of low temperature tolerance in Pacific white shrimp (penaeus vannamei). PvJNK was activated in response to low temperature stress. Treatments with different temperature caused oxidative stress as demonstrated by increased intensity of the ROS indicator H2DCF-DA, and induced apoptosis as confirmed by indicator FITC. Pretreatment with N-acetylcysteine, an ROS scavenger, attenuated low temperature induced apoptosis, and inhibited the expression of PvJNK. In addition, we demonstrate that mediator PvJNK translocated to nuclear through interacting with PvRheb. By using flow cytometry, inhibiting PvJNK can increase the expression of apoptosis related genes, accelerate tissue damage, and induce ROS and cell apoptosis. The ultimate inhibition of PvJNK accelerates the mortality of shrimp under low temperature stress. Overall, these findings suggest that during low temperature stress, PvJNK was activated by ROS to regulates apoptosis via interacting with PvRheb to promote PvJNK into the nucleus and to improve low temperature tolerance of shrimp.

Spoonbill positively regulates JNK signalling mediated apoptosis in Drosophila melanogaster.

A-kinase anchoring protein (AKAP) comprises a family of scaffold proteins, which decides the subcellular localisation of a combination of signalling molecules. Spoonbill (Spoon) is a putative A-kinase anchoring protein in Drosophila. We have earlier reported that Spoon suppresses ribonuclear foci formed by trinucleotide repeat expanded transcripts associated with Spinocerebellar Ataxia 8 neurodegeneration in Drosophila. However, the role of Spoonbill in cellular signalling was unexplored. In this report, we have unravelled a novel function of Spoon protein in the regulation of the apoptotic pathway. The Drosophila TNFα homolog, Eiger, induces apoptosis via activation of the JNK pathway. We have shown here that Spoonbill is a positive regulator of the Eiger-induced JNK signalling. Further genetic interaction studies show that the spoon interacts with components of the JNK pathway, TGF-ß activated kinase 1 (Tak1 - JNKKK), hemipterous (hep - JNKK) and basket (bsk - JNK). Interestingly, Spoonbill alone can also induce ectopic activation of the JNK pathway in a context-specific manner. To understand the molecular mechanism underlying Spoonbill-mediated modulation of the JNK pathway, the interaction between Spoon and Drosophila JNK was assessed. basket encodes the only known JNK in Drosophila. This serine/threonine-protein kinase phosphorylates Jra/Kay, which transcriptionally regulate downstream targets like Matrix metalloproteinase 1 (Mmp1), puckered (puc), and proapoptotic genes hid, reaper and grim. Interestingly, we found that Spoonbill colocalises and co-immunoprecipitates with the Basket protein in the developing photoreceptor neurons. Hence, we propose that Spoon plays a vital role in JNK-induced apoptosis. Furthermore, stress-induced JNK activation underlying Parkinson's Disease was also examined. In the Parkinson's Drosophila model of neurodegeneration, depletion of Spoonbill leads to a partial reduction of JNK pathway activation, along with improvement in adult motor activity. These observations suggest that the putative scaffold protein Spoonbill is a functional and physical interacting partner of the Drosophila JNK protein, Basket. Spoon protein is localised on the outer mitochondrial membrane (OMM), which may perhaps provide a suitable subcellular niche for activation of Drosophila Basket protein by its kinases which induce apoptosis.

KIAA1429 promotes tumorigenesis and gefitinib resistance in lung adenocarcinoma by activating the JNK/ MAPK pathway in an m6A-dependent manner.

Non-small cell lung cancer is the leading cause of cancer related mortality worldwide, and lung adenocarcinoma (LUAD) is one of the most common subtypes. The role of N6-methyladenosine (m6A) modification in tumorigenesis and drug resistance in LUAD remains unclear. In this study, we evaluated the effects of vir-like m6A methyltransferase-associated protein (KIAA1429) depletion on proliferation, migration, invasion, and drug resistance of LUAD cells, and identified m6A-dependent downstream genes influenced by KIAA1429. We found that KIAA1429 activated Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathway as a novel signaling event, which is responsible for tumorigenesis and resistance to gefitinib in LUAD cells. KIAA1429 and MAP3K2 showed high expression in LUAD patients' tissues. Knockdown of KIAA1429 inhibited MAP3K2 expression in an m6A methylation-dependent manner, restraining the progression of LUAD cells and inhibiting growth of gefitinib-resistant HCC827 cells. KIAA1429 positively regulated MAP3K2 expression, activated JNK/ MAPK pathway, and promoted drug resistance in gefitinib-resistant HCC827 cells. We reproduced the in vitro results in nude mouse xenografted with KIAA1429 knockdown cells. Our study showed that the mechanism of m6A KIAA1429-mediated gefitinib resistance in LUAD cells occurs by activating JNK/ MAPK signaling pathway. These findings provide potential targets for molecular therapy and clinical treatment in LUAD patients with gefitinib resistance.

Actin remodeling mediates ROS production and JNK activation to drive apoptosis-induced proliferation.

Stress-induced cell death, mainly apoptosis, and its subsequent tissue repair is interlinked although our knowledge of this connection is still very limited. An intriguing finding is apoptosis-induced proliferation (AiP), an evolutionary conserved mechanism employed by apoptotic cells to trigger compensatory proliferation of their neighboring cells. Studies using Drosophila as a model organism have revealed that apoptotic caspases and c-Jun N-terminal kinase (JNK) signaling play critical roles to activate AiP. For example, the initiator caspase Dronc, the caspase-9 ortholog in Drosophila, promotes activation of JNK leading to release of mitogenic signals and AiP. Recent studies further revealed that Dronc relocates to the cell cortex via Myo1D, an unconventional myosin, and stimulates production of reactive oxygen species (ROS) to trigger AiP. During this process, ROS can attract hemocytes, the Drosophila macrophages, which further amplify JNK signaling cell non-autonomously. However, the intrinsic components connecting Dronc, ROS and JNK within the stressed signal-producing cells remain elusive. Here, we identified LIM domain kinase 1 (LIMK1), a kinase promoting cellular F-actin polymerization, as a novel regulator of AiP. F-actin accumulates in a Dronc-dependent manner in response to apoptotic stress. Suppression of F-actin polymerization in stressed cells by knocking down LIMK1 or expressing Cofilin, an inhibitor of F-actin elongation, blocks ROS production and JNK activation, hence AiP. Furthermore, Dronc and LIMK1 genetically interact. Co-expression of Dronc and LIMK1 drives F-actin accumulation, ROS production and JNK activation. Interestingly, these synergistic effects between Dronc and LIMK1 depend on Myo1D. Therefore, F-actin remodeling plays an important role mediating caspase-driven ROS production and JNK activation in the process of AiP.

The immune deficiency and c-Jun N-terminal kinase pathways drive the functional integration of the immune and circulatory systems of mosquitoes.

The immune and circulatory systems of animals are functionally integrated. In mammals, the spleen and lymph nodes filter and destroy microbes circulating in the blood and lymph, respectively. In insects, immune cells that surround the heart valves (ostia), called periostial haemocytes, destroy pathogens in the areas of the body that experience the swiftest haemolymph (blood) flow. An infection recruits additional periostial haemocytes, amplifying heart-associated immune responses. Although the structural mechanics of periostial haemocyte aggregation have been defined, the genetic factors that regulate this process remain less understood. Here, we conducted RNA sequencing in the African malaria mosquito, Anopheles gambiae, and discovered that an infection upregulates multiple components of the immune deficiency (IMD) and c-Jun N-terminal kinase (JNK) pathways in the heart with periostial haemocytes. This upregulation is greater in the heart with periostial haemocytes than in the circulating haemocytes or the entire abdomen. RNA interference-based knockdown then showed that the IMD and JNK pathways drive periostial haemocyte aggregation and alter phagocytosis and melanization on the heart, thereby demonstrating that these pathways regulate the functional integration between the immune and circulatory systems. Understanding how insects fight infection lays the foundation for novel strategies that could protect beneficial insects and harm detrimental ones.

Dickkopf-1 expression is repressed by oncogenic human papillomaviruses (HPVs) and regulates the Cisplatin sensitivity of HPV-positive cancer cells in a JNK-dependent manner.

Oncogenic human papillomavirus (HPV) types control the phenotype of cervical cancer cells through the sustained expression of the viral E6/E7 oncogenes. Here, we show that they strongly restrain expression of the putative tumor suppressor protein Dkk1 (Dickkopf-1) in HPV-positive cervical cancer cells through the restriction of p53 expression by the continuously expressed endogenous E6 oncoprotein. Moreover, our study reveals that compromised Dkk1 expression is linked to increased resistance of HPV-positive cervical cancer cells toward the proapoptotic activity of Cisplatin. Although Dkk1 can act as a Wnt antagonist, the antiapoptotic effect resulting from Dkk1 repression is not linked to an activation of this pathway. Rather, transcriptome and functional analyses uncover that Dkk1 repression leads to a strongly diminished stimulation of c-Jun N-terminal kinase (JNK) signaling which is required for efficient apoptosis induction by Cisplatin in cervical cancer cells. Further, we observed that Dkk1-depleted cervical cancer cells induce senescence under Cisplatin treatment instead of apoptosis, suggesting that Dkk1 levels can strongly influence the phenotypic response of these cells toward Cisplatin. Collectively, these results provide new insights into the virus/host cell crosstalk in cervical cancer cells by identifying Dkk1 as a cellular target which is maintained under strong negative control by the continuous expression of the HPV oncogenes. Moreover, they identify Dkk1 as a critical determinant for the sensitivity of cervical cancer cells toward Cisplatin, showing that Dkk1 repression leads to increased Cisplatin resistance by impairing proapoptotic JNK signaling.

Hcmv-miR-UL148D regulates the staurosporine-induced apoptosis by targeting the Endoplasmic Reticulum to Nucleus signaling 1(ERN1).

The propensity of viruses to co-opt host cellular machinery by reprogramming the host's RNA-interference machinery has been a major focus of research, however, regulation of host defense mechanisms by virus-encoded miRNA, is an additional regulatory realm gaining momentum in the arena of host-viral interactions. The Human Cytomegalovirus (HCMV) miRNAs, regulate many cellular pathways alone or in concordance with HCMV proteins, thereby paving a conducive environment for successful infection in the human host. We show that HCMV miRNA, hcmv-miR-UL148D inhibits staurosporine-induced apoptosis in HEK293T cells. We establish that ERN1 mRNA is a bonafide target of hcmv-miR-UL148D and its encoded protein IRE1α is translationally repressed by the overexpression of hcmv-miR-UL148D resulting in the attenuation of apoptosis. Unlike the host microRNA seed sequence (6-8 nucleotides), hcmv-miR-UL148D has long complementarity to 3' UTR of ERN1 mRNA resulting in mRNA degradation. The repression of IRE1α by the hcmv-miR-UL148D further downregulates Xbp1 splicing and c-Jun N-terminal kinase phosphorylation thus regulating ER-stress and ER-stress induced apoptotic pathways. Strikingly, depletion of ERN1 attenuates staurosporine-induced apoptosis which further suggests that hcmv-miR-UL148D functions through regulation of its target ERN1. These results uncover a role for hcmv-miR-UL148D and its target ERN1 in regulating ER stress-induced apoptosis.

Genome-wide identification and expression analysis of mitogen-activated protein kinase (MAPK) genes in response to salinity stress in channel catfish (Ictalurus punctatus).

The mitogen-activated protein kinase (MAPK) gene family has been systematically described in several fish species, but less so in channel catfish (Ictalurus punctatus), which is an important global aquaculture species. In this study, 16 MAPK genes were identified in the channel catfish genome and classified into three subfamilies based on phylogenetic analysis, including six extracellular signal regulated kinase (ERK) genes, six p38-MAPK genes and four C-Jun N-terminal kinase (JNK) genes. All MAPK genes were distributed unevenly across 10 chromosomes, of which three (IpMAPK8, IpMAPK12 and IpMAPK14) underwent teleost-specific whole genome duplication during evolution. Gene expression profiles in channel catfish during salinity stress were analysed using transcriptome sequencing and qRT-PCR (quantitative reverse transcription PCR). Results from reads per kilobase million (RPKM) analysis showed IpMAPK13, IpMAPK14a and IpMAPK14b genes were differentially expressed when compared with other genes between treatment and control groups. Furthermore, three of these genes were validated by qRT-PCR, of which IpMAPK14a expression levels were significantly upregulated in treatment groups (high and low salinity) when compared with the control group, with the highest expression levels in the low salinity group (P < 0.05). Therefore, IpMAPK14a may have important response roles to salinity stress in channel catfish.