The cAMP receptor protein gene contributes to growth, stress resistance, and colonization of Actinobacillus pleuropneumoniae.

Porcine infectious pleuropneumonia (PCP) is a severe disease of porcine caused by Actinobacillus pleuropneumoniae (APP). The spread of PCP remains a threat to the porcine farms and has been known to cause severe economic losses. The cAMP receptor protein (CRP) serves as a pivotal player in helping bacteria adapt to shifts in their environment, particularly when facing the challenges posed by bacterial infections. In this study, we investigated the role of CRP in APP. Our results revealed that crp mutant (Δcrp) strains were more sensitive to acidic and osmotic stress resistance and had lower biofilm formation ability than wild-type (WT) strains. Furthermore, the Δcrp strains showed deficiencies in anti-phagocytosis, adhesion, and invasion upon interaction with host cells. Mice infected with the Δcrp strains demonstrated reduced bacterial loads in their lungs compared to those infected with the WT strains. This study reveals the pivotal role of crp gene expression in regulating pleuropneumonia growth, stress resistance, iron utilization, biofilm formation, phagocytosis, adhesion, invasion and colonization. Our discoveries offer novel perspectives on understanding the development and progression of APP infections.

Overexpression of PtoMYB99 diminishes poplar tolerance to osmotic stress by suppressing ABA and JA biosynthesis.

Drought poses a serious challenge to sustained plant growth and crop yields in the context of global climate change. Drought tolerance in poplars and their underlying mechanisms still remain largely unknown. In this article, we investigated the overexpression of PtoMYB99 - both a drought and abscisic acid (ABA) induced gene constraining drought tolerance in poplars (as compared with wild type poplars). First, we found that PtoMYB99-OE lines exhibited increased stomatal opening and conductance, higher transpiration and photosynthetic rates, as well as reduced levels of ABA and jasmonic acid (JA). Second, PtoMYB99-OE lines accumulated more reactive oxygen species (ROS), including H2O2 and O2-, as well as malonaldehyde (MDA), proline, and soluble sugar under osmotic stress; conversely, the activity of antioxidant enzymes (SOD, POD, and CAT), was weakened in the PtoMYB99-OE lines. Third, the expression of ABA biosynthetic genes, PtoNCED3.1 and PtoNCED3.2, as well as JA biosynthetic genes, PtoOPR3.1 and PtoOPR3.2, was significantly reduced in the PtoMYB99-OE lines under both normal conditions and osmotic stress. Based on our results, we conclude that the overexpression of PtoMYB99 compromises tolerance to osmotic stress in poplar. These findings contribute to the understanding of the role of the MYB genes in drought stress and the biosynthesis of ABA and JA.

NCI677397 targeting USP24-mediated induction of lipid peroxidation induces ferroptosis in drug-resistant cancer cells.

Cancer represents a profound challenge to healthcare systems and individuals worldwide. The development of multiple drug resistance is a major problem in cancer therapy and can result in progression of the disease. In our previous studies, we developed small-molecule inhibitors targeting ubiquitin-specific peptidase 24 (USP24) to combat drug-resistant lung cancer. Recently, we found that the USP24 inhibitor NCI677397 induced ferroptosis, a type of programmed cell death, in drug-resistant cancer cells by increasing lipid reactive oxygen species (ROS) levels. In the present study, we investigated the molecular mechanisms and found that the targeting of USP24 by NCI677397 increased gene expression of most lipogenesis-related genes, such as acyl-CoA synthetase long-chain family member 4 (ACSL4), and activated autophagy. In addition, the activity of several antioxidant enzymes, such as glutathione peroxidase 4 (GPX4) and dihydrofolate reductase (DHFR), was inhibited by NCI677397 treatment via an increase in protein degradation, thereby inducing lipid ROS production and lipid peroxidation. In summary, we demonstrated that NCI677397 induced a marked increase in lipid ROS levels, subsequently causing lipid peroxidation and leading to the ferroptotic death of drug-resistant cancer cells. Our study provides new insights into the clinical use of USP24 inhibitors as ferroptosis inducers (FINs) to block drug resistance during chemotherapy.

5,6-Dichloro-1-ß-D-ribofuranosylbenzimidazole (DRB) induces apoptosis in breast cancer cells through inhibiting of Mcl-1 expression.

The effective treatment of breast cancer remains a profound clinical challenge, especially due to drug resistance and metastasis which unfortunately arise in many patients. The transcription inhibitor 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole (DRB), as a selective inhibitor of cyclin-dependent kinase 9, was shown to be effective in inducing apoptosis in various hematopoietic malignancies. However, the anticancer efficacy of DRB against breast cancer is still unclear. Herein, we demonstrated that administration of DRB to the breast cancer cell line led to the inhibition of cellular proliferation and induction of the typical signs of apoptotic cells, including the increases in Annexin V-positive cells, DNA fragmentation, and activation of caspase-7, caspase-9, and poly (ADP ribose) polymerase (PARP). Treatment of DRB resulted in a rapid decline in the myeloid cell leukemia 1 (Mcl-1) protein, whereas levels of other antiapoptotic proteins did not change. Overexpression of Mcl-1 decreased the DRB-induced PARP cleavage, whereas knockdown of Mcl-1 enhanced the effects of DRB on PARP activation, indicating that loss of Mcl-1 accounts for the DRB-mediated apoptosis in MCF-7 cells, but not in T-47D. Furthermore, we found that co-treatment of MCF-7 cells with an inhibitor of AKT (LY294002) or an inhibitor of the proteasome (MG-132) significantly augmented the DRB-induced apoptosis. These data suggested that DRB in combination with LY294002 or MG-132 may have a greater therapeutic potency against breast cancer cells.

The adcA and lmb Genes Play an Important Role in Drug Resistance and Full Virulence of Streptococcus suis.

Streptococcus suis is an recognized zoonotic pathogen of swine and severely threatens human health. Zinc is the second most abundant transition metal in biological systems. Here, we investigated the contribution of zinc to the drug resistance and pathogenesis of S. suis. We knocked out the genes of AdcACB and Lmb, two Zn-binding lipoproteins. Compared to the wild-type strain, we found that the survival rate of this double-mutant strain (ΔadcAΔlmb) was reduced in Zinc-limited medium, but not in Zinc-supplemented medium. Additionally, phenotypic experiments showed that the ΔadcAΔlmb strain displayed impaired adhesion to and invasion of cells, biofilm formation, and tolerance of cell envelope-targeting antibiotics. In a murine infection model, deletion of the adcA and lmb genes in S. suis resulted in a significant decrease in strain virulence, including survival rate, tissue bacterial load, inflammatory cytokine levels, and histopathological damage. These findings show that AdcA and Lmb are important for biofilm formation, drug resistance, and virulence in S. suis. IMPORTANCE Transition metals are important micronutrients for bacterial growth. Zn is necessary for the catalytic activity and structural integrity of various metalloproteins involved in bacterial pathogenic processes. However, how these invaders adapt to host-imposed metal starvation and overcome nutritional immunity remains unknown. Thus, pathogenic bacteria must acquire Zn during infection in order to successfully survive and multiply. The host uses nutritional immunity to limit the uptake of Zn by the invading bacteria. The bacterium uses a set of high-affinity Zn uptake systems to overcome this host metal restriction. Here, we identified two Zn uptake transporters in S. suis, AdcA and Lmb, by bioinformatics analysis and found that an adcA and lmb double-mutant strain could not grow in Zn-deficient medium and was more sensitive to cell envelope-targeting antibiotics. It is worth noting that the Zn uptake system is essential for biofilm formation, drug resistance, and virulence in S. suis. The Zn uptake system is expected to be a target for the development of novel antimicrobial therapies.

The VraSR two-component signal transduction system contributes to the damage of blood-brain barrier during Streptococcus suis meningitis.

Streptococcus suis (S. suis) is an important zoonotic pathogen that can cause high morbidity and mortality in both humans and swine. As the most important life-threatening infection of the central nervous system (CNS), meningitis is an important syndrome of S. suis infection. The vancomycin resistance associated sensor/regulator (VraSR) is a critical two-component signal transduction system that affects the ability of S. suis to resist the host innate immune system and promotes its ability to adhere to brain microvascular endothelial cells (BMECs). Prior work also found mice infected with ΔvraSR had no obvious neurological symptoms, unlike mice infected with wild-type SC19. Whether and how VraSR participates in the development of S. suis meningitis remains unknown. Here, we found ΔvraSR-infected mice did not show obvious meningitis, compared with wild-type SC19-infected mice. Moreover, the proinflammatory cytokines and chemokines in serum and brains of ΔvraSR-infected mice, including IL-6, TNF-α, MCP-1 and IFN-γ, were significantly lower than wild-type infected group. Besides, blood-brain barrier (BBB) permeability also confirmed that the mutant had lower ability to disrupt BBB. Furthermore, in vivo and in vitro experiments showed that SC19 could increase BBB permeability by downregulating tight junction (TJ) proteins such as ZO-1, ß-Catenin, Occludin, and Clauidn-5, compared with mutant ΔvraSR. These findings provide new insight into the influence of S. suis VraSR on BBB disruption during the pathogenic process of streptococcal meningitis, thereby offering potential targets for future preventative and therapeutic strategies against this disease.

A 5`-tRNA Derived Fragment NamedtiRNA-Val-CAC-001 Works as a Suppressor in Gastric Cancer.

Background: Gastric cancer (GC) is a common type of gastrointestinal tumor in the world. Transfer RNA (tRNA) derived fragments (tsRNAs) implicate various cancers, but their roles in GC remain unclear. Our study aimed to investigate the potential biological functions and molecular mechanisms of tsRNAs in GC. Methods: Differentially expressed tsRNAs were identified using high-throughput sequencing. The expression levels of tsRNAs were validated in 62 paired GC tissues and adjacent normal tissues using RT-qPCR. In vitro functional assays were used to evaluate the influences of tsRNAs on GC cells. The potential mechanisms underlying tsRNAs were explored using bioinformatics analysis,RT-qPCR, RNA immunoprecipitation assays and Western blot. Results: We found that tiRNA-Val-CAC-001 was downregulated in GC tissues and cells, and demonstrated that tiRNA-Val-CAC-001 was a tsRNA sheared from mature tRNA-Val and mainly localized in the cytoplasm. tiRNA-Val-CAC-001 overexpression inhibited metastasis and proliferation but promoted apoptosis of GC cells; nevertheless, tiRNA-Val-CAC-001 knockdown increased metastasis and proliferation and reduced apoptosis (P<0.05). GO and KEGG analyses indicated tiRNA-Val-CAC-001 may exert its effects via Wnt/ß-catenin signaling pathway by targeting LRP6. Following experiments showed that tiRNA-Val-CAC-001 could downregulated the protein levels of LRP6 and ß-catenin, but up-regulated p-ß-catenin, which confirmed the findings in bioinformatics analysis. Conclusion: In conclusion, tiRNA-Val-CAC-001 works as a cancer suppressor in GC by targeting LRP6 via Wnt/ß-catenin signaling pathway. tiRNA-Val-CAC-001 may serve as a therapy target and a biomarker of GC in the future. Key Points: tiRNA-Val-CAC-001 is downregulated in gastric cancer tissues and cell lines, tiRNA-Val-CAC-001 has potential to become a novel diagnostic biomarker in gastric cancer, and tiRNA-Val-CAC-001 regulates gastric cancer cells by targeting LRP6.

Home Dust Mites Promote MUC5AC Hyper-Expression by Modulating the sNASP/TRAF6 Axis in the Airway Epithelium.

House dust mites (HDMs) are a common source of respiratory allergens responsible for allergic asthma and innate immune responses in human diseases. Since HDMs are critical factors in the triggering of allergen-induced airway mucosa from allergic asthma, we aimed to investigate the mechanisms of Toll-like receptors (TLR) in the signaling of the HDM extract that is involved in mucus hypersecretion and airway inflammation through the engagement of innate immunity. Previously, we reported that the somatic nuclear autoantigenic sperm protein (sNASP)/tumor necrosis factor receptor-associated factor 6 (TRAF6) axis controls the initiation of TLRs to maintain the homeostasis of the innate immune response. The present study showed that the HDM extract stimulated the biogenesis of Mucin 5AC (MUC5AC) in bronchial epithelial cells via the TLR2/4 signaling pathway involving MyD88 and TRAF6. Specifically, sNASP binds to TRAF6 in unstimulated bronchial epithelial cells to prevent the activation of TRAF6-depenedent kinases. Upon on HDMs' stimulation, sNASP is phosphorylated, leading to the activation of TRAF6 downstream of the p38 MAPK and NF-κB signaling pathways. Further, NASP-knockdown enhanced TRAF6 signaling and MUC5AC biogenesis. In the HDM-induced mouse asthma model, we found that the HDM extract promoted airway hyperresponsiveness (AHR), MUC5AC, and allergen-specific IgE production as well as IL-5 and IL-13 for recruiting inflammatory cells. Treatment with the PEP-NASP peptide, a selective TRAF6-blocking peptide, ameliorated HDM-induced asthma in mice. In conclusion, this study indicated that the sNASP/TRAF6 axis plays a regulatory role in asthma by modulating mucus overproduction, and the PEP-NASP peptide might be a potential target for asthma treatment.

Role of the Two-Component System CiaRH in the Regulation of Efflux Pump SatAB and Its Correlation with Fluoroquinolone Susceptibility.

Streptococcus suis is an important pathogen in both pigs and humans. Although the diseases associated with S. suis can typically be treated with antibiotics, such use has resulted in a sustained increase in drug resistance. Bacteria can sense and respond to antibiotics via two-component systems (TCSs). In this study, the TCS CiaRH was identified as playing an important role in the susceptibility of S. suis to fluoroquinolones (FQs). We found that a ΔciaRH mutant possessed lower susceptibility to FQs than the wild-type strain, with no observed growth defects at the tested concentrations and lower levels of intracellular drugs and dye. Proteomic data revealed that the levels of SatA and SatB expression were upregulated in the ΔciaRH mutant compared with their levels in the wild-type strain. The satA and satB genes encode a narrow-spectrum FQ efflux pump. The phenomena associated with combined ciaRH-and-satAB deletion mutations almost returned the ΔciaRH ΔsatAB mutant to the phenotype of the wild-type strain compared to the phenotype of the ΔciaRH mutant, suggesting that the resistance of the ΔciaRH strain to FQs could be attributed to satAB overexpression. Moreover, SatAB expression was regulated by CiaR (a response regulator of CiaRH) and SatR (a regulator of the MarR family). The ciaRH genes were consistently downregulated in response to antibiotic stress. The results of electrophoretic mobility shift assays (EMSAs) and affinity assays revealed that both regulator proteins directly controlled the ABC transporter proteins SatAB. Together, the results show that cascade-mediated regulation of antibiotic export by CiaRH is crucial for the ability of S. suis to adapt to conditions of antibiotic pressure. Our study may provide a new target for future antibiotic research and development. IMPORTANCE Streptococcus suis is a zoonotic pathogen with high incidence and mortality rates in both swine and humans. Following antibiotic treatment, the organism has evolved many resistance mechanisms, among which efflux pump overexpression can promote drug extrusion from the cell. This study clarified the role of CiaRH in fluoroquinolone resistance. A mutant with the ciaRH genes deleted showed decreased susceptibility to the antibiotics tested, an invariant growth rate, and reduced intracellular efflux pump substrates. This research also demonstrated that overexpression of the efflux pump SatAB was the main cause of ΔciaRH resistance. In addition, CiaR could combine with the promoter region of satAB to further directly suppress target gene transcription. Simultaneously, satAB was also directly regulated by SatR. Our findings may provide novel insights for the development of drug targets and help to exploit corresponding inhibitors to combat bacterial multidrug resistance.

PEP-sNASP Peptide Alleviates LPS-Induced Acute Lung Injury Through the TLR4/TRAF6 Axis.

Acute lung injury (ALI) is a severe inflammatory lung disease associated with macrophages. Somatic nuclear autoantigenic sperm protein (sNASP) is a negative regulator of Toll-like receptor (TLR) signaling that targets tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) in macrophages, which is required to maintain homeostasis of the innate immune response. In the present study, we generated a cell permeable PEP-sNASP peptide using the sNASP protein N-terminal domain, and examined its potential therapeutic effect in a mouse model of ALI induced by the intranasal administration of lipopolysaccharide (LPS) and elucidated the underlying molecular mechanisms in RAW 264.7 cells. In vivo, PEP-sNASP peptide treatment markedly ameliorated pathological injury, reduced the wet/dry (W/D) weight ratio of the lungs and the production of proinflammatory cytokines (interleukin (IL)-1ß, IL-6, and TNF-α). In vitro, we demonstrated that when the PEP-sNASP peptide was transduced into RAW 264.7 cells, it bound to TRAF6, which markedly decreased LPS-induced proinflammatory cytokines by inhibiting TRAF6 autoubiquitination, nuclear factor (NF)-κB activation, reactive oxygen species (ROS) and cellular nitric oxide (NO) levels. Furthermore, the PEP-sNASP peptide also inhibited NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. Our results therefore suggest that the PEP-sNASP may provide a potential protein therapy against oxidative stress and pulmonary inflammation via selective TRAF6 signaling.

M2 macrophage-derived exosomes promote lung adenocarcinoma progression by delivering miR-942.

Tumor-associated macrophages (TAMs) are the major components of the tumor microenvironment that contribute to metastasis in lung adenocarcinoma (LUAD). The potential of TAM-derived exosomes for biomarker discovery in tumor initiation and progression has been recently reported. However, studies on macrophage-derived exosomes in LUAD remain limited. We investigated the role of M2 macrophage-derived exosomes in LUAD both in vivo and in vitro and its underlying mechanism. We showed that the infiltration of M2 macrophages was positively correlated with LUAD metastasis. M2 macrophage-derived exosomes could be taken up by LUAD cells to promote cell migration, invasion, and angiogenesis. Furthermore, miR-942 could be packaged into exosomes secreted by M2 macrophages. Mechanistically, exosomal miR-942 regulates FOXO1 protein expression by binding to the 3'-UTR region of FOXO1 and further alleviates ß-catenin inhibition in LUAD cells. Collectively, we demonstrated that M2 macrophage-derived miRNA-containing exosomes promote LUAD cell invasion and migration and facilitate angiogenesis, thereby providing a new therapeutic target for metastatic LUAD.

Regulation of TLR4 signaling through the TRAF6/sNASP axis by reversible phosphorylation mediated by CK2 and PP4.

Recognition of invading pathogens by Toll-like receptors (TLRs) activates innate immunity through signaling pathways that involved multiple protein kinases and phosphatases. We previously demonstrated that somatic nuclear autoantigenic sperm protein (sNASP) binds to TNF receptor-associated factor 6 (TRAF6) in the resting state. Upon TLR4 activation, a signaling complex consisting of TRAF6, sNASP, interleukin (IL)-1 receptor-associated kinase 4, and casein kinase 2 (CK2) is formed. CK2 then phosphorylates sNASP to release phospho-sNASP (p-sNASP) from TRAF6, initiating downstream signaling pathways. Here, we showed that protein phosphatase 4 (PP4) is the specific sNASP phosphatase that negatively regulates TLR4-induced TRAF6 activation and its downstream signaling pathway. Mechanistically, PP4 is directly recruited by phosphorylated sNASP to dephosphorylate p-sNASP to terminate TRAF6 activation. Ectopic expression of PP4 specifically inhibited sNASP-dependent proinflammatory cytokine production and downstream signaling following bacterial lipopolysaccharide (LPS) treatment, whereas silencing PP4 had the opposite effect. Primary macrophages and mice infected with recombinant adenovirus carrying a gene encoding PP4 (Ad-PP4) showed significant reduction in IL-6 and TNF-α production. Survival of Ad-PP4-infected mice was markedly increased due to a better ability to clear bacteria in a sepsis model. These results indicate that the serine/threonine phosphatase PP4 functions as a negative regulator of innate immunity by regulating the binding of sNASP to TRAF6.

Metal tolerance protein MTP6 is involved in Mn and Co distribution in poplar.

With the booming demand of the electric vehicle industry, the concentration of manganese (Mn) and cobalt (Co) flowing into land ecosystems has also increased significantly. While these transition metals can promote the growth and development of plants, they may become toxic under high concentrations. It is thus important to understand how Mn and Co are distributed in plants to develop novel germplasms for the remediation of these heavy metals in contaminated soils. Here, an MTP gene that encodes the CDF (cation diffusion facilitator) protein in Populus trichocarpa, PtrMTP6, was screened as the key gene involved in the distribution of both Mn and Co in poplar. The PtrMTP6-GFP fusion protein was co-localized with the mRFP-VSR2, showing that PtrMTP6 proteins are present at the pre-vacuolar compartment (PVC). Yeast mutant complementation assays further identified that PtrMTP6 serves as a Mn and Co transporter, reducing yeast cell toxicity after exposure to excessive Mn or Co. Histochemical analyses showed that PtrMTP6 was mainly expressed in phloem, suggesting that PtrMTP6 probably involved in the Mn and Co transport via phloem in plants. Under excess Co, PtrMTP6 overexpressing poplar lines were more severely damaged than the control due to higher Co accumulations in young tissue. PtrMTP6 overexpressing lines showed little change in their tolerance to excess Mn, although young tissues also accumulated more Mn. PtrMTP6 play important roles in Mn and Co distribution in poplar and further research on its regulation will be important to increase bioremediation in Mn and Co polluted ecosystems.

Tumor-derived exosomal miR-3157-3p promotes angiogenesis, vascular permeability and metastasis by targeting TIMP/KLF2 in non-small cell lung cancer.

Metastasis is the main cause of death in patients with advanced lung cancer. The exosomes released by cancer cells create tumor microenvironment, and then accelerate tumor metastasis. Cancer-derived exosomes are considered to be the main driving force for metastasis niche formation at foreign sites, but the mechanism in Non-small cell lung carcinoma (NSCLC) is unclear. In metastatic NSCLC patients, the expression level of miR-3157-3p in circulating exosomes was significantly higher than that of non-metastatic NSCLC patients. Here, we found that miR-3157-3p can be transferred from NSCLC cells to vascular endothelial cells through exosomes. Our work indicates that exosome miR-3157-3p is involved in the formation of pre-metastatic niche formation before tumor metastasis and may be used as a blood-based biomarker for NSCLC metastasis. Exosome miR-3157-3p has regulated the expression of VEGF/MMP2/MMP9 and occludin in endothelial cells by targeting TIMP/KLF2, thereby promoted angiogenesis and increased vascular permeability. In addition, exosome miR-3157-3p promoted the metastasis of NSCLC in vivo.

Exosomal circSHKBP1 promotes gastric cancer progression via regulating the miR-582-3p/HUR/VEGF axis and suppressing HSP90 degradation.

BACKGROUND: Circular RNAs (circRNAs) play important regulatory roles in the development of various cancers. However, biological functions and the underlying molecular mechanism of circRNAs in gastric cancer (GC) remain obscure. METHODS: Differentially expressed circRNAs were identified by RNA sequencing. The biological functions of circSHKBP1 in GC were investigated by a series of in vitro and in vivo experiments. The expression of circSHKBP1 was evaluated using quantitative real-time PCR and RNA in situ hybridization, and the molecular mechanism of circSHKBP1 was demonstrated by western blot, RNA pulldown, RNA immunoprecipitation, luciferase assays and rescue experiments. Lastly, mouse xenograft and bioluminescence imaging were used to exam the clinical relevance of circSHKBP1 in vivo. RESULTS: Increased expression of circSHKBP1(hsa_circ_0000936) was revealed in GC tissues and serum and was related to advanced TNM stage and poor survival. The level of exosomal circSHKBP1 significantly decreased after gastrectomy. Overexpression of circSHKBP1 promoted GC cell proliferation, migration, invasion and angiogenesis in vitro and in vivo, while suppression of circSHKBP1 plays the opposite role. Exosomes with upregulated circSHKBP1 promoted cocultured cells growth. Mechanistically, circSHKBP1 sponged miR-582-3p to increase HUR expression, enhancing VEGF mRNA stability. Moreover, circSHKBP1 directly bound to HSP90 and obstructed the interaction of STUB1 with HSP90, inhibiting the ubiquitination of HSP90, resulting in accelerated GC development in vitro and in vivo. CONCLUSION: Our findings demonstrate that exosomal circSHKBP1 regulates the miR-582-3p/HUR/VEGF pathway, suppresses HSP90 degradation, and promotes GC progression. circSHKBP1 is a promising circulating biomarker for GC diagnosis and prognosis and an exceptional candidate for further therapeutic exploration.

The Biogenesis and Functions of piRNAs in Human Diseases.

Piwi-interacting RNAs (piRNAs) are a novel type of small noncoding RNAs, which are 26-30 nt in length and bind to Piwi proteins. These short RNAs were originally discovered in germline cells and are considered as key regulators for germline maintenance. A growing body of evidence has now extended our views into piRNA biological significance showing that they can also regulate gene expression in somatic cells through transposon silencing, epigenetic programming, DNA rearrangements, mRNA turnover, and translational control. Mounting studies have revealed that the dysregulation of piRNAs may cause epigenetic changes and contribute to diverse diseases. This review illustrates piRNA biogenesis, mechanisms behind piRNA-mediated gene regulation, and changes of piRNAs in different diseases, especially in cancers.

Correction: miR-1260b, mediated by YY1, activates KIT signaling by targeting SOCS6 to regulate cell proliferation and apoptosis in NSCLC.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Silencing of circRACGAP1 sensitizes gastric cancer cells to apatinib via modulating autophagy by targeting miR-3657 and ATG7.

The positive results of the apatinib phase III trial have cast new light on treatment for patients with advanced gastric cancer (GC). However, in terms of safety, apatinib toxicities may lead to a dose modification or treatment interruption. Therefore, proper intervention is urgently needed to help patients benefit from apatinib treatment. In this study, we found that apatinib promoted autophagy activation via upregulation of ATG7 expression and autophagy inhibition enhanced apatinib-induced apoptosis. With microRNA and circular RNA-sequencing analyses of GC xenograft models, we demonstrated that circRACGAP1 functioned as an endogenous sponge for miR-3657 to inhibit its activity and further upregulate ATG7 expression. Silencing of circRACGAP1 inhibited apatinib-induced autophagy, which was rescued by miR-3657. Moreover, knockdown of circRACGAP1 sensitized GC cells to apatinib via autophagy inhibition in vitro and in vivo. These findings provided the first evidence that the circRACGAP1-miR-3657-ATG7 axis mediates a novel regulatory pathway critical for the regulation of apatinib sensitivity in GC. Thus, specific blockage of circRACGAP1 may be a potential therapeutic strategy to reduce the toxicities of apatinib and enhance its therapeutic effect in human GC.

Genome-Wide Identification of Metal Tolerance Protein Genes in Populus trichocarpa and Their Roles in Response to Various Heavy Metal Stresses.

Metal tolerance proteins (MTPs) are plant divalent cation transporters that play important roles in plant metal tolerance and homeostasis. Poplar is an ideal candidate for the phytoremediation of heavy metals because of its numerous beneficial attributes. However, the definitive phylogeny and heavy metal transport mechanisms of the MTP family in poplar remain unknown. Here, 22 MTP genes in P. trichocarpa were identified and classified into three major clusters and seven groups according to phylogenetic relationships. An evolutionary analysis suggested that PtrMTP genes had undergone gene expansion through tandem or segmental duplication events. Moreover, all PtrMTPs were predicted to localize in the vacuole and/or cell membrane, and contained typical structural features of the MTP family, cation efflux domain. The temporal and spatial expression pattern analysis results indicated the involvement of PtrMTP genes in poplar developmental control. Under heavy metal stress, most of PtrMTP genes were induced by at least two metal ions in roots, stems or leaves. In addition, PtrMTP8.1, PtrMTP9 and PtrMTP10.4 displayed the ability of Mn transport in yeast cells, and PtrMTP6 could transport Co, Fe and Mn. These findings will provide an important foundation to elucidate the biological functions of PtrMTP genes, and especially their role in regulating heavy metal tolerance in poplar.