Nitrogen (N) deficiency responses are essential for plant survival and reproduction. Here, via an expression genome-wide association study (eGWAS), we reveal a mechanism that regulates microRNA (miRNA) dynamics necessary for N deficiency responses in Arabidopsis. Differential expression levels of three NAC transcription factor (TF) genes involved in leaf N deficiency responses among Arabidopsis accessions are most significantly associated with polymorphisms in HASTY (HST), which encodes an importin/exportin family protein responsible for the generation of mature miRNAs. HST acts as a negative regulator of N deficiency-induced leaf senescence, and the disruption and overexpression of HST differently modifies miRNA dynamics in response to N deficiency, altering levels of miRNAs targeting transcripts. Interestingly, N deficiency prevents the interaction of HST with HST-interacting proteins, DCL1 and RAN1, and some miRNAs. This suggests that HST-mediated regulation of miRNA dynamics collectively controls regulations mediated by multiple N deficiency response-associated NAC TFs, thereby being central to the N deficiency response network.

Exportin-1 (XPO1) is a major transporter for hundreds of proteins. Selinexor is the first generation XPO1 inhibitor. At present, selinexor has gained more attention in the application of multiple myeloma (MM). Meanwhile, the latest clinical trials have confirmed that whether it is a single agent or combined with other chemotherapy regimens, selinexor can also achieve good therapeutic effects in patients with leukemia and lymphoma. This review summarizes the results of preclinical studies and clinical trials of selinexor in treatment of non-MM hematological malignancies, aiming to explore how to choose single agent or in combination with other regimens as induction chemotherapy.
UNASSIGNED: 塞利尼索在非多发性骨髓瘤血液肿瘤中的应用及研究进展.
UNASSIGNED: .核输出蛋白1（XPO1）是数百种蛋白质的主要转运蛋白。塞利尼索是第一代XPO1抑制剂，目前在多发性骨髓瘤的治疗中获得了较多的关注，同时最新临床试验也证实，无论是单药还是联合其他化疗方案，塞利尼索在白血病、淋巴瘤中同样能取得较好的治疗效果。本文总结了塞利尼索治疗非多发性骨髓瘤血液肿瘤的临床前研究和临床试验结果，旨在探讨未来如何选择塞利尼索单药或联合其他方案进行诱导化疗。.

OBJECTIVE: To investigate the effects of selinexor, a inhibitor of nuclear export protein 1 (XPO1) on the proliferation inhibition and apoptosis of Kasumi-1 cells in acute myeloid leukemia (AML).
METHODS: MTS method was used to detect the inhibitory effect of different concentrations of selinexor on the proliferation of Kasumi-1 cells at different time points. The apoptosis rate and cell cycle changes after treatment with different concentration of selinexor were detected by flow cytometry.
RESULTS: Selinexor inhibited the growth of Kasumi-1 cells at different time points in a concentration-dependent manner (r 24 h=0.7592, r 48 h=0.9456, and r 72 h=0.9425). Selinexor inhibited Kasumi-1 cells growth in a time-dependent manner (r =0.9057 in 2.5 μmol/L group, r =0.9897 in 5 μmol/L group and r =0.9994 in 10 μmol/L group). Selinexor could induce apoptosis of Kasumi-1 cells in a dose-dependent manner (r =0.9732), and the apoptosis of Kasumi-1 cells was more obvious with the increase of drug concentration. The proportion of G0/G1 phase was significantly increased and the proportion of S phase was significantly decreased after the treatment of Kasumi-1 cells by selinexor. With the increase of drug concentration, the proportion of Kasumi-1 cells cycle arrest in G0/G1 phase was increased and the cell synthesis was decreased.
CONCLUSIONS: Selinexor can promote the death of tumor cells by inhibiting Kasumi-1 cells proliferation, inducing apoptosis and blocking cell cycle.
UNASSIGNED: XPO1抑制剂塞利尼索对急性髓系白血病Kasumi-1细胞增殖和凋亡的影响.
UNASSIGNED: 探讨核输出蛋白1（XPO1）抑制剂塞利尼索对急性髓系白血病（AML）Kasumi-1细胞增殖与凋亡的影响。.
UNASSIGNED: 用MTS法检测不同浓度塞利尼索（0、2.5、5、10 μmol/L）作用于Kasumi-1细胞不同时间点（24、48、72 h）的增殖抑制率；流式细胞术检测不同浓度塞利尼索作用于Kasumi-1细胞48 h后的细胞凋亡率和细胞周期变化情况。.
UNASSIGNED: 塞利尼索在不同时间点均可抑制Kasumi-1细胞生长，并呈浓度依赖(r 24 h=0.7592，r 48 h=0.9456，r 72 h=0.9425)；不同浓度塞利尼索均可抑制Kasumi-1细胞生长，并呈时间依赖(2.5 μmol/L组r =0.9057，5 μmol/L组r =0.9897，10 μmol/L组r =0.9994)。塞利尼索可诱导Kasumi-1细胞凋亡，且呈浓度依赖（r =0.9732），随着药物浓度的增大，诱导Kasumi-1细胞凋亡的作用越明显。塞利尼索作用于Kasumi-1细胞48 h后，G0/G1期细胞比例明显上升，S期细胞比例明显下降，并且随着塞利尼索药物浓度的增大，Kasumi-1细胞周期阻滞于G0 /G1期的细胞比例增加，细胞合成减少。.
UNASSIGNED: 塞利尼索可抑制Kasumi-1细胞增殖，诱导细胞凋亡，阻滞细胞周期于G0/G1期，导致肿瘤细胞的死亡。.

XPO1 (Exportin-1/CRM1) is a nuclear export protein that is frequently overexpressed in cancer and functions as a driver of oncogenesis. Currently small molecules that target XPO1 are being used in the clinic as anticancer agents. We identify XPO1 as a target for natural killer (NK) cells. Using immunopeptidomics, we have identified a peptide derived from XPO1 that can be recognized by the activating NK cell receptor KIR2DS2 in the context of human leukocyte antigen-C. The peptide can be endogenously processed and presented to activate NK cells specifically through this receptor. Although high XPO1 expression in cancer is commonly associated with a poor prognosis, we show that the outcome of specific cancers, such as hepatocellular carcinoma, can be substantially improved if there is concomitant evidence of NK cell infiltration. We thus identify XPO1 as a bona fide tumor antigen recognized by NK cells that offers an opportunity for a personalized approach to NK cell therapy for solid tumors.

BACKGROUND: Exportin 1 (XPO1) is a nuclear export protein that facilitates the transportation of various substances. XPO1 promotes tumor development as a poor prognostic factor in a variety of tumors and is a therapeutic target for screening inhibitors. However, the role of XPO1 in oral squamous cell carcinoma (OSCC) has yet to be determined.
METHODS: The expression patterns of XPO1 mRNA in OSCC were investigated using bioinformatics tools, and the expression levels of XPO1 protein in OSCC specimens were confirmed by immunohistochemical assays. Survival analysis was conducted to evaluate the impact of XPO1 on prognosis. GO and KEGG enrichment analyses were utilized to uncover the signaling pathways mediated by XPO1. Additionally, we examined the association between XPO1 and AKT/MAPK/TGFBR1 and immune infiltration.
RESULTS: XPO1 mRNA and protein expression levels were significantly enhanced in OSCC and associated with OSCC severity. Enhanced XPO1 expression was indicative of poor survival. Functional analysis showed that XPO1 mediated pathways associated with cell cycle and DNA replication and reduced immune infiltration in OSCC. Additionally, XPO1 mRNA and protein expression levels had significant positive relationships with AKT/MAPK/TGFBR1.
CONCLUSIONS: XPO1, as a marker of poor prognosis in OSCC, can promote OSCC through AKT/MAPK/TGFBR1.

Flaviviridae is a family of positive-stranded RNA viruses, including human pathogens, such as Japanese encephalitis virus (JEV), dengue virus (DENV), Zika virus (ZIKV), and West Nile virus (WNV). Nuclear localization of the viral core protein is conserved among Flaviviridae, and this feature may be targeted for developing broad-ranging anti-flavivirus drugs. However, the mechanism of core protein translocation to the nucleus and the importance of nuclear translocation in the viral life cycle remain unknown. We aimed to identify the molecular mechanism underlying core protein nuclear translocation. We identified importin-7 (IPO7), an importin-β family protein, as a nuclear carrier for Flaviviridae core proteins. Nuclear import assays revealed that core protein was transported into the nucleus via IPO7, whereas IPO7 deletion by CRISPR/Cas9 impaired their nuclear translocation. To understand the importance of core protein nuclear translocation, we evaluated the production of infectious virus or single-round-infectious-particles in wild-type or IPO7-deficient cells; both processes were significantly impaired in IPO7-deficient cells, whereas intracellular infectious virus levels were equivalent in wild-type and IPO7-deficient cells. These results suggest that IPO7-mediated nuclear translocation of core proteins is involved in the release of infectious virus particles of flaviviruses.

Though RNAi and RNA-splicing machineries are involved in regulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication, their precise roles in coronavirus disease 2019 (COVID-19) pathogenesis remain unclear. Herein, we show that decreased RNAi component (Dicer and XPO5) and splicing factor (SRSF3 and hnRNPA3) expression correlate with increased COVID-19 severity. SARS-CoV-2 N protein induces the autophagic degradation of Dicer, XPO5, SRSF3, and hnRNPA3, inhibiting miRNA biogenesis and RNA splicing and triggering DNA damage, proteotoxic stress, and pneumonia. Dicer, XPO5, SRSF3, and hnRNPA3 knockdown increases, while their overexpression decreases, N protein-induced pneumonia\'s severity. Older mice show lower expression of Dicer, XPO5, SRSF3, and hnRNPA3 in their lung tissues and exhibit more severe N protein-induced pneumonia than younger mice. PJ34, a poly(ADP-ribose) polymerase inhibitor, or anastrozole, an aromatase inhibitor, ameliorates N protein- or SARS-CoV-2-induced pneumonia by restoring Dicer, XPO5, SRSF3, and hnRNPA3 expression. These findings will aid in developing improved treatments for SARS-CoV-2-associated pneumonia.

Nuclear export of the viral ribonucleoprotein (vRNP) is a critical step in the influenza A virus (IAV) life cycle and may be an effective target for the development of anti-IAV drugs. The host factor ras-related nuclear protein (RAN) is known to participate in the life cycle of several viruses, but its role in influenza virus replication remains unknown. In the present study, we aimed to determine the function of RAN in influenza virus replication using different cell lines and subtype strains. We found that RAN is essential for the nuclear export of vRNP, as it enhances the binding affinity of XPO1 toward the viral nuclear export protein NS2. Depletion of RAN constrained the vRNP complex in the nucleus and attenuated the replication of various subtypes of influenza virus. Using in silico compound screening, we identified that bepotastine could dissociate the RAN-XPO1-vRNP trimeric complex and exhibit potent antiviral activity against influenza virus both in vitro and in vivo. This study demonstrates the important role of RAN in IAV replication and suggests its potential use as an antiviral target.

Covalent drug discovery has experienced a renaissance, with numerous electrophilic small molecules recently gaining FDA approval. Many structurally diverse electrophilic small molecules target exportin-1 (XPO1/CRM1) at cysteine 528, including the selective inhibitor of nuclear export (SINE) selinexor, which was FDA-approved as an anticancer agent in 2019. Emerging evidence supports additional pharmacological classes of XPO1 modulators targeting Cys528, including the selective inhibitors of transcriptional activation (SITAs) and probes that induce rapid degradation of XPO1. Here, we analyzed structure-activity relationships across multiple structural series of XPO1 Cys528-targeting probes. We observe that the electrophilic moiety of Cys528-targeting small molecules plays a decisive role in the cellular behavior observed, with subtle changes in electrophile structure being sufficient to convert XPO1-targeting probes to different pharmacological classes. This investigation represents a unique case study in which the electrophile functionality used to target a specific cysteine determines the pharmacological effect among diverse XPO1-targeting small molecules.

SF3B1 mutations frequently occur in cancer yet lack targeted therapies. Clinical trials of XPO1 inhibitors, selinexor and eltanexor, in high-risk myelodysplastic neoplasms (MDS) revealed responders were enriched with SF3B1 mutations. Given that XPO1 (Exportin-1) is a nuclear exporter responsible for the export of proteins and multiple RNA species, this led to the hypothesis that SF3B1-mutant cells are sensitive to XPO1 inhibition, potentially due to altered splicing. Subsequent RNA sequencing after XPO1 inhibition in SF3B1 wildtype and mutant cells showed increased nuclear retention of RNA transcripts and increased alternative splicing in the SF3B1 mutant cells particularly of genes that impact apoptotic pathways. To identify novel drug combinations that synergize with XPO1 inhibition, a forward genetic screen was performed with eltanexor treatment implicating anti-apoptotic targets BCL2 and BCLXL, which were validated by functional testing in vitro and in vivo. These targets were tested in vivo using Sf3b1K700E conditional knock-in mice, which showed that the combination of eltanexor and venetoclax (BCL2 inhibitor) had a preferential sensitivity for SF3B1 mutant cells without excessive toxicity. In this study, we unveil the mechanisms underlying sensitization to XPO1 inhibition in SF3B1-mutant MDS and preclinically rationalize the combination of eltanexor and venetoclax for high-risk MDS.