Nitrate (NO3-) and ammonium (NH4+) are major inorganic nitrogen (N) supplies for plants, but NH4+ as the sole or dominant N source causes growth inhibition in many plants, known as ammonium toxicity. Small amounts of NO3- can significantly mitigate ammonium toxicity, and the anion channel SLAC1 homologue 3 (SLAH3) is involved in this process, but the mechanistic detail of how SLAH3 regulates nitrate-dependent alleviation of ammonium toxicity is still largely unknown. In this study, we identified SnRK1.1, a central regulator involved in energy homeostasis and various stress responses, as a SLAH3-interactor in Arabidopsis (Arabidopsis thaliana). Our results suggest that SNF1-related protein kinase 1 (SnRK1.1) functions as a negative regulator of SLAH3. Kinase assays indicate SnRK1.1 strongly phosphorylates the C-terminal of SLAH3 at the site S601. Under high-NH4+/low-pH condition, phospho-mimetic and phospho-dead mutations in SLAH3 S601 result in barely rescued phenotypes and fully complemented phenotypes in slah3. Furthermore, SnRK1.1 migrates from cytoplasm to nucleus under high-NH4+/low-pH conditions. The translocation of SnRK1.1 from cytosol to nucleus under high-ammonium stress releases the inhibition on SLAH3, which allows SLAH3-mediated NO3- efflux leading to alleviation of high-NH4+/low-pH stress. Our study reveals that the C-terminal phosphorylation also plays important role in SLAH3 regulation and provides additional insights into nitrate-dependent alleviation of ammonium toxicity in plants.

Poly(ADP-ribose) polymerase-1 (PARP-1), a critical DNA repair enzyme in the base excision repair pathway, has been pursued as an attractive cancer therapeutic target. Intervention with PARP-1 has been proved to be more sensitive to cancer cells carrying BRCA1/2 mutations. Several PARP-1 inhibitors have been available on market for the treatment of breast, ovarian and prostatic cancer. Promisingly, the newly developed proteolysis targeting chimaeras (PROTACs) may provide a more potential strategy based on the degradation of PARP-1. Here we report the design, synthesis, and evaluation of a proteolysis targeting chimaera (PROTAC) based on the combination of PARP-1 inhibitor olaparib and the CRBN (cereblon) ligand lenalidomide. In SW620 cells, our probe-quality degrader compound 2 effectively induced PARP-1 degradation which results in anti-proliferation, cells apoptosis, cell cycle arresting, and cancer cells migratory inhibition. Thus, our findings qualify a new chemical probe for PARP-1 knockdown.

BackgroundThe epigenetic regulatory chemical lactate is a product of glycolysis. It can regulate gene expression through histone lactylation, thereby promoting tumor proliferation, metastasis, and immunosuppression.MethodsIn this study, a lactylation-related model for gastric cancer (GC) was constructed, and its relationships to prognosis, immune cell infiltration, and immunotherapy were investigated. By contrasting normal tissues and tumor tissues, four lactylation-related pathways that were substantially expressed in GC tissues were found in the GSEA database. Six lactylation-related genes were screened for bioinformatic analysis. The GC data sets from the TCGA and GEO databases were downloaded and integrated to perform cluster analysis, and the lactylation related model was constructed by secondary clustering.ResultsThe fingding demonstrated that the lactylation score has a strong correlation with the overall survival rate from GC and the progression of GC. Mechanistic experiments showed that abundant immune cell infiltration (macrophages showed the highest degree of infiltration) and increased genetic instability are traits of high lactylation scores. Immune checkpoint inhibitors (ICIs) demonstrated a reduced response rate in GC with high lactylation scores. At the same time, tumors with high lactylation scores had high Tumor Immune Dysfunction and Exclusion scores, which means that they had a higher risk of immune evasion and dysfunction.DiscussionThese findings indicate that the lactylation score can be used to predict the malignant progression and immune evasion of GC. This model also can guide the treatment response to ICIs of GC. The constructed model of the lactate gene is also expected to become a potential therapeutic target for GC and diagnostic marker.

Cancer stem cells (CSCs) play a critical role in cancer development and growth. The aim of this study was to identify and isolate cScs from populations of primary oral squamous cell carcinoma (OSCC) cells, which were obtained from OSCC specimens and identified by cell morphology and immunohistochemical staining for keratin. CD133 + cells detected by flow cytometry comprised 0.41 ± 0.06% of primary OSCC cells and were isolated from primary OSCC cell populations using magnetic-activated cell sorting, revealing that 93.39% of high-purity CD133 + cells were in the G0/ G1 phase of the cell cycle. Additionally, the growth rate of CD133 + cells was higher than that of CD133 − cells, and in vivo tumourigenesis experiments showed that the tumourigenic ability of CD133 + cells was markedly stronger than that of CD133 − cells. Moreover, CD133 + cells showed increased chemotherapeutic resistance to cisplatin and higher self-renewal ability according to sphere-formation assay, as well as higher mRNA levels of stemness-associated genes, including NANOG, SOX2, ALDH1A1, and OCT4. These results indicated that OSCC cells, which share certain characteristics of CSCs, harbour CD133 + cells potentially responsible for OSCC aggressiveness, suggesting CD133 as a potential prognostic marker and therapeutic target. Head and neck cancer (HNC) is the sixth most common malignancy worldwide, with oral squamous cell carcinoma (OSCC) the most common type of HNC and accounting for >90% of all oral cancers 1,2. Smoking, drinking, and chewing areca nuts are considered risk factors for OSCC, which can affect any part of the mouth, including the lips, tongue, and throat 3. Furthermore, when patients develop OSCC, they experience maxillofacial deformity and psychological trauma in addition to common symptoms of cancer. Although there have been advances in surgical techniques and chemotherapeutic strategies for OSCC, the patient survival rate remains low 4. Cisplatin is the first-line chemotherapeutic drug currently used to treat patients with locally advanced, resectable OSCC; however, cisplatin resistance poses a major challenge for its clinical application 5 and is considered the critical cause of tumour recurrence in OSCC patients 6. Therefore, a better understanding of the mechanisms underlying OSCC recurrence is required to develop novel therapeutic strategies 7. Studies have increasingly focused on the roles of cancer stem cells (CSCs) in cancer invasion and recurrence 8. CSCs represent highly heterogeneous subpopulations with functional heterogeneity in their respective tumours and are characterised by infinite proliferation, self-renewal, chemotherapeutic resistance, and multidirectionality 9. The role of CSCs was previously demonstrated in the development and therapeutic resistance of liver cancer 10. Similar to their roles in other malignancies, CSCs also play a pivotal role in OSCC development and progression 11,12. The study of CSCs, also referred to as tumour-initiating cells 13 , has recently become among the most popular research dire...

To investigate possible mechanism of abnormal methylation of long non-coding RNA (lncRNA) on endometrial carcinoma (EC) progression, we detected the genome methylation profiling of endometrial carcinoma by bioinformatic analysis. Accordingly, gene LOC134466 was chosen for the further research. We also found that TAC1 was the target gene of LOC134466 and miRNA, hsa-miR-196a-5p, might form a connection between LOC134466 and TAC1. The relationship was further proved by dual-luciferase reporter assay. In vitro studies, DNA methylation and expression were determined by MSP and qRT-PCR respectively. Cell proliferation, apoptosis and cell cycle were demonstrated by colony formation assay, Annexin V/PI double staining and flow cytometry. Besides, the function of LOC134466 and TAC1 in EC was further confirmed by Tumor Xenograft. Our results indicated that EC progression was promoted by hypermethylated LOC134466 and TAC1. Moreover, TAC1 transcription was regulated by LOC134466 via hsa-miR-196a-5p binding. LOC134466 and TAC1 demethylation by 5-Aza-2-Deoxycytidine inhibited EC cells proliferation and accelerated cell apoptosis. Furthermore, the expression of TACR1, TACR2 and TACR3 was remarkably decreased through LOC134466 and TAC1 treatments. Our findings establish a novel regulatory axis, LOC134466/hsa-miR-196a-5p/TAC1. Downregulation of the axis promoted EC development through TACR3, which further activated neuroactive ligand-receptor interaction.