A PilZ domain protein interacts with the transcriptional regulator HinK to regulate type VI secretion system in Pseudomonas aeruginosa.

Type VI secretion systems (T6SS) are bacterial macromolecular complexes that secrete effectors into target cells or the extracellular environment, leading to the demise of adjacent cells and providing a survival advantage. Although studies have shown that the T6SS in Pseudomonas aeruginosa is regulated by the Quorum Sensing system and second messenger c-di-GMP, the underlying molecular mechanism remains largely unknown. In this study, we discovered that the c-di-GMP-binding adaptor protein PA0012 has a repressive effect on the expression of the T6SS HSI-I genes in P. aeruginosa PAO1. To probe the mechanism by which PA0012 (renamed TssZ, Type Six Secretion System -associated PilZ protein) regulates the expression of HSI-I genes, we conducted yeast two-hybrid screening and identified HinK, a LasR-type transcriptional regulator, as the binding partner of TssZ. The protein-protein interaction between HinK and TssZ was confirmed through co-immunoprecipitation assays. Further analysis suggested that the HinK-TssZ interaction was weakened at high c-di-GMP concentrations, contrary to the current paradigm wherein c-di-GMP enhances the interaction between PilZ proteins and their partners. Electrophoretic mobility shift assays revealed that the non-c-di-GMP-binding mutant TssZR5A/R9A interacts directly with HinK and prevents it from binding to the promoter of the quorum-sensing regulator pqsR. The functional connection between TssZ and HinK is further supported by observations that TssZ and HinK impact the swarming motility, pyocyanin production, and T6SS-mediated bacterial killing activity of P. aeruginosa in a PqsR-dependent manner. Together, these results unveil a novel regulatory mechanism wherein TssZ functions as an inhibitor that interacts with HinK to control gene expression.

Analysis of Ethylene Signal Regulating Sucrose Metabolism in Strawberry Fruits Based on RNA-seq.

Ethylene is a key hormone that regulates the maturation and quality formation of horticultural crops, but its effects on non-respiratory climacteric fruits such as strawberries are not yet clear. In this study, strawberry fruits were treated with exogenous ethephon (ETH) and 1-methylcyclopropene (1-MCP). It was found that ETH treatment increased the soluble solids and anthocyanin content of the fruits, reduced hardness, and decreased organic acid content, while 1-MCP treatment inhibited these processes. Transcriptome analysis revealed that differentially expressed genes (DEGs) were enriched in the starch-sucrose metabolism pathway. qRT-PCR results further showed significant changes in the expression levels of sucrose metabolism genes, confirming the influence of ethylene signals on soluble sugar accumulation during strawberry fruit development. This study elucidates the quality changes and molecular mechanisms of ethylene signal in the development of strawberry fruits, providing some key targets and theoretical support for guiding strawberry cultivation and variety improvement.

Nanodrug-bacteria conjugates-mediated oncogenic collagen depletion enhances immune checkpoint blockade therapy against pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) cancer cells specifically produce abnormal oncogenic collagen to bind with integrin α3ß1 receptor and activate the downstream focal adhesion kinase (FAK), protein kinase B (AKT), and mitogen-activated protein kinase (MAPK) signaling pathway. Collectively, this promotes immunosuppression and tumor proliferation and restricts the response rate of clinical cancer immunotherapies. METHODS: Here, by leveraging the hypoxia tropism and excellent motility of the probiotic Escherichia coli strain Nissle 1917 (ECN), we developed nanodrug-bacteria conjugates to penetrate the extracellular matrix (ECM) and shuttle the surface-conjugated protein cages composed of collagenases and anti-programmed death-ligand 1 (PD-L1) antibodies to PDAC tumor parenchyma. FINDINGS: We found the oncogenic collagen expression in human pancreatic cancer patients and demonstrated its interaction with integrin α3ß1. We proved that reactive oxygen species (ROS) in the microenvironment of PDAC triggered collagenase release to degrade oncogenic collagen and block integrin α3ß1-FAK signaling pathway, thus overcoming the immunosuppression and synergizing with anti-PD-L1 immunotherapy. CONCLUSIONS: Collectively, our study highlights the significance of oncogenic collagen in PDAC immunotherapy, and consequently, we developed a therapeutic strategy that can deplete oncogenic collagen to synergize with immune checkpoint blockade for enhanced PDAC treatment efficacy. FUNDING: This work was supported by the University of Wisconsin Carbone Cancer Center Research Collaborative and Pancreas Cancer Research Task Force, UWCCC Transdisciplinary Cancer Immunology-Immunotherapy Pilot Project, and the start-up package from the University of Wisconsin-Madison (to Q.H.).

Estrogen receptor-negative/progesterone receptor-positive breast cancer has distinct characteristics and pathologic complete response rate after neoadjuvant chemotherapy.

PURPOSE: The status of hormone receptors (HR) is an independent factor affecting survival and chemotherapy sensitivity in breast cancer (BC) patients, with estrogen receptor (ER) and progesterone receptor (PR) having the most significant effects. The ER-/PR + phenotype has been controversial in BC, and experts will face many challenges in determining treatment strategies. Herein, we systematically analyzed the clinicopathological characteristics of the ER-/PR + phenotype in BC patients and the response to chemotherapy. PATIENTS AND METHODS: We included two cohorts. The first cohort counted the relationship between clinicopathologic data and survival outcomes for 72,666 female patients in the Surveillance, Epidemiology, and End Results (SEER) database. The second cohort analyzed the relationship between clinicopathological data and pathologic complete response (pCR) rate in 879 patients at the Harbin Medical University Cancer Hospital. The classification data were compared by the chi-square test and Fister's exact test of the Logistic regression model, and predictor variables with P < 0.05 in the univariate analysis were included in the multivariate regression analysis. The Kaplan-Meier method evaluated breast cancer-specific survival (BCSS) and overall survival (OS) to investigate the relationship between different HR typing and survival and pCR. RESULTS: In the two cohorts, 704 (0.9%) and 11 (1.3%) patients had the ER-/PR + phenotype, respectively. The clinicopathologic features of patients with the ER-/PR + phenotype are more similar to those of the ER-/PR- phenotype. The ER-/PR + phenotype is more common in younger and premenopausal women, and most ER-/PR + phenotypes exhibit higher histological grades. Survival analysis showed that there were significant differences in OS and BCSS among patients with different HR states (P < 0.001). The survival results of patients with the ER + /PR + phenotype were the best. The prognosis of the ER-/PR + phenotype was similar to that of the ER-/PR- phenotype. On the other hand, we found that HR status was also an independent predictor of post-NAC pCR rate in BC patients. The ER + /PR- and ER-/PR- phenotypes were more sensitive to chemotherapy than the ER + /PR + phenotypes. CONCLUSION: HR status is the main factor affecting BC's survival outcome and pCR rate. Patients with the ER-/PR + phenotype possess more aggressive biological factors and can benefit significantly from chemotherapy. We need to pay more attention to this group and achieve individualized treatment, which will help us treat BC better and provide new targets and blueprints for our clinical treatment.