Project description:Drought is a major abiotic stress that threatens crop production. Soil microbiomes are thought to play a role in enhancing plant adaptation to various stresses. However, it remains unclear whether soil microbiomes play a key role when plants are challenged by drought and whether different varieties are enriched with specific bacteria at the rhizosphere. In this study, we measured changes in growth phenotypes, physiological and biochemical characteristics of drought-tolerant alfalfa (AH) and drought-sensitive (QS) under sterilized and unsterilized soil conditions with adequate watering and with drought stress, and analyzed the rhizosphere bacterial community composition and changes using 16S rRNA high-throughput sequencing. We observed that the unsterilized treatment significantly improved the growth, and physiological and biochemical characteristics of alfalfa seedlings under drought stress compared to the sterilized treatment. Under drought stress, the fresh and dry weight of seedlings increased by 35.24, 29.04, and 11.64%, 2.74% for unsterilized AH and QS, respectively, compared to sterilized treatments. The improvement was greater for AH than for QS. AH and QS recruited different rhizosphere bacteria when challenged by drought. Interestingly, under well-watered conditions, the AH rhizosphere was already rich in drought-tolerant bacterial communities, mainly Proteobacteria and Bacteroidetes, whereas these bacteria started to increase only when QS was subjected to drought. When drought stress was applied, AH was enriched with more drought-tolerant bacteria, mainly Acidobacteria, while the enrichment was weaker in QS rhizosphere. Therefore, the increase in drought tolerance of the drought-tolerant variety AH was greater than that of the drought-sensitive variety QS. Overall, this study confirmed the key role of drought-induced rhizosphere bacteria in improving the adaptation of alfalfa to drought stress, and clarified that this process is significantly related to the variety (genotype). The results of this study provide a basis for improving drought tolerance in alfalfa by regulating the rhizosphere microbiome.

Project description:We previously identified stress keratin 17 (K17) as a host factor that contributes to immune evasion in the context of mouse papillomavirus-induced disease. Analyses of head and neck squamous cell carcinoma (HNSCC) patient TCGA and tissue microarray data revealed that K17 can be overexpressed in both HPV+ and HPV- human cancer samples, with a more profound upregulation in HPV- HNSCC samples. In this report, we investigated the role of K17 in regulating immune response in HPV- head and neck cancer. To test whether K17 mediates immune evasion and resistance to immune checkpoint blockade (ICB) therapy in HPV- HNC, we used MOC2, a K17-expressing murine HNC cell line, and knocked out the K17 gene from it using CRISPR/Cas9 (K17KO MOC2 cells). Then we injected K17KO MOC2 cells or parental MOC2 cells into NSG and C57BL/6 mice and monitored tumor growth, immune cell infiltration, and response to ICB treatment in vivo. In NSG mice, the K17KO MOC2 cell lines grew as fast as parental MOC2 tumors. In C57BL/6 mice, K17KO MOC2 tumors grew significantly slower than parental MOC2 tumors, with 50% tumor rejection rate, in a T-cell dependent manner. Flow cytometry of tumor infiltrating T cells and bulk tumor RNA seq analyses show an active anti-tumor microenvironment in the K17KO MOC2 tumors, compared to parental MOC2 tumors. In addition, we observed that 5 out of 5 anti-PD1 + anti-CTLA4 treated K17KO MOC2 tumors completely regressed, while only 1 out of 5 parental MOC2 tumors similarly treated at the same size completely regressed (p<0.05). In exploring the role of chemokine CXCL9 in increased T cell infiltration, we blocked the receptor CXCR3, a receptor often upregulated on activated T cells, and saw a delay in the immune-mediated rejection K17KO MOC2 tumors. Single cell RNA seq analyses revealed a completely different immune landscape including both lymphoid and myeloid populations in K17KO MOC2 tumors. Overall, we demonstrated that K17 expression in HNSCC contributes to immune evasion and resistance to immune checkpoint blockade treatment through modulating the immune landscape in the tumor microenvironment.

Dataset Information

Stress keratin 17 enhances papillomavirus infection-induced disease by downregulating T cell recruitment.

Publications

Stress keratin 17 enhances papillomavirus infection-induced disease by downregulating T cell recruitment.

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