Project description:Tumor microenvironment (TME) plays critical roles in both tumor progression and immunotherapeutic efficacy. Here using single-cell RNA sequencing (scRNA-seq), we described the TME heterogeneity and found a specific state of CCL22+ dendritic cell (mregDC) cross talk close to regulatory T cells (Treg). We analyzed cell–cell communication mediated by ligand–receptor interactions and finally found that mregDCs probably attract Treg cells via chemotaxis and physically interact with them in tumor. Within this cross talk, Treg cells received activation signals from mregDCs and upregulated suppressive and adhesion molecules, including PD-1, ICOS, CTLA-4 and OX-40, further enhancing their interaction with mregDCs. In turn, the association of Treg cells with mregDCs restrained the trafficking of tumor antigen-bearing dendritic cells to draining mesenteric lymph nodes and thus dampened the presentation of tumor antigens to initiate anti-tumor immune responses in a cell contact dependent manner.
Project description:To investigate the clonality of tumor Treg cells, we performed TCRseq on tumor Treg cells from Apc Min/+ mice versus normal colonic Treg cells from WT mice.
Project description:To investigate the mechanism by which Treg cell positioning is regulated in our manuscript,we performed RNAseq on tumor Treg cells from Apc Min/+ Foxp3 DTR mice versus normal colonic Treg cells from Foxp3 DTR mice.
Project description:Peripheral myelin protein 22 (PMP22) is a tetraspan integral membrane protein for which mistrafficking-causing mutations are linked to the inherited peripheral neuropathy, Charcot-Marie-Tooth disease (CMTD). Wild type (WT) PMP22 is an inefficient folder with ~20% of the protein trafficking to the plasma membrane. We discovered that N-linked glycosylation significantly limits forward trafficking of WT and disease variants of PMP22. N-glycosylation of WT PMP22 was found to occur primarily post-translationally. Glycosylation inhibition dramatically increased PMP22 trafficking efficiency. Quantitative proteomics identified novel PMP22 interacting proteins that may impact trafficking. Our results suggest that critical quality control decisions for unstable L16P PMP22 occur at earlier stages in the trafficking pathway than for the WT protein. Knock-out cell lines of likely PMP22 interactors led to the discovery that calnexin limits trafficking of stable PMP22 variants, UGGT1 promotes trafficking and RER1 limits trafficking of all PMP22 variants. This work establishes N-glycosylation as a key determinant of PMP22 retention in the ER, ultimately limiting forward surface-trafficking.