Project description:CT26 cells expressing lentiviral Cas9 and sgRNAs targeting either control or Gna13 were transplanted into immunocompetent BALB/c mice. Tumors were harvested and processed for RNA-seq
Project description:Increasing evidence suggests that microRNAs may play important roles in regulating self-renewal and differentiation in mammalian stem cells (SCs). Here, we explore this issue in skin. We first characterize microRNA expression profiles of skin SCs versus their committed proliferative progenies and identify a microRNA subset associating with “stemness”. Of these, miR-125b is dramatically downregulated in early SC-progeny. We engineer an inducible mice system and show that when miR-125b is sustained in SC-progenies, tissue balance is reversibly skewed towards stemness at the expense of epidermal, oil-gland and HF differentiation. Using gain-and-loss of function in vitro, we further implicate miR-125b as a repressor of SC differentiation. In vivo, transcripts repressed upon miR-125b induction are enriched >700% for predicted miR-125b targets normally downregulated upon SC-lineage commitment. We verify some of these miR-125b targets, and show that Blimp1 and VDR in particular can account for many tissue imbalances we see when miR-125b is deregulated. We used microarrays to compare the global miRNA expression profile of P4 stage hair follicle ORS cells from DTG (K14-rtTA,TRE-miR-125b) and control littermates. Hair follicle cells were isolated from P4 Backskin (Dox since P3 for 24hrs) of DTG (K14-rtTA/TRE-miR-125b/K14-H2BGFP), TRE (TRE-miR-125b/K14-H2BGFP), KrtA (K14-rtTA/K14-H2BGFP) as following: interfollicular epidermis sheet was pealed from hair follicle & dermis after dispase treatment.The hair follicle & dermis were first digested by collagenase (Sigma). Intact hair follicles were separated from dermal cells by low speed spinning (20g). The hair follicles were then digested by Trypsin and filtered by 40 µm cell strainers. The isolated hair follicle cells were FACS sorted. During FACS, cells were first gated against CD34 (endothelial cells), CD45 (immune cells), CD114 (melanocytes) and DAPI (dead cells). ORS cells were sorted from the remaining cells as α6HiGFPHi.
Project description:MHC I-associated peptides (MAPs) presented at the surface of nucleated cells play a central role in CD8 T-cell immunosurveillance. MAPs presented by mature (i.e. MHC IIhi) medullary thymic epithelial cells (mTEChi) are essential to eliminate self-reactive CD8 T cells in a process called central tolerance. On tumor cells, MAPs that do not induce tolerance (i.e. non-tolerogenic MAPs), because absent from mTEChi or any other normal cells, are referred to as tumor-specific antigens (TSAs). Despite their clinical relevance, very few have been identified, even in highly mutated tumor types. Thus, we developed a novel proteogenomic workflow able to characterize the full TSA landscape of any tumor. Briefly, using RNA-seq data, we subtracted the mTEChi from the tumor signal to generate tumor-specific protein databases enriched in non-tolerogenic sequences. Using these databases to analyze the MAP repertoire of two murine cell lines (CT26 and EL4) sequenced by mass spectrometry, we identified a total of 21 TSAs, 90% of which derived from allegedly non-coding regions. Interestingly, our results highlighted that 70% of those TSAs derived from non-mutated yet tumor-restricted sequences, e.g. endogenous retroelements. Focusing on 5 TSAs, we demonstrated that both TSA expression and TSA-specific T-cell frequency in the pre-immune repertoire influenced the overall survival of pre-immunized tumor-bearing mice. In conclusion, this proof-of-concept study demonstrates that non-coding-derived TSAs are frequent and protective in vivo, while they could be shared by several individuals. Altogether, our findings will help expand the repertoire of human TSAs and facilitate their prioritization in the clinic
Project description:Goal: Microsatellite-instable (MSI) tumors are one of the few cancers that respond to immune checkpoint blockade (ICB); however, the mechanism of MSI status development is unclear. Here, we report that protein phosphatase 2A (PP2A) deletion or inactivation converted cold microsatellite-stable (MSS) into MSI tumors. Objectives: Using RNA sequencing data of three CT26-shppp2r1a data and a CT26-scr data, we demonstrate that these intestinal tumors display differential core driver pathways.