Project description:Using killer cell lectin-like receptor G1 as a marker to distinguish terminal effector cells from memory precursors, we found that despite their diverse cell fates both subsets possessed remarkably similar gene expression profiles and functioned as equally potent killer cells. However, only the memory precursors were capable of making IL-2 thus defining a novel effector cell that was cytotoxic, expressed granzyme B, and produced inflammatory cytokines in addition to IL-2. This effector population then differentiated into long-lived protective memory T cells capable of self-renewal and rapid re-call responses. Mechanistic studies showed that cells that continued to receive antigenic stimulation during the later stages of infection were more likely to become terminal effectors. Importantly, curtailing antigenic stimulation towards the tail-end of the acute infection enhanced the generation of memory cells. These studies support the decreasing potential model of memory differentiation and show that the duration of antigenic stimulation is a critical regulator of memory formation Experiment Overall Design: An important question in memory development is understanding the differences between effector CD8 T cells that die versus effector cells that survive and give rise to memory cells. In this study we provide a comprehensive phenotypic, functional and genomic profiling of terminal effectors and memory precursors, towards better understanding the generation of these subsets. The two effector subsets were FACS purified during the early expansion phase (Days 4-5 post-infection) and extensively analyzed for their phenotypic (eg. CD127, CD62L, CD27, Bcl-2, Granzyme B, etc.) and functional properties (cytokine production, cytotoxicity, homeostatic proliferation, recall proliferation), and gene expression profiles (by genome-wide microarray analyses). Mechanistic studies involving the extent of proliferation and duration of antigen stimulation on memory differentiation potential of effectors were also performed using adoptive transfer techniques.

Project description:Background: Retinoblastoma (Rb) is a malignant neoplasm arising during retinal development from mutations in the RB1 gene. Loss or inactivation of both copies of RB1 results in initiation of retinoblastoma tumours, however additional genetic changes are needed for the continued growth and spread of the tumour. Ex vivo research has shown that in humans, retinoblastoma may initiate from Rb depleted cone precursors. Notwithstanding, it has not been possible to assess the full spectrum of clonal types within the tumour itself in vivo and the molecular changes occurring at the cells of origin, enabling their malignant conversion. To overcome these challenges, we have performed the first single cell (sc) RNA- and ATAC-Seq analyses of primary tumour tissues, enabling us to dissect the transcriptional and chromatin accessibility heterogeneity of proliferating cone precursors in human Rb tumours. Methods: Two Rb tumours each characterised by two pathogenic RB1 mutations were dissociated to single cells and subjected to scRNA-Seq & scATAC-Seq using the 10x Genomics platform. In addition, nine embryonic and fetal retina samples were dissociated to single cells and subjected to scRNA- and ATAC-Seq analyses. The scRNA- and ATAC-Seq data were embedded using Uniform Manifold Approximation and Projection (UMAP) and clustered using Seurat graph based-clustering. Integrated scATAC-Seq analysis of Rb tumours and human embryonic/fetal retina samples was performed to identify Rb cone enriched subsets. Pseudotime analysis of proliferating cones in the Rb samples was performed with Monocle. Ingenuity Pathway Analysis (IPA) was used to identify the signalling pathway and upstream regulators in the Rb cone enriched subclusters. Results: Our single cell analyses revealed the predominant presence of cone precursors at different stages of the cell cycle in the Rb tumours and amongst those identified the G2/M subset as the cell type of origin. scATAC-Seq analysis identified two Rb enriched cone subsets, each characterised by activation of different upstream regulators and signalling pathways, leading proliferating cone precursors to escape cell cycle arrest and/or apoptosis. Conclusions: Our study provides evidence of Rb tumor heterogeneity and defines molecular pathways that can be targeted to define new treatment strategies

			Action	DRS
	SRR23560931.fastq.gz	Fastqsanger.gz
	SRR23560931_1.fastq.gz	Fastqsanger.gz
	SRR23560931_2.fastq.gz	Fastqsanger.gz
	SRR23560932.fastq.gz	Fastqsanger.gz
	SRR23560932_1.fastq.gz	Fastqsanger.gz

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Memory B cell subsets to their proliferating precursors

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