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Histone post-translational modifications (PTMs) influence the overall structure of the chromatin and gene expression. Over the course of cell differentiation, the distribution of histone modifications is remodeled, resulting in cell type-specific patterns. In the past, their study was limited to abundant cell types that could be purified in necessary numbers. However, studying these cell type-specific dynamic changes in heterogeneous in vivo settings requires sensitive single-cell methods. Current advances in single-cell sequencing methods remove these limitations, allowing the study of nonpurifiable cell types. One complicating factor is that some of the most biologically interesting cell types, including stem and progenitor cells that undergo differentiation, only make up a small fraction of cells in a tissue. This makes whole-tissue analysis rather inefficient. In this chapter, we present a sort-assisted single-cell Chromatin ImmunoCleavage sequencing technique (sortChIC) to map histone PTMs in single cells. This technique combines the mapping of histone PTM location in combination with surface staining-based enrichment, to allow the integration of established strategies for rare cell type enrichment. In general terms, this will enable researchers to quantify local and global chromatin changes in dynamic complex biological systems and can provide additional information on their contribution to lineage and cell-type specification in physiological conditions and disease., (© 2024. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Human retinoblastoma gene RB1 is the first tumor suppressor gene (TSG) isolated by positional cloning in 1986. RB is extensively studied for its ability to regulate cell cycle by binding to E2F1 and inhibiting the transcriptional activity of the latter. In human embryonic stem cells (ESCs), only a minute trace of RB is found in complex with E2F1. Increased activity of RB triggers differentiation, cell cycle arrest, and cell death. On the other hand, inactivation of the entire RB family (RB1, RBL1, and RBL2) in human ESC induces G2/M arrest and cell death. These observations indicate that both loss and overactivity of RB could be lethal for the stemness of cells. A question arises why inactive RB is required for the survival and stemness of cells? To shed some light on this question, we analyzed the RB-binding proteins. In this review we have focused on 27 RB-binding partners that may have potential roles in different aspects of stem cell biology., (© 2016 Elsevier Inc. All rights reserved.)