Natural killer (NK) cells are circulating cytotoxic lymphocytes that exert potent and nonredundant antiviral activity and antitumoral activity in the mouse; however, their function in host defense in humans remains unclear. Here, we investigated 6 related patients with autosomal recessive growth retardation, adrenal insufficiency, and a selective NK cell deficiency characterized by a lack of the CD56 dim NK subset. Using linkage analysis and fine mapping, we identified the disease-causing gene, MCM4, which encodes a component of the MCM2-7 helicase complex required for DNA replication. A splice-site mutation in the patients produced a frameshift, but the mutation was hypomorphic due to the creation of two new translation initiation methionine codons downstream of the premature termination codon. The patients' fibroblasts exhibited genomic instability, which was rescued by expression of WT MCM4. These data indicate that the patients' growth retardation and adrenal insufficiency likely reflect the ubiquitous but heterogeneous impact of the MCM4 mutation in various tissues. In addition, the specific loss of the NK CD56 dim subset in patients was associated with a lower rate of NK CD56 bright cell proliferation, and the maturation of NK CD56 bright cells toward an NK CD56 dim phenotype was tightly dependent on MCM4-dependent cell division. Thus, partial MCM4 deficiency results in a genetic syndrome of growth retardation with adrenal insufficiency and selective NK deficiency.

Background: Orc1 is the largest subunit of the origin recognition complex that promotes genome duplication. Results: We studied the dynamics of Orc1 during the cell division cycle. Conclusion: Orc1 binds to mitotic chromosomes, and during G 1 phase in the daughter cells it then forms spatial-temporal patterns in the nucleus. Significance: The large subunit of ORC orchestrates the earliest stages of chromosome inheritance.

Cancer is associated with concomitant myeloid cell responses that are characterized by an expansion of tumor associated myeloid cells including, myeloid derived suppressor cells (MDSCs), tumor associated macrophages (TAMs) and neutrophils (TANs). These myeloid derived cells are known to modulate immune responses that enhance cancer cell stemness, angiogenesis, metastasis, invasion and immune escape. The prevailing paradigm is that cancer interferes with hematopoiesis and skews the host system to generate cells of myeloid origin with tumor-promoting functions. Intriguingly, tumor derived factors can perturbate normal bone marrow hematopoiesis and promote extramedullary hematopoiesis in organs such as the spleen. Advances in single cell multiomic technologies now enable the analysis of high dimensional protein and mRNA expression from thousands of cells simultaneously. Using the power of the BD Rhapsody™ Single-Cell Analysis system, we have carefully investigated melanoma associated extramedullary hematopoiesis in mice. To do this, we isolated four hematopoietic stem and progenitor cell populations simultaneously, including Lin- Sca-1+ c-Kit+ (LSK), common myeloid progenitor (CMP), granulocyte-macrophage progenitor (GMP) and megakaryocyte-erythrocyte progenitor (MEP) cells from the spleen and bone marrow of melanoma-bearing mice using the BD FACSMelody™ cell sorter in combination with a multiplex BD® AbSeq Oligos panel for surface protein expression and a single-cell whole transcriptome analysis. Using advanced analysis plugins in SeqGeq™ software, we were able to delineate the developmental trajectories of these hematopoietic stem and progenitor cells in this systemic immuno-suppressive myeloid environment. These advanced technologies are critical to uncover tumor mediated abnormalities in hematopoiesis. Disclaimers: For Research Use Only. Not for use in diagnostic or therapeutic procedures. Class 1 Laser Product. BD, the BD Logo, FACSMelody and Rhapsody are trademarks of Becton, Dickinson and Company or its affiliates. © 2019 BD. All rights reserved. Citation Format: Nihan Kara, Xiaoshan Shi, Nikolay Samusik, Stephanie Widmann, Aaron J. Tyznik. A single-cell multiomics approach to study tumor-driven perturbations during hematopoiesis in mice [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4497.

Summary Cytotoxic T lymphocytes and natural killer (NK) cells are key effector cells in immune defenses against intracellular pathogens and cancer. In human blood, effector T and NK cytotoxic cells comprise a diverse and relatively rare group of cells. Herein, we describe a simplified intracellular staining workflow for classification of circulating human T and NK cells with cytolytic potential. We suggest reagents for measuring cytolytic proteins and identification of cell subsets within conventional and unconventional T cells and NK cells.