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Direct visualization of the endomitotic cell cycle in living megakaryocytes: differential patterns in low and high ploidy cells.

ABSTRACT: Endomitosis in megakaryocytes (MKs) involves repeated DNA replication in the absence of cytokinesis and is a crucial part of MK development. However, chromosomal dynamics have never been observed in living MKs. We developed a new transgenic mouse model in which the expression of human histone H2B fused in-frame to green fluorescent protein is targeted to MKs. Ex vivo time-lapse microscopy analysis indicated that chromosomal condensation occurs at early mitosis in all MKs. In high ploidy MKs (>or=8N), late anaphase was marked by a ring-type alignment of chromosomes with multiple territories formed between them. By contrast, in low ploidy MKs mitotic chromosomes segregated to form two groups separated by a clear space before re-joining to one cluster. This is the first study to document chromosomal segregation patterns during endomitosis ex vivo and to indicate their potential differential regulation in low and high ploidy cells.

SUBMITTER: Papadantonakis N

PROVIDER: S-EPMC2861775 | biostudies-other | 2008 Aug

REPOSITORIES: biostudies-other

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Direct visualization of the endomitotic cell cycle in living megakaryocytes: differential patterns in low and high ploidy cells.

Papadantonakis Nicholas N Makitalo Maria M McCrann Donald J DJ Liu Kenian K Nguyen Hao G HG Martin Greg G Patel-Hett Sunita S Italiano Joseph E JE Ravid Katya K

Cell cycle (Georgetown, Tex.) 20080521 15

Endomitosis in megakaryocytes (MKs) involves repeated DNA replication in the absence of cytokinesis and is a crucial part of MK development. However, chromosomal dynamics have never been observed in living MKs. We developed a new transgenic mouse model in which the expression of human histone H2B fused in-frame to green fluorescent protein is targeted to MKs. Ex vivo time-lapse microscopy analysis indicated that chromosomal condensation occurs at early mitosis in all MKs. In high ploidy MKs (>or ...[more]

PMID: 18677109

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Project description:Abstract Objectives Viral respiratory infections cause considerable morbidity and economic loss. While rhinoviruses (RV) typically cause little more than the common cold, they can produce severe infections and disease exacerbations in susceptible individuals, such as those with asthma. Variations in the regulation of key antiviral cytokines, particularly type I interferon (IFN‐α and IFN‐β), may contribute to RV susceptibility. To understand this variability, we compared the transcriptomes of high and low type I IFN producers. Methods Blood mononuclear cells from 238 individuals with or without asthma were cultured in the presence or absence of RV. Those samples demonstrating high or low RV‐stimulated IFN‐α production (N = 75) underwent RNA‐sequencing. Results Gene expression patterns were similar in samples from healthy participants and those with asthma. At baseline, the high IFN‐α producer group showed higher expression of genes associated with plasmacytoid dendritic cells, the innate immune response and vitamin D activation, but lower expression of oxidative stress pathways than the low IFN‐α producer group. After RV stimulation, the high IFN‐α producer group showed higher expression of genes found in immune response biological pathways and lower expression of genes linked to developmental and catabolic processes when compared to the low IFN‐α producer group. Conclusions These differences suggest that the high IFN‐α group has a higher level of immune system readiness, resulting in a more intense and perhaps more focussed pathogen‐specific immune response. These results contribute to a better understanding of the variability in type I IFN production between individuals. For this study on variation in IFN‐α production, samples from high and low IFN‐α producers were selected and their transcriptomes were compared before and after rhinovirus stimulation. Differential gene expression analysis revealed immunological differences at baseline prior to stimulus and differences in antiviral response and expression of genes related to cellular functions.

Dataset Information

Direct visualization of the endomitotic cell cycle in living megakaryocytes: differential patterns in low and high ploidy cells.

Publications

Direct visualization of the endomitotic cell cycle in living megakaryocytes: differential patterns in low and high ploidy cells.

Similar Datasets

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