Biology subjects

Frobel, J.

Publications and source records attributed to Frobel, J..

3 recordsLinked to original sources

bioRxiv2018

Variants of DNMT3A cause transcript-specific DNA methylation patterns and affect hematopoietic differentiation

The de novo DNA methyltransferase 3A (DNMT3A) plays pivotal roles in hematopoietic differentiation. In this study, we followed the hypothesis that alternative splicing of DNMT3A has characteristic epigenetic and functional sequels. Specific DNMT3A transcripts were either downregulated or overexpressed in human hematopoietic stem and progenitor cells and this resulted in complementary and transcript-specific DNA methylation and gene expression changes. Functional analysis indicated that particularly transcript 2 (coding for DNMT3A2) activates proliferation and induces loss of a primitive immunophenotype, whereas transcript 4 interferes with colony formation of the erythroid lineage. Notably, in acute myeloid leukemia (AML) expression of transcript 2 correlates with its in vitro DNA methylation and gene expression signatures and is associated with overall survival, indicating that DNMT3A variants impact also on malignancies. Our results demonstrate that specific DNMT3A variants have distinct epigenetic and functional impact. Particularly DNMT3A2 triggers hematopoietic differentiation and the corresponding signatures are reflected in AML.

cell biology↗

bioRxiv2018

Epigenetic aging of human hematopoietic cells is not accelerated upon transplantation into mice

Transplantation of human hematopoietic stem cells into immunodeficient mice provides a powerful in vivo model system to gain functional insights into hematopoietic differentiation. So far, it remains unclear if epigenetic changes of normal human hematopoiesis are recapitulated upon engraftment into such \"humanized mice\". Mice have a much shorter life expectancy than men, and therefore we hypothesized that the xenogeneic environment might greatly accelerate the epigenetic clock. We demonstrate that genome-wide DNA methylation patterns of normal human hematopoietic development are indeed recapitulated upon engraftment in mice - particularly those of normal early B cell progenitor cells. Furthermore, we tested three epigenetic aging signatures and none of them indicated that the murine environment accelerated age-associated DNA methylation changes. These results demonstrate that the murine transplantation model overall recapitulates epigenetic changes of human hematopoietic development, whereas epigenetic aging seems to occur cell intrinsically.

genomics↗

bioRxiv2017

Leukocyte counts based on site-specific DNA methylation analysis

The composition of white blood cells is usually assessed by histomorphological parameters or flow cytometric measurements. Alternatively, leukocyte differential counts (LDCs) can be estimated by deconvolution algorithms for genome-wide DNA methylation (DNAm) profiles. We identified cell-type specific CG dinucleotides (CpGs) that facilitate relative quantification of leukocyte subsets. Site-specific analysis of DNAm levels by pyrosequencing provides similar precision of LDCs as conventional methods, whereas it is also applicable to frozen samples and requires only very small volumes of blood. Furthermore, we describe a new approach for absolute quantification of cell numbers based on a non-methylated reference DNA. Our \"Epi-Blood-Count\" facilitates robust and cost effective analysis of blood counts for clinical application.

molecular biology↗