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- Pottmeier, Philipp, 1987-
(författare)
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Genetic Sex Differences in Early Human Neuronal Development : An Investigation in Embryo Tissue and Embryonic Stem Cells
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sex differences in the human body affect many different organs and tissues, some of them have an effect on the human brain and its development. In the developing nervous system, sex differences can bias the number or functionality of neurons, glial cells or synapses. As a result, neural networks might develop with a sex-specific bias. A number of neurodevelopmental diseases, such as Tourette-Syndrome or Attention-Deficit/Hyperactivity Disorder, show sex differences in symptoms, onset and prevalence. It seems likely that sex differences in brain development contribute to differences in neurological disease susceptibility between males and females. In my work, I am investigating sex differences in gene expression during neuronal development in human embryo brain tissue, embryonic stem cells and neural stem cells. Of particular interest for sex differences are the genes of the sex chromosomes, since a large number of X-linked genes and even some Y-linked genes are implicated in neurodevelopment.In our first study, we found that Y chromosome genes are highly expressed in fetal brain tissues and 5 X/Y homologous genes have an increased gene dosage in male samples. We suggest 6 novel long non-coding RNAs that were expressed in previously unannotated regions of the Y chromosome in male fetal brain tissue. In our second study, we identified an increased rate of proliferation in male neural stem cells but similar neuronal differentiation trajectories in cells of both sexes. An increased expression of DCX and DLG4 suggests a faster differentiation of male neural stem cells, but sex differences disappeared after 14 days. Male cells overexpressed MASH1 and RELN, markers for Cajal-Retzius neurons, and the two demethylases KDM5D and UTY. Female cells overexpressed RMST a long non-coding RNA critical for neurogenesis. In the third study, sex-biased gene expression was investigated in human embryonic stem cells during 37 days of neuronal differentiation. Male and female cell lines showed sex-biased expression of genes involved in neurodevelopment, suggesting a sex difference in differentiation trajectory. We propose 13 sex-biased candidate genes that could strongly affect neuronal development. In addition, we confirmed the gene dosage compensation of X/Y homologs escaping XCI through the Y-homolog and identified a significant expression of the Y-homologs TXLNGY and UTY after 37 days of neuronal differentiation. We have also measured a significant increase of the Y-linked genes PCDH11Y, UTY and USP9Y during differentiation. The fourth study was an investigation of sex differences in H3 methylation and acetylation marks in embryonic stem cells. We found that H3K4me3, a transcription activation mark, was enriched at promotor sites of major pluripotency genes and related pathways, in female cell lines.In conclusion, we confirm the importance of Y chromosome genes for neuronal development and show that sex differences in gene expression exist during neuronal differentiation.
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| 2. |
- Pottmeier, Philipp, et al.
(författare)
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Increased Expression of Y-Encoded Demethylases During Differentiation of Human Male Neural Stem Cells
- 2020
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Ingår i: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 29:23, s. 1497-1509
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Tidskriftsartikel (refereegranskat)abstract
- Human neural stem cells (hNSCs) have long been used as an in vitro model to study neurogenesis and as candidates for nervous system therapy. Many parameters have been considered when evaluating the success of transplantation, but sex of donor and recipients is often not discussed. We investigated two commercial NSC lines, the female hNSC-H9 and male hNSC-H14, and we observed faster growth rates in the male cells. At 4 days of differentiation, male cells presented a significant increase in expression of DCX, an immature neuronal marker, while female cells showed a significant increase in RMST, a long noncoding RNA, which is indispensable during neurogenesis. In addition, expression of neural markers MAP2, PSD95, SYP, DCX, and TUJ1 at day 14 of differentiation suggested a similar differentiation potential in both lines. The most significant differences at day 14 of differentiation were the expression levels of RELN, with almost 100-fold difference between the sexes, and MASH1, with more than 1,000-fold increase in male cells. To evaluate whether some of the observed differences may be sex related, we measured the expression of gametologous genes located on the X- and Y-chromosome. Most noticeable was the increase of Y-encoded demethylases KDM6C (UTY) and KDM5D during differentiation of male cells. Our results indicate that attention should be paid to sex when planning neurogenesis and transplantation experiments.
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| 3. |
- Sundman, Ann-Sofie, et al.
(författare)
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DNA methylation in canine brains is related to domestication and dog-breed formation
- 2020
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:10
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Tidskriftsartikel (refereegranskat)abstract
- Epigenetic factors such as DNA methylation act as mediators in the interaction between genome and environment. Variation in the epigenome can both affect phenotype and be inherited, and epigenetics has been suggested to be an important factor in the evolutionary process. During domestication, dogs have evolved an unprecedented between-breed variation in morphology and behavior in an evolutionary short period. In the present study, we explore DNA methylation differences in brain, the most relevant tissue with respect to behavior, between wolf and dog breeds. We optimized a combined method of genotype-by-sequencing (GBS) and methylated DNA immunoprecipitation (MeDIP) for its application in canines. Genomic DNA from the frontal cortex of 38 dogs of 8 breeds and three wolves was used. GBS and GBS-MeDIP libraries were prepared and sequenced on Illuma HiSeq2500 platform. The reduced sample represented 1.18 ± 0.4% of the total dog genome (2,4 billion BP), while the GBS-MeDIP covered 11,250,788 ± 4,042,106 unique base pairs. We find substantial DNA methylation differences between wolf and dog and between the dog breeds. The methylation profiles of the different groups imply that epigenetic factors may have been important in the speciation from dog to wolf, but also in the divergence of different dog breeds. Specifically, we highlight methylation differences in genes related to behavior and morphology. We hypothesize that these differences are involved in the phenotypic variation found among dogs, whereas future studies will have to find the specific mechanisms. Our results not only add an intriguing new dimension to dog breeding but are also useful to further understanding of epigenetic involvement.
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