Sosa, C. | Search bioRxiv

bioRxiv2021

X-Linked Histone H3K27 Demethylase Kdm6a Regulates Sexually Dimorphic Differentiation of Hypothalamic Neurons

Several X-linked genes are involved in neuronal differentiation and may contribute to the generation of sex dimorphisms in brain. Previous results showed that XX hypothalamic neurons grow faster, have longer axons, and exhibit higher expression of the neuritogenic gene neurogenin 3 (Ngn3) than XY before perinatal masculinization. Here we evaluated the participation of candidate X-linked genes in the development of these sex differences, focusing mainly on Kdm6a, a gene encoding for an H3K27 demethylase with functions controlling gene expression genome-wide. We established hypothalamic neuronal cultures from wild-type or transgenic Four Core Genotypes mice, a model that allows evaluating the effect of sex chromosomes independently of gonadal type. X-linked genes Kdm6a, Eif2s3x and Ddx3x showed higher expression in XX compared to XY neurons, regardless of gonadal sex. Moreover, Kdm6a expression pattern with higher mRNA levels in XX than XY did not change with age at E14, P0, and P60 in hypothalamus or under 17{beta}-estradiol treatment in culture. Kdm6a pharmacological blockade by GSK-J4 reduced the expression of neuritogenic genes Neurod1, Neurod2 and Cdk5r1 in both sexes equally, while a sex-specific effect was observed on Ngn3 levels, with a decrease in XX and an increase in XY neurons. Finally, both Kdm6a inhibition and its downregulation using siRNA reduced axonal length only in female neurons, abolishing the sex differences observed in control conditions. Altogether, these results point to Kdm6a as a key mediator of the higher axogenesis and Ngn3 expression observed in XX neurons before critical period of brain masculinization.

neuroscience↗

bioRxiv2018

Transcriptomic analysis of fetal membranes reveals pathways involved in preterm birth

Preterm birth (PTB), defined as infant delivery before 37 weeks of completed gestation, results of the interaction of both genetic and environmental components and constitutes a complex multifactorial syndrome. Transcriptome analysis of PTB has proved challenging because of the multiple causes of PTB and the numerous maternal and fetal gestational tissues that must interact to facilitate parturition. A common pathway of labor and PTB may be the activation of fetal membranes. In this work, chorioamnion membranes from severe preterm and term fetus were analyzed using RNA sequencing. A total of 270 genes were differentially expressed (DE): 252 were up-regulated and 18 were down-regulated in the severe preterm compared to the term births. We found great gene expression homogeneity in the control samples, and not in severe preterm samples. In this work, we identified up-regulated pathways that were previously suggested as leading to PTB like immunological and inflammatory paths. New pathways that were not identified in preterm like the hemopoietic path appeared up-regulated in preterm membranes. A group of 18 down-regulated genes discriminates between term and severe preterm cases. These genes potentially characterize a severe preterm transcriptome pattern and therefore are candidate genes for understanding the syndrome. Some of the down-regulated genes are involved in the nervous system, morphogenesis (WNT-1, DLX5, PAPPA2) and ion channel complexes (KCNJ16, KCNB1), making them good candidates as biomarkers of PTB.\n\nThe identification of this DE gene pattern may help to develop a multi-gene disease classifier. These markers were generated in an admixtured South American population where PTB has a high incidence. Since genetic background may impact differentially in different populations it is mandatory to include populations like South American and African ones that are usually excluded from high throughput approaches. These classifiers should be compared to those in other populations to get a global landscape of PTB.

genetics↗