Heterogeneous Escape from X Chromosome Inactivation Results in Sex Differences in Type I IFN Responses at the Single Human pDC Level

Background: Aortic valve stenosis (AVS) is a sexually dimorphic disease, with women often presenting with sustained fibrosis and men with more extensive calcification. However, the intracellular molecular mechanisms that drive these clinically important sex differences remain under explored. Methods: Hydrogel scaffolds were designed to recapitulate key aspects of the valve tissue microenvironment and serve as a culture platform for sex-specific valvular interstitial cells (VICs; precursors to pro-fibrotic myofibroblasts). The hydrogel culture system was used to interrogate intracellular pathways involved in sex-dependent VIC-to-myofibroblast activation and deactivation. RNA-sequencing was used to define pathways involved in driving sex-dependent activation. Interventions using small molecule inhibitors and small interfering RNA (siRNA) transfections were performed to provide mechanistic insight into sex-specific cellular responses to microenvironmental cues, including matrix stiffness and exogenously delivered biochemical factors. Results: In both healthy porcine and human aortic valves, female leaflets had higher baseline activation of the myofibroblast marker, alpha-smooth muscle actin (α-SMA), compared to male leaflets. When isolated and cultured, female porcine and human VICs had higher levels of basal α-SMA stress fibers that further increased in response to the hydrogel matrix stiffness, both of which were higher than male VICs. A transcriptomic analysis of male and female porcine VICs revealed Rho-associated protein kinase (RhoA/ROCK) signaling as a potential driver of this sex-dependent myofibroblast activation. Further, we found that genes that escape X-chromosome inactivation, such as BMX and STS (encoding for Bmx non-receptor tyrosine kinase and steroid sulfatase, respectively) partially regulate the elevated female myofibroblast activation via RhoA/ROCK signaling. This finding was confirmed by treating male and female VICs with endothelin-1 and plasminogen activator inhibitor-1, factors that are secreted by endothelial cells and known to drive myofibroblast activation via RhoA/ROCK signaling. Conclusions: Together, in vivo and in vitro results confirm sex-dependencies in myofibroblast activation pathways and implicate genes that escape X-chromosome inactivation in regulating sex differences in myofibroblast activation and subsequent AVS progression. Our results underscore the importance of considering sex as a biological variable to understand the molecular mechanisms of AVS and help guide sex-based precision therapies.

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X-chromosome dosage as a modulator of pluripotency, signalling and differentiation?

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2016.0366 ◽

2017 ◽

Vol 372 (1733) ◽

pp. 20160366 ◽

Cited By ~ 8

Author(s):

Edda G. Schulz

Keyword(s):

Stem Cells ◽

Sex Differences ◽

Embryonic Stem Cells ◽

X Chromosome ◽

Mammalian Species ◽

Embryonic Stem ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Hormone Production ◽

Similar Phenotype

Already during early embryogenesis, before sex-specific hormone production is initiated, sex differences in embryonic development have been observed in several mammalian species. Typically, female embryos develop more slowly than their male siblings. A similar phenotype has recently been described in differentiating murine embryonic stem cells, where a double dose of the X-chromosome halts differentiation until dosage-compensation has been achieved through X-chromosome inactivation. On the molecular level, several processes associated with early differentiation of embryonic stem cells have been found to be affected by X-chromosome dosage, such as the transcriptional state of the pluripotency network, the activity pattern of several signal transduction pathways and global levels of DNA-methylation. This review provides an overview of the sex differences described in embryonic stem cells from mice and discusses a series of X-linked genes that are associated with pluripotency, signalling and differentiation and their potential involvement in mediating the observed X-dosage–dependent effects. This article is part of the themed issue ‘X-chromosome inactivation: a tribute to Mary Lyon’.

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DNA methylation and late replication probably aid cell memory, and type I DNA reeling could aid chromosome folding and enhancer function

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1990.0012 ◽

1990 ◽

Vol 326 (1235) ◽

pp. 285-297 ◽

Cited By ~ 78

Keyword(s):

Dna Methylation ◽

X Chromosome ◽

Replication Timing ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Type I ◽

Late Replication ◽

Cell Memory ◽

Strong Candidate

DNA methylation in mammals is reviewed, and it is concluded that one role of methylation is to aid cell memory, which is defined as the ability of mitotically derived progeny cells to remember and re-establish their proper cellular identity. Methylation of X-linked CpG-rich islands probably stabilizes X-chromosome inactivation, but other mechanisms appear to be involved. Late replication is discussed as a key ancestral mechanism for X inactivation, and it is emphasized that early and late replication domains may each be self perpetuating. Therefore, early-late replication timing becomes another strong candidate mechanism for cell memory. A chromosome-loop folding enigma is discussed, and it is concluded that special mechanisms are needed to explain the formation and maintenance of specific looped domains. DNA reeling, such as done by type I restriction-modification enzymes, is proposed to provide this special mechanism for folding. DNA reeling mechanisms can help to explain the cis -spreading of X-chromosome inactivation as well as long-range action by enhancers.

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A robust test for X-chromosome genetic association accounting for X-chromosome inactivation and imprinting

Genetics Research ◽

10.1017/s0016672320000026 ◽

2020 ◽

Vol 102 ◽

Author(s):

Yu Zhang ◽

Si-Qi Xu ◽

Wei Liu ◽

Wing Kam Fung ◽

Ji-Yuan Zhou

Keyword(s):

X Chromosome ◽

Type I Error ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Type I ◽

Nucleotide Polymorphisms ◽

X Chromosomes ◽

Robust Test ◽

The Difference ◽

And Performance

Abstract The X chromosome is known to play an important role in many sex-specific diseases. However, only a few single-nucleotide polymorphisms on the X chromosome have been found to be associated with diseases. Compared to the autosomes, conducting association tests on the X chromosome is more intractable due to the difference in the number of X chromosomes between females and males. On the other hand, X-chromosome inactivation takes place in female mammals, which is a phenomenon in which the expression of one copy of two X chromosomes in females is silenced in order to achieve the same gene expression level as that in males. In addition, imprinting effects may be related to certain diseases. Currently, there are some existing approaches taking X-chromosome inactivation into account when testing for associations on the X chromosome. However, none of them allows for imprinting effects. Therefore, in this paper, we propose a robust test, ZXCII, which accounts for both X-chromosome inactivation and imprinting effects without requiring specifying the genetic models in advance. Simulation studies are conducted in order to investigate the validity and performance of ZXCII under various scenarios of different parameter values. The simulation results show that ZXCII controls the type I error rate well when there is no association. Furthermore, with regards to power, ZXCII is robust in all of the situations considered and generally outperforms most of the existing methods in the presence of imprinting effects, especially under complete imprinting effects.

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Marsupials and Mechanisms of X-Chromosome Inactivation

Australian Journal of Zoology ◽

10.1071/zo9890419 ◽

1989 ◽

Vol 37 (3) ◽

pp. 419 ◽

Cited By ~ 26

Author(s):

AD Riggs

Keyword(s):

Dna Replication ◽

X Chromosome ◽

Molecular Mechanisms ◽

Chromosome Structure ◽

X Chromosome Inactivation ◽

Higher Order ◽

X Inactivation ◽

Chromosome Inactivation ◽

Type I

X chromosome inactivation is reviewed with molecular mechanisms in mind. Models for the various steps leading to the establishment and maintenance of X inactivation are discussed, with comparisons between eutherians and marsupials included. Late DNA replication is proposed to be an epigenetic, self-propagating mechanism aiding the somatic inheritance of determined states, and thus could be the ancestral mechanism for X inactivation. Also, a novel mechanism, Type I DNA-reeling, is proposed to maintain higher order chromosome structure and to help explain the cis-spreading of X inactivation.

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X-linked CNV and skewed X-chromosome inactivation

Nauchno-prakticheskii zhurnal «Medicinskaia genetika» ◽

10.25557/2073-7998.2020.03.19-21 ◽

2020 ◽

pp. 19-21

Author(s):

Е.А. Фонова ◽

Е.Н. Толмачева ◽

А.А. Кашеварова ◽

М.Е. Лопаткина ◽

К.А. Павлова ◽

...

Keyword(s):

Cell Proliferation ◽

Intellectual Disability ◽

X Chromosome ◽

Copy Number ◽

Copy Number Variations ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Chromosome X ◽

Skewed X Chromosome Inactivation

Смещение инактивации Х-хромосомы может быть следствием и маркером нарушения клеточной пролиферации при вариациях числа копий ДНК на Х-хромосоме. Х-сцепленные CNV выявляются как у женщин с невынашиванием беременности и смещением инактивации Х-хромосомы (с частотой 33,3%), так и у пациентов с умственной отсталостью и смещением инактивацией у их матерей (с частотой 40%). A skewed X-chromosome inactivation can be a consequence and a marker of impaired cell proliferation in the presence of copy number variations (CNV) on the X chromosome. X-linked CNVs are detected in women with miscarriages and a skewed X-chromosome inactivation (with a frequency of 33.3%), as well as in patients with intellectual disability and skewed X-chromosome inactivation in their mothers (with a frequency of 40%).

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Faculty of 1000 evaluation for Cellular resolution maps of x chromosome inactivation: implications for neural development, function, and disease.

F1000 - Post-publication peer review of the biomedical literature ◽

10.3410/f.718235579.793490044 ◽

2014 ◽

Author(s):

Franck Polleux ◽

Julien Courchet

Keyword(s):

X Chromosome ◽

Neural Development ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Cellular Resolution

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X-Linked Emery–Dreifuss Muscular Dystrophy: Study Of X-Chromosome Inactivation and Its Relation with Clinical Phenotypes in Female Carriers

Genes ◽

10.3390/genes10110919 ◽

2019 ◽

Vol 10 (11) ◽

pp. 919 ◽

Cited By ~ 1

Author(s):

Viggiano ◽

Madej-Pilarczyk ◽

Carboni ◽

Picillo ◽

Ergoli ◽

...

Keyword(s):

Muscular Dystrophy ◽

X Chromosome ◽

Clinical Symptoms ◽

Fibrous Tissue ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Cardiac Conduction ◽

Asymptomatic Carriers ◽

Cardiac Symptoms ◽

Female Carriers

X-linked Emery–Dreifuss muscular dystrophy (EDMD1) affects approximately 1:100,000 male births. Female carriers are usually asymptomatic but, in some cases, they may present clinical symptoms after age 50 at cardiac level, especially in the form of conduction tissue anomalies. The aim of this study was to evaluate the relation between heart involvement in symptomatic EDMD1 carriers and the X-chromosome inactivation (XCI) pattern. The XCI pattern was determined on the lymphocytes of 30 symptomatic and asymptomatic EDMD1 female carriers—25 familial and 5 sporadic cases—seeking genetic advice using the androgen receptor (AR) methylation-based assay. Carriers were subdivided according to whether they were above or below 50 years of age. A variance analysis was performed to compare the XCI pattern between symptomatic and asymptomatic carriers. The results show that 20% of EDMD1 carriers had cardiac symptoms, and that 50% of these were ≥50 years of age. The XCI pattern was similar in both symptomatic and asymptomatic carriers. Conclusions: Arrhythmias in EDMD1 carriers poorly correlate on lymphocytes to a skewed XCI, probably due to (a) the different embryological origin of cardiac conduction tissue compared to lymphocytes or (b) the preferential loss of atrial cells replaced by fibrous tissue.

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