Project description:Objective-Aortic pathologies exhibit sexual dimorphism, with aneurysms in the ascending, thoracic and abdominal aorta (AAA) exhibiting higher prevalence in males. Despite lower incidence of aortic vascular disease in women, aneurysms progress rapidly. Mechanisms for these sex differences are unclear. We defined the role of sex chromosome complement and testosterone in regional development and progression of angiotensin II (AngII)-induced vascular pathologies. Approach and Results-We used transgenic male mice expressing Sry on an autosome to create low density lipoprotein receptor (Ldlr) deficient male mice with an XY or XX sex chromosome complement. Subjects were then sham operated or orcheictomized. Transcriptional profiling on abdominal aortas from XY or XX males demonstrated1746 genes influenced by sex chromosomes, sex hormones, or an interaction. A second cohort of animals was then infused with AngII for 28 days. Diffuse aortic aneurysm pathology developed in XY AngII-infused males, while XX males developed discrete AAAs. Castration reduced all AngII-induced aortic pathologies in XY and XX males. Thoracic aortas from AngII-infused XY males, but not XX males exhibited adventitial thickening. We infused male XY and XX mice with saline or AngII and quantified mRNA abundance of key genes in thoracic versus abdominal aortas. Regional differences in mRNA abundance existed before AngII infusions, which were differentially influenced by AngII between genotypes. Prolonged AngII infusions resulted in AAA aortic wall thickening in XY males with diffuse aortic pathology, while XX males had dilated focal AAAs. Conclusions-An XY sex chromosome complement mediates diffuse aortic pathology, while an XX sex chromosome complement contributes to discrete AngII-induced AAAs.
Project description:Abdominal aortic aneurysms (AAAs) are a prevalent and deadly human pathology with strong sexual dimorphism. Research demonstrates that sex hormones influence, but do not fully explain, male versus female AAA pathology. In addition to sex hormones, the X and Y sex chromosomes, and their unique complements of genes, may contribute to sexually dimorphic AAA pathology. Here, for the first time, we defined the effect of female (XX) versus male (XY) chromosome complement on AAA formation and rupture in phenotypically female mice using an established murine model. Abdominal aortas from female mice bearing the XY chromosome selectively expressed Y chromosome genes, while genes known to escape X-inactivation were higher in XX females. The majority of gene differences in XY females fell within inflammatory pathways. When XY females were infused with AngII, AAA incidences doubled and aneurysms ruptured. AAAs from XY females exhibited significant inflammation. Moreover, infusion of AngII to XY females augmented aortic activity of matrix metalloproteinases. Finally, testosterone exposure applied chronically, or as a single bolus at postnatal day 1, markedly worsened AAA outcomes in XY compared to XX females. These results demonstrate that an XY sex chromosome complement profoundly influences aortic gene expression profiles and promotes AAA severity.
Project description:Objective: Turner Syndrome women (monosomy X) have high risk of aortopathies consistent with a role for sex chromosomes in disease development. We demonstrated that sex chromosomes influence regional development of angiotensin II (AngII)-induced aortopathies in mice. In this study, we determined if the number of X chromosomes regulates regional development of AngII-induced aortopathies. Approach and Results: We used females with varying numbers of X chromosomes (XXF or XOF) on an C57BL/6J (ascending aortopathies) or Ldlr-/- background (descending and abdominal aortopathies) compared to XY males (XYM). To induce aortopathies, mice were infused with AngII. XOF (C57BL/6J) exhibited larger percent increases in ascending aortic lumen diameters than AngII-infused XXF or XYM. AngII-infused XOF (Ldlr-/-) exhibited similar incidences of thoracic (XOF, 50%; XYM, 71%) and abdominal aortopathies (XOF, 83%; XYM, 71%) as XYM, which were greater than XXF (XXF, 0%). Abdominal aortic lumen diameters and maximal external diameters were similar between XOF and XYM but greater than XXF, and these effects persisted with extended AngII infusions. Larger aortic lumen diameters, abdominal aortopathy incidence (XXF, 20%; XOF, 75%), and maximal aneurysm diameters (XXF, 1.02 ± 0.17; XOF, 1.96 ± 0.32 mm; P=0.027) persisted in ovariectomized AngII-infused XOF mice. Data from RNA seq demonstrated that X chromosome genes that escape X-inactivation (histone lysine demethylases Kdm5c and Kdm6a), exhibited lower mRNA abundance in aortas of XOF than XXF (P=0.033 and 0.024 respectively). Conversely, DNA methylation was higher in aortas of XOF than XXF (P=0.038). Conclusion: The absence of a second X chromosome promotes diffuse AngII-induced aortopathies in females.
Project description:Sex differences in the brain as they relate to health and disease are often overlooked in experimental models. Many neurological disorders, like Alzheimer’s disease (AD), multiple sclerosis (MS), and autism, differ in prevalence between males and females. Sex differences originate either from differential gene expression on sex chromosomes or from hormonal differences, either directly or indirectly. To disentangle the relative contributions of genetic sex (XX v. XY) and gonadal sex (ovaries v. testes) to the regulation of hippocampal sex effects, we use the “sex-reversal” Four Core Genotype (FCG) mouse model which uncouples sex chromosome complement from gonadal sex. Transcriptomic and epigenomic analyses of hippocampal RNA and DNA from ∼12 month old FCG mice, reveals differential regulatory effects of sex chromosome content and gonadal sex on X- versus autosome-encoded gene expression and DNA modification patterns. Gene expression and DNA methylation patterns on the X chromosome were driven primarily by sex chromosome content, not gonadal sex. The majority of DNA methylation changes involved hypermethylation in the XX genotypes (as compared to XY) in the CpG context, with the largest differences in CpG islands, promoters, and CTCF binding sites. Autosomal gene expression and DNA modifications demonstrated regulation by sex chromosome complement and gonadal sex. These data demonstrate the importance of sex chromosomes themselves, independent of hormonal status, in regulating hippocampal sex effects. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosome regulate autosomes, and differentiate organizational from activational hormonal effects.
Project description:Sex differences in the brain as they relate to health and disease are often overlooked in experimental models. Many neurological disorders, like Alzheimer’s disease (AD), multiple sclerosis (MS), and autism, differ in prevalence between males and females. Sex differences originate either from differential gene expression on sex chromosomes or from hormonal differences, either directly or indirectly. To disentangle the relative contributions of genetic sex (XX v. XY) and gonadal sex (ovaries v. testes) to the regulation of hippocampal sex effects, we use the “sex-reversal” Four Core Genotype (FCG) mouse model which uncouples sex chromosome complement from gonadal sex. Transcriptomic and epigenomic analyses of hippocampal RNA and DNA from ∼12 month old FCG mice, reveals differential regulatory effects of sex chromosome content and gonadal sex on X- versus autosome-encoded gene expression and DNA modification patterns. Gene expression and DNA methylation patterns on the X chromosome were driven primarily by sex chromosome content, not gonadal sex. The majority of DNA methylation changes involved hypermethylation in the XX genotypes (as compared to XY) in the CpG context, with the largest differences in CpG islands, promoters, and CTCF binding sites. Autosomal gene expression and DNA modifications demonstrated regulation by sex chromosome complement and gonadal sex. These data demonstrate the importance of sex chromosomes themselves, independent of hormonal status, in regulating hippocampal sex effects. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosome regulate autosomes, and differentiate organizational from activational hormonal effects.
Project description:It is well recognized that men and women differ in circulating lipid profiles and consequently coronary artery disease (CAD). While sex hormones like estrogens are thought to protect women from CAD risk by promoting protective lipid profiles, hormone replacement therapy in women paradoxically increases CAD risk. Biological sex is determined by both sex chromosomes and sex hormones. We used mouse models to separate effects of sex chromosomes and hormones on atherosclerosis, circulating lipids and intestinal fat metabolism. We found that an XX sex chromosome complement increases food intake, body weight, fat absorption, serum lipid concentrations and atherosclerosis in gonadal male and female mice, indicating a primary effect of sex chromosome complement. Small intestine expression of enzymes involved in lipid absorption and chylomicron assembly were increased in XX male and female mice with elevated intestinal lipids. These results reveal that an XX sex chromosome complement promotes the absorption and bioavailability of dietary fat to accelerate the development of atherosclerosis.
Project description:Vascular smooth muscle cell (VSMC) phenotypic switching is widely recognized as a key mechanism responsible for the pathogenesis of several aortic diseases such as aortic aneurysm. Cellular communication network factor 2 (CCN2), often upregulated in human pathologies and animal disease models, exerts a myriad of context-dependent biological functions. However, current understanding of the role of SMC-CCN2 in SMC phenotypic switching and its function in the pathology of abdominal aortic aneurysm (AAA) is lacking. Here we report the effect of SMC-restricted CCN2 deficiency of hypercholesterolemic mice on gene expression in infrarenal aorta with or without angiotensin II (Ang II)-infusion.
Project description:Thoracic aortic aneurysms have a higher prevalence in male patients compared to female patients. Marfan syndrome causes a hereditary form of TAA with dilation of the aortic root. Male patients with Marfan syndrome are more likely than women to have aortic dilation and dissection and mouse models of Marfan syndrome demonstrate larger aortic roots in males compared to females even after adjustment for body size. Similar sex disparities are present in patients and models of abdominal aortic aneurysms where estrogen has been demonstrated to attenuate aneurysm formation perhaps through anti-inflammatory mechanisms. In this study we demonstrate the effects of estrogen on aortic dilation and rupture in a Marfan mouse model and we investigate if these effects operate through suppression of complement components of the immune system.