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:Men and women differ in circulating lipids and coronary artery disease (CAD). While sex hormones such as estrogens decrease CAD risk, hormone replacement therapy increases risk. Biological sex is determined by sex hormones and chromosomes, but effects of sex chromosomes on circulating lipids and atherosclerosis are unknown. Here, we use mouse models to separate effects of sex chromosomes and hormones on atherosclerosis, circulating lipids and intestinal fat metabolism. We assess atherosclerosis in multiple models and experimental paradigms that distinguish effects of sex chromosomes, and male or female gonads. Pro-atherogenic lipids and atherosclerosis are greater in XX than XY mice, indicating a primary effect of sex chromosomes. Small intestine expression of enzymes involved in lipid absorption and chylomicron assembly are greater in XX male and female mice with higher intestinal lipids. Together, our results show that an XX sex chromosome complement promotes the bioavailability of dietary fat to accelerate atherosclerosis.
Project description:Purpose: To understand how sex chromosome complement, XX, XO and XY, influences the transcriptome in the oocytes of grwoth phase. Methods: Oocytes of 50 and 60 µm in diameter were isolated from mouse ovaries at 18 dpp and subject to RNA-sequencing. Results: (1) Many X-linked genes are subject to X chromosome dosage dependent expression. (2) Many genes are expressed from both short and long arms of the Y chromosome. (3) The transcriptome landscape in XY oocytes is closer to XX oocytes than XO oocytes. (4) About 10 genes are differentially expressed in XY oocytes compared to XX or XO oocytes. Conclusions: The differences in XY oocytes became exacerbated to differ from XX or XO oocytes near the end of growth phase.
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:Differences in male vs. female immune responses are well-documented and have significant clinical implications. While the immunomodulatory effects of sex hormones are well established, the contributions of sex chromosome complement (XX vs. XY) and gut microbiome diversity on immune sexual dimorphisms have only recently become appreciated. Here we investigate the individual and collaborative influences of sex chromosome complements and gut microbiome bacteria on humoral immune activation. Sham-operated and gonadectomized male and female Four Core Genotype (FCG) mice were immunized with heat-killed Streptococcus pneumoniae (HKSP). Humoral immune responses were assessed and X-linked immune-related gene expression was evaluated to explain the identified XX-dependent phenotypes. Ex vivo studies investigated the functional role of Kdm6a, an X-linked epigenetic regulatory gene of interest, in mitogenic B cell activation. We further evaluated whether gut microbiome communities, or their metabolites, differentially influence immune cell activation in a sex chromosome-dependent manner. Endogenous gut microbiomes were antibiotically depleted and reconstituted with select short-chain fatty acid (SCFA)-producing bacteria prior to HKSP immunization and immune responses assessed. XX mice exhibited higher HKSP-specific IgM-secreting B cells and plasma cell frequencies than XY mice, regardless of gonadal sex. Although Kdm6a was identified as an X-linked gene overexpressed in XX B cells, inhibition of its enzymatic activity did not affect mitogen-induced plasma cell differentiation or antibody production in a sex chromosome-dependent manner ex vivo. Enhanced humoral responses in XX vs. XY immunized FCG mice were eliminated after microbiome depletion, indicating that the microbiome contributes to the identified XX-dependent immune enhancement. Reconstituting microbiota-depleted mice with select SCFA-producing bacteria increased humoral responses in XX, but not XY, FCG mice. This XX-dependent enhancement appears to be independent of SCFA production in males, while female XX-dependent responses relied on SCFAs. FCG mice have been used to assess sex hormones and sex chromosome complements influences on various sexually dimorphic traits. The current study indicates that the gut microbiome impacts humoral responses in an XX-dependent manner, suggesting that the collaborative influence of gut bacteria and other sex-specific factors should be considered when interpreting data aimed at delineating the mechanisms that promote sexual dimorphisms.
Project description:It has generally been assumed that most differences between males and females are due to developmental and hormonal differences between the sexes. Here we investigate the contribution of sex chromosomal complement to such sexual dimorphisms. These genome-wide transcription profiling showed that the expression of hundreds of autosomal genes was sensitive to sex chromosome complement, rather than gender. The existence of such differences between males and females holds important implications for understanding sexual dimorphisms in physiology and disease hitherto attributed solely to gender or hormonal effects. Thymic total RNA was isolated from 7-8 week old mice, with 3 biological replicates for each of four genotypes with different sex chromosome complements
Project description:It has generally been assumed that most differences between males and females are due to developmental and hormonal differences between the sexes. Here we investigate the contribution of sex chromosomal complement to such sexual dimorphisms. These genome-wide transcription profiling showed that the expression of hundreds of autosomal genes was sensitive to sex chromosome complement, rather than gender. The existence of such differences between males and females holds important implications for understanding sexual dimorphisms in physiology and disease hitherto attributed solely to gender or hormonal effects.
Project description:The XX sex chromosome complement provides enhanced responses to heat-killed Streptococcus pneumoniae immunization in a gut microbiome-dependent manner.
Project description:Effects of the sex chromosome complement, XX, XO or XY, on the transcriptome and development of mouse oocytes during follicular growth.