Temporal and Quantitative Transcriptomic Differences Define Sexual Dimorphism in Murine Post Natal Bone Aging
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ABSTRACT: Time is a central element to development, pathology and aging of the skeleton. Since the transcriptome is a representation of the phenome, we hypothesized that characterization of the sex-specific, temporal transcriptomic differences in male and female bones over an 18 month period would be informative to the underlying molecular processes that lead to postnatal sexual dimorphism. Sex-specific gene expression regardless of age was primarily associated with connective tissues. Temporal clustering of the transcriptome identified two skeletal tissue-associated, sex-specific patterns of gene expression. One set of genes, associated with skeletal patterning and morphology and showed peak expression earlier in females. The second set of genes, associated with coupled remodeling had quantitatively higher expression in females and exhibited a broad peak between 3 to 12 months, concurrent with the animals’ reproductive period. Results of phenome-level structural assessments of the tibia and vertebrae, and in vivo and in vitro analysis of cells having osteogenic potential, were consistent with the existence of functionally unique, skeletogenic cell populations that are separately responsible for appositional growth and intramedullary bone cell functions.
Project description:Ethanol is the most common substance of abuse in the US, and abuse can lead to physical dependence, addiction, brain damage and premature death. The cycle of alcohol addiction has been described as a composite consisting of three stages: intoxication, withdrawal and craving/abstinence. As a complex brain disorder, there is evidence for both a genetic contribution to risk and sexually-dimorphic responses in alcoholism, but an overall understanding of the biological contributions and the neuroadaptive underpinnings of alcohol addiction is limited. Utilizing novel genetic animal models with highly divergent withdrawal severity, Withdrawal Seizure-Resistant (WSR) and Withdrawal Seizure-Prone (WSP) selected lines of mice and by examining both sexes, the distinct or common contributions of response to alcohol genotype/phenotype and of sex to addiction stages over time were characterized. Transcriptional profiling was performed to identify neuroadaptive changes as a consequence of chronic intoxication in the medial prefrontal cortex (mPFC). Significant expression differences were identified for each line and tracked over a behaviorally-relevant time course that covered each stage of alcohol addiction; i.e., after chronic intoxication, during peak withdrawal, and after a defined period of abstinence. Females were more responsive to ethanol with higher fold expression differences. Data structure was analyzed by bioinformatics, which showed a strong effect of sex with high similarity of male vs. female expression profiles during chronic intoxication and at peak withdrawal irrespective of genetic background. However, during abstinence, striking differences were observed instead between the lines/phenotypes irrespective of sex. Because sex was the strongest influence on neuroadaptive changes overall, confirmation analysis compared males vs. females. Notably, results revealed distinct inflammatory signaling between males and females at peak withdrawal, with a pro-inflammatory inflammotoxic phenotype in females but in contrast overall suppression of immune signaling in males. Thus, the early response to chronic intoxication is strongly influenced by sex while pathways that are altered during a period of abstinence are dependent on genotype. Combined, these results suggest that each stage of the addiction cycle is influenced differentially by sex vs. genetic background and support the development of distinct translational targets for stage- and sex-specific therapies for the treatment of alcohol withdrawal and the maintenance of sobriety.
Project description:Sex bias is known in the prevalence/pathology of neurodevelopmental disorders. Sex-dependent differences of the certain brain areas are known to emerge perinatally through the exposure to sex hormones, while gene expression patterns in the rodent embryonic brain does not seem to be completely the same between male and female. To investigate potential sex differences in gene expression and cortical organization during the embryonic period in mice, we conducted a comprehensive analysis of gene expression for the telencephalon at embryonic day (E) 11.5 (a peak of neural stem cell expansion) and E14.5 (a peak of neurogenesis) using bulk RNA-seq data. As a result, our data showed the existence of notable sex differences in gene expression patterns not obviously at E11.5, but clearly at E14.5 when neurogenesis has become its peak. These data can be useful for exploring potential contribution of genes exhibiting sex differences to the divergence in brain development. Additionally, our data underscore the significance of studying the embryonic period to gain a deeper understanding of sex differences in brain development.
Project description:Ethanol is the most common substance of abuse in the US, and abuse can lead to physical dependence, addiction, brain damage and premature death. The cycle of alcohol addiction has been described as a composite consisting of three stages: intoxication, withdrawal and craving/abstinence. As a complex brain disorder, there is evidence for both a genetic contribution to risk and sexually-dimorphic responses in alcoholism, but an overall understanding of the biological contributions and the neuroadaptive underpinnings of alcohol addiction is limited. Utilizing novel genetic animal models with highly divergent withdrawal severity, Withdrawal Seizure-Resistant (WSR) and Withdrawal Seizure-Prone (WSP) selected lines of mice and by examining both sexes, the distinct or common contributions of response to alcohol genotype/phenotype and of sex to addiction stages over time were characterized. Transcriptional profiling was performed to identify neuroadaptive changes as a consequence of chronic intoxication in the medial prefrontal cortex (mPFC). Significant expression differences were identified for each line and tracked over a behaviorally-relevant time course that covered each stage of alcohol addiction; i.e., after chronic intoxication, during peak withdrawal, and after a defined period of abstinence. Females were more responsive to ethanol with higher fold expression differences. Data structure was analyzed by bioinformatics, which showed a strong effect of sex with high similarity of male vs. female expression profiles during chronic intoxication and at peak withdrawal irrespective of genetic background. However, during abstinence, striking differences were observed instead between the lines/phenotypes irrespective of sex. Because sex was the strongest influence on neuroadaptive changes overall, confirmation analysis compared males vs. females. Notably, results revealed distinct inflammatory signaling between males and females at peak withdrawal, with a pro-inflammatory inflammotoxic phenotype in females but in contrast overall suppression of immune signaling in males. Thus, the early response to chronic intoxication is strongly influenced by sex while pathways that are altered during a period of abstinence are dependent on genotype. Combined, these results suggest that each stage of the addiction cycle is influenced differentially by sex vs. genetic background and support the development of distinct translational targets for stage- and sex-specific therapies for the treatment of alcohol withdrawal and the maintenance of sobriety. A total of 32 microarrays were run with 4 biological replicates per treatment, line, and sex. Selection replicates (i.e. WSP-1 and WSP-2) for each treatment, line, and sex were collapsed to improve statistical power (n=4) and to facilitate in the identification of phenotype related effects and exclude selection artifacts. For comparisons, EtOH regulation was determined by comparing 4 arrays from (for example) Male WSR EtOH treated versus 4 arrays from Male WSR Air treated arrays.
Project description:The goal of this study was to examine whether immune responses to Plasmodium chabaudi infection differ between the sexes and are altered by the presence of gonadal steroids. Gonadally-intact males were more likely than intact females to die following P. chabaudi infection, exhibit slower recovery from infection-associated weight loss, hypothermia, and anemia, have reduced IFNγ-associated gene expression and IFNγ production during peak parasitemia, and produce less antibody during the recovery phase of infection. Gonadectomy of male and female mice altered these sex-associated differences, suggesting that sex steroid hormone, in particular androgens and estrogens, may modulate immune responses to infection. Keywords: Time Course
Project description:Cell type repertoires have expanded extensively in metazoan animals, with some clade-specific cells being paramount to their evolutionary success. A prime example are the skeletogenic cells of vertebrates that form the basis of their developing endoskeletons. Depending on anatomical location, these cells originate from three different embryonic precursor lineages – the neural crest, the somites, and the lateral plate mesoderm – yet they converge developmentally towards similar cellular phenotypes. Furthermore, these lineages have gained ‘skeletogenic competency’ at distinct timepoints during vertebrate evolution, thus questioning to what extent different parts of the vertebrate skeleton rely on truly homologous cell types. Here, we investigate how lineage-specific molecular properties of the three precursor pools are integrated at the gene regulatory level, to allow for phenotypic convergence towards a skeletogenic cell fate. Using single-cell transcriptomics and chromatin accessibility profiling along the precursor-to-skeletogenic cell continuum, we examine the gene regulatory dynamics associated with this cell fate convergence. We find that distinct transcription factor profiles are inherited from the three precursor states, and that lineage-specific enhancer elements integrate these different inputs at the cis-regulatory level, to execute a core skeletogenic program. We propose a lineage-specific gene regulatory logic for skeletogenic convergence from three embryonic precursor pools. Early skeletal cells in different body parts thus share only a partial ‘deep homology’. This regulatory uncoupling may render them amenable to individualized selection, to help to define distinct morphologies and biomaterial properties in the different parts of the vertebrate skeleton.
Project description:Cell type repertoires have expanded extensively in metazoan animals, with some clade-specific cells being paramount to their evolutionary success. A prime example are the skeletogenic cells of vertebrates that form the basis of their developing endoskeletons. Depending on anatomical location, these cells originate from three different embryonic precursor lineages – the neural crest, the somites, and the lateral plate mesoderm – yet they converge developmentally towards similar cellular phenotypes. Furthermore, these lineages have gained ‘skeletogenic competency’ at distinct timepoints during vertebrate evolution, thus questioning to what extent different parts of the vertebrate skeleton rely on truly homologous cell types. Here, we investigate how lineage-specific molecular properties of the three precursor pools are integrated at the gene regulatory level, to allow for phenotypic convergence towards a skeletogenic cell fate. Using single-cell transcriptomics and chromatin accessibility profiling along the precursor-to-skeletogenic cell continuum, we examine the gene regulatory dynamics associated with this cell fate convergence. We find that distinct transcription factor profiles are inherited from the three precursor states, and that lineage-specific enhancer elements integrate these different inputs at the cis-regulatory level, to execute a core skeletogenic program. We propose a lineage-specific gene regulatory logic for skeletogenic convergence from three embryonic precursor pools. Early skeletal cells in different body parts thus share only a partial ‘deep homology’. This regulatory uncoupling may render them amenable to individualized selection, to help to define distinct morphologies and biomaterial properties in the different parts of the vertebrate skeleton.
Project description:Sexually dimorphic tissues are formed by cells that are regulated by sex hormones. While a number of systemic hormones and transcription factors are known to regulate proliferation and differentiation of osteoblasts and osteoclasts, the mechanisms that determine sexually dimorphic differences in bone regeneration are unclear. To explore how sex hormones regulate bone regeneration, we compared bone fracture repair between adult male and female mice. We find that skeletal stem cell (SSC) mediated regeneration in female mice is dependent on estrogen signaling but SSCs from male mice do not exhibit similar estrogen responsiveness. Mechanistically, we found that estrogen acts directly on the SSC lineage in mice and humans by up-regulating multiple skeletogenic pathways and is necessary for the stem cell’s ability to self- renew and differentiate. Our results also suggest a clinically applicable strategy to accelerate bone healing using localized estrogen hormone therapy.
Project description:Linking the evolution of the phenotype to the underlying genotype is a key aim of evolutionary genetics and is crucial to our understanding of how natural selection shapes a trait. Here we consider the genetic basis of sex allocation behaviour in the parasitoid wasp Nasonia vitripennis using a transcriptomics approach. Females allocate offspring sex in line with Local Mate Competition (LMC) theory. Female-biased sex ratios are produced when one or few females lay eggs on a patch. As the number of females contributing offspring to a patch increases, less female-biased sex ratios are favoured. We contrasted the transcriptomic responses of females as they oviposit under conditions known to influence sex allocation: foundress number (a social cue) and the state of the host (parasitised or not). We found, that when females encounter other females on a patch, or assess host quality with their ovipositors, the resulting changes in sex allocation is not associated with significant changes in whole-body gene expression. We also found that the gene expression changes produced by females, as they facultatively allocate sex in response to a host cue and a social cue, are very closely correlated. We expanded the list of candidate genes associated with oviposition behaviour in Nasonia, some of which may be involved in fundamental processes underlying the ability to facultatively allocate sex, including sperm storage and utilisation.
Project description:Men are diagnosed with type 2 diabetes at lower body mass indexes than women; the role of skel-etal muscle in this sex difference is poorly understood. Type 2 diabetes impacts skeletal muscle, particularly in females who demonstrate a lower oxidative capacity compared to males. To ad-dress mechanistic differences underlying this sex disparity, we investigated skeletal muscle mito-chondrial respiration in female and male rats in response to chronic high-fat, high-sugar (HFHS) diet consumption. Four-week-old Wistar Rats were fed a standard chow or HFHS diet for 14 weeks to identify sex-specific adaptations in mitochondrial respirometry and characteristics, transcrip-tional patterns, and protein profiles. Fat mass was greater with the HFHS diet in both sexes when controlled for body mass (p < 0.0001). Blood glucose and insulin resistance were greater in males (p = 0.01) and HFHS-fed rats (p < 0.001). HFHS-fed males had higher mitochondrial respiration compared with females (p < 0.01 sex/diet interaction). No evidence of a difference by sex or diet was found for mitochondrial synthesis, dynamics, or quality to support the mitochondrial respi-ration sex/diet interaction. However, transcriptomic analyses indicate sex differences in nutrient handling. Sex-specific differences occurred in PI3K/AKT signaling, PPARα/RXRα, and triacyl-glycerol degradation. These findings may provide insight into the clinical sex differences in body mass index threshold for diabetes development and tissue-specific progression of insulin re-sistance.
Project description:Cell type repertoires have expanded extensively in metazoan animals, with some clade-specific cells being paramount to their evolutionary success. A prime example are the skeletogenic cells of the developing vertebrate endoskeleton. Depending on anatomical location, these cells originate from three different embryonic precursor lineages, yet they converge developmentally towards similar cellular phenotypes. Furthermore, these embryonic lineages have gained skeletogenic competency at distinct timepoints during vertebrate evolution, thus questioning to what extent different parts of the vertebrate skeleton rely on truly homologous cell types.
Here, we investigate how lineage-specific molecular properties of the three precursor pools are integrated at the gene regulatory level, to allow for phenotypic convergence towards a skeletogenic cell fate. Using single-cell transcriptomics and chromatin accessibility profiling along the precursor-to-skeletogenic cell continuum, we examine the gene regulatory dynamics associated with this cell fate convergence. We find that distinct transcription factor profiles are inherited and integrated from the three precursor states, and that lineage-specific enhancer elements incorporate these different inputs at the cis-regulatory level.
This lineage-specific gene regulatory logic for skeletogenic convergence from three embryonic precursor pools suggests that early skeletal cells in different body parts are distinct cell types. Their regulatory uncoupling may render them amenable to individualized selection, to help to define distinct morphologies and biomaterial properties in the different parts of the vertebrate skeleton.