Effects of chromosomal sex and hormonal influences on shaping sex differences in brain and behavior: Lessons from cases of disorders of sex development

Transcriptomic Analysis of Type 2 Diabetes Mellitus Combined with Lower Extremity Atherosclerotic Occlusive Disease

Background

The pathological damage mechanism of type 2 diabetes (T2D) and macroangiopathy is extremely complex, and T2D and arteriosclerosis obliterans have different biological behaviors and clinical features. To explore the mechanism of lower extremity arteriosclerosis occlusion (LEAOD) in T2D patients, we utilized RNA-seq to identify unique gene expression signatures of T2D and LEAOD through transcriptomic analysis.

Methods

We obtained blood samples and performed RNA sequencing from four patients with T2D, five of whom had LEAOD. Another six age- and gender-matched blood samples from healthy volunteers were used for control. By exploring the general and specific differential expression analysis after transcriptome sequencing, specific gene expression patterns of T2D and LEAOD were verified.

Results

Transcriptome analysis found differentially expressed genes in T2D, and T2D + LEAOD (vs normal) separately, of which 35/486 (T2D/T2D + LEAOD) were up-regulated and 1290/2970 (T2D/T2D + LEAOD) were down-regulated. A strong overlap of 571 genes across T2D, LEAOD, and coexisting conditions was mainly involved in extracellular exosomes and the transcription process. By exploring the sex difference gene expression features between T2D, T2D + LEAOD, and healthy controls, we noticed that sex chromosome-associated genes do not participate in the sexual dimorphism gene expression profiles of T2D and LEAOD. Protein-Protein Interaction Network analysis and drug target prediction provided the drug candidates to treat T2D and LEAOD.

Conclusion

This study provides some evidence at the transcript level to uncover the association of T2D with LEAOD. The screened hub genes and predicted target drugs may be therapeutic targets.

The Biological Basis of Sex Differences in Athletic Performance: Consensus Statement for the American College of Sports Medicine

ABSTRACT

Biological sex is a primary determinant of athletic performance because of fundamental sex differences in anatomy and physiology dictated by sex chromosomes and sex hormones. Adult men are typically stronger, more powerful, and faster than women of similar age and training status. Thus, for athletic events and sports relying on endurance, muscle strength, speed, and power, males typically outperform females by 10%-30% depending on the requirements of the event. These sex differences in performance emerge with the onset of puberty and coincide with the increase in endogenous sex steroid hormones, in particular testosterone in males, which increases 30-fold by adulthood, but remains low in females. The primary goal of this consensus statement is to provide the latest scientific knowledge and mechanisms for the sex differences in athletic performance. This review highlights the differences in anatomy and physiology between males and females that are primary determinants of the sex differences in athletic performance and in response to exercise training, and the role of sex steroid hormones (particularly testosterone and estradiol). We also identify historical and nonphysiological factors that influence the sex differences in performance. Finally, we identify gaps in the knowledge of sex differences in athletic performance and the underlying mechanisms, providing substantial opportunities for high-impact studies. A major step toward closing the knowledge gap is to include more and equitable numbers of women to that of men in mechanistic studies that determine any of the sex differences in response to an acute bout of exercise, exercise training, and athletic performance.

Developmental transcriptomic patterns can be altered by transgenic overexpression of Uty

The genetic material encoded on X and Y chromosomes provides the foundation by which biological sex differences are established. Epigenetic regulators expressed on these sex chromosomes, including Kdm6a (Utx), Kdm5c, and Ddx3x have far-reaching impacts on transcriptional control of phenotypic sex differences. Although the functionality of UTY (Kdm6c, the Y-linked homologue of UTX), has been supported by more recent studies, its role in developmental sex differences is not understood. Here we test the hypothesis that UTY is an important transcriptional regulator during development that could contribute to sex-specific phenotypes and disease risks across the lifespan. We generated a random insertion Uty transgenic mouse (Uty-Tg) to overexpress Uty. By comparing transcriptomic profiles in developmental tissues, placenta and hypothalamus, we assessed potential UTY functional activity, comparing Uty-expressing female mice (XX + Uty) with wild-type male (XY) and female (XX) mice. To determine if Uty expression altered physiological or behavioral outcomes, adult mice were phenotypically examined. Uty expression masculinized female gene expression patterns in both the placenta and hypothalamus. Gene ontology (GO) and gene set enrichment analysis (GSEA) consistently identified pathways including immune and synaptic signaling as biological processes associated with UTY. Interestingly, adult females expressing Uty gained less weight and had a greater glucose tolerance compared to wild-type male and female mice when provided a high-fat diet. Utilizing a Uty-overexpressing transgenic mouse, our results provide novel evidence as to a functional transcriptional role for UTY in developing tissues, and a foundation to build on its prospective capacity to influence sex-specific developmental and health outcomes.

Regulation of sexually dimorphic placental adaptation in LPS exposure-induced intrauterine growth restriction

BACKGROUND

Sexual dimorphism in placental physiology affects the functionality of placental adaptation during adverse pregnancy. Defects of placental function compromise fetal programming, affecting the offspring's adult life. However, studies focusing on the relationship between sex-specific placental adaptation and consequent fetal maldevelopment under sub-optimal uterus milieu are still elusive.

METHODS

Here, we investigated the effects of maternal lipopolysaccharide (LPS) exposure between placental sex. Pregnant ICR mice received intraperitoneal injection of phosphate-buffered saline or 100, 200, and 400 µg/kg LPS on the gestational day (GD) 15.5. To determine whether prenatal maternal LPS exposure resulted in complicated pregnancy outcomes, survival rate of embryos was calculated and the growth of embryos and placentas was examined. To elucidate global transcriptomic changes occurring in the placenta, total RNA-sequencing (RNA-seq) was performed in female and male placentas.

RESULTS

LPS administration induced placental inflammation in both sexes at GD 17.5. Prenatal infection resulted in growth retardation in both sexes of embryos, and especially more prevalently in male. Impaired placental development was observed in a sex-specific manner. LPS 400 µg/kg reduced the percentage area of the labyrinth in females and junctional zone in males, respectively. RNA-sequencing revealed widespread sexually dimorphic transcriptional changes in placenta. In particular, representative changes were involved in biological processes such as trophoblast differentiation, nutrient/ion transporter, pregnancy, and immune system.

CONCLUSIONS

Our results present the sexually dimorphic responses of placental physiology in intrauterine growth restriction model and provide tentative relationship further to be elucidated between sex-biased placental functional change and long-term effects on the offspring's later life.

The Neuroanatomy of Pregnancy and Postpartum

Pregnancy and giving birth are exceptional states in a woman's life for many reasons. While the effects of pregnancy and childbirth on the female body are obvious, less is known about their impact on the female brain, especially in humans. The scientific literature is still sparse but we have identified 12 longitudinal neuroimaging studies conducted in women whose brains were scanned before pregnancy, during pregnancy, and/or after giving birth. This review summarizes and discusses the reported neuroanatomical changes during pregnancy, postpartum, and beyond. Some studies suggest that pregnancy is mainly associated with tissue decreases, and a few studies suggest that this tissue loss is mostly permanent. In contrast, the majority of studies seems to indicate that the postpartum period is accompanied by substantial tissue increases throughout the entire brain. Future research is clearly warranted to replicate and extend the current findings, while addressing various limitations and shortcomings of existing studies.

Teaching About Sex and Gender in Neuroscience: More Than Meets the "XY"

Offering courses on the neuroscience of sex and gender can help support an inclusive curriculum in neuroscience. At the same time, developing and teaching such courses can be daunting to even the most enthusiastic educators, given the subject's complexities, nuances, and the difficult conversations that it invites. The authors of this article have all developed and taught such courses from different perspectives. Our aim is to provide educators with an overview of important conceptual topics as well as a comprehensive, but non-exhaustive, guide to resources for teaching about sex/gender in neuroscience based on our collective experience teaching courses on the topic. After defining vital terminology and briefly reviewing the biology of sex and sex determination, we describe some common topics within the field and contrast our current nuanced understandings from outdated misconceptions in the field. We review how (mis)representation of the neuroscience of sex/gender serves as a case study for how scientific results are communicated and disseminated. We consider how contextualization of sex/gender neuroscience research within a broader historical and societal framework can give students a wider perspective on the enterprise of science. Finally, we conclude with a brief discussion on how to choose learning goals for your course and implementation notes.

Sex and gender differences in the development of empathy

The topic of typical sex and gender difference in empathy is examined in both a developmental and neuroscientific perspective. Empathy is construed as a multi-layered phenomenon with various degrees of complexity unfolding in ontogeny. The different components of empathy (i.e., affective, cognitive, and prosocial motivation) will be discussed as they interact and are expressed behaviorally. Significant sex/gender differences in empathy are discussed in relation to putative bottom-up or top-down processes underlying empathetic responses. The early onset and the pervasive presence of such sex/gender differences throughout the lifespan are further discussed in light of social and neurobiological modeling factors, including early socialization, brain's structural/functional variances, as well as genetics and hormonal factors.

17β-hydroxysteroid dehydrogenase type 3 deficiency: female sex assignment and follow-up

BACKGROUND

Deficiency of 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) is a rare autosomal recessive 46,XY disorder of sex development (DSD). It is due to pathogenetic variants in the HSD17B3 gene. Mutated genes encode an abnormal enzyme with absent or reduced ability to convert Δ4-androstenedione (Δ4-A) to testosterone (T) in the fetal testis. Affected individuals are usually raised as females and diagnosis is made at puberty, when they show virilization.

METHODS

A girl with a presumptive diagnosis of complete androgen insensitivity syndrome underwent endocrine and genetic assessment. Long-term follow-up was reported.

RESULTS

The diagnosis of 17β-HSD3 deficiency was made (stimulated T/Δ4-A ratio: 0.15; HSD17B3 gene analysis: c.277+4A>T in intron 3/c.640_645del (p.Glu214_Glu215del) in exon 9. After extensive information, parents decided to maintain female sex. Gonadal removal was performed and histological evaluation demonstrated deep fibrosis of testicular tissue. Follow-up till 8.5 years of age showed somatic and neuro-psychological development fitting with the female sex.

CONCLUSIONS

Management of a child with the rare 17β-HSD3 deficiency remains challenging. Any decision must be carefully evaluated with parents. Long-term follow-up must be warranted by a multidisciplinary DSD team to evaluate the adequacy of the choices made on quality of life in later life.

Sex differences in cancer mechanisms

We now know that cancer is many different diseases, with great variation even within a single histological subtype. With the current emphasis on developing personalized approaches to cancer treatment, it is astonishing that we have not yet systematically incorporated the biology of sex differences into our paradigms for laboratory and clinical cancer research. While some sex differences in cancer arise through the actions of circulating sex hormones, other sex differences are independent of estrogen, testosterone, or progesterone levels. Instead, these differences are the result of sexual differentiation, a process that involves genetic and epigenetic mechanisms, in addition to acute sex hormone actions. Sexual differentiation begins with fertilization and continues beyond menopause. It affects virtually every body system, resulting in marked sex differences in such areas as growth, lifespan, metabolism, and immunity, all of which can impact on cancer progression, treatment response, and survival. These organismal level differences have correlates at the cellular level, and thus, males and females can fundamentally differ in their protections and vulnerabilities to cancer, from cellular transformation through all stages of progression, spread, and response to treatment. Our goal in this review is to cover some of the robust sex differences that exist in core cancer pathways and to make the case for inclusion of sex as a biological variable in all laboratory and clinical cancer research. We finish with a discussion of lab- and clinic-based experimental design that should be used when testing whether sex matters and the appropriate statistical models to apply in data analysis for rigorous evaluations of potential sex effects. It is our goal to facilitate the evaluation of sex differences in cancer in order to improve outcomes for all patients.

Genetics of sex differences in neuroanatomy and function

Sex differences are observed at many distinct biologic levels, such as in the anatomy and functioning of the brain, behavior, and susceptibility to neuropsychiatric disorders. Previously, these differences were believed to entirely result from the secretion of gonadal hormones; however, recent research has demonstrated that differences are also the consequence of direct or nonhormonal effects of genes located on the sex chromosomes. This chapter reviews the four core genotype model that separates the effects of hormones and sex chromosomes and highlights a few genes that are believed to be partly responsible for sex dimorphism of the brain, in particular, the Sry gene. Genetics of the brain's neurochemistry is discussed and the susceptibility to certain neurologic and psychiatric disorders is reviewed. Lastly, we discuss the sex-specific genetic contribution in disorders of sexual development. The precise molecular mechanisms underlying these differences are currently not entirely known. An increased knowledge and understanding of the role of candidate genes will undeniably be of great aid in elucidating the molecular basis of sex-biased disorders and potentially allow for more sex-specific therapies.

Sex steroid hormone modulation of neural stem cells: a critical review

While numerous in vivo experiments have sought to explore the effects of sex chromosome composition and sex steroid hormones on cellular proliferation and differentiation within the mammalian brain, far fewer studies as reviewed here, have explored these factors using a direct in vitro approach. Generally speaking, in vivo studies provide the gold standard to demonstrate applicable findings in regards to the role hormones play in development. However, in the case of neural stem cell (NSC) biology, there remain many unknown factors that likely contribute to observations made within the developed brain, specifically in regions where there are abundant sex steroid hormone receptors. For these reasons, using a NSC in vitro model may provide a more controlled and refined system to explore the direct effects of sex and hormone response, limiting the vast array of other influences on NSCs occurring during development and within adult cellular niches. These specific cellular models may have the ability to greatly improve the mechanistic understanding of changes occurring within the developing brain during the hormonal organization process, in addition to other modifications that may contribute to neuro-psychiatric sex-biased diseases.

Puberty and the human brain: Insights into adolescent development

Alongside the exponential flourish of research on age-related trajectories of human brain development during childhood and adolescence in the past two decades, there has been an increase in the body of work examining the association between pubertal development and brain maturation. This review systematically examines empirical research on puberty-related structural and functional brain development in humans, with the aim of identifying convergent patterns of associations. We emphasize longitudinal studies, and discuss pervasive but oft-overlooked methodological issues that may be contributing to inconsistent findings and hindering progress (e.g., conflating distinct pubertal indices and different measurement instruments). We also briefly evaluate support for prominent models of adolescent neurodevelopment that hypothesize puberty-related changes in brain regions involved in affective and motivational processes. For the field to progress, replication studies are needed to help resolve current inconsistencies and gain a clearer understanding of pubertal associations with brain development in humans, knowledge that is crucial to make sense of the changes in psychosocial functioning, risk behavior, and mental health during adolescence.

Sex-dependent impact of different degrees of maternal separation experience on OFT behavioral performances after adult chronic unpredictable mild stress exposure in rats

Early-life social-environmental factors are important for normal development, and different degrees of early-life stress experience have different impacts on adult behaviors and stress responsiveness. The aim of present study was to investigate the long-term effects of different degrees of maternal separation (MS) on male and female rats and subsequent responsiveness to chronic unpredictable mild stress (CUMS) exposure in adults. Sprague-Dawley (SD) newborn pups were exposed to either 15 min/day of MS (MS15), 360 min/day of MS (MS360) or no separation (NS) during postnatal day (PND)4-PND10. At PND56, behavioral tasks, including sucrose preference test (SPT), forced swimming test (FST) and open field test (OFT), were used to explore depressive and anxiety-like behaviors. Then the rats received a series of CUMS for 28 days, behavioral tasks were recorded after CUMS. Prior to CUMS, the behavioral performances in male and female rats were consistent, MS360 led to increased immobile time in FST and decreased activity in OFT, while MS15 rats exhibited behavioral performances similar to NS group. After CUMS, sexual dimorphism was observed in the OFT behavioral responses to adult stress re-exposure, but no differences in FST were observed. CUMS male rats with MS360 experiences showed the worst behavioral performances in OFT compared to those of the other male rats groups, while CUMS female rats without MS experience showed the worst behavioral performances in OFT compared to those of the other female rats groups. Both CUMS male and female rats with MS15 experiences showed better trend in OFT performances than those of CUMS rats with MS360 experience and without MS experiences. These results suggest that brief MS experiences increase the OFT behavioral resilience of rats to adult stress re-exposure, and prolonged MS promotes OFT behavioral resilience of female rats to adult stress re-exposure, while increases vulnerability of male rats to adult stress re-exposure.

Gene regulatory mechanisms underlying sex differences in brain development and psychiatric disease

The sexual differentiation of the mammalian nervous system requires the precise coordination of the temporal and spatial regulation of gene expression in diverse cell types. Sex hormones act at multiple developmental time points to specify sex-typical differentiation during embryonic and early development and to coordinate subsequent responses to gonadal hormones later in life by establishing sex-typical patterns of epigenetic modifications across the genome. Thus, mutations associated with neuropsychiatric conditions may result in sexually dimorphic symptoms by acting on different neural substrates or chromatin landscapes in males and females. Finally, as stress hormone signaling may directly alter the molecular machinery that interacts with sex hormone receptors to regulate gene expression, the contribution of chronic stress to the pathogenesis or presentation of mental illness may be additionally different between the sexes. Here, we review the mechanisms that contribute to sexual differentiation in the mammalian nervous system and consider some of the implications of these processes for sex differences in neuropsychiatric conditions.