Obesity is a major risk factor for type 2 diabetes, dyslipidemia, cardiovascular disease, and hypertension. Intriguingly, there is a subset of metabolically healthy obese (MHO) individuals who are seemingly able to maintain a healthy metabolic profile free of metabolic syndrome. The molecular underpinnings of MHO, however, are not well understood. Here, we report that CTRP10/C1QL2-deficient mice represent a unique female model of MHO. CTRP10 modulates weight gain in a striking and sexually dimorphic manner. Female, but not male, mice lacking CTRP10 develop obesity with age on a low-fat diet while maintaining an otherwise healthy metabolic profile. When fed an obesogenic diet, female Ctrp10 knockout (KO) mice show rapid weight gain. Despite pronounced obesity, Ctrp10 KO female mice do not develop steatosis, dyslipidemia, glucose intolerance, insulin resistance, oxidative stress, or low-grade inflammation. Obesity is largely uncoupled from metabolic dysregulation in female KO mice. Multi-tissue transcriptomic analyses highlighted gene expression changes and pathways associated with insulin-sensitive obesity. Transcriptional correlation of the differentially expressed gene (DEG) orthologous in humans also show sex differences in gene connectivity within and across metabolic tissues, underscoring the conserved sex-dependent function of CTRP10. Collectively, our findings suggest that CTRP10 negatively regulates body weight in females, and that loss of CTRP10 results in benign obesity with largely preserved insulin sensitivity and metabolic health. This female MHO mouse model is valuable for understanding sex-biased mechanisms that uncouple obesity from metabolic dysfunction.
Prenatal hyperandrogenism is hypothesized as one of the main factors contributing to the development of polycystic ovary syndrome (PCOS). PCOS patients have high risk of developing fatty liver and steatosis. This study aimed to evaluate the role of prenatal hyperandrogenism in liver lipid metabolism and fatty liver development. Pregnant rats were hyperandrogenized with testosterone. At pubertal age, the prenatally hyperandrogenized (PH) female offspring displayed both ovulatory (PHov) and anovulatory (PHanov) phenotypes that mimic human PCOS features. We evaluated hepatic transferases, liver lipid content, the balance between lipogenesis and fatty acid oxidation pathway, oxidant/antioxidant balance and proinflammatory status. We also evaluated the general metabolic status through growth rate curve, basal glucose and insulin levels, glucose tolerance test, HOMA-IR index and serum lipid profile. Although neither PH group showed signs of liver lipid content, the lipogenesis and fatty oxidation pathways were altered. The PH groups also showed impaired oxidant/antioxidant balance, a decrease in the proinflammatory pathway (measured by prostaglandin E2 and cyclooxygenase-2 levels), decreased glucose tolerance, imbalance of circulating lipids and increased risk of metabolic syndrome. We conclude that prenatal hyperandrogenism generates both PHov and PHanov phenotypes with signs of liver alterations, imbalance in lipid metabolism and increased risk of developing metabolic syndrome. The anovulatory phenotype showed more alterations in liver lipogenesis and a more impaired balance of insulin and glucose metabolism, being more susceptible to the development of steatosis.
Esta contribucion es un homenaje a Jose Yepes por los 75 anos transcurridos desde que describiera el genero Tympanoctomys, y por los 90 anos de su ingreso al Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”. Las ratas vizcacha son la epitome de roedores sudamericanos adaptados al desierto, y han constituido un verdadero modelo, no solo presentar distintos atributos especializados para la vida en ambientes xericos, sino tambien como uno de los mamiferos con mayor numero cromosomico. En este capitulo brindamos un panorama global sobre el estado del conocimiento del genero y las especies relacionadas, en areas como sistematica, distribucion, ecologia, genetica y conservacion. Las perspectivas futuras orientan sobre los vacios y preguntas en temas aun no resueltos y que constituyen lineas fascinantes y promisorias para investigar y profundizar.
Abstract/Introduction Proteins secreted from skeletal muscle, termed myokines, allow muscle to impact systemic physiology and disease. Myokines play critical roles in a variety of processes, including metabolic homeostasis, exercise improvements, inflammation, cancer and cognitive functions 1–6 . Despite the clear relevance of these factors in mediating a multitude of physiological outcomes, the genetic architecture, regulation and functions of myokines, as well as degree of conservation of these communication circuits remains inadequately understood. Given that biologic sex controls critical aspects of nearly every physiologic outcome, it is essential to consider when relating specific mechanisms to complex genetic and metabolic interactions. Specifically, many metabolic traits impacted by myokines show striking sex differences arising from hormonal 7–10 , genetic 7,11 or gene-by-sex interactions 12,13 . In this study, we performed a genetic survey of myokine gene regulation and cross-tissue signaling in humans where sex as a biological variable was emphasized. While expression levels of a majority of myokines and cell proportions within skeletal muscle showed little differences between males and females, nearly all significant cross-tissue enrichments operated in a sex-specific or hormone-dependent fashion; in particular, with estrogens. These sex- and hormone-specific effects were consistent across key metabolic tissues: liver, pancreas, hypothalamus, intestine, heart, visceral and subcutaneous adipose tissue. Skeletal muscle estrogen receptor enrichments across metabolic tissues appeared stronger than androgen receptor and, surprisingly, ~3-fold higher in males compared to females. To define the causal roles of estrogen signaling on myokine gene expression and functions, we generated male and female mice which lack estrogen receptor α ( Esr1 ) specifically in skeletal muscle and integrated global RNA-Sequencing with human data. These analyses highlighted mechanisms of sex-dependent myokine signaling conserved between species, such as myostatin enriched for divergent substrate utilization pathways between sexes. Several other sex-dependent mechanisms of myokine signaling were uncovered, such as muscle-derived TNF α exerting stronger inflammatory signaling in females compared to males and GPX3 as a male-specific link between glycolytic fiber abundance and hepatic inflammation. Collectively, we provide the first genetic survey of human myokines and highlight sex and estrogen receptor signaling as critical variables when assaying myokine functions and how changes in cell composition impact other metabolic organs.
Androgens may directly modulate early ovarian follicular development in preantral stages and androgen excess before puberty may disrupt this physiological process. Therefore, the aim of this study was to investigate the dynamics of follicular morphology and circulating androgen and estradiol levels in prepubertal Wistar rats acutely exposed to androgens. Prepubertal female Wistar rats were distributed into three groups: control, equine chorionic gonadotropin (eCG) intervention and eCG plus dehydroepiandrosterone (DHEA) intervention (eCG+DHEA). Serum DHEA, testosterone and estradiol levels were determined, and ovarian morphology and morphometry were assessed. The eCG+DHEA group presented increased serum estradiol and testosterone levels as compared with the control group ( P <0.01), and higher serum DHEA concentration v . the eCG-only and control groups ( P <0.01). In addition, the eCG+DHEA group had a higher number of, and larger-sized, primary and secondary follicles as compared with the control group ( P <0.05). The eCG group presented intermediate values for number and size of primary and secondary follicles, without significant differences as compared with the other two groups. The number of antral follicles was higher in the eCG+DHEA and eCG groups v . controls ( P <0.05). The number of primordial, atretic and cystic follicles were similar in all groups. In conclusion, the present experimental model using an acute eCG+DHEA intervention was useful to investigate events involved in initial follicular development under hyperandrogenic conditions, and could provide a reliable tool to study defective follicular development with possible deleterious reproductive consequences later in life.
Abstract Disclosure: L.M. Velez: None. C. Johnson: None. I. Tamburrini: None. M. Zhou: None. C. Viesi: None. N. Ujagar: None. D. Ashbrook: None. M. Nelson: None. A. Senior: None. D. James: None. R. Williams: None. D. Nicholas: None. M. Seldin: None. Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women, with a prevalence of ∼4-20% in women of reproductive age. The diagnosis of the syndrome generally occurs when the patient consults for fertility issues and is only based on a reproductive criterion, which includes (1) hyperandrogenism, (2) oligo-anovulation, and (3) polycystic ovary morphology. However, the overlap of PCOS with cardiometabolic diseases is significant. To put in numbers; up to 75% of PCOS women present some degree of insulin insensitivity, 38-88% present obesity or overweight, 20-50% develop type 2 diabetes by age 40, and PCOS women are at increased risk of cardiovascular disease. Despite these facts, shared reproductive/metabolic mechanisms are largely underexplored. Moreover, studies addressing the genetic architecture of PCOS are missing. Here, we induced a PCOS-like condition in 25 recombinant and classical inbred female strains and matched placebo controls over 6 weeks. Comprehensive in vivo and terminal reproductive/metabolic analyses were performed, as well as ovary and adipose RNA-Seq. These strains varied in PCOS response in a number of key metabolic and reproductive traits, including circulating hormone levels, glucose metabolism, and cardiac function. We applied a linear mixed-effects model to estimate heritability, and genetic (h2), PCOS, and gene-by-PCOS interactions. High h2 was observed for lean and fat mass, glucose, and AUC, whereas PCOS effects were high for the BW change, testosterone, and AUC. Substantial gene-by-PCOS interactions were found for reproductive hormones. Undirected network construction and centrality estimates showed that the reproductive hormones LH and LH/FSH ratio were the strongest central traits connecting metabolic phenotypes. We also showed select strains represent subtypes of human PCOS-metabolism interaction with varied susceptibilities to disease in a PCOS setting. Ovarian RNA-seq analysis of PCOS DEGs showed strong enrichments with human disease settings such as hyperandrogenism, inflammation, and pregnancy hypertension. Similar analyses in GWAT RNA-seq showed enrichments in weight gain, liposarcoma, inflammation, and reproductive diseases were at the top, with adipose genes connecting these diseases and potentially involved with PCOS. In conclusion, we established a PCOS model to study relevant mechanisms intersecting reproduction with metabolism in the context of genetic variation. Presentation: 6/2/2024
Obesity is a major risk factor for type 2 diabetes, dyslipidemia, cardiovascular disease, and hypertension. Intriguingly, there is a subset of metabolically healthy obese (MHO) individuals who are seemingly able to maintain a healthy metabolic profile free of metabolic syndrome. The molecular underpinnings of MHO, however, are not well understood. Here, we report that CTRP10/C1QL2-deficient mice represent a unique female model of MHO. CTRP10 modulates weight gain in a striking and sexually dimorphic manner. Female, but not male, mice lacking CTRP10 develop obesity with age on a low-fat diet while maintaining an otherwise healthy metabolic profile. When fed an obesogenic diet, female Ctrp10 knockout (KO) mice show rapid weight gain. Despite pronounced obesity, Ctrp10 KO female mice do not develop steatosis, dyslipidemia, glucose intolerance, insulin resistance, oxidative stress, or low-grade inflammation. Obesity is largely uncoupled from metabolic dysregulation in female KO mice. Multi-tissue transcriptomic analyses highlighted gene expression changes and pathways associated with insulin-sensitive obesity. Transcriptional correlation of the differentially expressed gene (DEG) orthologous in humans also show sex differences in gene connectivity within and across metabolic tissues, underscoring the conserved sex-dependent function of CTRP10. Collectively, our findings suggest that CTRP10 negatively regulates body weight in females, and that loss of CTRP10 results in benign obesity with largely preserved insulin sensitivity and metabolic health. This female MHO mouse model is valuable for understanding sex-biased mechanisms that uncouple obesity from metabolic dysfunction.
African Americans have a higher prevalence of Type 2 Diabetes (T2D) compared to White groups. T2D is a health disparity clinically characterized by dysregulation of lipids and chronic inflammation. However, how the relationships among biological and sociological predictors of T2D drive this disparity remains to be addressed.
Inter-organ communication is a vital process to maintain physiologic homeostasis, and its dysregulation contributes to many human diseases. Given that circulating bioactive factors are stable in serum, occur naturally, and are easily assayed from blood, they present obvious focal molecules for therapeutic intervention and biomarker development. Recently, studies have shown that secreted proteins mediating inter-tissue signaling could be identified by 'brute force' surveys of all genes within RNA-sequencing measures across tissues within a population. Expanding on this intuition, we reasoned that parallel strategies could be used to understand how individual genes mediate signaling across metabolic tissues through correlative analyses of gene variation between individuals. Thus, comparison of quantitative levels of gene expression relationships between organs in a population could aid in understanding cross-organ signaling. Here, we surveyed gene-gene correlation structure across 18 metabolic tissues in 310 human individuals and 7 tissues in 103 diverse strains of mice fed a normal chow or high-fat/high-sucrose (HFHS) diet. Variation of genes such as
Abstract Disclosure: N. Ujagar: None. G. De Robles: None. L.M. Velez: None. M. Seldin: None. D. Nicholas: None. The etiology behind polycystic ovary syndrome (PCOS) is elusive due to the heterogeneity of its symptoms and varying severity in patients. There are a wide variety of factors associated with PCOS, like hyperinsulinemia, hyperandrogenism, endotoxemia and chronic inflammation that have been implicated as causal factors in the condition. However mechanisms of cause and effect are difficult to establish in human cohorts. Endotoxemia, observed in humans and mouse models of PCOS, is known to trigger chronic inflammation by activating immune cells. Although correlation of chronic inflammation with PCOS has been established, the type of inflammation in PCOS patients has not been defined, in part due to the genetic variance from person to person. Using a systems immunology approach to mimic human genetic diversity, combined with a letrozole-induced PCOS mouse model, we aim to distinguish the types of inflammation present in PCOS. We analyzed the immune cells from lymph nodes and spleens of 21 different strains of PCOS induced and control mice (130 mice in total), and found that based on genetic background the reproductive and metabolic phenotypes differed- similar to how PCOS presents clinically. We were able to categorize each letrozole-induced mouse strain into the sub-phenotypes of PCOS based on the current guidelines for diagnosing PCOS published in 2023 and extensive characterization of each strain. Splenocytes from these control and PCOS mice were activated in vitro to trigger T cell and myeloid cell cytokine secretion, which was measured via luminex. Clustering analysis of these multi-analyte cytokine measurements together with flow cytometry of the immune cells allowed us to identify T-helper 17 (Th17) cells as the prominent immune cell driving inflammation in letrozole-induce mouse model of PCOS independent of genetic background. This systems immunology approach has allowed us to define PCOS associated inflammation and will be the basis for integrating human inflammation in PCOS with mouse models that appropriately recapitulate disease. The discovery of Th17 cells as key inflammatory mediators provide targets for understanding the mechanisms linking chronic inflammation to reproductive and metabolic outcomes in PCOS, and will assist in future development of anti-inflammatory therapies. Presentation: 6/2/2024
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