Tissue regenerative potential displays striking divergence across phylogeny and ontogeny, but the underlying mechanisms remain enigmatic. Loss of mammalian cardiac regenerative potential correlates ...with cardiomyocyte cell-cycle arrest and polyploidization as well as the development of postnatal endothermy. We reveal that diploid cardiomyocyte abundance across 41 species conforms to Kleiber's law-the ¾-power law scaling of metabolism with bodyweight-and inversely correlates with standard metabolic rate, body temperature, and serum thyroxine level. Inactivation of thyroid hormone signaling reduces mouse cardiomyocyte polyploidization, delays cell-cycle exit, and retains cardiac regenerative potential in adults. Conversely, exogenous thyroid hormones inhibit zebrafish heart regeneration. Thus, our findings suggest that loss of heart regenerative capacity in adult mammals is triggered by increasing thyroid hormones and may be a trade-off for the acquisition of endothermy.
Resistance to thyroid hormone can be due to heterozygous, dominant negative (DN) THRA (RTHα) or THRB (RTHβ) mutations, but the underlying mechanisms are incompletely understood. Here, we delineate ...the spatiotemporal expression of TH receptors (TRs) in zebrafish and generated morphants expressing equivalent amounts of wild-type and DN TRαs (thraa_MOs) and TRβs (thrb_MOs) in vivo. Both morphants show severe developmental abnormalities. The phenotype of thraa_MOs includes brain and cardiac defects, but normal thyroid volume and tshba expression. A combined modification of dio2 and dio3 expression can explain the high T3/T4 ratio seen in thraa_MOs, as in RTHα. Thrb_MOs show abnormal eyes and otoliths, with a typical RTHβ pattern of thyroid axis. The coexpression of wild-type, but not mutant, human TRs can rescue the phenotype in both morphants. High T3 doses can partially revert the dominant negative action of mutant TRs in morphant fish.
Therefore, our morphants recapitulate the RTHα and RTHβ key manifestations representing new models in which the functional consequences of human TR mutations can be rapidly and faithfully evaluated.
•We characterize the expression of TRs in zebrafish embryos and adult tissues.•TR-morphants recapitulate the clinical features of RTHα or RTHβ patients.•Changes in the expression of deiodinases can explain the high T3/T4 ratio of RTHα.•Zebrafish and human TRs are functionally interchangeable.•Mutant hTRs can variably rescue the morphant phenotypes only after high T3 doses.
Higher androgen and lower estrogen levels are associated with cardiovascular disease (CVD) risk factors in women. However, studies on sex hormones and incident CVD events in women have yielded ...conflicting results.
The authors assessed the associations of sex hormone levels with incident CVD, coronary heart disease (CHD), and heart failure (HF) events among women without CVD at baseline.
The authors studied 2,834 post-menopausal women participating in the MESA (Multi-Ethnic Study of Atherosclerosis) with testosterone, estradiol, dehydroepiandrosterone, and sex hormone binding globulin (SHBG) levels measured at baseline (2000 to 2002). They used Cox hazard models to evaluate associations of sex hormones with each outcome, adjusting for demographics, CVD risk factors, and hormone therapy use.
The mean age was 64.9 ± 8.9 years. During 12.1 years of follow-up, 283 CVD, 171 CHD, and 103 HF incident events occurred. In multivariable-adjusted models, the hazard ratio (95% confidence interval CI) associated with 1 SD greater log-transformed sex hormone level for the respective outcomes of CVD, CHD, and HF were as follows: total testosterone: 1.14 (95% CI: 1.01 to 1.29), 1.20 (95% CI: 1.03 to 1.40), 1.09 (95% CI: 0.90 to 1.34); estradiol: 0.94 (95% CI: 0.80 to 1.11), 0.77 (95% CI: 0.63 to 0.95), 0.78 (95% CI: 0.60 to 1.02); and testosterone/estradiol ratio: 1.19 (95% CI: 1.02 to 1.40), 1.45 (95% CI: 1.19 to 1.78), 1.31 (95% CI: 1.01 to 1.70). Dehydroepiandrosterone and SHBG levels were not associated with these outcomes.
Among post-menopausal women, a higher testosterone/estradiol ratio was associated with an elevated risk for incident CVD, CHD, and HF events, higher levels of testosterone associated with increased CVD and CHD, whereas higher estradiol levels were associated with a lower CHD risk. Sex hormone levels after menopause are associated with women’s increased CVD risk later in life.
Display omitted
Ghrelin, a circulating appetite-inducing hormone, is derived from a prohormone by posttranslational processing. On the basis of the bioinformatic prediction that another peptide also derived from ...proghrelin exists, we isolated a hormone from rat stomach and named it obestatin-a contraction of obese, from the Latin "obedere," meaning to devour, and "statin," denoting suppression. Contrary to the appetite-stimulating effects of ghrelin, treatment of rats with obestatin suppressed food intake, inhibited jejunal contraction, and decreased body-weight gain. Obestatin bound to the orphan G protein-coupled receptor GPR39. Thus, two peptide hormones with opposing action in weight regulation are derived from the same ghrelin gene. After differential modification, these hormones activate distinct receptors.
Aggressive treatment with antibiotics in patients infected with Streptococcus pneumoniae induces release of the bacterial virulence factor pneumolysin (PLY). Days after lungs are sterile, this ...pore-forming toxin can still induce pulmonary permeability edema in patients, characterized by alveolar/capillary barrier dysfunction and impaired alveolar liquid clearance (ALC). ALC is mainly regulated through Na+ transport by the apically expressed epithelial sodium channel (ENaC) and the basolaterally expressed Na+/K+-ATPase in type II alveolar epithelial cells. Because no standard treatment is currently available to treat permeability edema, the search for novel therapeutic candidates is of high priority. We detected mRNA expression for the active receptor splice variant SV1 of the hypothalamic polypeptide growth hormone-releasing hormone (GHRH), as well as for GHRH itself, in human lung microvascular endothelial cells (HL-MVEC). Therefore, we have evaluated the effect of the GHRH agonist JI-34 on PLY-induced barrier and ALC dysfunction. JI-34 blunts PLY-mediated endothelial hyperpermeability in monolayers of HL-MVEC, in a cAMP-dependent manner, by means of reducing the phosphorylation of myosin light chain and vascular endothelial (VE)-cadherin. In human airway epithelial H441 cells, PLY significantly impairs Na+ uptake, but JI-34 restores it to basal levels by means of increasing cAMP levels. Intratracheal instillation of PLY into C57BL6 mice causes pulmonary alveolar epithelial and endothelial hyperpermeability as well as edema formation, all of which are blunted by JI-34. These findings point toward a protective role of the GHRH signaling pathway in PLY-induced permeability edema.
The stem cell niche is a complex local signaling microenvironment that sustains stem cell activity during organ maintenance and regeneration. The mammary gland niche must support its associated stem ...cells while also responding to systemic hormonal regulation that triggers pubertal changes. We find that
, the major Hedgehog pathway transcriptional effector, acts within mouse mammary stromal cells to direct a hormone-responsive niche signaling program by activating expression of factors that regulate epithelial stem cells as well as receptors for the mammatrophic hormones estrogen and growth hormone. Whereas prior studies implicate stem cell defects in human disease, this work shows that niche dysfunction may also cause disease, with possible relevance for human disorders and in particular the breast growth pathogenesis associated with combined pituitary hormone deficiency.
The purpose of this study is to compare the relative efficacy and safety of long-acting growth hormone (LAGH) as a growth hormone replacement therapy in prepubertal children with growth hormone ...deficiency (GHD). We searched the PubMed, Embase, CNKI, and Wanfang databases from inception to July 2023 and identified eleven relevant studies. PEG-LAGH showed better effect on height velocity (mean difference MD: - 0.031, 95% credibility interval CrI: - 0.278, 0.215) than somatrogon (MD: 0.105, 95% CrI: - 0.419, 0.636), somapacitan (MD: 0.802, 95% CrI: - 0.451, 2.068) and lonapegsomatropin (MD: 1.335, 95% CrI: - 0.3, 2.989) when compared with daily growth hormone (DGH). Furthermore, in terms of height standard deviation score, PEG-LAGH demonstrated better improvement (MD: - 0.15, 95% CrI: - 1.1, 0.66) than somatrogon (MD: - 0.055, 95% CrI: - 1.3, 0.51) and somapacitan (MD: 0.22, 95% CrI: - 0.91, 1.3). PEG-LAGH (risk ratio RR: 1.00, 95% CrI: 0.82, 1.2) reduced the risk of adverse events compared with other LAGH (somatrogon, RR: 1.1, 95% CrI: 0.98, 1.2; somapacitan, RR: 1.1, 95% CrI: 0.96, 1.4; lonapegsomatropin, RR, 1.1, 95% CrI: 0.91, 1.3) and was comparable with DGH. This is the first study to indirectly compare the LAGH thorough a network meta-analysis and provide evidence of the optimal efficacy of various LAGH specifically PEG-LAGH and acceptable safety profile in prepubertal children with GHD.
Thyroid hormones (TH) play critical roles during nervous system development and patients carrying coding variants of MCT8 (monocarboxylate transporter 8) or THRA (thyroid hormone receptor alpha) ...present a spectrum of neurological phenotypes resulting from perturbed local TH action during early brain development. Recently, human cerebral organoids (hCOs) emerged as powerful in vitro tools for disease modelling recapitulating key aspects of early human cortex development. To begin exploring prospects of this model for thyroid research, we performed a detailed characterization of the spatiotemporal expression of MCT8 and THRA in developing hCOs. Immunostaining showed MCT8 membrane expression in neuronal progenitor cell types including early neuroepithelial cells, radial glia cells (RGCs), intermediate progenitors and outer RGCs. In addition, we detected robust MCT8 protein expression in deep layer and upper layer neurons. Spatiotemporal SLC16A2 mRNA expression, detected by fluorescent in situ hybridization (FISH), was highly concordant with MCT8 protein expression across cortical cell layers. FISH detected THRA mRNA expression already in neuroepithelium before the onset of neurogenesis. THRA mRNA expression remained low in the ventricular zone, increased in the subventricular zone whereas strong THRA expression was observed in excitatory neurons. In combination with a robust up-regulation of known T3 response genes following T3 treatment, these observations show that hCOs provide a promising and experimentally tractable model to probe local TH action during human cortical neurogenesis and eventually to model the consequences of impaired TH function for early cortex development.
FSH, a glycoprotein hormone, and the FSH receptor (FSHR), a G protein-coupled receptor, play central roles in human reproduction. We report the crystal structure of FSH in complex with the entire ...extracellular domain of FSHR (FSHR ED), including the enigmatic hinge region that is responsible for signal specificity. Surprisingly, the hinge region does not form a separate structural unit as widely anticipated but is part of the integral structure of FSHR ED. In addition to the known hormone-binding site, FSHR ED provides interaction sites with the hormone: a sulfotyrosine (sTyr) site in the hinge region consistent with previous studies and a potential exosite resulting from putative receptor trimerization. Our structure, in comparison to others, suggests FSHR interacts with its ligand in two steps: ligand recruitment followed by sTyr recognition. FSH first binds to the high-affinity hormone-binding subdomain of FSHR and reshapes the ligand conformation to form a sTyr-binding pocket. FSHR then inserts its sTyr (i.e., sulfated Tyr335) into the FSH nascent pocket, eventually leading to receptor activation.
Thyroid hormone (TH) and TH receptors (TRs) α and β act by binding to TH response elements (TREs) in regulatory regions of target genes. This nuclear signaling is established as the canonical or type ...1 pathway for TH action. Nevertheless, TRs also rapidly activate intracellular second-messenger signaling pathways independently of gene expression (noncanonical or type 3 TR signaling). To test the physiological relevance of noncanonical TR signaling, we generated knockin mice with a mutation in the TR DNA-binding domain that abrogates binding to DNA and leads to complete loss of canonical TH action. We show that several important physiological TH effects are preserved despite the disruption of DNA binding of TRα and TRβ, most notably heart rate, body temperature, blood glucose, and triglyceride concentration, all of which were regulated by noncanonical TR signaling. Additionally, we confirm that TRE-binding–defective TRβ leads to disruption of the hypothalamic–pituitary–thyroid axis with resistance to TH, while mutation of TRα causes a severe delay in skeletal development, thus demonstrating tissue- and TR isoform-specific canonical signaling. These findings provide in vivo evidence that noncanonical TR signaling exerts physiologically important cardiometabolic effects that are distinct from canonical actions. These data challenge the current paradigm that in vivo physiological TH action is mediated exclusively via regulation of gene transcription at the nuclear level.
PDF
