Cerebral cortex hyperthyroidism of newborn Mct8-deficient mice transiently suppressed by Lat2 inactivation

Thyroid hormone entry into cells is facilitated by transmembrane transporters. Mutations of the specific thyroid hormone transporter, MCT8 (Monocarboxylate Transporter 8, SLC16A2) cause an X-linked syndrome of profound neurological impairment and altered thyroid function known as the Allan-Herndon-Dudley syndrome. MCT8 deficiency presumably results in failure of thyroid hormone to reach the neural target cells in adequate amounts to sustain normal brain development. However during the perinatal period the absence of Mct8 in mice induces a state of cerebral cortex hyperthyroidism, indicating increased brain access and/or retention of thyroid hormone. The contribution of other transporters to thyroid hormone metabolism and action, especially in the context of MCT8 deficiency is not clear. We have analyzed the role of the heterodimeric aminoacid transporter Lat2 (Slc7a8), in the presence or absence of Mct8, on thyroid hormone concentrations and on expression of thyroid hormone-dependent cerebral cortex genes. To this end we generated Lat2-/-, and Mct8-/yLat2-/- mice, to compare with wild type and Mct8-/y mice during postnatal development. As described previously the single Mct8 KO neonates had a transient increase of 3,5,3′-triiodothyronine concentration and expression of thyroid hormone target genes in the cerebral cortex. Strikingly the absence of Lat2 in the double Mct8Lat2 KO prevented the effect of Mct8 inactivation in newborns. The Lat2 effect was not observed from postnatal day 5 onwards. On postnatal day 21 the Mct8 KO displayed the typical pattern of thyroid hormone concentrations in plasma, decreased cortex 3,5,3′-triiodothyronine concentration and Hr expression, and concomitant Lat2 inactivation produced little to no modifications. As Lat2 is expressed in neurons and in the choroid plexus, the results support a role for Lat2 in the supply of thyroid hormone to the cerebral cortex during early postnatal development

Prenatal Treatment of Thyroid Hormone Cell Membrane Transport Defect Caused by MCT8 Gene Mutation

[Background]: Mutations of the thyroid hormone (TH)-specific cell membrane transporter, monocarboxylate transporter 8 (MCT8), produce an X-chromosome-linked syndrome of TH deficiency in the brain and excess in peripheral tissues. The clinical consequences include brain hypothyroidism causing severe psychoneuromotor abnormalities (no speech, truncal hypotonia, and spastic quadriplegia) and hypermetabolism (poor weight gain, tachycardia, and increased metabolism, associated with high serum levels of the active TH, T3). Treatment in infancy and childhood with TH analogues that reduce serum triiodothyronine (T3) corrects hypermetabolism, but has no effect on the psychoneuromotor deficits. Studies of brain from a 30-week-old MCT8-deficient embryo indicated that brain abnormalities were already present during fetal life. [Methods]: A carrier woman with an affected male child (MCT8 A252fs268*), pregnant with a second affected male embryo, elected to carry the pregnancy to term. We treated the fetus with weekly 500 μg intra-amniotic instillation of levothyroxine (LT4) from 18 weeks of gestation until birth at 35 weeks. Thyroxine (T4), T3, and thyrotropin (TSH) were measured in the amniotic fluid and maternal serum. Treatment after birth was continued with LT4 and propylthiouracil. Follow-up included brain magnetic resonance imaging (MRI) and neurodevelopmental evaluation, both compared with the untreated brother. [Results]: During intrauterine life, T4 and T3 in the amniotic fluid were maintained above threefold to twofold the baseline and TSH was suppressed by 80%, while maternal serum levels remained unchanged. At birth, the infant serum T4 was 14.5 μg/dL and TSH 8 mU/L, respectively. MRI at six months of age showed near-normal brain myelination compared with much reduced in the untreated brother. Neurodevelopmental assessment showed developmental quotients in receptive language and problem-solving, and gross motor and fine motor function ranged from 12 to 25 at 31 months in the treated boy and from 1 to 7 at 58 months in the untreated brother. [Conclusions]: This is the first demonstration that prenatal treatment improved the neuromotor and neurocognitive function in MCT8 deficiency. Earlier treatment with TH analogues that concentrate in the fetus when given to the mother may further rescue the phenotype.This work was supported by grants from the National Institutes of Health, USA, DK15070 to Samuel Refetoff and DK110322 to Alexandra M. Dumitrescu, and by funds from the Esformes Thyroid Research Fund to Roy E. Weiss

Cross-Species Analyses Identify Dlgap2 as a Regulator of Age-Related Cognitive Decline and Alzheimer\u27s Dementia.

Genetic mechanisms underlying age-related cognitive decline and dementia remain poorly understood. Here, we take advantage of the Diversity Outbred mouse population to utilize quantitative trait loci mapping and identify Dlgap2 as a positional candidate responsible for modifying working memory decline. To evaluate the translational relevance of this finding, we utilize longitudinal cognitive measures from human patients, RNA expression from post-mortem brain tissue, data from a genome-wide association study (GWAS) of Alzheimer\u27s dementia (AD), and GWAS results in African Americans. We find an association between Dlgap2 and AD phenotypes at the variant, gene and protein expression, and methylation levels. Lower cortical DLGAP2 expression is observed in AD and is associated with more plaques and tangles at autopsy and faster cognitive decline. Results will inform future studies aimed at investigating the cross-species role of Dlgap2 in regulating cognitive decline and highlight the benefit of using genetically diverse mice to prioritize novel candidates

Sex differences in the genetic architecture of cognitive resilience to Alzheimer\u27s disease.

Approximately 30% of elderly adults are cognitively unimpaired at time of death despite the presence of Alzheimer\u27s disease neuropathology at autopsy. Studying individuals who are resilient to the cognitive consequences of Alzheimer\u27s disease neuropathology may uncover novel therapeutic targets to treat Alzheimer\u27s disease. It is well established that there are sex differences in response to Alzheimer\u27s disease pathology, and growing evidence suggests that genetic factors may contribute to these differences. Taken together, we sought to elucidate sex-specific genetic drivers of resilience. We extended our recent large scale genomic analysis of resilience in which we harmonized cognitive data across four cohorts of cognitive ageing, in vivo amyloid PET across two cohorts, and autopsy measures of amyloid neuritic plaque burden across two cohorts. These data were leveraged to build robust, continuous resilience phenotypes. With these phenotypes, we performed sex-stratified [n (males) = 2093, n (females) = 2931] and sex-interaction [n (both sexes) = 5024] genome-wide association studies (GWAS), gene and pathway-based tests, and genetic correlation analyses to clarify the variants, genes and molecular pathways that relate to resilience in a sex-specific manner. Estimated among cognitively normal individuals of both sexes, resilience was 20-25% heritable, and when estimated in either sex among cognitively normal individuals, resilience was 15-44% heritable. In our GWAS, we identified a female-specific locus on chromosome 10 [rs827389, β (females) = 0.08, P (females) = 5.76 × 10-09, β (males) = -0.01, P(males) = 0.70, β (interaction) = 0.09, P (interaction) = 1.01 × 10-04] in which the minor allele was associated with higher resilience scores among females. This locus is located within chromatin loops that interact with promoters of genes involved in RNA processing, including GATA3. Finally, our genetic correlation analyses revealed shared genetic architecture between resilience phenotypes and other complex traits, including a female-specific association with frontotemporal dementia and male-specific associations with heart rate variability traits. We also observed opposing associations between sexes for multiple sclerosis, such that more resilient females had a lower genetic susceptibility to multiple sclerosis, and more resilient males had a higher genetic susceptibility to multiple sclerosis. Overall, we identified sex differences in the genetic architecture of resilience, identified a female-specific resilience locus and highlighted numerous sex-specific molecular pathways that may underly resilience to Alzheimer\u27s disease pathology. This study illustrates the need to conduct sex-aware genomic analyses to identify novel targets that are unidentified in sex-agnostic models. Our findings support the theory that the most successful treatment for an individual with Alzheimer\u27s disease may be personalized based on their biological sex and genetic context

Metamodernism, the Anthropocene, and the Resurgence of Historicity: Ben Lerner’s 10:04 and “the utopian glimmer of fiction”

Postmodernism has been characterized by a reductive presentism that suppresses historicity and neglects the possibility of the future. If we have seen a shift from postmodernism to a different cultural logic and structure of feeling—as, indeed, many critics argue—it therefore follows that this may also entail a new dominant in temporal dynamics. In this article, I take Ben Lerner’s 2014 novel 10:04 as a case study in literary metamodernism, though I also make reference to Adam Thirlwell’s 2011 novella Kapow! and Ruth Ozeki’s 2013 novel A Tale for the Time Being. Across these texts, and primarily in 10:04 as a quintessentially metamodernist fiction, I observe and explicate a metamodern temporality characterized, interconnectedly, by the aesthetics of heterochrony, sideshadowing, and the anticipation of retrospection. Whilst this temporal dynamic emerges from the precarity and volatility of experience in the twenty-first century, anthropocenic climate change has been and remains—I suggest—the greatest catalyst in producing this new temporal experience which resurrects historicity and resuscitates the future as a field of possibilities

Anemia in Patients With Resistance to Thyroid Hormone α: A Role for Thyroid Hormone Receptor α in Human Erythropoiesis

Context: Patients with resistance to thyroid hormone (TH) α (RTHα) are characterized by growth retardation, macrocephaly, constipation, and abnormal thyroid function tests. In addition, almost all RTHα patients have mild anemia, the pathogenesis of which is unknown. Animal studies suggest an important role for TH and TH receptor (TR)α in erythropoiesis. Objective: To investigate whether a defect in TRα affects the maturation of red blood cells in RTHα patients. Design, Setting, and Patients: Cultures of primary human erythroid progenitor cells (HEPs), from peripheral blood of RTHα patients (n = 11) harboring different inactivating mutations in TRα (P398R, F397fs406X, C392X, R384H, A382fs388X, A263V, A263S), were compared with healthy controls (n = 11). During differentiation, erythroid cells become smaller, accumulate hemoglobin, and express different cell surface markers. We assessed cell number and cell size, and used cell staining and fluorescence-activated cell sorter analysis to monitor maturation at different time points. Results: After ∼14 days of ex vivo expansion, both control and patient-derived progenitors differentiated spontaneously. However, RTHα-derived cells differentiated more slowly. During spontaneous differentiation, RTHα-derived HEPs were larger, more positive for c-Kit (a proliferation marker), and less positive for glycophorin A (a differentiation marker). The degree of abnormal spontaneous maturation of RTHα-derived progenitors did not correlate with severity of underlying TRα defect. Both control and RTHα-derived progenitors responded similarly when differentiation was induced. T3 exposure accelerated differentiation of both control- and RTHα patient-derived HEPs. Conclusions: Inactivating mutations in human TRα affect the balance between proliferation and differentiation of progenitor cells during erythropoiesis, which may contribute to the mild anemia seen in most RTHα patients.A.L.M.v.G., M.E.M., and R.P.P. are supported by ZonMWTOP Grant 91212044 and an Erasmus MC Medical Research Advisory Committee (MRACE) grant. A.L.M.v.G. and R.P.P. are also supported by a European Thyroid Association (ETA) research grant. K. Chatterjee is supported by Wellcome Trust Investigator Award 095564/Z/11/Z. K. Chatterjee and C.M. are supported by the National Institute for Health Research Cambridge Biomedical Research Centre

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Graves’ disease and papillary thyroid carcinoma: case report and literature review of a single academic center

Background: Graves’ disease (GD) and papillary thyroid cancer (PTC) can be concomitant. The existence of a link between these entities has long been investigated, but a clear correlation hasn’t been established. We report a case of GD resistant to medical treatment in which surgery revealed unsuspected PTC and we aim to study the prevalence of PTC in Graves’ disease, its clinical characteristics and review of the literature. Case presentation: Report of a 32 yo man who presented with weight loss and was found to be biochemically hyperthyroid. Antibodies were positive. Incremental doses of methimazole provided no improvement in thyroid tests. Hypervascularity and a spongiform nodule were noted on ultrasound. Thyroid uptake and scan showed 70.2% uptake. Thyroidectomy was performed due to inadequate therapeutic response. Pathology revealed PTC with extrathyroidal extension and positive lymph nodes. A retrospective review (2000–2021) and literature review of PTC in GD was performed. Clinical data were reviewed. Statistical analysis was calculated to identify correlations. 243 GD patients had total thyroidectomy at an academic center, 50 (20%) had PTC, 14% were microcarcinomas. 76% of cases were less than 55yo, 82% female, 78% stage 1, PTC diagnosis was incidental in 48%, hyperthyroidism was difficult to treat in 10% and only 2% had recurrence of PTC. There was no correlation between demographic or clinical data. Conclusions: Evidence is controversial with some studies showing GD does not affect PTC prognosis. PTC may not be well recognized in GD, pre-operative assessment should consider risk of cancer.</p

A Novel Syndrome Combining Thyroid and Neurological Abnormalities Is Associated with Mutations in a Monocarboxylate Transporter Gene

Thyroid hormones are iodothyronines that control growth and development, as well as brain function and metabolism. Although thyroid hormone deficiency can be caused by defects of hormone synthesis and action, it has not been linked to a defect in cellular hormone transport. In fact, the physiological role of the several classes of membrane transporters remains unknown. We now report, for the first time, mutations in the monocarboxylate transporter 8 (MCT8) gene, located on the X chromosome, that encodes a 613–amino acid protein with 12 predicted transmembrane domains. The propositi of two unrelated families are males with abnormal relative concentrations of three circulating iodothyronines, as well as neurological abnormalities, including global developmental delay, central hypotonia, spastic quadriplegia, dystonic movements, rotary nystagmus, and impaired gaze and hearing. Heterozygous females had a milder thyroid phenotype and no neurological defects. These findings establish the physiological importance of MCT8 as a thyroid hormone transporter