Taconic (United States)

Infertility affects one in six people, but the underlying mechanisms remain unclear. We show that the microbiota governs female reproductive longevity in mice. Germ-free mice have fewer primordial follicles, increased atresia, and ovarian fibrosis, leading to smaller litters, fewer offspring, and a shorter reproductive lifespan. Germ-free mice are born with a similar ovarian reserve but display excessive activation, impaired progression, and increased atresia during post-natal development. Microbiome colonization during a critical post-natal window rescues premature ovarian reserve loss by normalizing follicle kinetics and gene expression patterns. These changes parallel increased short-chain fatty acids (SCFAs), and SCFA administration mitigates ovarian dysfunction in germ-free mice. Similar oocyte dysfunction occurred in conventionally raised mice fed a high-fat diet, but additional dietary fiber helped preserve oocyte quality and embryo competence. Thus, host-microbe interactions shape female fertility, and microbiota-targeted interventions may offer strategies to address reproductive disorders.

A spontaneous mutation in the wild type C57BL/6NTac mouse was discovered that is associated with early-onset histopathologic sequalae typical of thyroid dysplasia. The spontaneous mutation resulted from insertion of a L1 long interspersed nuclear element (LINE-1) into an intron within the Thyroglobulin (Tg) gene. The mouse genome contains a significant amount of retrotransposon DNA, and these mobile genetic elements routinely change genomic location through retrotransposition, including in germ cells. Analysis of the thyroid transcriptome suggested that the presence of the LINE-1 interferes with the Tg gene splicing, resulting in exclusion of exon 26 from most Tg transcripts in animals homozygous (HOM) for the insertion. The LINE-1 insertion allele of the Tg gene has been designated Tgtdys-Tac. The resulting phenotype is inherited in an autosomal dominant manner with affected mice exhibiting thyroid follicular cell dysplasia that progresses to thyroid adenoma by 9 months of age with complete penetrance in homozygotes. Serum thyroid hormone measurements revealed a decrease in triiodothyronine (T3) levels in homozygotes at 12 months of age, as well as a decrease in tetraiodothyronine (T4) levels at 6-9 months and at 12 months of age in both heterozygotes and homozygotes. In addition, serum Thyroid Stimulating Hormone (TSH) level was strongly increased in homozygotes at 6-8 months of age, consistent with hypothyroidism. Computational molecular modeling showed that omission of the 64 amino acids from the TG protein arm domain, which is the consequence of exon 26-skipping in the Tg transcript, results in decreased local stability. This result in combination with the observed up-regulation in unfolded protein response (UPR) pathways in the thyroids of affected animals, identifies the arm domain of TG as important for its proper cellular distribution. This report describes a spontaneous retrotransposon insertion causatively linked to dysregulated physiological phenotypes in a widely used inbred mouse strain.

Infertility is a devastating condition affecting one in six people globally. In many cases, the underlying causes are unknown. Emerging evidence suggests that the microbiota influences reproduction, yet the mechanistic link between the microbiota, ovarian function, and length of the fertile lifespan remain unexplored. Here we report that the microbiota controls the length of the reproductive lifespan by maintaining the primordial follicle pool, a process mediated by microbiota-derived short chain fatty acids modulating gene regulatory networks crucial for the survival of the ovarian reserve. Dietary perturbation of the microbiota during a critical developmental window is sufficient to diminish the ovarian reserve, reduce oocyte retrieval, and impair preimplantation embryo viability, mirroring challenges in human fertility treatments. Targeted interventions to restore microbiota improve assisted reproductive outcomes, particularly when implemented early. These findings reveal a novel contribution of host-microbe interactions in mammalian reproduction and demonstrate that the microbiota impacts ovarian function and fertility.

NSG-SGM3 and NOG-EXL mice combine severe immunodeficiency with transgenic expression of human myeloid stimulatory cytokines, resulting in marked expansion of myeloid populations upon humanization with CD34+ hematopoietic stem cells (HSCs). Humanized NSG-SGM3 mice typically develop a lethal macrophage activation syndrome and mast cell hyperplasia that limit their use in long-term studies (e.g., humanization followed by tumor xenotransplantation). It is currently unclear to what extent humanized NOG-EXL mice suffer from the same condition observed in humanized NSG-SGM3 mice. We compared the effects of human CD34+ HSC engraftment in these two strains in an orthotopic patient-derived glioblastoma model. NSG-SGM3 mice humanized in-house were compared to NOG-EXL mice humanized in-house and commercially available humanized NOG-EXL mice. Mice were euthanized at humane or study endpoints, and complete pathological assessments were performed. A semiquantitative multiparametric clinicopathological scoring system was developed to characterize chimeric myeloid cell hyperactivation (MCH) syndrome. NSG-SGM3 mice were euthanized at 16 weeks after humanization because of severe deterioration of clinical conditions. Humanized NOG-EXL mice survived to the study endpoint at 22 weeks after humanization and showed less-severe MCH phenotypes than NSG-SGM3 mice. Major differences included the lack of mast cell expansion and limited tissue/organ involvement in NOG-EXL mice compared to NSG-SGM3 mice. Engraftment of human lymphocytes, assessed by immunohistochemistry, was similar in the two strains. The longer survival and decreased MCH phenotype severity in NOG-EXL mice enabled their use in a tumor xenotransplantation study. The NOG-EXL model is better suited than the NSG-SGM3 model for immuno-oncology studies requiring long-term survival after humanization.

Multiple mutations have been described in the human GBA1 gene, which encodes the lysosomal enzyme beta-glucocerebrosidase (GCase) that degrades glucosylceramide and is pivotal in glycosphingolipid substrate metabolism. Depletion of GCase, typically by homozygous mutations in GBA1, is linked to the lysosomal storage disorder Gaucher’s disease (GD) and distinct or heterozygous mutations in GBA1 are associated with increased Parkinson’s disease (PD) risk. While numerous genes have been linked to heritable PD, GBA1 mutations in aggregate are the single greatest risk factor for development of idiopathic PD. The importance of GCase in PD necessitates preclinical models in which to study GCase-related mechanisms and novel therapeutic approaches, as well as to elucidate the molecular mechanisms leading to enhanced PD risk in GBA1 mutation carriers. The aim of this study was to develop and characterize a novel GBA1 mouse model and to facilitate wide accessibility of the model with phenotypic data. Herein we describe the results of molecular, biochemical, histological, and behavioral phenotyping analyses in a GBA1 D409V knock-in (KI) mouse. This mouse model exhibited significantly decreased GCase activity in liver and brain, with substantial increases in glycosphingolipid substrates in the liver. While no changes in the number of dopamine neurons in the substantia nigra were noted, subtle changes in striatal neurotransmitters were observed in GBA1 D409V KI mice. Alpha-synuclein pathology and inflammation were not observed in the nigrostriatal system of this model. In summary, the GBA1 D409V KI mouse model provides an ideal model for studies aimed at pharmacodynamic assessments of potential therapies aiming to restore GCase.

ABSTRACTAlthough the fast antidepressant effect of ketamine is now well established clinically, neither its mechanism(s) nor its main site(s) of action is clearly defined. Because enhanced serotoninergic (5-HT) transmission is an important part of the antidepressant effect of various drug classes, we asked whether ketamine and one of its metabolites (hydroxynorketamine [HNK]), both used in their racemic form, may modulate the excitatory drive onto these neurons.Using whole-cell recordings from pharmacologically identified 5-HT and non-5-HT neurons in juvenile rat dorsal raphe slices, we found that both ketamine and HNK (10 µM) increase excitatory AMPA neurotransmission onto a subset (50%) of 5-HT neurons, whereas other 5-HT cells were unaffected. Both compounds increased the amplitude as well as the frequency of spontaneous excitatory post-synaptic currents (sEPSCs) mediated by AMPA receptors. The effect of ketamine was more robust than the one of HNK, since it significantly enhanced the charge transfer through AMPA channels, whereas HNK did not. The increase in the excitatory drive induced by ketamine was dependent on NMDA receptor blockade. In the presence of tetrodotoxin, the effect of ketamine was markedly reduced. Non-5-HT neurons, on the other hand, were unaffected by the drugs.We conclude that ketamine and HNK increase the excitatory drive onto a subset of 5-HT neurons by promoting glutamate release and possibly also through a postsynaptic action. The effect of ketamine is dependent on NMDA receptor modulation and appears to involve a network effect. These findings improve our understanding of the fast-acting antidepressant effect of ketamine.SIGNIFICANCE STATEMENTThe mechanisms of ketamine’s antidepressant effect are currently controversial. We asked whether the drug would produce changes is the strength of synaptic inputs onto serotoninergic neurons of the dorsal raphe. We found that this is indeed the case in about half of these neurons. The action of ketamine was mimicked to some extent by its well-known metabolite hydroxynorketamine, was dependent on NMDA receptor activation and probably involved a local network effect. It remains to be determined if the differential susceptibility of serotoninergic neurons to the drug correlates with any differential inputs and/or outputs.

Drawing an inspiration from behavioral studies of human decision making, we propose here a general parametric framework for a reinforcement learning problem, which extends the standard Q-learning approach to incorporate a two-stream framework of reward processing with biases biologically associated with several neurological and psychiatric conditions, including Parkinson's and Alzheimer's diseases, attention-deficit/hyperactivity disorder (ADHD), addiction, and chronic pain. For AI community, the development of agents that react differently to different types of rewards can enable us to understand a wide spectrum of multi-agent interactions in complex real-world socioeconomic systems. Moreover, from the behavioral modeling perspective, our parametric framework can be viewed as a first step towards a unifying computational model capturing reward processing abnormalities across multiple mental conditions and user preferences in long-term recommendation systems.

Predicting drug‐induced hepatotoxicity remains a critical, yet elusive, goal in drug safety studies and pharmaceutical development. This difficulty is, in part, a result of the often‐weak relationship between in vitro and animal toxicity models. To address this weakness, we have employed a high‐throughput, three‐dimensional (3D) cell culture platform containing two cell types to screen a library of 26 small molecule drugs of various mechanisms of action and modes of toxicity. Correlations of in vitro toxicity to in vivo murine toxicity are substantially improved with primary human hepatocytes vs. a human hepatocyte cell line, HepG2. At a murine LD50 (lethal dose for 50% of population) cutoff of 300 mg/kg, the calculated predictivity for primary human hepatocytes is 76%, as compared to a calculated predictivity for HepG2 cells of 54%. These results demonstrate that primary human hepatocytes may be highly predictive of in vivo outcomes, and the use of the 3D chip platform enables substantial reduction in the number of hepatocytes required for in vitro toxicology studies. © 2018 American Institute of Chemical Engineers AIChE J, 64: 4331–4340, 2018