The G protein-coupled receptor 83 (Gpr83) is widely expressed in brain regions regulating energy metabolism. Here we report that hypothalamic expression of Gpr83 is regulated in response to nutrient availability and is decreased in obese mice compared with lean mice. In the arcuate nucleus, Gpr83 colocalizes with the ghrelin receptor (Ghsr1a) and the agouti-related protein. In vitro analyses show heterodimerization of Gpr83 with Ghsr1a diminishes activation of Ghsr1a by acyl-ghrelin. The orexigenic and adipogenic effect of ghrelin is accordingly potentiated in Gpr83-deficient mice. Interestingly, Gpr83 knock-out mice have normal body weight and glucose tolerance when fed a regular chow diet, but are protected from obesity and glucose intolerance when challenged with a high-fat diet, despite hyperphagia and increased hypothalamic expression of agouti-related protein, Npy, Hcrt and Ghsr1a. Together, our data suggest that Gpr83 modulates ghrelin action but also indicate that Gpr83 regulates systemic metabolism through other ghrelin-independent pathways.

Mutations in the human gene MCPH1 cause primary microcephaly associated with a unique cellular phenotype with premature chromosome condensation (PCC) in early G2 phase and delayed decondensation post-mitosis (PCC syndrome). The gene encodes the BRCT-domain containing protein microcephalin/BRIT1. Apart from its role in the regulation of chromosome condensation, the protein is involved in the cellular response to DNA damage. We report here on the first mouse model of impaired Mcph1-function. The model was established based on an embryonic stem cell line from BayGenomics (RR0608) containing a gene trap in intron 12 of the Mcph1 gene deleting the C-terminal BRCT-domain of the protein. Although residual wild type allele can be detected by quantitative real-time PCR cell cultures generated from mouse tissues bearing the homozygous gene trap mutation display the cellular phenotype of misregulated chromosome condensation that is characteristic for the human disorder, confirming defective Mcph1 function due to the gene trap mutation. While surprisingly the DNA damage response (formation of repair foci, chromosomal breakage, and G2/M checkpoint function after irradiation) appears to be largely normal in cell cultures derived from Mcph1gt/gt mice, the overall survival rates of the Mcph1gt/gt animals are significantly reduced compared to wild type and heterozygous mice. However, we could not detect clear signs of premature malignant disease development due to the perturbed Mcph1 function. Moreover, the animals show no obvious physical phenotype and no reduced fertility. Body and brain size are within the range of wild type controls. Gene expression on RNA and protein level did not reveal any specific pattern of differentially regulated genes. To the best of our knowledge this represents the first mammalian transgenic model displaying a defect in mitotic chromosome condensation and is also the first mouse model for impaired Mcph1-function.

Thyroid hormones (THs) are charged and iodinated amino acid derivatives that need to pass the cell membrane facilitated by thyroid hormone transmembrane transporters (THTT) to exert their biological function. The importance of functional THTT is affirmed by the devastating effects of mutations in the human monocarboxylate transporter (MCT) 8, leading to a severe form of psychomotor retardation. Modulation of THTT function by pharmacological or environmental compounds might disturb TH action on a tissue-specific level. Therefore, it is important to identify compounds with relevant environmental exposure and THTT-modulating activity. Based on a nonradioactive TH uptake assay, we performed a screening of 13 chemicals, suspicious for TH receptor interaction, to test their potential effects on THTT in MCT8-overexpressing MDCK1-cells. We identified silymarin, an extract of the milk thistle, to be a potent inhibitor of T3 uptake by MCT8. Because silymarin is a complex mixture of flavonolignan substances, we further tested its individual components and identified silychristin as the most effective one with an IC50 of approximately 100 nM. The measured IC50 value is at least 1 order of magnitude below those of other known THTT inhibitors. This finding was confirmed by T3 uptake in primary murine astrocytes expressing endogenous Mct8 but not in MCT10-overexpressing MDCK1-cells, indicating a remarkable specificity of the inhibitor toward MCT8. Because silymarin is a frequently used adjuvant therapeutic for hepatitis C infection and chronic liver disease, our observations raise questions regarding its safety with respect to unwanted effects on the TH axis.

Background: The Allan-Herndon-Dudley syndrome is a severe psychomotor retardation accompanied by specific changes in circulating thyroid hormone levels (high T₃, low T₄). These are caused by mutations in the thyroid hormone transmembrane transport protein monocarboxylate transporter 8 (MCT8). Objective: To test the hypothesis that circulating low T₄ and high T₃ levels are caused by enhanced conversion of T₄ via increased activity of hepatic type I deiodinase (Dio1). Methods: We crossed mice deficient in Mct8 with mice lacking Dio1 activity in hepatocytes. Translation of the selenoenzyme Dio1 was abrogated by hepatocyte-specific inactivation of selenoprotein biosynthesis. Results: Inactivation of Dio1 activity in the livers of global Mct8-deficient mice does not restore normal circulating thyroid hormone levels. Conclusions: Our data suggest that although hepatic Dio1 activity is increased in Mct8-deficient mice, it does not cause the observed abnormal circulating thyroid hormone levels. Since global inactivation of Dio1 in Mct8-deficient mice does normalize circulating thyroid hormone levels, the underlying mechanism and relevant tissues involved remain to be elucidated.

Solutions for the generation of FAIR (Findable, Accessible, Interoperable, and Reusable) data and metadata in experimental tribology are currently lacking. Nonetheless, FAIR data production is a promising path for implementing scalable data science techniques in tribology, which can lead to a deeper understanding of the phenomena that govern friction and wear. Missing community-wide data standards, and the reliance on custom workflows and equipment are some of the main challenges when it comes to adopting FAIR data practices. This paper, first, outlines a sample framework for scalable generation of FAIR data, and second, delivers a showcase FAIR data package for a pin-on-disk tribological experiment. The resulting curated data, consisting of 2,008 key-value pairs and 1,696 logical axioms, is the result of (1) the close collaboration with developers of a virtual research environment, (2) crowd-sourced controlled vocabulary, (3) ontology building, and (4) numerous – seemingly – small-scale digital tools. Thereby, this paper demonstrates a collection of scalable non-intrusive techniques that extend the life, reliability, and reusability of experimental tribological data beyond typical publication practices.

Thyroid hormones (TH) are actively taken up into target cells via TH-transmembrane transporters (THTT). Their activity and expression patterns define a layer of endocrine regulation that is poorly understood. Therefore, THTT are potential targets for interfering agents (endocrine disruptors) as well as for pharmacological interventions. Inactivating mutations have been identified as the underlying cause of heritable diseases (monocarboxylate transporter 8-associated Allan-Herndon-Dudley syndrome) and might also define a class of subclinical TH insensitivity. As a basic tool to solve questions regarding THTT substrate specificity, activation or inactivation by compounds and functional changes from mutations, uptake assays with radiolabeled tracers are standard. Due to the need for radioactive isotopes, this technique is limited to screening of labelled substrates and disadvantageous regarding handling, setup, and regulatory issues. To overcome these hurdles, we developed an uptake assay protocol using nonradioactive ligands. In brief, uptake of nonradioactive iodine-containing substrate molecules was monitored via Sandell-Kolthoff reaction. The novel assay was designed to the common microtiter plate layout. As a prove-of-principle, we measured TH uptake by monocarboxylate transporter 8-transfected MDCK1 cells. Titrations with bromosulphthalein as an example for inhibitor screening setups and a side-by-side comparison with the radioactive method prove this assay to be reliable, sensitive, and convenient. Furthermore, the method was applicable on primary murine astrocytes, which enables high-throughput screening studies on in vitro model systems with physiological transporter regulation. Due to its design, it is applicable for high-throughput screening of modulatory compounds, but it is also a safe, inexpensive and an easily accessible method for functional testing of THTT in basic science.

Background Ketogenic dietary interventions (KDI) have been shown to be effective in animal models of polycystic kidney disease, but data from clinical trials are lacking. Methods Ten ADPKD patients with rapid disease progression were enrolled at visit V1 and initially maintained a carbohydrate (CHO)-rich diet. At V2, patients entered one of the two KDI arms: a 3-day water fast (WF) or a 14-day ketogenic diet (KD). At V3, they resumed their normal diet for 3 to 6 weeks until V4. At each visit, MRI kidney and liver volumetry was performed. Ketone bodies were evaluated to assess metabolic efficacy and questionnaires were used to determine feasibility. Results All participants (KD n = 5, WF n = 5; age 39.8 ± 11.6 years; eGFR 82 ± 23.5 ml/min; total kidney volume (TKV) 2224 ± 1156 ml) were classified as Mayo Class 1C to 1E. Acetone levels in breath and BHB blood levels increased in both study arms (V1 to V2 average acetone: 2.7±1.2 ppm, V2 to V3: 22.8±11.9 ppm, p = 0.0006; V1 to V2 average BHB: 0.22±0.08 mmol/l, V2 to V3: 1.88±0.93 mmol/l, p = 0.0008). 9/10 patients reached a ketogenic state and 9/10 evaluated KDIs as feasible. TKV did not change during this trial. However, we found a significant impact on total liver volume (ΔTLV V2 to V3: -7.7%, p = 0.01), mediated by changes in its non-cystic fraction. Conclusions RESET-PKD demonstrates that short-term KDIs potently induce ketogenesis and are feasible for ADPKD patients in daily life. While TLV quickly changed upon the onset of ketogenesis, changes in TKV may require longer-term interventions.

Background Our laboratory published the first evidence that nutritional ketosis, induced by ketogenic diet (KD) or time-restricted diet (TRD), ameliorates disease progression in PKD animal models. We reasoned that, due to their frequent use for numerous health benefits, some ADPKD patients may already have had experience with ketogenic dietary interventions (KDIs). This retrospective case series study is designed to collect first real-life observations of ADPKD patients about safety, feasibility, and possible benefits of KDIs in ADPKD as part of a translational project pipeline. Methods Patients with ADPKD who had already used KDIs were recruited to retrospectively collect observational and medical data about beneficial or adverse effects, the feasibility and safety of KDIs in questionnaire-based interviews. Results 131 ADPKD patients took part in this study. 74 executed a KD and 52 TRD, for 6 months on average. 86% of participants reported that KDIs had improved their overall health. 67% described improvements in ADPKD-associated health issues. 90% observed significant weight loss. 64% of participants with hypertension reported improvements in blood pressure. 66% noticed adverse effects that are frequently observed with KDIs. 22 participants reported safety concerns like hyperlipidemia. 45 participants reported slight improvements in eGFR. 92% experienced KDIs as feasible while 53% reported breaks during their diet. Discussion Our preliminary data indicate that KDIs may be safe, feasible, and potentially beneficial for ADPKD patients highlighting that prospective clinical trials are warranted to confirm these results in a controlled setting and elucidate the impact of KDIs specifically on kidney function and cyst progression.