👤 Daniela Winkler

High-sugar diets cause human metabolic diseases, yet several bird lineages convergently adapted to feeding on sugar-rich nectar or fruits. We investigated the underlying molecular mechanisms in hummingbirds, parrots, honeyeaters, and sunbirds by generating nine new genomes and 90 tissue-specific transcriptomes. Comparative screens revealed an excess of repeated selection in both protein-coding and regulatory sequences in sugar-feeding birds, suggesting reuse of genetic elements. Sequence or expression changes in sugar-feeders affect genes involved in blood pressure regulation and lipid, amino acid, and carbohydrate metabolism, with experiments showing functional changes in honeyeater hexokinase 3. Show less

Fasting triggers complex physiological and neuroimmune adaptations, yet its impact on hypothalamic microglia and the underlying regulatory role of glucocorticoids remains incompletely understood. The present study focused on fasting-induced systemic changes and cellular adaptations seen in the hypothalamus where components of metabolic- hormonal- and immune regulations are integrated. Adult male microglia reporter (CX3CR1 Overnight fasting resulted in a decrease in energy expenditure and respiratory exchange ratio (RER) indicating conservation of energy and a metabolic shift towards utilization of fatty acids as alternative energy source. Fasting increased hypothalamic expression of orexigenic neuropeptides and mRNA levels of Pdk4, Glut1, and Mct2 genes, in line with metabolic compensation. Upregulation of hypothalamic Crh and increased plasma concentration of corticosterone indicated sustained activation of the HPA axis. Importantly, fasting promoted an anti-inflammatory milieu in the hypothalamus characterized by elevated Il-4, Il-10 and IkBα genes without significant activation of pro-inflammatory cytokines (e.g., Il-1β, Il-6, Tnfα). Morphological analysis revealed region-specific changes in microglia number and branching complexity, particularly in hypothalamic regions directly exposed to blood-borne signals. Functional profiling showed increased microglial expression of IkBα and decreased pIkBα, indicating suppressed NFkB signaling. Adrenalectomy (1 week) and acute pharmacological inhibition of corticosterone synthesis (methyrapone) revealed that fasting-induced anti-inflammatory and metabolic gene expression, as well as microglial plasticity were largely glucocorticoid dependent. Hypothalamic expression of fasting-related neuropeptides (Npy, Agrp) and genes, related to the metabolic shift (Pdk4, Glut-1, Mct2, Angptl4) as well as some immune-related genes (Il10, Iba1) was dependent on presence of the adrenal gland or fasting-induced elevation of corticosterone. These findings highlight short term fasting as a potent modulator of hypothalamic immune-metabolic crosstalk and reveal critical role of adrenal glucocorticoids in orchestrating microglial responses to energetic challenges. The results have potential implications for therapeutic interventions targeting metabolic and inflammatory disorders. Show less

Type 1 diabetes is a chronic, autoimmune disease characterized by the destruction of insulin-producing β-cells in the pancreas. Early detection can facilitate timely intervention, potentially delaying or preventing disease onset. Circulating proteins reflect dysregulated biological processes and offer insights into early disease mechanisms. Here, we construct a genome-wide pQTL map of 1985 proteins in 695 newborn babies (median age 2 days) at increased genetic risk of developing Type 1 diabetes. We identify 535 pQTLs (352 cis-pQTLs, 183 trans-pQTLs), 62 of which characteristic of newborns. We show colocalization of pQTLs for CTRB1, APOBR, IL7R, CPA1, and PNLIPRP1 with Type 1 diabetes GWAS signals, and Mendelian randomization causally implicates each of these five proteins in the aetiology of Type 1 diabetes. Our study illustrates the utility of newborn molecular profiles for discovering potential drug targets for childhood diseases of significant concern. Show less

Nintedanib is a small molecule tyrosine kinase inhibitor (TKI) targeting vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR). The purpose of the study was to evaluate the response rate for patients with advanced non-small cell lung cancer (NSCLC) with mutations in Patients with advanced NSCLC previously treated with platinum-doublet chemotherapy with the above mutations were enrolled. Exclusion criteria included necrotic tumors with invasion of blood vessels, history of recent thromboembolic events, increased risk of bleeding or thrombosis, myocardial infarction, and weight loss >10% within past 6 months. Nintedanib was administered at a dose of 200 mg orally twice daily until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Secondary endpoints included progression-free survival (PFS) and correlating outcomes with specific mutations. This study was registered with ClinicalTrials.gov, number NCT02299141. Between 2015 and 2019, 20 patients were enrolled with a median age was 66 years, 15 (75%) were females, 15 (75%) had adenocarcinoma, and 17 patients had a In this pilot study in heavily pretreated and molecularly selected patients with metastatic NSCLC, nintedanib showed modest activity. Show less

Advanced age-related macular degeneration (AMD) is a leading cause of blindness. While around half of the genetic contribution to advanced AMD has been uncovered, little is known about the genetic architecture of early AMD. To identify genetic factors for early AMD, we conducted a genome-wide association study (GWAS) meta-analysis (14,034 cases, 91,214 controls, 11 sources of data including the International AMD Genomics Consortium, IAMDGC, and UK Biobank, UKBB). We ascertained early AMD via color fundus photographs by manual grading for 10 sources and via an automated machine learning approach for > 170,000 photographs from UKBB. We searched for early AMD loci via GWAS and via a candidate approach based on 14 previously suggested early AMD variants. Altogether, we identified 10 independent loci with statistical significance for early AMD: (i) 8 from our GWAS with genome-wide significance (P < 5 × 10 Our GWAS on early AMD identified novel loci, highlighted shared and distinct genetics between early and advanced AMD and provides insights into AMD etiology. Our data provide a resource comparable in size to the existing IAMDGC data on advanced AMD genetics enabling a joint view. The biological relevance of this joint view is underscored by the ability of early AMD effects to differentiate the major pathways for advanced AMD. Show less

Effector functions of IgG Abs are regulated by their Fc N-glycosylation pattern. IgG Fc glycans that lack galactose and terminal sialic acid residues correlate with the severity of inflammatory (auto)immune disorders and have also been linked to protection against viral infection and discussed in the context of vaccine-induced protection. In contrast, sialylated IgG Abs have shown immunosuppressive effects. We sought to investigate IgG glycosylation programming during the germinal center (GC) reaction following immunization of mice with a foreign protein antigen and different adjuvants. Mice were analyzed for GC T-cell, B-cell, and plasma cell responses, as well as for antigen-specific serum IgG subclass titers and Fc glycosylation patterns. Different adjuvants induce distinct IgG This study's findings regarding adjuvant-dependent GC responses and IgG glycosylation programming may aid in the development of novel vaccination strategies to induce IgG Abs with both high affinity and defined Fc glycosylation patterns in the GC. Show less

Cholesterylester transfer protein (CETP) modulates the composition of various lipoproteins associated with cardiovascular disease. Despite its central role in lipoprotein metabolism, its mode of action is still not fully understood. Here we present a simple way to estimate CETP-mediated lipid fluxes between different lipoprotein fractions. The model derived adequately describes the observed findings, especially regarding low- and high dense lipoproteins (LDL and HDL), delivering correlation coefficients of R Our model approach is independent of CETP-action's exact mechanistic mode. It is simple and easy to apply, and may be a useful tool in revealing CETP's ambiguous role in lipid metabolism. The model mirrors a diffusion-like exchange of triglycerides between lipoproteins. Cholesteryl ester and triglyceride concentrations measured in HDL, LDL and VLDL are sufficient to apply the model on a plasma sample. Show less

Genome-wide association studies (GWAS) have identified >250 loci for body mass index (BMI), implicating pathways related to neuronal biology. Most GWAS loci represent clusters of common, noncoding variants from which pinpointing causal genes remains challenging. Here we combined data from 718,734 individuals to discover rare and low-frequency (minor allele frequency (MAF) < 5%) coding variants associated with BMI. We identified 14 coding variants in 13 genes, of which 8 variants were in genes (ZBTB7B, ACHE, RAPGEF3, RAB21, ZFHX3, ENTPD6, ZFR2 and ZNF169) newly implicated in human obesity, 2 variants were in genes (MC4R and KSR2) previously observed to be mutated in extreme obesity and 2 variants were in GIPR. The effect sizes of rare variants are ~10 times larger than those of common variants, with the largest effect observed in carriers of an MC4R mutation introducing a stop codon (p.Tyr35Ter, MAF = 0.01%), who weighed ~7 kg more than non-carriers. Pathway analyses based on the variants associated with BMI confirm enrichment of neuronal genes and provide new evidence for adipocyte and energy expenditure biology, widening the potential of genetically supported therapeutic targets in obesity. Show less

The postsynaptic density proteins 95 (PSD95) and 93 (PSD93) belong to a family of scaffolding proteins, the membrane-associated guanylate kinases (MAGUKs), which are highly enriched in synapses and responsible for organizing the numerous protein complexes required for synaptic development and plasticity. Genetic studies have associated MAGUKs with diseases like autism and schizophrenia, but knockout mice show severe, complex defects with difficult-to-interpret behavioral abnormalities due to major motor dysfunction which is atypical for psychiatric phenotypes. Therefore, rather than studying loss-of-function mutants, we comprehensively investigated the behavioral consequences of reduced PSD95 expression, using heterozygous PSD95 knockout mice (PSD95 Show less

The Hey protein family, comprising Hey1, Hey2 and HeyL in mammals, conveys Notch signals in many cell types. The helix-loop-helix (HLH) domain as well as the Orange domain, mediate homo- and heterodimerization of these transcription factors. Although distinct interaction partners have been identified so far, their physiological relevance for Hey functions is still largely unclear. Using a tandem affinity purification approach and mass spectrometry analysis we identified members of an ubiquitin E3-ligase complex consisting of FBXO45, PAM and SKP1 as novel Hey1 associated proteins. There is a direct interaction between Hey1 and FBXO45, whereas FBXO45 is needed to mediate indirect Hey1 binding to SKP1. Expression of Hey1 induces translocation of FBXO45 and PAM into the nucleus. Hey1 is a short-lived protein that is degraded by the proteasome, but there is no evidence for FBXO45-dependent ubiquitination of Hey1. On the contrary, Hey1 mediated nuclear translocation of FBXO45 and its associated ubiquitin ligase complex may extend its spectrum to additional nuclear targets triggering their ubiquitination. This suggests a novel mechanism of action for Hey bHLH factors. Show less

Deviations from normal body weight are observed prior to and after the onset of Alzheimer's disease (AD). Midlife obesity confers increased AD risk in later life, whereas late-life obesity is associated with decreased AD risk. The role of underweight and weight loss for AD risk is controversial. Based on the hypothesis of shared genetic variants for both obesity and AD, we analyzed the variants identified for AD or obesity from genome-wide association meta-analyses of the GERAD (AD, cases = 6,688, controls = 13,685) and GIANT (body mass index [BMI] as measure of obesity, n = 123,865) consortia. Our cross-disorder analysis of genome-wide significant 39 obesity SNPs and 23 AD SNPs in these two large data sets revealed that: (1) The AD SNP rs10838725 (pAD  = 1.1 × 10(-08)) at the locus CELF1 is also genome-wide significant for obesity (pBMI  = 7.35 × 10(-09) ). (2) Four additional AD risk SNPs were nominally associated with obesity (rs17125944 at FERMT2, pBMI  = 4.03 × 10(-05), pBMI corr  = 2.50 × 10(-03) ; rs3851179 at PICALM; pBMI  = 0.002, rs2075650 at TOMM40/APOE, pBMI  = 0.024, rs3865444 at CD33, pBMI  = 0.024). (3) SNPs at two of the obesity risk loci (rs4836133 downstream of ZNF608; pAD  = 0.002 and at rs713586 downstream of RBJ/DNAJC27; pAD  = 0.018) were nominally associated with AD risk. Additionally, among the SNPs used for confirmation in both studies the AD risk allele of rs1858973, with an AD association just below genome-wide significance (pAD  = 7.20 × 10(-07)), was also associated with obesity (SNP at IQCK/GPRC5B; pBMI  = 5.21 × 10(-06) ; pcorr  = 3.24 × 10(-04)). Our first GWAS based cross-disorder analysis for AD and obesity suggests that rs10838725 at the locus CELF1 might be relevant for both disorders. Show less

HEY bHLH transcription factors have been shown to regulate multiple key steps in cardiovascular development. They can be induced by activated NOTCH receptors, but other upstream stimuli mediated by TGFß and BMP receptors may elicit a similar response. While the basic and helix-loop-helix domains exhibit strong similarity, large parts of the proteins are still unique and may serve divergent functions. The striking overlap of cardiac defects in HEY2 and combined HEY1/HEYL knockout mice suggested that all three HEY genes fulfill overlapping function in target cells. We therefore sought to identify target genes for HEY proteins by microarray expression and ChIPseq analyses in HEK293 cells, cardiomyocytes, and murine hearts. HEY proteins were found to modulate expression of their target gene to a rather limited extent, but with striking functional interchangeability between HEY factors. Chromatin immunoprecipitation revealed a much greater number of potential binding sites that again largely overlap between HEY factors. Binding sites are clustered in the proximal promoter region especially of transcriptional regulators or developmental control genes. Multiple lines of evidence suggest that HEY proteins primarily act as direct transcriptional repressors, while gene activation seems to be due to secondary or indirect effects. Mutagenesis of putative DNA binding residues supports the notion of direct DNA binding. While class B E-box sequences (CACGYG) clearly represent preferred target sequences, there must be additional and more loosely defined modes of DNA binding since many of the target promoters that are efficiently bound by HEY proteins do not contain an E-box motif. These data clearly establish the three HEY bHLH factors as highly redundant transcriptional repressors in vitro and in vivo, which explains the combinatorial action observed in different tissues with overlapping expression. Show less

Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ∼ 2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10⁻⁸), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation. Show less

PURPOSE. Jeune's asphyxiating thoracic dystrophy (JATD) is an autosomal recessive disorder with symptoms of retinal degeneration, kidney cysts, and chondrodysplasia and results from mutations in the ift80 gene. This study was conducted to characterize zebrafish lacking ift80 function for photoreceptor degeneration and defects in ciliogenesis to establish zebrafish as a vertebrate model for visual dysfunction in JATD and to determine whether ift80 interacts genetically with Bardet-Biedl syndrome (BBS) genes. METHODS. Zebrafish were injected with morpholinos (MOs) targeted to the ift80 gene. Retinas were analyzed by histology, transmission electron microscopy, and immunohistochemistry. Ear and kidney cilia were analyzed by whole-mount immunostaining. Intraflagellar transport (IFT) particle composition was subjected to Western blot analysis. Genetic interactions were tested by coinjection of MOs against ift80 and bbs4 or bbs8 followed by in situ hybridization. RESULTS. Zebrafish lacking ift80 function exhibited defects in photoreceptor outer segment formation and photoreceptor death. Staining with opsin antibodies revealed opsin mislocalization in both rods and cones. Ultrastructural analysis showed abnormal disc stacking and shortened photoreceptor outer segments. The kinocilia of the ear and motile cilia in the kidney were shorter and reduced in number. Western blot analysis revealed a slight increase in the stability of other IFT proteins. Coinjection of MOs against ift80 and BBS genes led to convergent-extension defects. CONCLUSIONS. Zebrafish lacking ift80 exhibited defects characteristic of JATD. Because the developing outer segments degenerated, Ift80 could possibly act as a maintenance factor for the IFT particle. Show less

Peroxisome proliferator-activated receptor (PPAR)gamma is a key regulator in adipose tissue. The rare variant Pro12Ala of PPARgamma2 is associated with a decreased risk of insulin resistance. Being dietary PPARgamma ligands, conjugated linoleic acids (CLAs) received considerable attention because of their effects on body composition, cancer, atherosclerosis, diabetes, obesity and inflammation, although some effects were only demonstrated in animal trials and the results in human studies were not always consistent. In the present study effects of CLA supplementation on genome wide gene expression in adipose tissue biopsies from 11 Ala12Ala and 23 Pro12Pro men were investigated. Subjects underwent four intervention periods (4 wk) in a randomized double blind cross-over design receiving 4.25 g/d of either cis-9, trans-11 CLA, trans-10,cis-12 CLA, 1:1 mixture of both isomers or a reference linoleic acid oil preparation. After each intervention biopsies were taken, whole genome expression microarrays were applied, and genes of interest were verified by realtime PCR. The following genes of lipid metabolism were regulated by CLA: LDLR, FASN, SCD, FADS1 and UCP2 were induced, while ABCA1, CD36 and CA3 were repressed. Transcription factors PPARgamma, NFAT5, CREB5 and EBF1, the adipokine NAMPT, members of the insulin signaling cascade SORBS1 and IGF1 and IL6ST were repressed, while the adipokine THBS1 and GLUT4 involved in insulin signaling were induced. Compared to trans-10,cis-12 CLA and the CLA mixture the cis-9, trans-11 CLA isomer exerted weaker effects. Only CD36 (-1.2 fold) and THBS1 (1.5 fold) were regulated. The CLA effect on expression of PPARgamma and leptin genes depends on the PPARgamma2 genotype. The data suggest that the isomer specific influence of CLA on glucose and lipid metabolism is genotype dependent and at least in part mediated by PPARgamma. http://www.controlled-trials.com: ISRCTN91188075. Show less

Adequate response to low oxygen levels (hypoxia) by hypoxia inducible factor (HIF) is essential for normal development and physiology, but this pathway may also contribute to pathological processes like tumor angiogenesis. Here we show that hypoxia is an inducer of Notch signaling. Hypoxic conditions lead to induction of the Notch ligand Dll4 and the Notch target genes Hey1 and Hey2 in various cell lines. Promoter analysis revealed that Hey1, Hey2 and Dll4 are induced by HIF-1alpha and Notch activation. Hypoxia-induced Notch signaling may also determine endothelial identity. Endothelial progenitor cells (EPCs) contain high amounts of COUP-TFII, a regulator of vein identity, while levels of the arterial regulators Dll4 and Hey2 are low. Hypoxia-mediated upregulation of Dll4 and Hey2 leads to repression of COUP-TFII in eEPCs. Finally, we show that Hey factors are capable of repressing HIF-1alpha-induced gene expression, suggesting a negative feedback loop to prevent excessive hypoxic gene induction. Thus, reduced oxygen levels lead to activation of the Dll4-Notch-Hey2 signaling cascade and subsequent repression of COUP-TFII in endothelial progenitor cells. We propose that this is an important step in the developmental regulation of arterial cell fate decision. Show less

Epithelialized somites form repeatedly from the unsegmented presomitic mesoderm (PSM) in the tailbud of vertebrate embryos. Mutant analysis has shown that the Delta-Notch pathway is essential for the temporal and spatial control of somite formation. Several components of this pathway show cyclic transcription, which is driven by a molecular oscillator. This oscillator is thought to act similarly in different vertebrates. In this study, we used the Japanese Medaka (Oryzias latipes) to examine the expression of three factors of the Delta-Notch cascade that are known to show cyclic expression in the PSM of higher vertebrates. We report that in contrast to the situation in mice, lunatic fringe (lfng) in medaka is expressed in a non-dynamic fashion in the rostral halves of the formed somites and the anteriormost PSM. On the other hand, her7, a member of the hairy/Enhancer-of-split related (Her) gene family, shows cyclic expression in the medaka PSM. Although this is similar in zebrafish, there are important differences in the distribution of transcripts in the PSM indicating different modes of regulation in both fish species. Finally, we show that hey1, another Delta-Notch regulated bHLH gene, is dynamically expressed in the PSM of medaka, similar to hey1 in zebrafish and the hey2 orthologs in mice and chicken. Interestingly, medaka hey1 is also expressed in the dorsal aorta and the heart, two tissues where hey2, but not hey1, is expressed in zebrafish. This shows that several components of the Delta-Notch pathway are differently regulated during somitogenesis in different species. Show less

Hairy-related basic helix-loop-helix (bHLH) transcription factors are targets of Delta-Notch signaling and represent essential components for a number of cell fate decisions during vertebrate embryogenesis. Hey genes encode a subfamily of hairy-related proteins that have been implicated in processes like somitogenesis, blood vessel and heart development. We have identified and characterized hey genes in three teleost fish lineages using degenerate PCR and database searches. Phylogenetic analysis of Hey proteins suggests a complex pattern of evolution with high divergence of hey2 in Takifugu rubripes (Fugu, Japanese pufferfish) and possibly loss in the related Tetraodon nigroviridis (the freshwater pufferfish). In addition, duplication of hey1 in both pufferfishes, Fugu and Tetraodon, was observed. Conversely, zebrafish (Danio rerio) has the same complement of three hey genes as known from mammals. All three hey genes show much more restricted gene expression profiles in zebrafish when compared to mouse. Importantly, while all three murine Hey genes are expressed in overlapping patterns in the presomitic mesoderm (PSM) and somites, in zebrafish only hey1 shows PSM and somite expression in a highly dynamic fashion. Therefore, while overlapping expression might account for redundancy of hey function in higher vertebrates, this is unlikely to be the case in zebrafish. In deltaD (dlD) deficient after-eight zebrafish mutants, the dynamic expression of hey1 in the PSM is impaired and completely lost in newly formed somitomeres. Overexpression of dlD on the other hand results in the ectopic expression of hey1 in the axial mesoderm. Hence, hey1 represents a target of Delta-Notch signaling dynamically expressed during somite formation in zebrafish. Show less

The purpose of the present experiments was to enhance understanding of the factors that are critical for the survival of retinal cells exposed to mitochondrial inhibition. Confluent cultures of Müller cells (rMC-1) and human retinal pigment epithelial cells (hRPE) were incubated in Dulbecco's minimal essential medium in the presence and absence of 1x10(-5)M Antimycin A, an inhibitor of mitochondrial electron transport. To modulate the rates of aerobic and anaerobic glycolysis, cells were incubated in media containing varying concentrations of glucose and 1-100 micro M of iodoacetic acid (IAA), an inhibitor of glyceraldehdye-3-phosphate dehydrogenase (G3PDH). Measurements were made of G3PDH, lactic acid production, and cellular ATP levels, along with an examination of cellular morphology, the latter providing an index of cellular viability. Control rMC-1 and hRPE produced lactate aerobically, respectively, at 0.48 and 1.50 micro molhr(-1)/10(6) cells. Anaerobically, lactate production increased 2-fold in rMC-1 and 3-fold in hRPE. Anaerobic ATP levels in both types of cells were maintained at control levels over 8hr. Experimental conditions were sought that would modulate only the capacity of rMC-1 and hRPE to increase glycolysis following mitochondrial inhibition, i.e. alter their Pasteur effect. We used low concentrations of IAA to partially inhibit G3PDH. Incubation of rMC-1 with IAA for 6hr caused a graded inhibition of G3PDH: 70% inhibition with 1 micro M, 90% with 5 micro M, 97% with 10 micro M, and 100% with 100 micro M. While the aerobic and anaerobic rates of lactic acid production were not altered by 1 micro M IAA, both were suppressed completely by 100 micro M IAA. However, incubation of rMC-1 with 5 micro M IAA caused a decrease of 30% in the rate of anaerobic lactic acid production but no change in the rate of aerobic glycolysis. Moreover, with 5 micro M IAA, rMC-1 incubated aerobically maintained ATP levels, but anaerobic ATP content decreased to a low level and cell morphology and viability were compromised. Essentially similar results were observed with hRPE. Both rMC-1 and hRPE are remarkably resistant to mitochondrial inhibition. This resistance is linked directly to the magnitude of the increase in the Pasteur effect. When the capacity of rMC-1 and hRPE to generate a Pasteur effect is selectively curtailed, these cells no longer are resistant to mitochondrial inhibition. It is suggested that in an intact tissue the ability of a cell to withstand a metabolic challenge will depend very much on the adequacy of the supply of glucose. Even a small limitation in the availability of this utilizable substrate and in the rate of the compensatory increase in the rate of anaerobic glycolysis could put the cell at greater risk during the challenge. Show less