Showing papers by "Eero Vasar published in 2017"

Wfs1- deficient rats develop primary symptoms of Wolfram syndrome: insulin-dependent diabetes, optic nerve atrophy and medullary degeneration.

Abstract: Wolfram syndrome (WS) is a rare autosomal-recessive disorder that is caused by mutations in the WFS1 gene and is characterized by juvenile-onset diabetes, optic atrophy, hearing loss and a number of other complications. Here, we describe the creation and phenotype of Wfs1 mutant rats, in which exon 5 of the Wfs1 gene is deleted, resulting in a loss of 27 amino acids from the WFS1 protein sequence. These Wfs1-ex5-KO232 rats show progressive glucose intolerance, which culminates in the development of diabetes mellitus, glycosuria, hyperglycaemia and severe body weight loss by 12 months of age. Beta cell mass is reduced in older mutant rats, which is accompanied by decreased glucose-stimulated insulin secretion from 3 months of age. Medullary volume is decreased in older Wfs1-ex5-KO232 rats, with the largest decreases at the level of the inferior olive. Finally, older Wfs1-ex5-KO232 rats show retinal gliosis and optic nerve atrophy at 15 months of age. Electron microscopy revealed axonal degeneration and disorganization of the myelin in the optic nerves of older Wfs1-ex5-KO232 rats. The phenotype of Wfs1-ex5-KO232 rats indicates that they have the core symptoms of WS. Therefore, we present a novel rat model of WS.

Profiling of acylcarnitines in first episode psychosis before and after antipsychotic treatment

Abstract: Acylcarnitines (ACs) have been shown to have a potential to activate pro-inflammatory signaling pathways and to foster the development of insulin resistance. The first task of the current study was to study the full list of ACs (from C2 to C18) in first episode psychosis (FEP) patients before and after antipsychotic treatment. The second task was to relate ACs to inflammatory and metabolic biomarkers established in the same patient cohort as in our previous studies. Serum levels of ACs were determined with the AbsoluteIDQ p180 kit (BIOCRATES Life Sciences AG, Innsbruck, Austria) using the flow injection analysis tandem mass spectrometry ([FIA]–MS/MS) as well as liquid chromatography ([LC]–MS/MS) technique. Identification and quantification of the metabolites was achieved using multiple reactions monitoring along with internal standards. The comparison of ACs in antipsychotic-naive first-episode psychosis (FEP) patients (N = 38) and control subjects (CSs, N = 37) revealed significantly increased levels of ...

Promoter-Specific Expression and Genomic Structure of IgLON Family Genes in Mouse.

Abstract: IgLON family is composed of five genes: Lsamp, Ntm, Opcml, Negr1 and Iglon5; encoding for five highly homologous neural adhesion proteins that regulate neurite outgrowth and synapse formation. In the current study we performed in silico analysis revealing that Ntm and Opcml display similar genomic structure as previously reported for Lsamp, characterized by two alternative promotors 1a and 1b. Negr1 and Iglon5 transcripts have uniform 5’ region, suggesting single promoter. Iglon5, the recently characterized family member, shares high level of conservation and structural qualities characteristic to IgLON family such as N-terminal signal peptide, three Ig domains and GPI anchor binding site. By using custom 5’-isoform-specific TaqMan gene-expression assay, we demonstrated heterogeneous expression of IgLON transcripts in different areas of mouse brain and several-fold lower expression in selected tissues outside central nervous system. As an example, the expression of IgLON transcripts in urogenital and reproductive system is in line with repeated reports of urogenital tumors accompanied by mutations in IgLON genes. Considering the high levels of intra-family homology shared by IgLONs, we investigated potential compensatory effects at the level of IgLON isoforms in the brains of mice deficient of one or two family members. We found that the lack of IgLONs is not compensated by a systematic quantitative increase of the other family members. On the contrary, the expression of Ntm 1a transcript and NEGR1 protein was significantly reduced in the frontal cortex of Lsamp-deficient mice suggesting that the expression patterns within IgLON family are balanced coherently. The actions of individual IgLONs, however, can be antagonistic as demonstrated by differential expression of Syp in deletion mutants of IgLONs. In conclusion, we show that the genomic twin-promoter structure has impact on both anatomical distribution and intra-family interactions of IgLON family members. Remarkable variety in the activity levels of 1a and 1b promoters both in the brain and in other tissues, suggests complex functional regulation of IgLONs by alternative signal peptides driven by 1a and 1b promoters.

Tolerance Does Not Develop Toward Liraglutide’s Glucose-Lowering Effect

Abstract: Context Glucagon-like peptide-1 receptor agonists are popular antidiabetic drugs with potent glucose-lowering effects and low risk of hypoglycemia. Animal experiments and human data indicate that tolerance develops toward at least some of their effects (e.g., gastric motility). Whether tolerance develops toward the glucose-lowering effect of glucagon-like peptide-1 receptor agonists has never been formally tested. Objective The objective of this pilot study was to test the hypothesis whether tolerance develops toward glucagon-like peptide-1 receptor agonists' glucose-lowering effect in chronic use. Design, Setting, Participants, and Intervention We conducted a single group, open-label clinical trial. Ten healthy volunteers were treated with 0.6 mg liraglutide once daily subcutaneously for 21 days. The drug's effect was quantified by serial graded glucose infusion tests, with glucose and c-peptide measured every 20 minutes and insulin secretion rate calculated. Main Outcome Measure The primary outcome was a change in the dose-response relationship between calculated insulin secretion rate and blood glucose level after acute and chronic administration of liraglutide. Results Liraglutide clearly decreased the glucose values during the graded glucose infusion test and robustly enhanced insulin secretion. For all parameters, chronic liraglutide was as effective as acute treatment in human subjects. Conclusions We conclude that our results largely refute the hypothesis of tolerance development with prolonged liraglutide use in healthy nonobese humans.

Wfs1 is expressed in dopaminoceptive regions of the amniote brain and modulates levels of D1-like receptors.

Abstract: During amniote evolution, the construction of the forebrain has diverged across different lineages, and accompanying the structural changes, functional diversification of the homologous brain regions has occurred. This can be assessed by studying the expression patterns of marker genes that are relevant in particular functional circuits. In all vertebrates, the dopaminergic system is responsible for the behavioral responses to environmental stimuli. Here we show that the brain regions that receive dopaminergic input through dopamine receptor D1 are relatively conserved, but with some important variations between three evolutionarily distant vertebrate lines–house mouse (Mus musculus), domestic chick (Gallus gallus domesticus) / common quail (Coturnix coturnix) and red-eared slider turtle (Trachemys scripta). Moreover, we find that in almost all instances, those brain regions expressing D1-like dopamine receptor genes also express Wfs1. Wfs1 has been studied primarily in the pancreas, where it regulates the endoplasmic reticulum (ER) stress response, cellular Ca2+ homeostasis, and insulin production and secretion. Using radioligand binding assays in wild type and Wfs1-/- mouse brains, we show that the number of binding sites of D1-like dopamine receptors is increased in the hippocampus of the mutant mice. We propose that the functional link between Wfs1 and D1-like dopamine receptors is evolutionarily conserved and plays an important role in adjusting behavioral reactions to environmental stimuli.

Correction: Melanocytes in the Skin - Comparative Whole Transcriptome Analysis of Main Skin Cell Types.

Abstract: The following information is missing from the Data Availability section: Raw sequencing data are hosted at the Gene Expression Omnibus repository under the accession number GSE94655. This data can be found at the following URL: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE94655.