BMP4-BMPR1A Signaling in β Cells Is Required for and Augments Glucose-Stimulated Insulin Secretion

SummaryImpaired glucose-stimulated insulin secretion (GSIS) and perturbed proinsulin processing are hallmarks of β cell dysfunction in type 2 diabetes. Signals that can preserve and/or enhance β cell function are therefore of great therapeutic interest. Here we show that bone morphogenetic protein 4 (Bmp4) and its high-affinity receptor, Bmpr1a, are expressed in β cells. Mice with attenuated BMPR1A signaling in β cells show decreased expression of key genes involved in insulin gene expression, proinsulin processing, glucose sensing, secretion stimulus coupling, incretin signaling, and insulin exocytosis and develop diabetes due to impaired insulin secretion. We also show that transgenic expression of Bmp4 in β cells enhances GSIS and glucose clearance and that systemic administration of BMP4 protein to adult mice significantly stimulates GSIS and ameliorates glucose tolerance in a mouse model of glucose intolerance. Thus, BMP4-BMPR1A signaling in β cells plays a key role in GSIS

Certifieringars betydelse för livsmedelsaktörer - Explicita och implicita effekter för säkrare livsmedel

Certifieringar påverkar aktörerna inom livsmedelsbranschen. Vi menar, efter vår studie av producenter i Svenska frukt och gröntbranschen, att certifieringar har både explicita och implicita effekter för att säkra livsmedel. Dels bidrar de till att förebygga osäkra livsmedel genom att kvalitetssäkra processer genom hela värdekedjan. Att de flesta aktörerna inom branschen har som krav att bara arbeta med certifierade leverantörer samtidigt som systemet bygger på tredjepartsgranskningar leder det till att man måste jobba med de interna processerna för att nå vissa standarder som mäts i granskningarna för att vara med på marknaden. Förutom att säkra livsmedel, påverkas aktörer även indirekt av certifieringar. Bland annat kan certifieringar spela en viktig roll som kunskapsspridare för organisationer och för de människor som arbetar inom den. Vidare innebär tredjepartskontrollerna, som certifieringssystemen bygger på, att producenter som köper råvaror och själva slipper lägga tid och pengar på att göra grundläggande kontroller. Detta friar upp resurser för att göra kompletterande kontroller, som annars inte skulle utföras. Indirekt leder detta till en förhöjd kvalitetsnivå inom branschen då aktörer granskas mer på djupet än de skulle gjorts utan ett etablerat certifieringssystem. Certifieringar signalerar även ett kvalitetsvärde, detta i sin tur betyder att det skapas en polarisering mellan certifierade och icke certifierade aktörer inom branschen. För de certifierade aktörerna leder certifieringen till en marknadsfördel, med andra ord, man får tillgång till marknaden, medan det för icke certifierade aktörer kan leda till en marknadsbarriär och utanförskap. Det har visserligen negativa aspekter för den fria marknaden men samtidigt positivt för att säkra livsmedel

Meroanencephaly in an English Pointer Neonate

Background: Malformations are structural or functional abnormalities in the organs and structures present at birth. These conditions are rarely described in the newborns of dogs and can lead to their death. Meroanencephaly is a defect of the neural tube closure malformation. This study aims to characterize the clinical-pathological aspects of neonatal meroanencephaly since brain malformations are rare in newborn dogs.Case: A two-day-old English Pointer canine was sent for a necropsy. The newborn belonged to a litter of eight puppies, and only this one had macroscopic cranial alterations. Another puppy that died as a consequence of being trampled by the bitch was also necropsied. The newborn was alive for 48 h until death and presented apathy, crying, sucking reflex and opisthotonus. Macroscopic examination of the baby revealed flattening of the skull, with a slit at the site of bone symphysis fusion, and a slit in the skin of the parietal region, covered by thin, translucent meningeal tissue. The heads of the two animals were examined by radiography to identify the features of anencephaly in one of the animals by visualizing skull bone flattening. Upon removing the skin and exposing the cranial cavity, an irregular reddish mass was revealed, that corresponded microscopically to area cerebrovasculosa, composed of neurons, rudimentary glial tissue, vascular neoformations, as well as hemorrhagic areas.Discussion: Meroanencephaly is a type of anencephaly, a congenital malformation originating from abnormal neurulation, which results from the absence of neural fold fusion during neural tube formation. Live-born anencephalics have some brainstem-driven functions such as spontaneous breathing and some reflex responses, for instance, suction. Several genetic or teratogenic factors, such as viruses, radiation, drugs administered during pregnancy and other pathologies transmitted from bitch to fetus, can lead to this defect. The reports on anatomopathological findings and the presence of area cerebrovasculosa are rare

Identification and analysis of deletion breakpoints in four Mohr-Tranebjærg syndrome (MTS) patients

Mohr-Tranebjærg syndrome is an X-linked syndrome characterized by sensorineural hearing impairment in childhood, followed by progressive neurodegeneration leading to a broad phenotypic spectrum. Genetically MTS is caused by pathogenic variants in the TIMM8A gene, including gene deletions and larger contiguous gene deletions. Some of the latter involve the neighboring gene BTK, resulting in agammaglobulinemia. By next-generation mate-pair sequencing we have mapped the chromosomal deletion breakpoints of one MTS case and three XLA-MTS cases and used breakpoint-spanning PCR to fine map the breakpoints by Sanger sequencing. Two of the XLA-MTS cases presented with large deletions (63.5 and 27.2 kb), and the junctional regions were characterized by long stretches of microhomology, indicating that the events have emerged through homologous recombination. Conversely, the MTS case exhibited a small 2 bp region of microhomology, and the regions were not characterized by extensive microhomology. The third XLA-MTS case had a more complex breakpoint, including a 59 bp inverted insertion, thus at least four breakpoints were involved in this event. In conclusion, mate-pair library generation combined with next-generation sequencing is an efficient method for breakpoint identification, also in regions characterized by repetitive elements

Heterochromatin-Driven Nuclear Softening Protects the Genome against Mechanical Stress-Induced Damage

Summary Tissue homeostasis requires maintenance of functional integrity under stress. A central source of stress is mechanical force that acts on cells, their nuclei, and chromatin, but how the genome is protected against mechanical stress is unclear. We show that mechanical stretch deforms the nucleus, which cells initially counteract via a calcium-dependent nuclear softening driven by loss of H3K9me3-marked heterochromatin. The resulting changes in chromatin rheology and architecture are required to insulate genetic material from mechanical force. Failure to mount this nuclear mechanoresponse results in DNA damage. Persistent, high-amplitude stretch induces supracellular alignment of tissue to redistribute mechanical energy before it reaches the nucleus. This tissue-scale mechanoadaptation functions through a separate pathway mediated by cell-cell contacts and allows cells/tissues to switch off nuclear mechanotransduction to restore initial chromatin state. Our work identifies an unconventional role of chromatin in altering its own mechanical state to maintain genome integrity in response to deformation.Peer reviewe

Accurate Whole-Genome Sequencing and Haplotyping from 10 to 20 Human Cells

Recent advances in whole genome sequencing have brought the vision of personal genomics and genomic medicine closer to reality. However, current methods lack clinical accuracy and the ability to describe the context (haplotypes) in which genome variants co-occur in a cost-effective manner. Here we describe a low-cost DNA sequencing and haplotyping process, Long Fragment Read (LFR) technology, similar to sequencing long single DNA molecules without cloning or separation of metaphase chromosomes. In this study, ten LFR libraries were made using only ~100 pg of human DNA per sample. Up to 97% of the heterozygous single nucleotide variants (SNVs) were assembled into long haplotype contigs. Removal of false positive SNVs not phased by multiple LFR haplotypes resulted in a final genome error rate of 1 in 10 Mb. Cost-effective and accurate genome sequencing and haplotyping from 10-20 human cells, as demonstrated here, will enable comprehensive genetic studies and diverse clinical applications

Retinoic Acid Promotes the Generation of Pancreatic Endocrine Progenitor Cells and Their Further Differentiation into β-Cells

The identification of secreted factors that can selectively stimulate the generation of insulin producing β-cells from stem and/or progenitor cells represent a significant step in the development of stem cell-based β-cell replacement therapy. By elucidating the molecular mechanisms that regulate the generation of β-cells during normal pancreatic development such putative factors may be identified. In the mouse, β-cells increase markedly in numbers from embryonic day (e) 14.5 and onwards, but the extra-cellular signal(s) that promotes the selective generation of β-cells at these stages remains to be identified. Here we show that the retinoic acid (RA) synthesizing enzyme Raldh1 is expressed in developing mouse and human pancreas at stages when β-cells are generated. We also provide evidence that RA induces the generation of Ngn3+ endocrine progenitor cells and stimulates their further differentiation into β-cells by activating a program of cell differentiation that recapitulates the normal temporal program of β-cell differentiation

Abnormal neutrophil signature in the blood and pancreas of presymptomatic and symptomatic type 1 diabetes

BACKGROUND. Neutrophils and their inflammatory mediators are key pathogenic components in multiple autoimmune diseases, while their role in human type 1 diabetes (T1D), a disease that progresses sequentially through identifiable stages prior to the clinical onset, is not well understood. We previously reported that the number of circulating neutrophils is reduced in patients with T1D and in presymptomatic at-risk subjects. The aim of the present work was to identify possible changes in circulating and pancreas-residing neutrophils throughout the disease course to better elucidate neutrophil involvement in human T1D. METHODS. Data collected from 389 subjects at risk of developing T1D, and enrolled in 4 distinct studies performed by TrialNet, were analyzed with comprehensive statistical approaches to determine whether the number of circulating neutrophils correlates with pancreas function. To obtain a broad analysis of pancreas-infiltrating neutrophils throughout all disease stages, pancreas sections collected worldwide from 4 different cohorts (i.e., nPOD, DiViD, Siena, and Exeter) were analyzed by immunohistochemistry and immunofluorescence. Finally, circulating neutrophils were purified from unrelated nondiabetic subjects and donors at various T1D stages and their transcriptomic signature was determined by RNA sequencing. RESULTS. Here, we show that the decline in β cell function is greatest in individuals with the lowest peripheral neutrophil numbers. Neutrophils infiltrate the pancreas prior to the onset of symptoms and they continue to do so as the disease progresses. Of interest, a fraction of these pancreasinfiltrating neutrophils also extrudes neutrophil extracellular traps (NETs), suggesting a tissue-specific pathogenic role. Whole-transcriptome analysis of purified blood neutrophils revealed a unique molecular signature that is distinguished by an overabundance of IFN-associated genes; despite being healthy, said signature is already present in T1D-autoantibody-negative at-risk subjects. CONCLUSIONS. These results reveal an unexpected abnormality in neutrophil disposition both in the circulation and in the pancreas of presymptomatic and symptomatic T1D subjects, implying that targeting neutrophils might represent a previously unrecognized therapeutic modality

The mTOR Signalling Pathway in Human Cancer

The conserved serine/threonine kinase mTOR (the mammalian target of rapamycin), a downstream effector of the PI3K/AKT pathway, forms two distinct multiprotein complexes: mTORC1 and mTORC2. mTORC1 is sensitive to rapamycin, activates S6K1 and 4EBP1, which are involved in mRNA translation. It is activated by diverse stimuli, such as growth factors, nutrients, energy and stress signals, and essential signalling pathways, such as PI3K, MAPK and AMPK, in order to control cell growth, proliferation and survival. mTORC2 is considered resistant to rapamycin and is generally insensitive to nutrients and energy signals. It activates PKC-α and AKT and regulates the actin cytoskeleton. Deregulation of multiple elements of the mTOR pathway (PI3K amplification/mutation, PTEN loss of function, AKT overexpression, and S6K1, 4EBP1 and eIF4E overexpression) has been reported in many types of cancers, particularly in melanoma, where alterations in major components of the mTOR pathway were reported to have significant effects on tumour progression. Therefore, mTOR is an appealing therapeutic target and mTOR inhibitors, including the rapamycin analogues deforolimus, everolimus and temsirolimus, are submitted to clinical trials for treating multiple cancers, alone or in combination with inhibitors of other pathways. Importantly, temsirolimus and everolimus were recently approved by the FDA for the treatment of renal cell carcinoma, PNET and giant cell astrocytoma. Small molecules that inhibit mTOR kinase activity and dual PI3K-mTOR inhibitors are also being developed. In this review, we aim to survey relevant research, the molecular mechanisms of signalling, including upstream activation and downstream effectors, and the role of mTOR in cancer, mainly in melanoma