Sec24D-Dependent Transport of Extracellular Matrix Proteins Is Required for Zebrafish Skeletal Morphogenesis

Protein transport from endoplasmic reticulum (ER) to Golgi is primarily conducted by coated vesicular carriers such as COPII. Here, we describe zebrafish bulldog mutations that disrupt the function of the cargo adaptor Sec24D, an integral component of the COPII complex. We show that Sec24D is essential for secretion of cartilage matrix proteins, whereas the preceding development of craniofacial primordia and pre-chondrogenic condensations does not depend on this isoform. Bulldog chondrocytes fail to secrete type II collagen and matrilin to extracellular matrix (ECM), but membrane bound receptor β1-Integrin and Cadherins appear to leave ER in Sec24D-independent fashion. Consequently, Sec24D-deficient cells accumulate proteins in the distended ER, although a subset of ER compartments and Golgi complexes as visualized by electron microscopy and NBD C6-ceramide staining appear functional. Consistent with the backlog of proteins in the ER, chondrocytes activate the ER stress response machinery and significantly upregulate BiP transcription. Failure of ECM secretion hinders chondroblast intercalations thus resulting in small and malformed cartilages and severe craniofacial dysmorphology. This defect is specific to Sec24D mutants since knockdown of Sec24C, a close paralog of Sec24D, does not result in craniofacial cartilage dysmorphology. However, craniofacial development in double Sec24C/Sec24D-deficient animals is arrested earlier than in bulldog/sec24d, suggesting that Sec24C can compensate for loss of Sec24D at initial stages of chondrogenesis, but Sec24D is indispensable for chondrocyte maturation. Our study presents the first developmental perspective on Sec24D function and establishes Sec24D as a strong candidate for cartilage maintenance diseases and craniofacial birth defects

MYH3-associated distal arthrogryposis zebrafish model is normalized with para-aminoblebbistatin

Distal arthrogryposis (DA) is group of syndromes characterized by congenital joint contractures. Treatment development is hindered by the lack of vertebrate models. Here, we describe a zebrafish model in which a common MYH3 missense mutation (R672H) was introduced into the orthologous zebrafish gene smyhc1 (slow myosin heavy chain 1) (R673H). We simultaneously created a smyhc1 null allele (smyhc

Gene expression time delays & Turing pattern formation systems

The incorporation of time delays can greatly affect the behaviour of partial differential equations and dynamical systems. In addition, there is evidence that time delays in gene expression due to transcription and translation play an important role in the dynamics of cellular systems. In this paper, we investigate the effects of incorporating gene expression time delays into a one-dimensional putative reaction diffusion pattern formation mechanism on both stationary domains and domains with spatially uniform exponential growth. While oscillatory behaviour is rare, we find that the time taken to initiate and stabilise patterns increases dramatically as the time delay is increased. In addition, we observe that on rapidly growing domains the time delay can induce a failure of the Turing instability which cannot be predicted by a naive linear analysis of the underlying equations about the homogeneous steady state. The dramatic lag in the induction of patterning, or even its complete absence on occasions, highlights the importance of considering explicit gene expression time delays in models for cellular reaction diffusion patterning

Aberrant behaviours of reaction diffusion self-organisation models on growing domains in the presence of gene expression time delays

Turing’s pattern formation mechanism exhibits sensitivity to the details of the initial conditions suggesting that, in isolation, it cannot robustly generate pattern within noisy biological environments. Nonetheless, secondary aspects of developmental self-organisation, such as a growing domain, have been shown to ameliorate this aberrant model behaviour. Furthermore, while in-situ hybridisation reveals the presence of gene expression in developmental processes, the influence of such dynamics on Turing’s model has received limited attention. Here, we novelly focus on the Gierer–Meinhardt reaction diffusion system considering delays due the time taken for gene expression, while incorporating a number of different domain growth profiles to further explore the influence and interplay of domain growth and gene expression on Turing’s mechanism. We find extensive pathological model behaviour, exhibiting one or more of the following: temporal oscillations with no spatial structure, a failure of the Turing instability and an extreme sensitivity to the initial conditions, the growth profile and the duration of gene expression. This deviant behaviour is even more severe than observed in previous studies of Schnakenberg kinetics on exponentially growing domains in the presence of gene expression (Gaffney and Monk in Bull. Math. Biol. 68:99–130, 2006). Our results emphasise that gene expression dynamics induce unrealistic behaviour in Turing’s model for multiple choices of kinetics and thus such aberrant modelling predictions are likely to be generic. They also highlight that domain growth can no longer ameliorate the excessive sensitivity of Turing’s mechanism in the presence of gene expression time delays. The above, extensive, pathologies suggest that, in the presence of gene expression, Turing’s mechanism would generally require a novel and extensive secondary mechanism to control reaction diffusion patterning

Markers of Antioxidant Defense in Patients with Type 2 Diabetes

Aims. Diabetes is considered a state of increased oxidative stress. This study evaluates blood concentrations of selected markers of antioxidant defense in patients with type 2 diabetes. Methods. The study included 80 type 2 diabetes patients and 79 apparently healthy controls. Measured markers included ferric reducing ability of plasma (FRAP), reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione reductase (GR), -glutamyltransferase (GGT) and uric acid serum, and plasma and/or hemolysate levels. Results. FRAP, uric acid, CRP, and GGT levels were significantly higher in patients with diabetes. Plasma and hemolysate GR was significantly higher whereas GPx activity was significantly lower in patients with diabetes. There were no significant differences in antioxidant defense markers between patients with and without chronic diabetes complications. Fasting serum glucose correlated with plasma GPx, plasma and hemolysate GR, FRAP, and serum GGT, and HbA1c correlated with serum GGT. Only FRAP and serum uric acid were significantly higher in obese (BMI > 30 kg/m 2 ) patients with diabetes than in nonobese patients. Conclusions. Some components of antioxidant defense such as GR, uric acid, and GGT are increased in patients with type 2 diabetes. However, the whole system cannot compensate for an enhanced production of ROS as reflected by the trend toward decreased erythrocytes GSH

Practical guidelines for the supplementation of vitamin D and the treatment of deficits in Central Europe — recommended vitamin D intakes in the general population and groups at risk of vitamin D deficiency

Wstęp: Wyniki badań z ostatnich lat dokumentują wiele korzyści wynikających z działania witaminy D na organizm człowieka na wszystkichetapach jego życia. Większość badań epidemiologicznych sugeruje, że niedobór witaminy D jest powszechny wśród mieszkańców EuropyŚrodkowej. Naturalną konsekwencją tej sytuacji jest konieczność ciągłego uświadamiania społeczeństwu oraz środowisku medycznemu,jaką rolę odgrywa witamina D w rozwoju i funkcjonowaniu organizmu ludzkiego.Metody: Na podstawie przeglądu danych literaturowych Polski Zespół Wielodyscyplinarny opracował tezy dotyczące zasad suplementacjiwitaminą D, które przesłano do członków Komitetu Naukowego konferencji „Witamina D — minimum, maksimum, optimum”,19–20 Październik, 2012, Warszawa. W trakcie powyższej konferencji z udziałem 550 delegatów oraz Ekspertów różnych dziedzin medycynyomówiono i przedyskutowano propozycje wytycznych suplementacji witaminą D populacji Europy Środkowej.Wyniki: W efekcie przeprowadzonych dyskusji Zespół Ekspertów opracował wytyczne suplementacji witaminą D dla wszystkich grupwiekowych populacji Europy Środkowej. Określono również kryteria diagnostyczne charakteryzujące stan zaopatrzenia organizmu w witaminę D: deficyt witaminy D ustalono jako stężenie 25(OH)D < 20 ng/mL (< 50 nmol/L)], suboptymalne zaopatrzenie jako stężenie25(OH)D wynoszące 20–30 ng/mL (50–75 nmol/L), a stężenie 30–50 ng/mL (75–125 nmol/L) uznano za docelowe dla zapewnienia efektuplejotropowego witaminy D.Wnioski: Poprawa obecnego stanu zaopatrzenia witaminy D w grupach dzieci, młodzieży, osób aktywnych zawodowo i seniorówpowinna zostać włączona do priorytetów polityki zdrowotnej społeczeństw Europy Środkowej.Introduction: Adequate Vitamin D intake and its concentration in serum are important for bone health and calcium–phosphate metabolismas well as for optimal function of many organs and tissues. Documented trends in lifestyle, nutritional habits and physical activityappear to be associated with moderate or severe Vitamin D deficits resulting in health problems. Most epidemiological studies suggest thatVitamin D deficiency is prevalent among Central European populations. Concern about this problem led to the organising of a conferencefocused on overcoming Vitamin D deficiency.Methods: After reviewing the epidemiological evidence and relevant literature, a Polish multidisciplinary group formulated theses onrecommendations for Vitamin D screening and supplementation in the general population. These theses were subsequently sent to ScientificCommittee members of the ‘Vitamin D — minimum, maximum, optimum’ conference for evaluation based on a ten-point scale.With 550 international attendees, the meeting ‘Vitamin D — minimum, maximum, optimum’ was held on October 19–20, 2012 in Warsaw(Poland). Most recent scientific evidence of both skeletal and non-skeletal effects of Vitamin D as well as the results of panellists’ votingwere reviewed and discussed during eight plenary sessions and two workshops.Results: Based on many polemical discussions, including post-conference networking, the key opinion leaders established ranges ofserum 25-hydroxyVitamin D concentration indicating Vitamin D deficiency [< 20 ng/mL (< 50 nmol/L)], suboptimal status [20–30 ng/mL(50–75 nmol/L)], and target concentration for optimal Vitamin D effects [30–50 ng/mL (75–125 nmol/L)]. General practical guidelines regardingsupplementation and updated recommendations for prophylactic Vitamin D intakes in Central European neonates, infants, childrenand adolescents as well as in adults (including recommendations for pregnant and breastfeeding women and the elderly) were developed.Conclusions: Improving the Vitamin D status of children, adolescents, adults and the elderly must be included in the priorities of physicians,healthcare professionals and healthcare regulating bodies. The present paper offers elaborated consensus on supplementationguidance and population strategies for Vitamin D in Central Europe

Unc5B Interacts with FLRT3 and Rnd1 to Modulate Cell Adhesion in Xenopus Embryos

The FLRT family of transmembrane proteins has been implicated in the regulation of FGF signalling, neurite outgrowth, homotypic cell sorting and cadherin-mediated adhesion. In an expression screen we identified the Netrin receptors Unc5B and Unc5D as high-affinity FLRT3 interactors. Upon overexpression, Unc5B phenocopies FLRT3 and both proteins synergize in inducing cell deadhesion in Xenopus embryos. Morpholino knock-downs of Unc5B and FLRT3 synergistically affect Xenopus development and induce morphogenetic defects. The small GTPase Rnd1, which transmits FLRT3 deadhesion activity, physically and functionally interacts with Unc5B, and mediates its effect on cell adhesion. The results suggest that FLRT3, Unc5B and Rnd1 proteins interact to modulate cell adhesion in early Xenopus development

Mutation in utp15 Disrupts Vascular Patterning in a p53-Dependent Manner in Zebrafish Embryos

Angiogenesis is the process by which the highly branched and functional vasculature arises from the major vessels, providing developing tissues with nutrients, oxygen, and removing metabolic waste. During embryogenesis, vascular patterning is dependent on a tightly regulated balance between pro- and anti-angiogenic signals, and failure of angiogenesis leads to embryonic lethality. Using the zebrafish as a model organism, we sought to identify genes that influence normal vascular patterning.In a forward genetic screen, we identified mutant LA1908, which manifests massive apoptosis during early embryogenesis, abnormal expression of several markers of arterial-venous specification, delayed angiogenic sprouting of the intersegmental vessels (ISV), and malformation of the caudal vein plexus (CVP), indicating a critical role for LA1908 in cell survival and angiogenesis. Genetic mapping and sequencing identified a G to A transition in the splice site preceding exon 11 of utp15 in LA1908 mutant embryos. Overexpression of wild type utp15 mRNA suppresses all observed mutant phenotypes, demonstrating a causative relationship between utp15 and LA1908. Furthermore, we found that injecting morpholino oligonucleotides inhibiting p53 translation prevents cell death and rescues the vascular abnormalities, indicating that p53 is downstream of Utp15 deficiency in mediating the LA1908 phenotypes.Taken together, our data demonstrate an early embryonic effect of Utp15 deficiency on cell survival and the normal patterning of the vasculature and highlight an anti-angiogenic role of p53 in developing embryos

The Tumor Suppressor PRDM5 Regulates Wnt Signaling at Early Stages of Zebrafish Development

PRDM genes are a family of transcriptional regulators that modulate cellular processes such as differentiation, cell growth and apoptosis. Some family members are involved in tissue or organ maturation, and are differentially expressed in specific phases of embryonic development. PRDM5 is a recently identified family member that functions as a transcriptional repressor and behaves as a putative tumor suppressor in different types of cancer. Using gene expression profiling, we found that transcriptional targets of PRDM5 in human U2OS cells include critical genes involved in developmental processes, and specifically in regulating wnt signaling. We therefore assessed PRDM5 function in vivo by performing loss-of-function and gain-of-function experiments in zebrafish embryos. Depletion of prdm5 resulted in impairment of morphogenetic movements during gastrulation and increased the occurrence of the masterblind phenotype in axin+/− embryos, characterized by the loss of eyes and telencephalon. Overexpression of PRDM5 mRNA had opposite effects on the development of anterior neural structures, and resulted in embryos with a shorter body axis due to posterior truncation, a bigger head and abnormal somites. In situ hybridization experiments aimed at analyzing the integrity of wnt pathways during gastrulation at the level of the prechordal plate revealed inhibition of non canonical PCP wnt signaling in embryos overexpressing PRDM5, and over-activation of wnt/β-catenin signaling in embryos lacking Prdm5. Our data demonstrate that PRDM5 regulates the expression of components of both canonical and non canonical wnt pathways and negatively modulates wnt signaling in vivo