Xenopus NM23-X4 regulates retinal gliogenesis through interaction with p27Xic1

Background. In Xenopus retinogenesis, p27Xic1, a Xenopus cyclin dependent kinase inhibitor, functions as a cell fate determinant in both gliogenesis and neurogenesis in a context dependent manner. This activity is essential for co-ordination of determination and cell cycle regulation. However, very little is known about the mechanism regulating the context dependent choice between gliogenesis versus neurogenesis. Results. We have identified NM23-X4, a NM23 family member, as a binding partner of p27Xic1. NM23-X4 is expressed at the periphery of the ciliary marginal zone of the Xenopus retina and the expression overlaps with p27Xic1 at the central side. Our in vivo functional analysis in Xenopus retina has shown that knockdown of NM23-X4 activates gliogenesis. Furthermore, co-overexpression of NM23-X4 with p27Xic1 results in the inhibition of p27Xic1-mediated gliogenesis, through direct interaction of NM23-X4 with the amino-terminal side of p27Xic1. This inhibitory effect on gliogenesis requires serine-150 and histidine-148, which correspond to the important residues for the kinase activities of NM23 family members. Conclusion. This study demonstrates that NM23-X4 functions as an inhibitor of p27Xic1-mediated gliogenesis in Xenopus retina and suggests that this activity contributes to the proper spatio-temporal regulation of gliogenesis

Spatial and temporal expressions of prune reveal a role in Muller gliogenesis during Xenopus retinal development

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Treatment gaps in the implementation of LDL cholesterol control among high- and very high-risk patients in Europe between 2020–2021: the multinational observational SANTORINI study

Background European data pre-2019 suggest statin monotherapy is the most common approach to lipid management for preventing cardiovascular (CV) events, resulting in only one-fifth of high- and very high-risk patients achieving the 2019 ESC/EAS recommended low-density lipoprotein cholesterol (LDL-C) goals. Whether the treatment landscape has evolved, or gaps persist remains of interest. Methods Baseline data are presented from SANTORINI, an observational, prospective study that documents the use of lipid-lowering therapies (LLTs) in patients ≥18 years at high or very high CV risk between 2020 and 2021 across primary and secondary care settings in 14 European countries. Findings Of 9602 enrolled patients, 9044 with complete data were included (mean age: 65.3 ± 10.9 years; 72.6% male). Physicians reported using 2019 ESC/EAS guidelines as a basis for CV risk classification in 52.0% (4706/9044) of patients (overall: high risk 29.2%; very high risk 70.8%). However, centrally re-assessed CV risk based on 2019 ESC/EAS guidelines suggested 6.5% (308/4706) and 91.0% (4284/4706) were high- and very high-risk patients, respectively. Overall, 21.8% of patients had no documented LLTs, 54.2% were receiving monotherapy and 24.0% combination LLT. Median (interquartile range [IQR]) LDL-C was 2.1 (1.6, 3.0) mmol/L (82 [60, 117] mg/dL), with 20.1% of patients achieving risk-based LDL-C goals as per the 2019 ESC/EAS guidelines. Interpretation At the time of study enrolment, 80% of high- and very high-risk patients failed to achieve 2019 ESC/EAS guidelines LDL-C goals. Contributory factors may include CV risk underestimation and underutilization of combination therapies. Further efforts are needed to achieve current guideline-recommended LDL-C goals. Trial registration ClinicalTrials.gov Identifier: NCT04271280. Funding This study is funded by Daiichi Sankyo Europe GmbH, Munich, Germany

Evaluation of contemporary treatment of high- and very high-risk patients for the prevention of cardiovascular events in Europe – Methodology and rationale for the multinational observational SANTORINI study

Publisher Copyright: © 2021 The AuthorsBackground and aims: Clinical practice before 2019 suggests a substantial proportion of high and very high CV risk patients taking lipid-lowering therapy (LLT) would not achieve the new LDL-C goals recommended in the 2019 ESC/EAS guidelines (<70 and < 55 mg/dL, respectively). To what extent practice has changed since the last ESC/EAS guideline update is uncertain, and quantification of remaining implementation gaps may inform health policy. Methods: The SANTORINI study is a multinational, multicentre, prospective, observational, non-interventional study documenting patient data at baseline (enrolment) and at 12-month follow-up. The study recruited 9606 patients ≥18 years of age with high and very high CV risk (as assigned by the investigators) requiring LLT, with no formal patient or comparator groups. The primary objective is to document, in the real-world setting, the effectiveness of current treatment modalities in managing plasma levels of LDL-C in high- and very high-risk patients requiring LLT. Key secondary effectiveness objectives include documenting the relationship between LLT and levels of other plasma lipids, high-sensitivity C-reactive protein (hsCRP) and overall predicted CV risk over one year. Health economics and patient-relevant parameters will also be assessed. Conclusions: The SANTORINI study, which commenced after the 2019 ESC/EAS guidelines were published, is ideally placed to provide important contemporary insights into the evolving management of LLT in Europe and highlight factors contributing to the low levels of LDL-C goal achievement among high and very high CV risk patients. It is hoped the findings will help enhance patient management and reduce the burden of ASCVD in Europe.Peer reviewe

The NM23-H1/H2 homolog NDK-1 is required for full activation of Ras signaling in C. elegans

The group I members of the Nm23 (non-metastatic) gene family encode nucleoside diphosphate kinases (NDPKs) that have been implicated in the regulation of cell migration, proliferation and differentiation. Despite their developmental and medical significance, the molecular functions of these NDPKs remain ill defined. To minimize confounding effects of functional compensation between closely related Nm23 family members, we studied ndk-1, the sole Caenorhabditis elegans ortholog of group I NDPKs, and focused on its role in Ras/mitogen-activated protein kinase (MAPK)-mediated signaling events during development. ndk-1 inactivation leads to a protruding vulva phenotype and affects vulval cell fate specification through the Ras/MAPK cascade. ndk-1 mutant worms show severe reduction of activated, diphosphorylated MAPK in somatic tissues, indicative of compromised Ras/MAPK signaling. A genetic epistasis analysis using the vulval induction system revealed that NDK-1 acts downstream of LIN-45/Raf, but upstream of MPK-1/MAPK, at the level of the kinase suppressors of ras (KSR-1/2). KSR proteins act as scaffolds facilitating Ras signaling events by tethering signaling components, and we suggest that NDK-1 modulates KSR activity through direct physical interaction. Our study reveals that C. elegans NDK-1/Nm23 influences differentiation by enhancing the level of Ras/MAPK signaling. These results might help to better understand how dysregulated Nm23 in humans contributes to tumorigenesis. © 2013. Published by The Company of Biologists Ltd

Extracellular Nm23H1 stimulates neurite outgrowth from dorsal root ganglia neurons in vitro independently of nerve growth factor supplementation or its nucleoside diphosphate kinase activity

The nucleoside diphosphate (NDP) kinase, Nm23H1, is a highly expressed during neuronal development, whilst induced over-expression in neuronal cells results in increased neurite outgrowth. Extracellular Nm23H1 affects the survival, proliferation and differentiation of non-neuronal cells. Therefore, this study has examined whether extracellular Nm23H1 regulates nerve growth. We have immobilised recombinant Nm23H1 proteins to defined locations of culture plates, which were then seeded with explants of embryonic chick dorsal root ganglia (DRG) or dissociated adult rat DRG neurons. The substratum-bound extracellular Nm23H1 was stimulatory for neurite outgrowth from chick DRG explants in a concentration-dependent manner. On high concentrations of Nm23H1, chick DRG neurite outgrowth was extensive and effectively limited to the location of the Nm23H1, i.e. neuronal growth cones turned away from adjacent collagen-coated substrata. Nm23H1-coated substrata also significantly enhanced rat DRG neuronal cell adhesion and neurite outgrowth in comparison to collagen-coated substrata. These effects were independent of NGF supplementation. Recombinant Nm23H1 (H118F), which does not possess NDP kinase activity, exhibited the same activity as the wild-type protein. Hence, a novel neuro-stimulatory activity for extracellular Nm23H1 has been identified in vitro, which may function in developing neuronal systems

Metastases suppressor NME2 associates with telomere ends and telomerase and reduces telomerase activity within cells

Analysis of chromatin-immunoprecipitation followed by sequencing (ChIP-seq) usually disregards sequence reads that do not map within binding positions (peaks). Using an unbiased approach, we analysed all reads, both that mapped and ones that were not included as part of peaks. ChIP-seq experiments were performed in human lung adenocarcinoma and fibrosarcoma cells for the metastasis suppressor non-metastatic 2 (NME2). Surprisingly, we identified sequence reads that uniquely represented human telomere ends in both cases. In vivo presence of NME2 at telomere ends was validated using independent methods and as further evidence we found intranuclear association of NME2 and the telomere repeat binding factor 2. Most remarkably, results demonstrate that NME2 associates with telomerase and reduces telomerase activity in vitro and in vivo, and sustained NME2 expression resulted in reduced telomere length in aggressive human cancer cells. Anti-metastatic function of NME2 has been demonstrated in human cancers, however, mechanisms are poorly understood. Together, findings reported here suggest a novel role for NME2 as a telomere binding protein that can alter telomerase function and telomere length. This presents an opportunity to investigate telomere-related interactions in metastasis suppression

Sponge non-metastatic Group I Nme gene/protein - structure and function is conserved from sponges to humans

<p>Abstract</p> <p>Background</p> <p>Nucleoside diphosphate kinases NDPK are evolutionarily conserved enzymes present in Bacteria, Archaea and Eukarya, with human Nme1 the most studied representative of the family and the first identified metastasis suppressor. Sponges (Porifera) are simple metazoans without tissues, closest to the common ancestor of all animals. They changed little during evolution and probably provide the best insight into the metazoan ancestor's genomic features. Recent studies show that sponges have a wide repertoire of genes many of which are involved in diseases in more complex metazoans. The original function of those genes and the way it has evolved in the animal lineage is largely unknown. Here we report new results on the metastasis suppressor gene/protein homolog from the marine sponge <it>Suberites domuncula</it>, NmeGp1Sd. The purpose of this study was to investigate the properties of the sponge Group I Nme gene and protein, and compare it to its human homolog in order to elucidate the evolution of the structure and function of Nme.</p> <p>Results</p> <p>We found that sponge genes coding for Group I Nme protein are intron-rich. Furthermore, we discovered that the sponge NmeGp1Sd protein has a similar level of kinase activity as its human homolog Nme1, does not cleave negatively supercoiled DNA and shows nonspecific DNA-binding activity. The sponge NmeGp1Sd forms a hexamer, like human Nme1, and all other eukaryotic Nme proteins. NmeGp1Sd interacts with human Nme1 in human cells and exhibits the same subcellular localization. Stable clones expressing sponge NmeGp1Sd inhibited the migratory potential of CAL 27 cells, as already reported for human Nme1, which suggests that Nme's function in migratory processes was engaged long before the composition of true tissues.</p> <p>Conclusions</p> <p>This study suggests that the ancestor of all animals possessed a NmeGp1 protein with properties and functions similar to evolutionarily recent versions of the protein, even before the appearance of true tissues and the origin of tumors and metastasis.</p

In the Absence of Sonic Hedgehog, p53 Induces Apoptosis and Inhibits Retinal Cell Proliferation, Cell-Cycle Exit and Differentiation in Zebrafish

Background: Sonic hedgehog (Shh) signaling regulates cell proliferation during vertebrate development via induction of cell-cycle regulator gene expression or activation of other signalling pathways, prevents cell death by an as yet unclear mechanism and is required for differentiation of retinal cell types. Thus, an unsolved question is how the same signalling molecule can regulate such distinct cell processes as proliferation, cell survival and differentiation. Methodology/Principal Findings: Analysis of the zebrafish shh 2/2 mutant revealed that in this context p53 mediates elevated apoptosis during nervous system and retina development and interferes with retinal proliferation and differentiation. While in shh 2/2 mutants there is activation of p53 target genes and p53-mediated apoptosis, an increase in Hedgehog (Hh) signalling by over-expression of dominant-negative Protein Kinase A strongly decreased p53 target gene expression and apoptosis levels in shh 2/2 mutants. Using a novel p53 reporter transgene, I confirm that p53 is active in tissues that require Shh for cell survival. Proliferation assays revealed that loss of p53 can rescue normal cell-cycle exit and the mitotic indices in the shh 2/2 mutant retina at 24, 36 and 48 hpf. Moreover, generation of amacrine cells and photoreceptors was strongly enhanced in the double p53 2/2 shh 2/2 mutant retina suggesting the effect of p53 on retinal differentiation. Conclusions: Loss of Shh signalling leads to the p53-dependent apoptosis in the developing nervous system and retina