WIP1 Phosphatase as a Potential Therapeutic Target in Neuroblastoma

The wild-type p53-induced phosphatase 1 (WIP1) is a serine/threonine phosphatase that negatively regulates multiple proteins involved in DNA damage response including p53, CHK2, Histone H2AX, and ATM, and it has been shown to be overexpressed or amplified in human cancers including breast and ovarian cancers. We examined WIP1 mRNA levels across multiple tumor types and found the highest levels in breast cancer, leukemia, medulloblastoma and neuroblastoma. Neuroblastoma is an exclusively TP53 wild type tumor at diagnosis and inhibition of p53 is required for tumorigenesis. Neuroblastomas in particular have previously been shown to have 17q amplification, harboring the WIP1 (PPM1D) gene and associated with poor clinical outcome. We therefore sought to determine whether inhibiting WIP1 with a selective antagonist, GSK2830371, can attenuate neuroblastoma cell growth through reactivation of p53 mediated tumor suppression. Neuroblastoma cell lines with wild-type TP53 alleles were highly sensitive to GSK2830371 treatment, while cell lines with mutant TP53 were resistant to GSK2830371. The majority of tested neuroblastoma cell lines with copy number gains of the PPM1D locus were also TP53 wild-type and sensitive to GSK2830371A; in contrast cell lines with no copy gain of PPM1D were mixed in their sensitivity to WIP1 inhibition, with the primary determinant being TP53 mutational status. Since WIP1 is involved in the cellular response to DNA damage and drugs used in neuroblastoma treatment induce apoptosis through DNA damage, we sought to determine whether GSK2830371 could act synergistically with standard of care chemotherapeutics. Treatment of wild-type TP53 neuroblastoma cell lines with both GSK2830371 and either doxorubicin or carboplatin resulted in enhanced cell death, mediated through caspase 3/7 induction, as compared to either agent alone. Our data suggests that WIP1 inhibition represents a novel therapeutic approach to neuroblastoma that could be integrated with current chemotherapeutic approaches.     

Spatial phylogenetics of the native woody plant species in Hainan,China

To better identify biodiversity hotspots for conservation on Hainan Island, a tropical island in southern China, we assessed spatial variation in phylogenetic diversity and species richness using 18,976 georeferenced specimen records and a newly reconstructed molecular phylogeny of 957 native woody plants. Within this framework, we delineated bioregions based on vegetation composition and mapped areas of neoendemism and paleoendemism to identify areas of priority for conservation. Our results reveal that the southwest of Hainan is the most important hot spot for endemism and plant diversity followed by the southeast area. The distribution of endemic species showed a scattered, rather than clustered, pattern on the island. Based on phylogenetic range‐weighted turnover metrics, we delineated three major vegetational zones in Hainan. These largely correspond to natural secondary growth and managed forests (e.g., rubber and timber forests) in central Hainan, old‐growth forests and natural secondary growth forest at the margins of Hainan, and nature reserves on the island (e.g., Jianfeng and Diaoluo National Nature Reserves). Our study helps to elucidate potential botanical conservation priorities for Hainan within an evolutionary, phylogenetic framework.     

A network-based approach to classify the three domains of life

Background

Chromosomal orthologs can reveal the shared ancestral gene set and their evolutionary trends. Additionally, physico-chemical properties of encoded proteins could provide information about functional adaptation and ecological niche requirements.

Results

We analyzed 7080 genes (five groups of 1416 orthologs each) from Rhizobiales species (S. meliloti, R. etli, and M. loti, plant symbionts; A. tumefaciens, a plant pathogen; and B. melitensis, an animal pathogen). We evaluated their phylogenetic relationships and observed three main topologies. The first, with closer association of R. etli to A. tumefaciens; the second with R. etli closer to S. meliloti; and the third with A. tumefaciens and S. meliloti as the closest pair. This was not unusual, given the close relatedness of these three species. We calculated the synonymous (dS) and nonsynonymous (dN) substitution rates of these orthologs, and found that informational and metabolic functions showed relatively low dN rates; in contrast, genes from hypothetical functions and cellular processes showed high dN rates. An alternative measure of sequence variability, percentage of changes by species, was used to evaluate the most specific proportion of amino acid residues from alignments. When dN was compared with that measure a high correlation was obtained, revealing that much of evolutive information was extracted with the percentage of changes by species at the amino acid level. By analyzing the sequence variability of orthologs with a set of five properties (polarity, electrostatic charge, formation of secondary structures, molecular volume, and amino acid composition), we found that physico-chemical characteristics of proteins correlated with specific functional roles, and association of species did not follow their typical phylogeny, probably reflecting more adaptation to their life styles and niche preferences. In addition, orthologs with low dN rates had residues with more positive values of polarity, volume and electrostatic charge.

Conclusions

These findings revealed that even when orthologs perform the same function in each genomic background, their sequences reveal important evolutionary tendencies and differences related to adaptation. This article was reviewed by: Dr. Purificación López-García, Prof. Jeffrey Townsend (nominated by Dr. J. Peter Gogarten), and Ms. Olga Kamneva.     

Hochstetter's frog (Leiopelma hochstetteri) egg,mobile larvae and froglet development

Egg strings and larvae of Hochstetter's frog (Leiopelma hochstetteri) were located at three widely separated North Island sites: in seeps at Brynderwyns in December 2004, in an open pool at Wharerino in March 2009, and in an underground pool near the Kaipawa Track, Coromandel, in late May 2009. Ten egg strings were also laid by captive frogs in water courses at Hamilton Zoo in April 2009. All egg strings held from 11 to 13 eggs. The egg strings laid in the Brynderwyns were regularly observed until metamorphosis was completed in March 2005. Twenty-four swimming larvae emerged from 25 capsules at c. 40 days after discovery, and at least 14 froglets were produced at c. 90 days. All of them developed in darkness, in a 120 ml pool <30 mm deep. The emerged froglets ranged from 9.8 to 10.8 mm snout-vent length. The detection of eggs, larvae and <11 mm froglets indicates that the egg laying period is at least from late September to May.     

Specific antioxidant selenoproteins are induced in the heart during hypertrophy

Selenium (Se) is thought to confer cardioprotective effects through the actions of antioxidant selenoprotein enzymes that directly limit levels of ROS such as hydrogen peroxide (H₂O₂) or that reverse oxidative damage to lipids and proteins. To determine how the selenoproteome responds to myocardial hypertrophy, two mouse models were employed: triidothyronine (T3)- or isoproterenol (ISO)-treatment. After 7 days of T3- and ISO-treatment, cardiac stress was demonstrated by increased H₂O₂ and caspase-3 activity. Neither treatment produced significant increases in phospholipid peroxidation or TUNEL-positive cells, suggesting that antioxidant systems were protecting the cardiomyocytes from damage. Many selenoprotein mRNAs were induced by T3- and ISO-treatment, with levels of methionine sulfoxide reductase 1 (MsrB1, also called SelR) mRNA showing the largest increases. MsrB enzymatic activity was also elevated in both models of cardiac stress, while glutathione peroxidase (GPx) activity and thioredoxin reductase (Trxrd) activity were moderately and nonsignificantly increased, respectively. Western blot assays revealed a marked increase in MsrB1 and moderate increases in GPx3, GPx4, and Trxrd1, particularly in T3-treated hearts. Thus, the main response of the selenoproteome during hypertrophy does not involve increased GPx1, but increased GPx3 for reducing extracellular H₂O₂ and increased GPx4, Trxrd1, and MsrB1 for minimizing intracellular oxidative damage.     

Cubozoan Venom-Induced Cardiovascular Collapse Is Caused by Hyperkalemia and Prevented by Zinc Gluconate in Mice

Chironex fleckeri (Australian box jellyfish) stings can cause acute cardiovascular collapse and death. We developed methods to recover venom with high specific activity, and evaluated the effects of both total venom and constituent porins at doses equivalent to lethal envenomation. Marked potassium release occurred within 5 min and hemolysis within 20 min in human red blood cells (RBC) exposed to venom or purified venom porin. Electron microscopy revealed abundant ∼12-nm transmembrane pores in RBC exposed to purified venom porins. C57BL/6 mice injected with venom showed rapid decline in ejection fraction with progression to electromechanical dissociation and electrocardiographic findings consistent with acute hyperkalemia. Recognizing that porin assembly can be inhibited by zinc, we found that zinc gluconate inhibited potassium efflux from RBC exposed to total venom or purified porin, and prolonged survival time in mice following venom injection. These findings suggest that hyperkalemia is the critical event following Chironex fleckeri envenomation and that rapid administration of zinc could be life saving in human sting victims.     

Time Space Translation: A Hox Mechanism for Vertebrate A-P Patterning

The vertebrate A-P axis is a time axis. The head is made first and more and more posterior levels are made at later and later stages. This is different to the situation in most other animals, for example, in Drosophila. Central to this timing is Hox temporal collinearity (see below). This occurs rarely in the animal kingdom but is characteristic of vertebrates and is used to generate the primary axial Hox pattern using time space translation and to integrate successive derived patterns (see below). This is thus a different situation than in Drosophila, where the primary pattern guiding Hox spatial collinearity is generated externally, by the gap and segmentation genes.