Constitutive over-expression of VEGF results in reduced expression of Hand-1 during cardiac development in Xenopus

During heart development, various signaling cascades are tightly regulated in a stage- and region-dependent manner. Vascular endothelial growth factor (VEGF) is one of the important molecules required for both vascular development and cardiac morphogenesis. VEGF receptors are present in the embryonic heart, so we focused on heart formation in VEGF-over-expressing Xenopus embryos. Over-expression of VEGF(170) caused disorganized vessels, while the expression of an endothelial marker, Tie-2, was increased. The embryo's heart was distinctly larger than that of control, and showed abnormal morphology. Histological analysis of these embryos showed failure of heart looping. In situ hybridization with Hand-1, which controls intrinsic morphogenetic pathways, revealed that the expression level of Hand-1 was decreased in the heart region. These results suggest that increased VEGF(170) levels disturb Hand-1 expression in the region required for normal heart morphogenesis. VEGF expression level may be important in heart morphology during embryonic development.     

Purification, cloning and characterization of egg lectins from the teleost Tribolodon brandti

Three L-rhamnose-binding egg lectins, TBL1, TBL2 and TBL3, were isolated from the eggs of the Far East dace Tribolodon brandti by a combination of affinity chromatography on L-rhamnose-Sepharose 6B gel and reversed-phase HPLC. L-rhamnose is a common inhibitor of the purified lectins and strongly inhibited the hemagglutinating activity of TBL2 and TBL3, but less weakly that of TBL1. L-arabinose, which has the same hydroxyl group orientation at C2 and C4 as L-rhamnose, and D-galactose showed no inhibitory activity against TBL1 but showed weak inhibitory activity against TBL2 and TBL3. The open reading frames of the cDNAs of TBL1, TBL2 and TBL3 encoded for mature proteins of 207, 189, and 293 amino acid residues, respectively. A BLAST homology search showed that the TBLs have about 40% homology to the carbohydrate recognition domains of rhamnose-binding lectins in salmonid eggs. The tandem repeated domains present in TBL1, TBL2 and TBL3 were two, two and three, respectively. TBL2 was exclusively expressed in ovary, while TBL1 and TBL3 were expressed mainly in ovary and weakly in various tissues including gill, heart, kidney, liver, spleen and testis.     

Plasma cholesterol-lowering and transient liver dysfunction in mice lacking squalene synthase in the liver

Squalene synthase (SS) catalyzes the biosynthesis of squalene, the first specific intermediate in the cholesterol biosynthetic pathway. To test the feasibility of lowering plasma cholesterol by inhibiting hepatic SS, we generated mice in which SS is specifically knocked out in the liver (L-SSKO) using Cre-loxP technology. Hepatic SS activity of L-SSKO mice was reduced by >90%. In addition, cholesterol biosynthesis in the liver slices was almost eliminated. Although the hepatic squalene contents were markedly reduced in L-SSKO mice, the hepatic contents of cholesterol and its precursors distal to squalene were indistinguishable from those of control mice, indicating the presence of sufficient centripetal flow of cholesterol and/or its precursors from the extrahepatic tissues. L-SSKO mice showed a transient liver dysfunction with moderate hepatomegaly presumably secondary to increased farnesol production. In a fed state, the plasma total cholesterol and triglyceride were significantly reduced in L-SSKO mice, primarily owing to reduced hepatic VLDL secretion. In a fasted state, the hypolipidemic effect was lost. mRNA expression of liver X receptor α target genes was reduced, while that of sterol-regulatory element binding protein 2 target genes was increased. In conclusion, liver-specific ablation of SS inhibits hepatic cholesterol biosynthesis and induces hypolipidemia without increasing significant mortality.     

Identification of tammar wallaby SIRH12, derived from a marsupial-specific retrotransposition event

In humans and mice, there are 11 genes derived from sushi-ichi related retrotransposons, some of which are known to play essential roles in placental development. Interestingly, this family of retrotransposons was thought to exist only in eutherian mammals, indicating their significant contributions to the eutherian evolution, but at least one, PEG10, is conserved between marsupials and eutherians. Here we report a novel sushi-ichi retrotransposon-derived gene, SIRH12, in the tammar wallaby, an Australian marsupial species of the kangaroo family. SIRH12 encodes a protein highly homologous to the sushi-ichi retrotransposon Gag protein in the tammar wallaby, while SIRH12 in the South American short-tailed grey opossum is a pseudogene degenerated by accumulation of multiple nonsense mutations. This suggests that SIRH12 retrotransposition occurred only in the marsupial lineage but acquired and retained some as yet unidentified novel function, at least in the lineage of the tammar wallaby.     

Numb controls E-cadherin endocytosis through p120 catenin with aPKC

Cadherin trafficking controls tissue morphogenesis and cell polarity. The endocytic adaptor Numb participates in apicobasal polarity by acting on intercellular adhesions in epithelial cells. However, it remains largely unknown how Numb controls cadherin-based adhesion. Here, we found that Numb directly interacted with p120 catenin (p120), which is known to interact with E-cadherin and prevent its internalization. Numb accumulated at intercellular adhesion sites and the apical membrane in epithelial cells. Depletion of Numb impaired E-cadherin internalization, whereas depletion of p120 accelerated internalization. Expression of the Numb-binding fragment of p120 inhibited E-cadherin internalization in a dominant-negative fashion, indicating that Numb interacts with the E-cadherin/p120 complex and promotes E-cadherin endocytosis. Impairment of Numb induced mislocalization of E-cadherin from the lateral membrane to the apical membrane. Atypical protein kinase C (aPKC), a member of the PAR complex, phosphorylated Numb and inhibited its association with p120 and α-adaptin. Depletion or inhibition of aPKC accelerated E-cadherin internalization. Wild-type Numb restored E-cadherin internalization in the Numb-depleted cells, whereas a phosphomimetic mutant or a mutant with defective α-adaptin-binding ability did not restore the internalization. Thus, we propose that aPKC phosphorylates Numb to prevent its binding to p120 and α-adaptin, thereby attenuating E-cadherin endocytosis to maintain apicobasal polarity.     

New insights into the phylogenetic distribution and evolutionary origins of the septins

Until recently, it had appeared that the septin family of proteins was restricted to the opisthokont eukaryotes (the fungi and animals and their close relatives the microsporidia and choanoflagellates). It has now become apparent that septins are also present in several other widely divergent eukaryotic lineages (chlorophyte algae, brown algae, and ciliates). This distribution and the details of the non-opisthokont septin sequences appear to require major revisions to hypotheses about the origins and early evolution of the septins.     

Scaling up towards international targets for AIDS, tuberculosis, and malaria: contribution of global fund-supported programs in 2011-2015

Objective

The paper projects the contribution to 2011–2015 international targets of three major pandemics by programs in 140 countries funded by the Global Fund to Fight AIDS, Tuberculosis and Malaria, the largest external financier of tuberculosis and malaria programs and a major external funder of HIV programs in low and middle income countries.

Design

Estimates, using past trends, for the period 2011–2015 of the number of persons receiving antiretroviral (ARV) treatment, tuberculosis case detection using the internationally approved DOTS strategy, and insecticide-treated nets (ITNs) to be delivered by programs in low and middle income countries supported by the Global Fund compared to international targets established by UNAIDS, Stop TB Partnership, Roll Back Malaria Partnership and the World Health Organisation.

Results

Global Fund-supported programs are projected to provide ARV treatment to 5.5–5.8 million people, providing 30%–31% of the 2015 international target. Investments in tuberculosis and malaria control will enable reaching in 2015 60%–63% of the international target for tuberculosis case detection and 30%–35% of the ITN distribution target in sub-Saharan Africa.

Conclusion

Global Fund investments will substantially contribute to the achievement by 2015 of international targets for HIV, TB and malaria. However, additional large scale international and domestic financing is needed if these targets are to be reached by 2015.