Expression of functional recombinant human factor IX in milk of mice

Human factor IX is synthesized in the liver and secreted in the blood, where it participates in a group of reactions involving coagulation factors and proteins that permit sanguinary coagulation. In this work two lines of transgenic mice were developed to express the FIX gene in the mammalian glands under control of milk β-casein promoter. The founding females secreted the FIX in their milk (3% total soluble protein). The stable integration of transgene was confirmed by southern blot analysis. The presence of the FIX recombinant protein in the milk of transgenic females was confirmed by western blot and the clotting activity was revealed in blood-clotting assays. The coagulation activity in human blood treated with recombinant FIX increased while the time of coagulation decreased. Our results confirm the production of a large amount of recombinant biologically active FIX in the mammary gland of transgenic mice.     

Suppression of translation during in vitro maturation of pig oocytes despite enhanced formation of cap-binding protein complex eIF4F and 4E-BP1 hyperphosphorylation

In this study, we document that the overall rate of protein synthesis decreases during in vitro maturation (IVM) of pig oocytes despite enhanced formation of the 5' cap structure eIF4F. Within somatic/interphase cells, formation of the eIF4F protein complex correlates very well with overall rates of protein translation, and the formation of this complex is controlled primarily by the availability of the 5' cap binding protein eIF4E. We show that the eIF4E inhibitory protein, 4E-BP1, becomes phosphorylated during IVM, which results in gradual release of eIF4E from 4E-BP1, as documented by immunoprecipitation analyses. Isoelectric focusing and Western blotting experiments show conclusively that eIF4E becomes gradually phosphorylated with a maximum at metaphase II (M II). The activity of eIF4E and its ability to bind mRNA also increases during oocyte maturation as documented in experiments with m7-methyl GTP-Sepharose, which mimics the cap structure of mRNA. Complementary analysis of flow-through fraction for 4E-BP1, and eIF4G proteins additionally provides evidence for enhanced formation of cap-binding protein complex eIF4F. Altogether, our results bring new insights to the regulation of translation initiation during meiotic division, and more specifically clarify that 4E-BP1 hyper-phosphorylation is not the cause of the observed suppression of overall translation rates.     

Scavenger receptor gp340 aggregates group A streptococci by binding pili

Group A streptococci (GAS) are the most frequent cause of bacterial pharyngitis. The first obstacle to GAS colonization of the pharynx is saliva. As well as forming a physical barrier, saliva contains components of innate and acquired immunity. Previous work has shown that saliva induces bacterial aggregation, which may serve as a clearance mechanism. As the aggregation of some oral streptococci in saliva is mediated by long proteinaceous appendages, we hypothesized that pili of GAS might behave similarly. Wild-type GAS M1 strain SF370 aggregated in saliva, while pilus-defective mutants did not. Similarly, heterologous expression of diverse GAS pili on the surface of Lactococcus lactis induced aggregation in saliva, while control strains were unaffected. Further studies revealed that aggregating bacteria bound salivary component gp340. Purified gp340 aggregated wild-type GAS and L. lactis expressing GAS pili, but not control strains. GAS pilus-defective mutants were abrogated in gp340 binding and aggregation. Furthermore, gp340-mediated aggregation reduced bacterial adhesion to human epithelial cells, suggesting a role in host defence.     

Contribution of the residue at position 4 within classical nuclear localization signals to modulating interaction with importins and nuclear targeting

Nuclear import involves the recognition by importin (IMP) superfamily members of nuclear localization signals (NLSs) within protein cargoes destined for the nucleus, the best understood being recognition of classical NLSs (cNLSs) by the IMPα/β1 heterodimer. Although the cNLS consensus [K-(K/R)-X-(K/R) for positions P2–P5] is generally accepted, recent studies indicated that the contribution made by different residues at the P4 position can vary. Here, we apply a combination of microscopy, molecular dynamics, crystallography, in vitro binding, and bioinformatics approaches to show that the nature of residues at P4 indeed modulates cNLS function in the context of a prototypical Simian Virus 40 large tumor antigen-derived cNLS (KKRK, P2–5). Indeed, all hydrophobic substitutions in place of R impaired binding to IMPα and nuclear targeting, with the largest effect exerted by a G residue at P4. Substitution of R with neutral hydrophobic residues caused the loss of electrostatic and van der Waals interactions between the P4 residue side chains and IMPα. Detailed bioinformatics analysis confirmed the importance of the P4 residue for cNLS function across the human proteome, with specific residues such as G being associated with low activity. Furthermore, we validate our findings for two additional cNLSs from human cytomegalovirus (HCMV) DNA polymerase catalytic subunit UL54 and processivity factor UL44, where a G residue at P4 results in a 2–3-fold decrease in NLS activity. Our results thus showed that the P4 residue makes a hitherto poorly appreciated contribution to nuclear import efficiency, which is essential to determining the precise nuclear levels of cargoes.     

Perinatal Na(+) Overload Programs Raised Renal Proximal Na(+) Transport and Enalapril-Sensitive Alterations of Ang II Signaling Pathways during Adulthood

Background

High Na⁺ intake is a reality in nowadays and is frequently accompanied by renal and cardiovascular alterations. In this study, renal mechanisms underlying perinatal Na⁺ overload-programmed alterations in Na⁺ transporters and the renin/angiotensin system (RAS) were investigated, together with effects of short-term treatment with enalapril in terms of reprogramming molecular alterations in kidney.

Methodology/Principal Findings

Male adult Wistar rats were obtained from dams maintained throughout pregnancy and lactation on a standard diet and drinking water (control) or 0.17 M NaCl (saline group). Enalapril (100 mg/l), an angiotensin converting enzyme inhibitor, was administered for three weeks after weaning. Ninety day old offspring from dams that drank saline presented with proximal tubules exhibiting increased (Na⁺+K⁺)ATPase expression and activity. Ouabain-insensitive Na⁺-ATPase activity remained unchanged but its response to angiotensin II (Ang II) was lost. PKC, PKA, renal thiobarbituric acid reactive substances (TBARS), macrophage infiltration and collagen deposition markedly increased, and AT₂ receptor expression decreased while AT₁ expression was unaltered. Early treatment with enalapril reduced expression and activity of (Na⁺+K⁺)ATPase, partially recovered the response of Na⁺-ATPase to Ang II, and reduced PKC and PKA activities independently of whether offspring were exposed to high perinatal Na⁺ or not. In addition, treatment with enalapril per se reduced AT₂ receptor expression, and increased TBARS, macrophage infiltration and collagen deposition. The perinatally Na⁺-overloaded offspring presented high numbers of Ang II-positive cortical cells, and significantly lower circulating Ang I, indicating that programming/reprogramming impacted systemic and local RAS.

Conclusions/Significance

Maternal Na⁺ overload programmed alterations in renal Na⁺ transporters and in its regulation, as well as severe structural lesions in adult offspring. Enalapril was beneficial predominantly through its influence on Na⁺ pumping activities in adult offspring. However, side effects including down-regulation of PKA, PKC and AT₂ receptors and increased TBARS could impair renal function in later life.     

Roles of NHERF1/EBP50 in cancer

This review summarizes the emerging roles of NHERF1/EBP50 adaptor protein in tumorigenesis. NHERF1/EBP50 (Na(+)/H(+) exchanger regulating factor 1; ezrin-radixin-moesin (ERM) binding phosphoprotein of 50 kDa) is a PDZ domain-containing protein with physiological localization at the plasma membrane. We discuss in this review the functions of NHERF1/EBP50 as a linker between membrane proteins and the cytoskeleton network, as well as its involvement in different types of cancer, such as breast and liver cancers. Recent evidence obtained from our laboratory and from other groups shows that NHERF1/EBP50 is an important player in cancer progression. It appears that, depending on its subcellular distribution, NHERF1/EBP50 may behave either as a tumor suppressor, when it is localized at the plasma membrane, or as an oncogenic protein, when it is shifted to the cytoplasm. We provide here an overview of the mechanisms by which this adaptor protein controls cell transformation, and propose a model suggesting a dual role of NHERF1/EBP50 in cancer.     

Impact of the deletion of the six mce operons in Mycobacterium smegmatis

The Mycobacterium smegmatis genome contains six operons designated mce (mammalian cell entry). These operons, which encode membrane and exported proteins, are highly conserved in pathogenic and non-pathogenic mycobacteria. Although the function of the Mce protein family has not yet been established in Mycobacterium smegmatis, the requirement of the mce4 operon for cholesterol utilization and uptake by Mycobacterium tuberculosis has recently been demonstrated. In this study, we report the construction of an M. smegmatis knock-out mutant deficient in the expression of all six mce operons. The consequences of these mutations were studied by analyzing physiological parameters and phenotypic traits. Differences in colony morphology, biofilm formation and aggregation in liquid cultures were observed, indicating that mce operons of M. smegmatis are implicated in the maintenance of the surface properties of the cell. Importantly, the mutant strain showed reduced cholesterol uptake when compared to the parental strain. Further cholesterol uptake studies using single mce mutant strains showed that the mutation of operon mce4 was reponsible for the cholesterol uptake failure detected in the sextuple mce mutant. This finding demonstrates that mce4operon is involved in cholesterol transport in M. smegmatis.