Survivin as a target for new anticancer interventions

Survivin is a member of the inhibitor of apoptosis protein (IAP) family, that has been implicated in both control of cell division and inhibition of apoptosis. Specifically, its anti-apoptotic function seems to be related to the ability to directly or indirectly inhibit caspases. Survivin is selectively expressed in the most common human neoplasms and appears to be involved in tumor cell resistance to some anticancer agents and ionizing radiation. On the basis of these findings survivin has been proposed as an attractive target for new anticancer interventions. Several preclinical studies have demonstrated that down-regulation of survivin expression/function, accomplished through the use of antisense oligonucleotides, dominant negative mutants, ribozymes, small interfering RNAs and cyclin-dependent kinase inhibitors, increased the apoptotic rate, reduced tumor-growth potential and sensitized tumor cells to chemotherapeutic drugs with different action mechanisms and gamma-irradiation in in vitro and in vivo models of different human tumor types.     

Diffusible signals and fasciculated growth in reticulospinal axon pathfinding in the hindbrain

We have addressed the control of longitudinal axon pathfinding in the developing hindbrain, including the caudal projections of reticular and raphe neurons. To test potential sources of guidance signals, we assessed axon outgrowth from embryonic rat hindbrain explants cultured in collagen gels at a distance from explants of midbrain-hindbrain boundary (isthmus), caudal hindbrain, or cervical spinal cord. Our results showed that the isthmus inhibited caudally directed axon outgrowth by 80% relative to controls, whereas rostrally directed axon outgrowth was unaffected. Moreover, caudal hindbrain or cervical spinal cord explants did not inhibit caudal axons. Immunohistochemistry for reticular and raphe neuronal markers indicated that the caudal, but not the rostral projections of these neuronal subpopulations were inhibited by isthmic explants. Companion studies in chick embryos showed that, when the hindbrain was surgically separated from the isthmus, caudal reticulospinal axon projections failed to form and that descending pioneer axons of the medial longitudinal fasciculus (MLF) play an important role in the caudal reticulospinal projection. Taken together, these results suggest that diffusible chemorepellent or nonpermissive signals from the isthmus and substrate-anchored signals on the pioneer MLF axons are involved in the caudal direction of reticulospinal projections and might influence other longitudinal axon projections in the brainstem.     

Bile acids,FGF15/19 and liver regeneration: From mechanisms to clinical applications

The liver has an extraordinary regenerative capacity rapidly triggered upon injury or resection. This response is intrinsically adjusted in its initiation and termination, a property termed the “hepatostat”. Several molecules have been involved in liver regeneration, and among them bile acids may play a central role. Intrahepatic levels of bile acids rapidly increase after resection. Through the activation of farnesoid X receptor (FXR), bile acids regulate their hepatic metabolism and also promote hepatocellular proliferation. FXR is also expressed in enterocytes, where bile acids stimulate the expression of fibroblast growth factor 15/19 (FGF15/19), which is released to the portal blood. Through the activation of FGFR4 on hepatocytes FGF15/19 regulates bile acids synthesis and finely tunes liver regeneration as part of the “hepatostat”. Here we review the experimental evidences supporting the relevance of the FXR-FGF15/19-FGFR4 axis in liver regeneration and discuss potential therapeutic applications of FGF15/19 in the prevention of liver failure. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.     

Purification, Characterization, and Functional Role of a Novel Extracellular Protease from Pleurotus ostreatus

A new extracellular protease (PoSl; Pleurotus ostreatus subtilisin-like protease) from P. ostreatus culture broth has been purified and characterized. PoSl is a monomeric glycoprotein with a molecular mass of 75 kDa, a pI of 4.5, and an optimum pH in the alkaline range. The inhibitory profile indicates that PoSl is a serine protease. The N-terminal and three tryptic peptide sequences of PoSl have been determined. The homology of one internal peptide with conserved sequence around the Asp residue of the catalytic triad in the subtilase family suggests that PoSl is a subtilisin-like protease. This hypothesis is further supported by the finding that PoSl hydrolysis sites of the insulin B chain match those of subtilisin. PoSl activity is positively affected by calcium. A 10-fold decrease in the K_m value in the presence of calcium ions can reflect an induced structural change in the substrate recognition site region. Furthermore, Ca²⁺ binding slows PoSl autolysis, triggering the protein to form a more compact structure. These effects have already been observed for subtilisin and other serine proteases. Moreover, PoSl protease seems to play a key role in the regulation of P. ostreatus laccase activity by degrading and/or activating different isoenzymes.     

Species diversity of the genus Osmundea (Ceramiales,Rhodophyta) in the Macaronesian region

Species diversity within the genus Osmundea in the Macaronesian region was explored by conducting a comprehensive sampling in the Azores, the Canary, and the Madeira archipelagos. Toward identification, all specimens were first observed alive to verify the absence of corps en cerise, a diagnostic character for the genus and morphometric data were measured (thallus length and width, first‐order branches length and width, branchlets length and width, cortical cell length and width in surface view, cortical cell length and width in transverse section). Specimens were sequenced for COI‐5P (39 specimens) and three species delimitation methods (Generalized Mixed Yule Coalescent, Automatic Barcode Gap Discovery method, and Poisson Tree Processes) were used to assess the threshold between infra‐ and interspecific relationships. Subsequently, one or several sequences of plastid‐encoded large subunit of RuBisCO (21 specimens) per delimited species were generated to assess the phylogenetic relationships among Macaronesian Osmundea. Moreover, for each delineated species, vegetative and reproductive anatomy was thoroughly documented and, when possible, specimens were either assigned to existing taxa or described as novel species. This integrative approach has provided data for (i) the presence of O. oederi, O. pinnatifida, and O. truncata in Macaronesia; (ii) the proposal of two novel species, O. prudhommevanreinei sp. nov. and O. silvae sp. nov.; and (iii) evidence of an additional species referred as “Osmundea sp.1,” which is a sister taxon of O. hybrida.     

The chimeric cytokine Hyper-IL-6 enhances the efficiency of lentiviral gene transfer in hepatocytes both in vitro and in vivo

Lentiviral vectors have been used for gene transfer into the liver but their ability to efficiently transduce quiescent hepatocytes remains controversial. Lentivirus-mediated gene transfer is more efficient in cycling cells. We determine the effect of H-IL6 in the lentiviral transduction. The lentiviral vector was used to transduce HepG2 cells and mice liver cells, previously treated with H-IL6. The highest transduction level was observed in HepG2 cells treated with 30 ng/mL H-IL6 and in the mice that received 4 μg H-IL6. Our results suggest that H-IL6 is an inducer of lentiviral gene transfer into the liver cells without any toxicity.     

A set of fluorescent protein‐based markers expressed from constitutive and arbuscular mycorrhiza‐inducible promoters to label organelles,membranes and cytoskeletal elements in Medicago truncatula

Medicago truncatula is widely used for analyses of arbuscular mycorrhizal (AM) symbiosis and nodulation. To complement the genetic and genomic resources that exist for this species, we generated fluorescent protein fusions that label the nucleus, endoplasmic reticulum, Golgi apparatus, trans‐Golgi network, plasma membrane, apoplast, late endosome/multivesicular bodies (MVB), transitory late endosome/ tonoplast, tonoplast, plastids, mitochondria, peroxisomes, autophagosomes, plasmodesmata, actin, microtubules, periarbuscular membrane (PAM) and periarbuscular apoplastic space (PAS) and expressed them from the constitutive AtUBQ10 promoter and the AM symbiosis‐specific MtBCP1 promoter. All marker constructs showed the expected expression patterns and sub‐cellular locations in M. truncatula root cells. As a demonstration of their utility, we used several markers to investigate AM symbiosis where root cells undergo major cellular alterations to accommodate their fungal endosymbiont. We demonstrate that changes in the position and size of the nuclei occur prior to hyphal entry into the cortical cells and do not require DELLA signaling. Changes in the cytoskeleton, tonoplast and plastids also occur in the colonized cells and in contrast to previous studies, we show that stromulated plastids are abundant in cells with developing and mature arbuscules, while lens‐shaped plastids occur in cells with degenerating arbuscules. Arbuscule development and secretion of the PAM creates a periarbuscular apoplastic compartment which has been assumed to be continuous with apoplast of the cell. However, fluorescent markers secreted to the periarbuscular apoplast challenge this assumption. This marker resource will facilitate cell biology studies of AM symbiosis, as well as other aspects of legume biology.     

The book reopened on infectious diseases

Emerging infectious diseases represent a major challenge to human health worldwide. The risk of evolving new infectious pathogens has been intensifying due to urbanization, demographic changes, air travel, inappropriate use of antibiotics, and climate change. These pathogens can affect humans from urban centers to the remotest corners of the globe. Far from being a scourge of the past, infectious diseases are relevant for the world today.     

Cultural transmission of ethnobotanical knowledge in a rural community of northwestern Patagonia, Argentina

In the present study we analyzed medicinal and edible plant utilization in Cuyin Manzano, a small rural population located near the Andean forests of Argentina. We also studied where and when plant knowledge was learned, who the principal transmitters were, and how people were taught. The participants were interviewed individually and at random, by means of a semi-structured questionnaire. Interviews were carried out in 16 families in order to examine the present use of wild plants. The inhabitants of Cuyin Manzano cited 87 plants: 63 medicinal and 24 edible species. They mentioned on average 31 ± 10 species per person. Similar patterns of plant use were found in young and old people alike, irrespective of gender. Learning about useful plants took place at an early age as a result of family tradition. This local knowledge is acquired and taught “by doing,” and is mostly transmitted vertically through family dissemination. Wild plant learning implies the acquisition of plants' physical and functional features as well as their environmental characteristics.