Fundación Instituto Leloir

About: Fundación Instituto Leloir is a facility organization based out in Buenos Aires, Argentina. It is known for research contribution in the topics: Dentate gyrus & Neurogenesis. The organization has 702 authors who have published 1052 publications receiving 39299 citations.

Revisiting the evolutionary history and roles of protein phosphatases with Kelch-like domains in plants

Abstract: Protein phosphatases with Kelch-like domains (PPKL) are members of the phosphoprotein phosphatases family present only in plants and alveolates. PPKL have been described as positive effectors of brassinosteroid (BR) signaling in plants. Most of the evidence supporting this role has been gathered using one of the four homologs in Arabidopsis (Arabidopsis thaliana), BRASSINOSTEROID-INSENSITIVE1 SUPPRESSOR (BSU1). We reappraised the roles of the other three members of the family, BSL1, BSL2, and BSL3, through phylogenetic, functional, and genetic analyses. We show that BSL1 and BSL2/BSL3 belong to two ancient evolutionary clades that have been highly conserved in land plants. In contrast, BSU1-type genes are exclusively found in the Brassicaceae and display a remarkable sequence divergence, even among closely related species. Simultaneous loss of function of the close paralogs BSL2 and BSL3 brings about a peculiar array of phenotypic alterations, but with marginal effects on BR signaling; loss of function of BSL1 is, in turn, phenotypically silent. Still, the products of these three genes account for the bulk of PPKL-related activity in Arabidopsis and together have an essential role in the early stages of development that BSU1 is unable to supplement. Our results underline the functional relevance of BSL phosphatases in plants and suggest that BSL2/BSL3 and BSU1 may have contrasting effects on BR signaling. Given that BSU1-type genes have likely undergone a functional shift and are phylogenetically restricted, we caution that inferences based on these genes to the whole family or to other species may be misleading.

Development of camelid single chain antibodies against Shiga toxin type 2 (Stx2) with therapeutic potential against Hemolytic Uremic Syndrome (HUS)

Abstract: Shiga toxin (Stx)-producing Escherichia coli (STEC) infections are implicated in the development of the life-threatening Hemolytic Uremic Syndrome (HUS). Despite the magnitude of the social and economic problems caused by STEC infections, no licensed vaccine or effective therapy is presently available for human use. Single chain antibodies (VHH) produced by camelids exhibit several advantages in comparison with conventional antibodies, making them promising tools for diagnosis and therapy. In the present work, the properties of a recently developed immunogen, which induces high affinity and protective antibodies against Stx type 2 (Stx2), were exploited to develop VHHs with therapeutic potential against HUS. We identified a family of VHHs against the B subunit of Stx2 (Stx2B) that neutralize Stx2 in vitro at subnanomolar concentrations. One VHH was selected and was engineered into a trivalent molecule (two copies of anti-Stx2B VHH and one anti-seroalbumin VHH). The resulting molecule presented extended in vivo half-life and high therapeutic activity, as demonstrated in three different mouse models of Stx2-toxicity: a single i.v. lethal dose of Stx2, several i.v. incremental doses of Stx2 and intragastrical STEC infection. This simple antitoxin agent should offer new therapeutic options for treating STEC infections to prevent or ameliorate HUS outcome.

Overexpression of SPARC obliterates the in vivo tumorigenicity of human hepatocellular carcinoma cells

Abstract: Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third leading cause of cancer-related death worldwide Current treatments are extremely disappointing SPARC (Secreted protein, acidic and rich in cysteine) is a matricellular glycoprotein with differential expression in several tumors, including HCC, which significance remains unclear We infected HCC cells (HepG2, Hep3B and Huh7) with an adenovirus expressing SPARC (AdsSPARC) to examine the role of SPARC expression on HCC cells and its effect on tumor aggressiveness The in vitro HCC cells substrate-dependent proliferation and cell cycle profile were unaffected; however, SPARC overexpression reduced HCC proliferation when cells were grown in spheroids A mild induction of cellular apoptosis was observed upon SPARC overexpression SPARC overexpression resulted in spheroid growth inhibition in vitro while no effects were found when recombinant SPARC was exogenously applied Moreover, the clonogenic and migratory capabilities were largely decreased in SPARC-overexpressing HCC cells, altogether suggesting a less aggressive HCC cell phenotype Consistently, AdsSPARC-transduced cells showed increased E-cadherin expression and a concomitant decrease in N-cadherin expression Furthermore, SPARC overexpression was found to reduce HCC cell viability in response to 5-FU-based chemotherapy in vitro, partially through induction of apoptosis In vivo experiments revealed that SPARC overexpression in HCC cells inhibited their tumorigenic capacity and increased animal survival through a mechanism that partially involves host macrophages Our data suggest that SPARC overexpression in HCC cells results in a reduced tumorigenicity partially through the induction of mesenchymal-to-epithelial transition (MET) These evidences point to SPARC as a novel target for HCC treatment

N-glycan trimming by glucosidase II is essential for Arabidopsis development

Abstract: Glucosidase II, one of the early N-glycan processing enzymes and a major player in the glycoprotein folding quality control, has been described as a soluble heterodimer composed of α and β subunits. Here we present the first characterization of a plant glucosidase II α subunit at the molecular level. Expression of the Arabidopsis α subunit restored N-glycan maturation capacity in Schizosaccharomyces pombe α− or αβ−deficient mutants, but with a lower efficiency in the last case. Inactivation of the α subunit in a temperature sensitive Arabidopsis mutant blocked N-glycan processing after a first trimming by glucosidase I and strongly affected seedling development.