A single tryptophan residue of endomannosidase is crucial for Golgi localization and <Emphasis Type="Italic">in vivo</Emphasis> activity

Golgi-endomannosidase provides an alternate glucosidase-independent pathway of glucose trimming. Activity for endomannosidase is detectable in various tissues and cell lines but not in CHO cells. Cloning of CHO cell endomannosidase revealed that the highly conserved Trp188 and Arg177 of vertebrate endomannosidase were both substituted by Cys. The Trp188Cys substitution was functionally important since it alone resulted in endoplasmic reticulum (ER) mislocalization of endomannosidase and caused the greatly reduced in vivo activity. These effects could be reversed in cells with a back-engineered Cys188Trp CHO cell endomannosidase, in particular N-glycans of α1-antitrypsin became fully processed. The intramolecular disulfide bridge of CHO cell endomannosidase formed with the additional Cys188 was not solely responsible for the reduced enzyme activity since endomannosidase with engineered Cys188Ala or Ser substitutions did not restore enzyme activity and was ER mislocalized. Thus, the conserved Trp188 residue in endomannosidases is of critical importance for correct subcellular localization and in vivo activity of the enzyme. Received 7 May 2007; received after revision 31 May 2007; accepted 11 June 2007     

The many faces of semaphorins: from development to pathology

The semaphorin family is a large group of proteins controlling cell migration and axonal growth cone guidance. These proteins are bi-functional signals capable of growth promotion or growth inhibition. Initially described in the nervous system, the majority of studies related to semaphorins and semaphorin signalling are nowadays performed in model systems outside the nervous system. Here, we provide an exhaustive review of the many faces of semaphorins both during developmental, regulatory and pathological processes. Indeed, because of their crucial fundamental roles, the semaphorins and their receptors represent important targets for the development of drugs directed at a variety of diseases. Received 22 August 2008; received after revision 22 September 2008; accepted 24 September 2008 L. Roth, E. Koncina, S. Satkauskas: These authors contributed equally to this work.     

Institutionalizing Insider Action Research Initiatives in Organizations: The Role of Learning Mechanisms

Managers face increasing pressure to find ways to surface, utilize and integrate bits and pieces of relevant knowledge that reside within and outside the organizational boundaries to address emerging challenges. Grappling with this issue and based on a longitudinal study with a biopharma company, this paper offers the notion that insider action research coupled with the design and management of learning mechanism tapestry can enhance continuous organizational learning and improvement. The institutionalization of the learning mechanism tapestry provided new capability that enhanced the organization’s agility as well as a way to stabilize insider action research role and practices.     

The RAG2 C terminus suppresses genomic instability and lymphomagenesis

Misrepair of DNA double-strand breaks produced by the V(D)J recombinase (the RAG1/RAG2 proteins) at immunoglobulin (Ig) and T cell receptor (Tcr) loci has been implicated in pathogenesis of lymphoid malignancies in humans and in mice. Defects in DNA damage response factors such as ataxia telangiectasia mutated (ATM) protein and combined deficiencies in classical non-homologous end joining and p53 predispose to RAG-initiated genomic rearrangements and lymphomagenesis. Although we showed previously that RAG1/RAG2 shepherd the broken DNA ends to classical non-homologous end joining for proper repair, roles for the RAG proteins in preserving genomic stability remain poorly defined. Here we show that the RAG2 carboxy (C) terminus, although dispensable for recombination, is critical for maintaining genomic stability. Thymocytes from 'core' Rag2 homozygotes (Rag2(c/c) mice) show dramatic disruption of Tcrα/δ locus integrity. Furthermore, all Rag2(c/c) p53(-/-) mice, unlike Rag1(c/c) p53(-/-) and p53(-/-) animals, rapidly develop thymic lymphomas bearing complex chromosomal translocations, amplifications and deletions involving the Tcrα/δ and Igh loci. We also find these features in lymphomas from Atm(-/-) mice. We show that, like ATM-deficiency, core RAG2 severely destabilizes the RAG post-cleavage complex. These results reveal a novel genome guardian role for RAG2 and suggest that similar 'end release/end persistence' mechanisms underlie genomic instability and lymphomagenesis in Rag2(c/c) p53(-/-) and Atm(-/-) mice.     

Image-based genome-wide siRNA screen identifies selective autophagy factors

Selective autophagy involves the recognition and targeting of specific cargo, such as damaged organelles, misfolded proteins, or invading pathogens for lysosomal destruction. Yeast genetic screens have identified proteins required for different forms of selective autophagy, including cytoplasm-to-vacuole targeting, pexophagy and mitophagy, and mammalian genetic screens have identified proteins required for autophagy regulation. However, there have been no systematic approaches to identify molecular determinants of selective autophagy in mammalian cells. Here, to identify mammalian genes required for selective autophagy, we performed a high-content, image-based, genome-wide small interfering RNA screen to detect genes required for the colocalization of Sindbis virus capsid protein with autophagolysosomes. We identified 141 candidate genes required for viral autophagy, which were enriched for cellular pathways related to messenger RNA processing, interferon signalling, vesicle trafficking, cytoskeletal motor function and metabolism. Ninety-six of these genes were also required for Parkin-mediated mitophagy, indicating that common molecular determinants may be involved in autophagic targeting of viral nucleocapsids and autophagic targeting of damaged mitochondria. Murine embryonic fibroblasts lacking one of these gene products, the C2-domain containing protein, SMURF1, are deficient in the autophagosomal targeting of Sindbis and herpes simplex viruses and in the clearance of damaged mitochondria. Moreover, SMURF1-deficient mice accumulate damaged mitochondria in the heart, brain and liver. Thus, our study identifies candidate determinants of selective autophagy, and defines SMURF1 as a newly recognized mediator of both viral autophagy and mitophagy.     

Enniatin,ein neues,gegen Mykobakterien wirksames Antibiotikum

Summary From the mycelium ofFusarium orthoceras App. et Wr. var.enniatinum n. v. we have isolated in crystalline form a new antibiotic substance called Enniatin. The chemical and biological characteristics of this substance are described. Enniatin is especially activein vitro against several mycobacteria.

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Ausgeführt mit einem Beitrag aus den Arbeitsbeschaffungskrediten des Eidg. Militärdepartements.