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The endosomal sorting complex required for transport (ESCRT) machinery is composed of an articulated architecture of proteins that assemble at multiple cellular sites. The ESCRT machinery is involved in pathways that are pivotal for the physiology of the cell, including vesicle transport, cell division, and membrane repair. The subunits of the ESCRT I complex are mainly responsible for anchoring the machinery to the action site. The ESCRT II subunits function to bridge and recruit the ESCRT III subunits. The latter are responsible for finalizing operations that, independently of the action site, involve the repair and fusion of membrane edges. In this review, we report on the data related to the activity of the ESCRT machinery at two sites: the nuclear membrane and the midbody and the bridge linking cells in the final stages of cytokinesis. In these contexts, the machinery plays a significant role for the protection of genome integrity by contributing to the control of the abscission checkpoint and to nuclear envelope reorganization and correlated resilience. Consistently, several studies show how the dysfunction of the ESCRT machinery causes genome damage and is a codriver of pathologies, such as laminopathies and cancer. [ABSTRACT FROM AUTHOR]

The Gsα/cAMP signaling pathway mediates the effect of a variety of hormones and factors that regulate the homeostasis of the post-natal skeleton. Hence, the dysregulated activity of Gsα due to gain-of-function mutations (R201C/R201H) results in severe architectural and functional derangements of the entire bone/bone marrow organ. While the consequences of gain-of-function mutations of Gsα have been extensively investigated in osteoblasts and in bone marrow osteoprogenitor cells at various differentiation stages, their effect in adipogenically-committed bone marrow stromal cells has remained unaddressed. We generated a mouse model with expression of GsαR201C driven by the Adiponectin (Adq) promoter. Adq-GsαR201C mice developed a complex combination of metaphyseal, diaphyseal and cortical bone changes. In the metaphysis, GsαR201C caused an early phase of bone resorption followed by bone deposition. Metaphyseal bone formation was sustained by cells that were traced by Adq-Cre and eventually resulted in a high trabecular bone mass phenotype. In the diaphysis, GsαR201C, in combination with estrogen, triggered the osteogenic activity of Adq-Cre-targeted perivascular bone marrow stromal cells leading to intramedullary bone formation. Finally, consistent with the previously unnoticed presence of Adq-Cre-marked pericytes in intraosseous blood vessels, GsαR201C caused the development of a lytic phenotype that affected both cortical (increased porosity) and trabecular (tunneling resorption) bone. These results provide the first evidence that the Adq-cell network in the skeleton not only regulates bone resorption but also contributes to bone formation, and that the Gsα/cAMP pathway is a major modulator of both functions. [ABSTRACT FROM AUTHOR]

Byline: Stefania Piersanti (1), Gioia Cherubini (1), Yuri Martina (1), Barbara Salone (1), Daniele Avitabile (1), Fabiana Grosso (2), Enrico Cundari (3), Giovanni Zenzo (2), Isabella Saggio (1,3) Keywords: Bacteriophage; Adenovirus; Gene therapy; Endosomal escape Abstract: In recent years a strong effort has been devoted to the search for new, safe and efficient gene therapy vectors. Phage [lambda] is a promising backbone for the development of new vectors: its genome can host large inserts, DNA is protected from degradation by the capsid and the ligand-exposed D and V proteins can be extensively modified. Current phage-based vectors are inefficient and/or receptor-independent transducers. To produce new, receptor-selective and transduction-efficient vectors for mammalian cells we engineered [lambda] by inserting into its genome a GFP expression cassette, and by displaying the penton base (Pb) of adenovirus or its central region (amino acids 286--393). The Pb mediates attachment, entry and endosomal escape of adenovirus in mammalian cells, and its central region (amino acids 286--393) includes the principal receptor-binding motif [(.sup.340]RGD.sup.342). Both the phage chimerae [lambda] Pb and [lambda] Pb (286--393) were able to transduce cell lines and primary cultures of human fibroblasts. Competition experiments showed that the transduction pathway was receptor-dependent. We also describe the different trafficking properties of [lambda] Pb and [lambda] Pb (286--393). Bafilomycin, which blocks endosome maturation, influenced the intracellular distribution of [lambda] Pb (286--393), but not that of [lambda] Pb. The proteasome inhibitor MG-132 improved the efficiency of [lambda] Pb (286--393)-mediated transduction, but not that of [lambda] Pb. In summary, this work shows the feasibility of using [lambda] phage as an efficient vector for gene transfer into mammalian cells. We show that [lambda] Pb and [lambda] Pb (286--393) can both mediate receptor-dependent transduction while only [lambda] Pb is able to promote endosomal escape and proteasome resistance of phage particles. Author Affiliation: (1) Department of Genetics and Molecular Biology, University La Sapienza and Parco Scientifico Biomedico di Roma, S. Raffaele, Rome, Italy (2) Laboratory of Molecular and Cell Biology, IDI-IRCCS, Rome, Italy (3) Institute of Cell Biology and Pathology, CNR, Rome, Italy Article History: Registration Date: 19/03/2004 Received Date: 04/12/2003 Accepted Date: 08/03/2004 Online Date: 19/05/2004