Recombinant adeno-associated virus (rAAV)-mediated gene transfer is an attractive approach to the treatment of Duchenne muscular dystrophy (DMD). We investigated the muscle transduction profiles and immune responses associated with the administration of rAAV2 and rAAV8 in normal and canine X-linked muscular dystrophy in Japan (CXMD(J)) dogs. rAAV2 or rAAV8 encoding the lacZ gene was injected into the skeletal muscles of normal dogs. Two weeks after the injection, we detected a larger number of beta-galactosidase-positive fibers in rAAV8-transduced canine skeletal muscle than in rAAV2-transduced muscle. Although immunohistochemical analysis using anti-CD4 and anti-CD8 antibodies revealed less T-cell response to rAAV8 than to rAAV2, beta-galactosidase expression in rAAV8-injected muscle lasted for <4 weeks with intramuscular transduction. Canine bone marrow-derived dendritic cells (DCs) were activated by both rAAV2 and rAAV8, implying that innate immunity might be involved in both cases. Intravenous administration of rAAV8-lacZ into the hind limb in normal dogs and rAAV8-microdystrophin into the hind limb in CXMD(J) dogs resulted in improved transgene expression in the skeletal muscles lasting over a period of 8 weeks, but with a declining trend. The limb perfusion transduction protocol with adequate immune modulation would further enhance the rAAV8-mediated transduction strategy and lead to therapeutic benefits in DMD gene therapy.

Heart failure (HF) is a common and potentially deadly condition, which frequently develops as a consequence of various diseases of the heart. The incidence of heart failure continuously increases in aging societies illustrating the need for new therapeutic approaches. We recently discovered that continuous activation of oncostatin M (OSM), a cytokine of the interleukin-6 family that induces dedifferentiation of cardiomyocytes, promotes progression of heart failure in dilative cardiomyopathy. To evaluate whether inhibition of OSM signaling represents a meaningful therapeutic approach to prevent heart failure we attenuated OSM-receptor (Oβ) signaling in a mouse model of inflammatory dilative cardiomyopathy. We found that administration of an antibody directed against the extracellular domain of Oβ or genetic inactivation of a single allele of the Oβ gene reduced cardiomyocyte remodeling and dedifferentiation resulting in improved cardiac performance and increased survival. We conclude that pharmacological attenuation of long-lasting Oβ signaling is a promising strategy to treat different types and stages of HF that go along with infiltration by OSM-releasing inflammatory cells.

Rho GTPases control fundamental cellular processes and Cdc42 is a well-studied member of the family that controls filopodia formation and cell migration. Although the regulation of Cdc42 activity by nucleotide binding is well documented, the mechanisms driving its proteostasis are not clear. Here, we demonstrate that the highly conserved, RING domain containing E3 ubiquitin ligase XIAP controls the protein stability of Cdc42. XIAP binds to Cdc42 and directly conjugates poly ubiquitin chains to the Lysine 166 of Cdc42 targeting it for proteasomal degradation. Depletion of XIAP led to an increased protein stability and activity of Cdc42 in normal and tumor cells. Consistently, loss of XIAP enhances filopodia formation in a Cdc42-dependent manner and this phenomenon phenocopies EGF stimulation. Further, XIAP depletion promotes lung colonization of tumor cells in mice in a Cdc42-dependent manner. These observations shed molecular insights into ubiquitin-dependent regulation of Cdc42 and that of actin cytoskeleton.

Background/Aims: Cell adhesion molecules play a critical role in the invasion and metastasis of a variety of human tumors. Abnormal expression of VCAM-1 has been demonstrated to correlate with the malignant progression of gastric tumors, but the molecular mechanism underlying the VCAM-1-dependent metastasis has been rarely investigated. To explore the role for tumor cell-expressing adhesion molecules in the carcinoma-endothelium adhesion, we analyzed expression status of adhesion molecules in gastric cancer cells and its association with tumor cell capability of endothelial adhesion. Methods: Endothelial adhesion ability of gastric tumor cells was tested using calcein AM staining assay. Expression of cell surface proteins was determined by Western blot, flow cytometry, and immunofluorescence assays. RNAi-mediated knockdown of gene expression and neutralization with specific antibodies were utilized for functional analysis. Results: One of three cell lines tested was identified to be adhesive to endothelial cells and express VCAM-1. Adherence ability of the cells was dramatically decreased by neutralization of surface VCAM-1. VCAM-1 was co-localized with Caveolin-1 and siRNA-mediated knockdown of Caveolin-1 expression significantly blocked the VCAM-1-dependent cell adhesion. Conclusions: Our data imply important roles for VCAM-1 and Caveolin- 1 in the regulation of metastatic potential of gastric tumor cells.