Shigeki Kato

The lentiviral vector system based on human immunodeficiency virus type 1 (HIV-1) is used extensively in gene therapy trials of neurological and neurodegenerative diseases. Retrograde axonal transport of viral vectors offers a great advantage to the delivery of genes into neuronal cell bodies that are situated in regions distant from the injection site. Pseudotyping of HIV-1-based vectors with selective variants of rabies virus glycoprotein (RV-G) increases gene transfer via retrograde transport into the central nervous system. Because large-scale application for gene therapy trials requires high titer stocks of the vector, pseudotyping of a lentiviral vector that produces more efficient retrograde transport is needed. In the present study, we developed a novel vector system for highly efficient retrograde gene transfer by pseudotyping an HIV-1 vector with a fusion envelope glycoprotein (termed FuG-B) in which the cytoplasmic domain of RV-G was substituted by the corresponding part of vesicular stomatitis virus glycoprotein. The FuG-B pseudotype shifted the transducing property of the lentiviral vector and enhanced the retrograde transport-mediated gene transfer into different brain regions innervating the striatum with greater efficiency than that of the RV-G pseudotype in mice. In addition, injection of the FuG-B-pseudotyped vector into monkey striatum (caudate and putamen) allowed for highly efficient gene delivery into the nigrostriatal dopamine system, which is a major target for gene therapy of Parkinson's disease. Our strategy provides a powerful tool for the treatment of certain neurological and neurodegenerative diseases by promoting retrograde gene delivery via a lentiviral vector.

Mutations in methyl-CpG-binding protein 2 (MeCP2) cause Rett syndrome and related autism spectrum disorders (Amir et al., 1999). MeCP2 is believed to be required for proper regulation of brain gene expression, but prior microarray studies in Mecp2 knock-out mice using brain tissue homogenates have revealed only subtle changes in gene expression (Tudor et al., 2002; Nuber et al., 2005; Jordan et al., 2007; Chahrour et al., 2008). Here, by profiling discrete subtypes of neurons we uncovered more dramatic effects of MeCP2 on gene expression, overcoming the "dilution problem" associated with assaying homogenates of complex tissues. The results reveal misregulation of genes involved in neuronal connectivity and communication. Importantly, genes upregulated following loss of MeCP2 are biased toward longer genes but this is not true for downregulated genes, suggesting MeCP2 may selectively repress long genes. Because genes involved in neuronal connectivity and communication, such as cell adhesion and cell-cell signaling genes, are enriched among longer genes, their misregulation following loss of MeCP2 suggests a possible etiology for altered circuit function in Rett syndrome.