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Kenichi Morikawa, Akihisa Nakamura, Tomoe Shimazaki, Naoya Sakamoto Department of Gastroenterology and Hepatology, Hokkaido University Faculty of Medicine and Graduate School of Medicine, Sapporo, Japan Abstract: Treatments for hepatitis C virus (HCV) have advanced greatly, becoming more efficacious with fewer adverse events, due to the availability of direct-acting antiviral agents, which target specific steps in the HCV life cycle. Recently, a combination regimen consisting of the HCV nonstructural protein 5A inhibitor elbasvir (EBR) and the HCV NS3/4A protease inhibitor grazoprevir (GZR) was approved for the treatment of patients with chronic HCV and genotypes (Gts) 1 and 4 in various countries. In Phase III trials, the combination of EBR/GZR (fixed-dose combination table or single agent) for 12 or 16 weeks of treatment with or without ribavirin resulted in a high sustained virological response at 12 weeks in treatment-naïve and treatment-experienced patients with HCV Gt 1a, 1b, 4, or 6, including special populations, such as individuals with advanced chronic kidney disease, HCV-HIV coinfection, and compensated cirrhosis. In this review, we focus on the mode of action, pharmacokinetics, clinical applications, efficacy, and safety profile of EBR/GZR, including special populations who have been considered refractory from the extensive evidence of clinical trials. Keywords: HCV, DAAs, compensated LC, HCV/HIV

Mammalian corticogenesis occurs through a complex process that includes neurogenesis, in which neural progenitor cells proliferate, differentiate, and migrate. It has been reported recently that neurogenesis occurs in the subventricular zone (SVZ), a region previously thought to be the primary site of gliogenesis. It has been recognized that in the SVZ, intermediate progenitor cells, derived from radial glial cells that are multipotent neural stem cells, produce only neurons. However, the molecular mechanisms underlying the regulation of neural stem cells and intermediate progenitor cells as well as their contribution to overall corticogenesis remain unknown. The docking protein FRS2[alpha] is a major mediator of signaling by means of FGFs and neurotrophins. FRS2[alpha] mediates many of its pleiotropic cellular responses by recruiting the adaptor protein Grb2 and the protein tyrosine phosphatase Shp2 upon ligand stimulation. Here, we report that targeted disruption of Shp2-binding sites in FRS2[alpha] leads to severe impairment in cerebral cortex development in mutant mice. The defect in corticogenesis appears to be due at least in part to abnormalities in intermediate progenitor cells. Genetic evidence is provided that FRS2[alpha] plays critical roles in the maintenance of intermediate progenitor cells and in neurogenesis in the cerebral cortex. Moreover, FGF2-responsive neurospheres, which are cell aggregates derived from neural stem/progenitor cells (NSPCs), from FRS2[alpha] mutant mice were smaller than those of WT mice. However, mutant NSPCs were able to self-renew, demonstrating that Shp2-binding sites on FRS2[alpha] play an important role in NSPC proliferation but are dispensable for NSPC self-renewing capacity after FGF2 stimulation. cell signaling | docking proteins | neuronal development | stem cells | tyrosine phosphorylation