The proliferation and differentiation of neural precursor cells are mutually exclusive during brain development. Despite its importance for precursor cell self renewal, the molecular linkage between these two events has remained unclear. Fibroblast growth factor 2 (FGF2) promotes neural precursor cell proliferation and concurrently inhibits their differentiation, suggesting a cross talk between proliferation and differentiation signaling pathways downstream of the FGF receptor. We demonstrate that FGF2 signaling through phosphatidylinositol 3 kinase activation inactivates glycogen synthase kinase 3␤ (GSK3␤) and leads to the accumulation of ␤-catenin in a manner different from that in the Wnt canonical pathway. The nuclear accumulated ␤-catenin leads to cell proliferation by activating LEF/TCF transcription factors and concurrently inhibits neuronal differentiation by potentiating the Notch1-RBP-J signaling pathway. ␤-Catenin and the Notch1 intracellular domain form a molecular complex with the promoter region of the antineurogenic hes1 gene, allowing its expression. This signaling interplay is especially essential for neural stem cell maintenance, since the misexpression of dominant-active GSK3␤ completely inhibits the self renewal of neurosphere-forming stem cells and prompts their neuronal differentiation. Thus, the GSK3␤/␤-catenin signaling axis regulated by FGF and Wnt signals plays a pivotal role in the maintenance of neural stem/precursor cells by linking the cell proliferation to the inhibition of differentiation.

No abstract

The lack of intravital imaging of axonal transport of mitochondria in the mammalian CNS precludes characterization of the dynamics of axonal transport of mitochondria in the diseased and aged mammalian CNS. Glaucoma, the most common neurodegenerative eye disease, is characterized by axon degeneration and the death of retinal ganglion cells (RGCs) and by an age-related increase in incidence. RGC death is hypothesized to result from disturbances in axonal transport and in mitochondrial function. Here we report minimally invasive intravital multiphoton imaging of anesthetized mouse RGCs through the sclera that provides sequential timelapse images of mitochondria transported in a single axon with submicrometer resolution. Unlike findings from explants, we show that the axonal transport of mitochondria is highly dynamic in the mammalian CNS in vivo under physiological conditions. Furthermore, in the early stage of glaucoma modeled in adult (4-mo-old) mice, the number of transported mitochondria decreases before RGC death, although transport does not shorten. However, with increasing age up to 23-25 mo, mitochondrial transport (duration, distance, and duty cycle) shortens. In axons, mitochondria-free regions increase and lengths of transported mitochondria decrease with aging, although totally organized transport patterns are preserved in old (23-to 25-mo-old) mice. Moreover, axonal transport of mitochondria is more vulnerable to glaucomatous insults in old mice than in adult mice. These mitochondrial changes with aging may underlie the age-related increase in glaucoma incidence. Our method is useful for characterizing the dynamics of axonal transport of mitochondria and may be applied to other submicrometer structures in the diseased and aged mammalian CNS in vivo.mammalian CNS | in vivo imaging | mitochondrial axonal transport | neurodegeneration | aging

No abstract

ABSTRACT.Purpose: To investigate the intra-ocular pressure (IOP)-lowering effects and safety of 0.4% ripasudil (K-115), a Rho kinase inhibitor, twice daily for 52 weeks, in patients with open-angle glaucoma or ocular hypertension (OHT). Methods: In this multicentre, prospective, open-label study, 388 patients with primary open-angle glaucoma, OHT or exfoliation glaucoma were enrolled and 354 of them were subdivided into four cohorts (monotherapy, 173; additive therapy to prostaglandin analogs, 62; b-blockers, 60; or fixed combination drugs, 59). The IOP reduction at trough and peak from baseline and adverse events was investigated. Results: Ripasudil showed IOP-lowering effects over 52 weeks in all the analyses of monotherapy, additive therapy and both subgroups (baseline IOP ≥21 mmHg and <21 mmHg) of monotherapy. The mean IOP reductions at trough and peak at week 52 were À2.6 and À3.7 mmHg for monotherapy, and À1.4 and À2.4, À2.2 and À3.0, and À1.7 and À1.7 mmHg, respectively, for additive therapy described above. The most frequently observed adverse events were conjunctival hyperaemia (n = 264, 74.6%), blepharitis (n = 73, 20.6%) and allergic conjunctivitis (n = 61, 17.2%). Most of the conjunctival hyperaemia findings were mild (97.0%), transient and resolved spontaneously (78.0%). Although 51 patients discontinued from the study due to blepharitis and/or allergic conjunctivitis (blepharitis, 28; allergic conjunctivitis, 17; both, 6), all the events resolved with or without treatment after the discontinuation of ripasudil administration. Conclusion: Fifty-two week administration of 0.4% ripasudil revealed IOPlowering effects and an acceptable safety profile when administered as monotherapy or as additive therapy, in patients with open-angle glaucoma or OHT.