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

Trabeculectomy with MMC was less effective in maintaining intraocular pressure reduction in UG eyes than in POAG eyes. The prognostic factors for surgical failure of trabeculectomy in UG eyes were previous cataract surgery and granulomatous uveitis. In addition, UG eyes after trabeculectomy more frequently required additional cataract surgery.

Neurons in the adult mammalian CNS decrease in intrinsic axon growth capacity during development in concert with changes in Krüppel-like transcription factors (KLFs). KLFs regulate axon growth in CNS neurons including retinal ganglion cells (RGCs). Here, we found that knock-down of KLF9, an axon growth suppressor that is normally upregulated 250-fold in RGC development, promotes long-distance optic nerve regeneration in adult rats of both sexes. We identified a novel binding partner, MAPK10/JNK3 kinase, and found that JNK3 (c-Jun N-terminal kinase 3) is critical for KLF9's axon-growth-suppressive activity. Interfering with a JNK3-binding domain or mutating two newly discovered serine phosphorylation acceptor sites, Ser106 and Ser110, effectively abolished KLF9's neurite growth suppression and promoted axon regeneration These findings demonstrate a novel, physiologic role for the interaction of KLF9 and JNK3 in regenerative failure in the optic nerve and suggest new therapeutic strategies to promote axon regeneration in the adult CNS. Injured CNS nerves fail to regenerate spontaneously. Promoting intrinsic axon growth capacity has been a major challenge in the field. Here, we demonstrate that knocking down Krüppel-like transcription factor 9 (KLF9) via shRNA promotes long-distance axon regeneration after optic nerve injury and uncover a novel and important KLF9-JNK3 interaction that contributes to axon growth suppression and regenerative failure These studies suggest potential therapeutic approaches to promote axon regeneration in injury and other degenerative diseases in the adult CNS.