RESUMO
Glaucoma is the main cause of irreversible blindness worldwide. This disease is characterized by apoptosis of retinal ganglion cells (RGC) and visual field loss that seems to be related to elevated intraocular pressure (IOP). Several lines of evidences have implicated the crucial role of mitochondrial dysfunction in the pathogenesis of glaucoma. Increased mitochondrial oxidative stress in RGC may underlie or contribute to susceptibility of RGC to apoptosis. In our work we (i) designed a rabbit model of chronic, moderately elevated IOP for studying glaucoma and (ii) demonstrated efficacy of mitochondria-targeted antioxidant SkQ1 as a tool to reverse several traits of experimental glaucoma induced by a series of injections of hydroxypropylmethylcellulose (HPMC) to the anterior chamber of the rabbit eye. It is shown that 6 months instillations of drops of 0.2.5-5 microM solution of SkQ1 normalize IOP and eye hydrodynamics and abolish an increase in lens thickness that accompanies glaucoma.
Assuntos
Antioxidantes/farmacologia , Glaucoma/tratamento farmacológico , Mitocôndrias/efeitos dos fármacos , Plastoquinona/análogos & derivados , Animais , Antioxidantes/uso terapêutico , Modelos Animais de Doenças , Glaucoma/fisiopatologia , Pressão Intraocular/efeitos dos fármacos , Masculino , Plastoquinona/farmacologia , Plastoquinona/uso terapêutico , CoelhosRESUMO
Recoverin is a Ca(2+)-regulated signal transduction modulator expressed in the vertebrate retina that has been implicated in visual adaptation. An intriguing feature of recoverin is a cluster of charged residues at its C terminus, the functional significance of which is largely unclear. To elucidate the impact of this segment on recoverin structure and function, we have investigated a mutant lacking the C-terminal 12 amino acids. Whereas in myristoylated recoverin the truncation causes an overall decrease in Ca(2+) sensitivity, results for the non-myristoylated mutant indicate that the truncation primarily affects the high affinity EF-hand 3. The three-dimensional structure of the mutant has been determined by x-ray crystallography. In addition to significant changes in average coordinates compared with wild-type recoverin, the structure provides strong indication of increased conformational flexibility, particularly in the C-terminal domain. Based on these observations, we propose a novel role of the C-terminal segment of recoverin as an internal modulator of Ca(2+) sensitivity.
