抄録
In our previous study we cloned from renal IMCD (inner medullary collecting duct) cells, a novel molecular chaperone gene, Osp94 (osmotic stress protein 94kD), whose expression is up-regulated by hypertonic stress. Our recent studies have reported that Osp94 knock-down induces neuronal cells death, accompanied by accumulation of ubiquitinated proteins. Therefore, to clarify a biological role of Osp94 in neuronal cells, we investigated changes in a velocity of microtubule transport of lysosome and tau alternative splicing variants synthesis. The velocity of microtubule transport of lysosome in Osp94-siRNA treated Neuro2a cells were monitored under a confocal microscope and its transport velocity was image analyzed. Moreover, the effect of Osp94-siRNA on the synthesis of tau alternative splicing variants, 4R- and 3R-tau, was analyzed by Real-time PCR and Western blotting. Treatment with Osp94-siRNA for 48 h resulted in a decrease in the microtubule transport velocity of lysosome. Real-time PCR and Western blotting revealed that 3R-tau mRNA and protein were down-regulated at 48 h after Osp94-siRNA treatment. At 72 h after Osp94-siRNA exposure, 3R-tau protein level was markedly decreased, accompanied by a significant accumulation of ubiquitinated proteins. No obvious changes in 4R-tau mRNA and protein levels were observed. These results suggest that Osp94 may play a role in the microtubule transport function through a regulation of synthesis of tau alternative splicing variants.
