Abstract
Local protein synthesis in axons has been proposed to participate in the basal level growth, navigation and synaptogensis of axons. A large population of mRNA has been identified in the axons of different neurons. These mRNAs are believed to travel to the axon after being packed in ribonucleoprotein granules. The protein and microRNA components of these granules participate in not only the transport of mRNA, but they also regulate the splicing and editing of precursor mRNA and the translation of mRNA. Here, we culture rat cortical neurons of embryonic day 18 (E18) on a micropattern-coated glass chip, on which pure axons are guided to grow in designated areas. By means of fluorescence immunocytochemistry, hnRNP (heterogeneous nuclear ribonucleoprotein)-Q is found in axons. Upon treatments with brain-derived neurotrophic factorn (BDNF), hnRNP-Q expression level in axons increases. However, such increase in axons does not occur in axons which have been severed from their cell bodies. This finding indicates the trafficking of hnRNP-Q from somatodendrites to the axon after BDNF treatment. I have also isolated the proteins associated with hnRNP-Q from the lysates of cultured rat cortical neurons which have or have not been treated with BDNF by using immunoprecipitation. The co-immunoprecipitated proteins are first separated by gel-electrophoresis, subjected to in-gel digestion and finally identified by mass spectrometry. The results will shed lights to understanding the mechanism(s) underlying the transport of mRNAs in neurons when subjected to various stimulations.