Abstract
Receptor-triggered control of local postsynaptic protein synthesis plays a crucial role for enabling long lasting changes in synaptic functions, but signaling pathways that link receptor stimulation with translational control remain poorly known. Among the putative regulatory factors are mRNA-binding proteins (messenger ribonucleoprotein, mRNP), which control the fate of cytosolic localized mRNAs. Based on the assumption that a subset of mRNA is maintained in an inactive state, mRNP-mRNA complexes were separated into polysome-bound (translated) and polysome-free (nontranslated) fractions by sucrose density centrifugation. Poly(A) mRNA-mRNP complexes were purified from a postmitochondrial extract of rat cerebral cortex by oligo(dT)-cellulose affinity chromatography. The mRNA processing proteins were characterized, from solution, by a nanoflow reverse phase-high pressure liquid chromatography-mu-electrospray ionization mass spectrometry. The majority of detected mRNA-binding proteins was found in both fractions. However, a small number of proteins appeared to be fraction-specific. This subset of proteins is by far the most interesting because the proteins are potentially involved in controlling an activity-dependent onset of translation. They include transducer proteins, kinases, and anchor proteins. This study of the mRNP proteome is the first step in allowing future experimentation to characterize individual proteins responsible for mRNA processing and translation in dendrites.
Highlights
Receptor-triggered control of local postsynaptic protein synthesis plays a crucial role for enabling long lasting changes in synaptic functions, but signaling pathways that link receptor stimulation with translational control remain poorly known
Specific mRNA-binding proteins that bind preferentially to either nontranslated or translated poly(A) mRNAs have not been well characterized in neurons. To search for such putative neuronal poly(A) mRNA masking proteins and proteins involved in mechanisms of receptor-stimulated protein translation, we separated and enriched messenger ribonucleoproteins (mRNPs) complexes associated with nontranslated poly(A) mRNAs and those associated with translated poly(A) mRNAs, and we determined the composition of co-purified proteins by mass spectrometry
To search for candidates that are involved in such a process of masking/unmasking and in receptor-triggered control of translation, we have begun to characterize the protein composition of mRNP complexes associated with nontranslated poly(A) mRNAs and associated with translated poly(A) mRNAs in rat cortical tissue
Summary
Receptor-triggered control of local postsynaptic protein synthesis plays a crucial role for enabling long lasting changes in synaptic functions, but signaling pathways that link receptor stimulation with translational control remain poorly known. A small number of proteins appeared to be fraction-specific This subset of proteins is by far the most interesting because the proteins are potentially involved in controlling an activity-dependent onset of translation. Specific mRNA-binding proteins that bind preferentially to either nontranslated or translated poly(A) mRNAs have not been well characterized in neurons To search for such putative neuronal poly(A) mRNA masking proteins and proteins involved in mechanisms of receptor-stimulated protein translation, we separated and enriched mRNP complexes associated with nontranslated poly(A) mRNAs and those associated with translated poly(A) mRNAs, and we determined the composition of co-purified proteins by mass spectrometry. Proteins such as FMRP, regulator of nonsense transcript 1, protein similar to protein C9orf, BC010304, protein similar to ubiquitin C-terminal hydrolase-related polypeptide, protein similar to RNA helicase A, and RACK1, which were identified as part of the translated mRNA-mRNP complexes, are potentially involved in processes of translational control
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call