The suppression of testis-brain RNA binding protein and kinesin heavy chain disrupts mRNA sorting in dendrites.

Ribonucleoprotein particles (RNPs) are thought to be key players in somato-dendritic sorting of mRNAs in CNS neurons and are implicated in activity-directed neuronal remodeling. Here, we use reporter constructs and gel mobility shift assays to show that the testis brain RNA-binding protein (TB-RBP) associates with mRNPs in a sequence (Y element) dependent manner. Using antisense oligonucleotides (anti-ODN), we demonstrate that blocking the TB-RBP Y element binding site disrupts and mis-localizes mRNPs containing (alpha)-calmodulin dependent kinase II (alpha)-CAMKII) and ligatin mRNAs. In addition, we show that suppression of kinesin heavy chain motor protein alters only the localization of (alpha)-CAMKII mRNA. Thus, differential sorting of mRNAs involves multiple mRNPs and selective motor proteins permitting localized mRNAs to utilize common mechanisms for shared steps.