Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5507785 | Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms | 2017 | 35 Pages |
Abstract
The differential expression of mRNAs containing tandem alternative 3â² UTRs, achieved by mechanisms of alternative polyadenylation and post-transcriptional regulation, has been correlated with a variety of cellular states. In differentiated cells and brain tissues there is a general use of distal polyadenylation signals, originating mRNAs with longer 3â² UTRs, in contrast with proliferating cells and other tissues such as testis, where most mRNAs contain shorter 3â² UTRs. Although cell type and state are relevant in many biological processes, how these mechanisms occur in specific brain cell types is still poorly understood. Rac1 is a member of the Rho family of small GTPases with essential roles in multiple cellular processes, including cell differentiation and axonal growth. Here we used different brain cell types and tissues, including oligodendrocytes, microglia, astrocytes, cortical and hippocampal neurons, and optical nerve, to show that classical Rho GTPases express mRNAs with alternative 3â² UTRs differently, by gene- and cell- specific mechanisms. In particular, we show that Rac1 originate mRNA isoforms with longer 3â² UTRs specifically during neurite growth of cortical, but not hippocampal neurons. Furthermore, we demonstrate that the longest Rac1 3â² UTR is necessary for driving the mRNA to the neurites, and also for neurite outgrowth in cortical neurons. Our results indicate that the expression of Rac1 longer 3â² UTR is a gene and cell-type specific mechanism in the brain, with a new physiological function in cortical neuron differentiation.
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Authors
Sandra Oliveira Braz, Andrea Cruz, Andrea Lobo, Joana Bravo, Joana Moreira-Ribeiro, Isabel Pereira-Castro, Jaime Freitas, Joao B. Relvas, Teresa Summavielle, Alexandra Moreira,