Poster abstracts

Poster number 75 submitted by Huiwen Wang

Promotion of Exon 6 Inclusion in HuD Pre-mRNA by Hu Protein Family Members

Huiwen Wang (department of Genetics, School of Medicine, Case Western Reserve University), Jill Molfenter (department of Genetics, School of Medicine, Case Western Reserve University), Hui Zhu (department of Genetics, School of Medicine, Case Western Reserve University), Hua Lou (department of Genetics, School of Medicine, Case Western Reserve University)

Abstract:
The Hu RNA-binding protein family consists of four members: HuR/A, HuB, HuC and HuD. HuR expression is widespread. The other three neuron-specific Hu proteins play an important role in neuronal differentiation through modulating multiple processes of RNA metabolism. In all of the splicing events examined, Hu proteins promote skipping of the alternative exons. Here we report the first example where Hu proteins promote inclusion of an alternative exon, exon 6 of the HuD pre-mRNA. Sequence alignment analysis indicates the presence of several conserved AU-rich sequences both upstream and downstream to this alternatively spliced exon. We generated a human HuD exon 6 mini-gene reporter construct that includes these conserved sequences. Hu protein over-expression led to significantly increased exon 6 inclusion from this reporter and endogenous HuD. Studies using truncated and mutant HuD exon 6 reporters demonstrate that two AU-rich sequences located downstream of exon 6 are important. RNAi knockdown of Hu proteins decreased exon 6 inclusion. An in vitro splicing assay indicate that Hu proteins promote HuD exon 6 inclusion directly at the level of splicing. Our studies demonstrate that Hu proteins function as splicing enhancers and expand the functional role of Hu proteins as splicing regulators.

Keywords: alternative splicing, HuD