Talk abstracts

Talk on Friday 03:10-03:30pm submitted by Bing Zhang

Induction of neuronal differentiation in muscle precursor cells by a large non-coding RNA

Bing Zhang (Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, OH 44106, USA), Fereshteh Jahaniani Kenari (Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, OH 44106, USA)

Abstract:
Recent studies have indicated that while 93% of the human genome is transcribed into RNA, only 2% of it codes for proteins. It is estimated that human genome contains 70,000 large non-protein coding transcripts; however, the functional mechanism of this novel class of cellular regulators is almost completely unknown. We have analyzed the cellular function of one such RNA, the BORG RNA, which was originally described as a BMP2-responsive gene (Takeda et al., 1998). BORG is a 2766 nucleotide long transcript and is both spliced and polyadenylated. Phylogenetic analyses proved that the RNA is found in several mammalian genomes including human, chimpanzee, macaque, cow, pig, dog, and rat in addition to mouse, with ~ 65% conservation between human and mouse in a conserved region in its third exon.
Analysis of BORG expression in mouse tissues indicated that it is highly expressed in neural tissues. To determine the role of BORG in cellular differentiation, we took advantage of mouse C2C12 pre-myocytic cell line. BORG is expressed in C2C12 cells at a low level. We obtained stable cell lines that overexpressed full-length BORG and induced muscle differentiation to determine if BORG overexpression affects their ability to differentiate. Surprisingly, rather than differentiating into muscles, the cells developed round cell bodies and long branched processes that interconnected to form a network, features characteristic of neuronal progenitor cells. Wild type cells, those transfected with empty vectors and BORG shRNA knockdown cells did not display this phenotype when received differentiation media, rather, they showed phenotypic changes characteristic of muscle differentiation. Immunostaining and RT-PCR assays on differentiated BORG overexpression cells indicated that they express neuronal markers TUJ1, while neither the precursor cells nor BORG shRNA knock down cells express these markers. The differentiated cells had lost the ability to divide, consistent with neuronal differentiation. The ability of a large non-coding RNA to reprogram muscle precursor cells, which are of mesodermal origin, to neuronal cells, which are of ectodermal origin, provides an example of the crucial, and hitherto unknown, roles played by non-coding RNAs in regulation of cellular function and development.

Keywords: non-coding RNA