Long Noncoding RNAs Expressed in Mouse Pituitary Development and Mature Hormone-Producing Cells

Mammalian genomes contain thousands of genes for long noncoding RNA (lncRNAs), some of which have been shown to affect protein coding gene expression through diverse mechanisms. The lncRNA transcripts are longer than 200 nucleotides and are often capped, spliced, and polyadenylated, but not translated into protein. Nuclear lncRNAs can modify chromatin structure and transcription in trans or cis by interacting with the DNA, forming R-loops, and recruiting regulatory proteins. Not much is known about the role of lncRNA in pituitary gland differentiation and function. We mined transcriptome data from mouse pituitary glands collected at embryonic days 12.5 and 14.5 and identified over 200 different lncRNA transcripts. To develop a research resource for the study of lncRNA, we used pituitary cre transgenes to tag pituitary cell types in adult mice with fluorescent markers, and enriched for thyrotropes, gonadotropes, and somatotropes using fluorescence-activated cell sorting. We determined the transcriptome of each cell population using RNA sequencing and mined the data for lncRNA. We detected hundreds of lncRNAs in adult pituitary cells; a few were located immediately nearby genes that encode pituitary hormones or lineage-specific transcription factors. The location of these lncRNAs suggests the possibility of a cis-acting regulatory role in pituitary development or function, and we observe coordinated expression of 2 of them with their putative target genes in transgenic mice. This research resource sets the foundation for examining the actions of lncRNAs on their putative target genes and determining whether they have roles during development and in response to physiological demand.