Long read sequencing of RHOH mRNA transcripts in B-cells reveals new exons and splicing patterns.

Our previous works about the RHOH gene structure analysis allowed us to show that it is composed of seven exons among them one single encoding exon located at the 3prime side of the gene and preceded by six so called 5prime non coding exons, among them exon 2 and exon 4 preceded by two different alternative promoters with B or T cell lineage specificity. Our study allowed to identify a total of 38 mRNA molecules, among them 18 contained new RHOH exons spliced to upstream exon 2 or exon 4. Moreover, in parallel to this qualitative analysis, our method allowed quantitative measurements of the different mRNA species relative to each other in the different B cell lines that were studied. Interestingly, some quantitative differences were observed as a function of differentiation of the Lila-1 cell line from pre-B to more mature CD19 positive cells. Cryptic splice sites as well as intron retention were detected inside some of the new RHOH exons, and we describe new fusion transcripts that could act in the regulation of the RhoH gene.