Evolution of the Small Family of Alternative Splicing Modulators Nuclear Speckle RNA-binding Proteins in Plants

LUCERO, LEANDRO; BAZIN, JEREMIE; RODRIGUEZ MELO, JOHAN; IBAÑEZ, FERNANDO; CRESPI, MARTÍN D.; ARIEL, FEDERICO

Genes

MDPI

Año: 2020 vol. 11

RNA-Binding Protein 1 (RBP1) was first identified as a protein partner of the longnoncoding RNA (lncRNA) ENOD40 in Medicago truncatula, involved in symbiotic noduledevelopment. RBP1 is localized in nuclear speckles and can be relocalized to the cytoplasm by theinteraction with ENOD40. The two closest homologs to RBP1 in Arabidopsis thaliana were calledNuclear Speckle RNA-binding proteins (NSRs) and characterized as alternative splicing modulatorsof specific mRNAs. They can recognize in vivo the lncRNA ALTERNATIVE SPLICINGCOMPETITOR (ASCO) among other lncRNAs, regulating lateral root formation. Here, weperformed a phylogenetic analysis of NSR/RBP proteins tracking the roots of the family to theEmbryophytes. Strikingly, eudicots faced a reductive trend of NSR/RBP proteins in comparisonwith other groups of flowering plants. In Medicago truncatula and Lotus japonicus, their expressionprofile during nodulation and in specific regions of the symbiotic nodule was compared to that ofthe lncRNA ENOD40, as well as to changes in alternative splicing. This hinted at distinct and specificroles of each member during nodulation, likely modulating the population of alternatively splicedtranscripts. Our results establish the basis to guide future exploration of NSR/RBP function inalternative splicing regulation in different developmental contexts along the plant lineage.