PT - JOURNAL ARTICLE AU - Marcella de Francisco Amorim AU - Eva-Maria Willing AU - Emese Xochitl Szabo AU - Irina Droste-Borel AU - Boris Maček AU - Korbinian Schneeberger AU - Sascha Laubinger TI - Arabidopsis U1 snRNP subunit LUC7 functions in alternative splicing and preferential removal of terminal introns AID - 10.1101/150805 DP - 2017 Jan 01 TA - bioRxiv PG - 150805 4099 - http://biorxiv.org/content/early/2017/06/16/150805.short 4100 - http://biorxiv.org/content/early/2017/06/16/150805.full AB - Introns are removed by the spliceosome, a large complex composed of five ribonucleoprotein subcomplexes (U snRNP). The U1 snRNP, which binds to 5’ splice sites, plays an essential role in early steps of the splicing reaction. Here, we show that Arabidopsis LUC7 is a U1 snRNP subunit that affects constitutive and alternative splicing. Interestingly, LUC7 specifically promotes splicing of a subset of terminal introns. Splicing of LUC7-dependent terminal introns is a prerequisite for nuclear export and can be modulated by stress. Globally, intron retention under stress conditions occurs preferentially among first and terminal introns, uncovering an unknown bias for splicing regulation in Arabidopsis. Taken together, our study reveals that the Arabidopsis U1 snRNP component LUC7 is important for alternative splicing and removal of terminal introns and it suggests that Arabidopsis terminal introns fine-tune gene expression under stress conditions.