Figures & data
Figure 1. SRSF1 regulates SUMO conjugation to different spliceosomal proteins. Top panels indicate the snRNP protein components that have been so far described as SUMO conjugation targets by proteomic studies [Citation54, Citation63, Citation66]. Middle scheme represents a proposed model of action of SRSF1 in which this RBP, by binding to a specific exonic splicing enhancer (ESE) assists with spliceosome recruitment and, at the same time, by its ability to interact with SUMO pathway components can regulate the SUMOylation of spliceosomal protein components. For the sake of simplicity, the cartoon shows only one spliceosomal complex. The precise step along the spliceosome assembly cycle at which each of the listed proteins is conjugated to SUMO, it is recruited to the spliceosome in its SUMO-conjugated form or interacts with SRSF1 that enhances its SUMOylation, remains unknown. Bottom panels correspond to western blot analysis of SUMO conjugation to particular spliceosomal proteins (U2AF2 – U2-associated protein-; Snu114 and Prp28 –U5 components; and Prp3 –U4/U6 component) upon SRSF1 overexpression or siRNA-mediated depletion in human cultured cells. The effect of SRSF1 depletion is only shown for Prp3 SUMOylation. HEK 293T cells were transfected with the siRNAs and/or DNA expression vectors as indicated at the top of each panel. After 48 h, cells were lysed and cell lysates were subjected to Nickel affinity chromatography (Ni-NTA). Aliquots of the cell lysates and eluates (Ni-NTA) were analyzed by western blot with antibodies against over-expressed HA-U2AF65; T7-Prp28; T7-Prp3 or endogenous Snu114. [Reprinted in part from Pozzi B., et al. SUMO conjugation to spliceosomal proteins is required for efficient pre-mRNA splicing. Nucleic Acids Research, Oxford University Press. 2017 Jun 20;45(11):6729-6745].
![Figure 1. SRSF1 regulates SUMO conjugation to different spliceosomal proteins. Top panels indicate the snRNP protein components that have been so far described as SUMO conjugation targets by proteomic studies [Citation54, Citation63, Citation66]. Middle scheme represents a proposed model of action of SRSF1 in which this RBP, by binding to a specific exonic splicing enhancer (ESE) assists with spliceosome recruitment and, at the same time, by its ability to interact with SUMO pathway components can regulate the SUMOylation of spliceosomal protein components. For the sake of simplicity, the cartoon shows only one spliceosomal complex. The precise step along the spliceosome assembly cycle at which each of the listed proteins is conjugated to SUMO, it is recruited to the spliceosome in its SUMO-conjugated form or interacts with SRSF1 that enhances its SUMOylation, remains unknown. Bottom panels correspond to western blot analysis of SUMO conjugation to particular spliceosomal proteins (U2AF2 – U2-associated protein-; Snu114 and Prp28 –U5 components; and Prp3 –U4/U6 component) upon SRSF1 overexpression or siRNA-mediated depletion in human cultured cells. The effect of SRSF1 depletion is only shown for Prp3 SUMOylation. HEK 293T cells were transfected with the siRNAs and/or DNA expression vectors as indicated at the top of each panel. After 48 h, cells were lysed and cell lysates were subjected to Nickel affinity chromatography (Ni-NTA). Aliquots of the cell lysates and eluates (Ni-NTA) were analyzed by western blot with antibodies against over-expressed HA-U2AF65; T7-Prp28; T7-Prp3 or endogenous Snu114. [Reprinted in part from Pozzi B., et al. SUMO conjugation to spliceosomal proteins is required for efficient pre-mRNA splicing. Nucleic Acids Research, Oxford University Press. 2017 Jun 20;45(11):6729-6745].](/cms/asset/13c2994b-7b7c-4b7e-8702-486d46bc86c2/krnb_a_1457936_f0001_oc.jpg)
