TY - JOUR
T1 - Splicing regulator SRSF1-3 that controls somatic hypermutation of IgV genes interacts with topoisomerase 1 and AID
AU - Kumar Singh, Amit
AU - Tamrakar, Anubhav
AU - Jaiswal, Ankit
AU - Kanayama, Naoki
AU - Agarwal, Anshu
AU - Tripathi, Prabhanshu
AU - Kodgire, Prashant
N1 - Funding Information:
No competing financial interests have been declared. Funding for this work was provided by Department of Science and Technology, Govt. of India, for research grants (EMR/2016/003547), (SR/S2/RJN-109/2011) and Department of Biotechnology, Govt. of India, for a research grant (BT/PR20319/BBE/117/189/2016).
Funding Information:
Authors thank Prof. J. L. Manley, Columbia University, USA, for a kind gift of DT40-ASF cells. We thank Dr. S. Shukla, IISER Bhopal, India, for Histone H3 antibody. A. K. Singh, A. Tamrakar, and A. Jaiswal thank Department of Science and Technology (DST), University Grants Commission (UGC) and Council of Scientific and Industrial Research (CSIR), Government of India, respectively, for PhD fellowship. A. Agarwal is supported by DST-WOS-A fellowship. Authors are thankful to Sophisticated Instrumentation Facility at IIT Indore and THSTI, Faridabad, for confocal experiments.
Funding Information:
Authors thank Prof. J. L. Manley, Columbia University, USA, for a kind gift of DT40-ASF cells. We thank Dr. S. Shukla, IISER Bhopal, India, for Histone H3 antibody. A. K. Singh, A. Tamrakar, and A. Jaiswal thank Department of Science and Technology (DST), University Grants Commission (UGC) and Council of Scientific and Industrial Research (CSIR), Government of India , respectively, for PhD fellowship. A. Agarwal is supported by DST-WOS-A fellowship . Authors are thankful to Sophisticated Instrumentation Facility at IIT Indore and THSTI, Faridabad, for confocal experiments.
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2019/12
Y1 - 2019/12
N2 - Somatic hypermutation (SHM) of Ig genes is initiated by activation-induced cytidine deaminase (AID) and requires target gene transcription. A splice isoform of SRSF1, SRSF1-3, is necessary for AID-dependent SHM of IgV genes. Nevertheless, its exact molecular mechanism of action in SHM remains unknown. Our in silico studies show that, unlike SRSF1, SRSF1-3 lacks a strong nuclear localization domain. We show that the absence of RS domain in SRSF1-3 affects its nuclear localization, as compared to SRSF1. Consequently, SRSF1-3 is predominantly present in the cytoplasm. Remarkably, co-immunoprecipitation studies showed that SRSF1-3 interacts with Topoisomerase 1 (TOP1), a crucial regulator of SHM that assists in generating ssDNA for AID activity. Moreover, the immunofluorescence studies confirmed that SRSF1-3 and TOP1 are co-localized in the nucleus. Furthermore, Proximity Ligation Assay corroborated the direct interaction between SRSF1-3 and TOP1. An interaction between SRSF1-3 and TOP1 suggests that SRSF1-3 likely influences the TOP1 activity and consequently can aid in SHM. Accordingly, SRSF1-3 probably acts as a link between TOP1 and SHM, by spatially regulating TOP1 activity at the Ig locus. We also confirmed the interaction between SRSF1-3 and AID in chicken B-cells. Thus, SRSF1-3 shows dual-regulation of SHM, via interacting with AID as well as TOP1.
AB - Somatic hypermutation (SHM) of Ig genes is initiated by activation-induced cytidine deaminase (AID) and requires target gene transcription. A splice isoform of SRSF1, SRSF1-3, is necessary for AID-dependent SHM of IgV genes. Nevertheless, its exact molecular mechanism of action in SHM remains unknown. Our in silico studies show that, unlike SRSF1, SRSF1-3 lacks a strong nuclear localization domain. We show that the absence of RS domain in SRSF1-3 affects its nuclear localization, as compared to SRSF1. Consequently, SRSF1-3 is predominantly present in the cytoplasm. Remarkably, co-immunoprecipitation studies showed that SRSF1-3 interacts with Topoisomerase 1 (TOP1), a crucial regulator of SHM that assists in generating ssDNA for AID activity. Moreover, the immunofluorescence studies confirmed that SRSF1-3 and TOP1 are co-localized in the nucleus. Furthermore, Proximity Ligation Assay corroborated the direct interaction between SRSF1-3 and TOP1. An interaction between SRSF1-3 and TOP1 suggests that SRSF1-3 likely influences the TOP1 activity and consequently can aid in SHM. Accordingly, SRSF1-3 probably acts as a link between TOP1 and SHM, by spatially regulating TOP1 activity at the Ig locus. We also confirmed the interaction between SRSF1-3 and AID in chicken B-cells. Thus, SRSF1-3 shows dual-regulation of SHM, via interacting with AID as well as TOP1.
KW - (AID)
KW - Activation-induced cytidine deaminase
KW - Immunoglobulin (Ig) genes
KW - Somatic hypermutation (SHM)
KW - Splicing regulator SRSF1-3
KW - Topoisomerase 1 (TOP1)
UR - http://www.scopus.com/inward/record.url?scp=85073108109&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85073108109&partnerID=8YFLogxK
U2 - 10.1016/j.molimm.2019.10.002
DO - 10.1016/j.molimm.2019.10.002
M3 - Article
C2 - 31622795
AN - SCOPUS:85073108109
SN - 0161-5890
VL - 116
SP - 63
EP - 72
JO - Immunochemistry
JF - Immunochemistry
ER -