title: Isolation and characterization of alternatively spliced variants of the mouse sigma1 receptor gene, Sigmar1.
abstract: The sigma1 receptor acts as a chaperone at the endoplasmic reticulum, associates with multiple proteins in various cellular systems, and involves in a number of diseases, such as addiction, pain, cancer and psychiatric disorders. The sigma1 receptor is encoded by the single copy SIGMAR1 gene. The current study identifies five alternatively spliced variants of the mouse sigma1 receptor gene using a polymerase chain reaction cloning approach. All the splice variants are generated by exon skipping or alternative 3' or 5' splicing, producing the truncated sigma1 receptor. Similar alternative splicing has been observed in the human SIGMAR1 gene based on the molecular cloning or genome sequence prediction, suggesting conservation of alternative splicing of SIGMAR1 gene. Using quantitative polymerase chain reactions, we demonstrate differential expression of several splice variants in mouse tissues and brain regions. When expressed in HEK293 cells, all the splice variants fail to bind sigma ligands, implicating that each truncated region in these splice variants is important for ligand binding. However, co-immunoprecipitation (Co-IP) study in HEK293 cells co-transfected with tagged constructs reveals that all the splice variants maintain their ability to physically associate with a mu opioid receptor (mMOR-1), providing useful information to correlate the motifs/sequences necessary for their physical association. Furthermore, a competition Co-IP study showed that all the variants can disrupt in a dose-dependent manner the dimerization of the original sigma1 receptor with mMOR-1, suggesting a potential dominant negative function and providing significant insights into their function.
authors.affiliation: Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: Ling
authors.initials: L
authors.lastname: Pan
authors.affiliation: Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Pasternak
authors.affiliation: Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: Mingming
authors.initials: M
authors.lastname: Xu
authors.affiliation: Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing, Jianshu, China.|First Clinical Medical College, Nanjing University of Chinese Medicine, Nanjing, Jiangshu, China.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: Gavril W
authors.initials: GW
authors.lastname: Pasternak
authors.affiliation: Department of Neurology and the Molecular Pharmacology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, United States of America.
authors.forename: Ying-Xian
authors.identifier: http://orcid.org/0000-0002-4006-8304
authors.initials: YX
authors.lastname: Pan
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D005091:Exons / Q000235:genetics*; D020869:Gene Expression Profiling / Q000379:methods*; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D008810:Mice, Inbred C57BL; D008957:Models, Genetic; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017480:Receptors, sigma / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D000097605:Sigma-1 Receptor
chemical_list: D020033:Protein Isoforms; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor