title: SMC1B is present in mammalian somatic cells and interacts with mitotic cohesin proteins.
abstract: Cohesin is an evolutionarily conserved protein complex that plays a role in many biological processes: it ensures faithful chromosome segregation, regulates gene expression and preserves genome stability. In mammalian cells, the mitotic cohesin complex consists of two structural maintenance of chromosome proteins, SMC1A and SMC3, the kleisin protein RAD21 and a fourth subunit either STAG1 or STAG2. Meiotic paralogs in mammals were reported for SMC1A, RAD21 and STAG1/STAG2 and are called SMC1B, REC8 and STAG3 respectively. It is believed that SMC1B is only a meiotic-specific cohesin member, required for sister chromatid pairing and for preventing telomere shortening. Here we show that SMC1B is also expressed in somatic mammalian cells and is a member of a mitotic cohesin complex. In addition, SMC1B safeguards genome stability following irradiation whereas its ablation has no effect on chromosome segregation. Finally, unexpectedly SMC1B depletion impairs gene transcription, particularly at genes mapping to clusters such as HOX and PCDHB. Genome-wide analyses show that cluster genes changing in expression are enriched for cohesin-SMC1B binding.
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Linda
authors.initials: L
authors.lastname: Mannini
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cucco
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Quarantotti
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Clelia
authors.initials: C
authors.lastname: Amato
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Mara
authors.initials: M
authors.lastname: Tinti
authors.affiliation: Azienda Ospedaliero Universitaria Pisana, U.O. Fisica Sanitaria, Pisa, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Tana
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Milan, Italy.|Dipartimento di Medicina Clinica e Sperimentale, Università degli Studi dell'Insubria, Varese, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Frattini
authors.affiliation: Fondazione IRCCS Istituto Nazionale Tumori, Department of Experimental Oncology, Milan, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Delia
authors.affiliation: Division of Human Genetics, The Children's Hospital of Philadelphia and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, USA.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Krantz
authors.affiliation: Institute of Physiological Chemistry, Technische Universität Dresden, Dresden, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Jessberger
authors.affiliation: Istituto di Ricerca Genetica e Biomedica, Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Musio
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D020090:Chromosome Segregation / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D008297:Male; D018345:Mice, Knockout; D008938:Mitosis / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D000097722:Cohesins; C000611898:SMC1B protein, human; C438001:Smc1l2 protein, mouse