Isolation, characterization and mapping of the mouse and human RB1CC1 genes Tokuhiro Chano a,b, * , Shiro Ikegawa c , Fumiko Saito-Ohara d , Johji Inazawa d , Akihiko Mabuchi c , Yukikazu Saeki b , Hidetoshi Okabe a a Department of Clinical Laboratory Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan b Department of Basic Science for Health and Nursing, Shiga University of Medical Science, Shiga, Japan c Laboratory for Bone and Joint Diseases, SNP Research Center, RIKEN (The Institute of Physical and Chemical Research), Tokyo, Japan d Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan Received 26 November 2001; received in revised form 7 March 2002; accepted 19 March 2002 Received by T. Sekiya Abstract RB1CC1 ( RB1-inducible Coiled- Coil 1), a putative transcription factor implicated in the regulation of RB1 (retinoblastoma 1) expression, was recently identified in a screen for genes involved in multi-drug resistance to anticancer agents. Information about the RB1CC1 gene is limited, however, and its biological function is not determined. Here we report the isolation, characterization and mapping of the mouse RB1CC1 gene (Rb1cc1), together with further characterization of the human RB1CC1 gene. Mouse Rb1cc1 encodes 1588 amino acids, sharing 89% identity and key sequence motifs with its human counterpart. Rb1cc1 is expressed abundantly in heart and testis, with lower levels detected in lung and spleen. Immunohistochemical analysis revealed the Rb1cc1 and Rb1 proteins are co-localized in the cell nuclei of NIH3T3-3 cell and various mouse tissues. The human and mouse RB1CC1 genes, both of which contain 24 exons, span 74 kb on chromosome 8q11.2 and 57 kb on chromosome 1A2–4, respectively. Conserved sequence motifs and nuclear localization suggest that the RB1CC1 proteins function as transcription factors. q 2002 Elsevier Science B.V. All rights reserved. Keywords: RB1CC; RB1-inducible coiled-coil 1; RB; Retinoblastoma 1; Cloning; Mapping 1. Introduction We recently identified a novel human gene, RB1CC1 ( RB1-inducible Coiled- Coil 1: Human Gene Nomenclature Committee-approved gene symbol), during a search for genes implicated in multi-drug resistance (MDR) to antic- ancer agents (Chano et al., 2002). RB1CC1 expression is associated with the survival of MDR cancer cells treated with anticancer agents. Preliminary experiments also suggest that RB1CC1 may function as a key regulator for RB1 (retinoblastoma 1) expression: RB1CC1 expression correlates closely with that of RB1 in various cancer cell lines and normal human tissues, and introduction of wild- type RB1CC1 induced significant RB1 expression in human leukemic cells (Chano et al., 2002). Two previous studies have independently identified mouse Rb1cc1 as a cytoplasmic protein with varied func- tions, however. Maucuer et al. (1995) called Rb1cc1 as Cc1, and reported that it interacts with stathmin, a ubiquitous cytoplasmic protein, and predicted that Cc1 responds to many regulatory signals through its interaction with stath- min. Pfeuffer et al. (2000) called it as LaXp180, and proposed that it binds to the Listeria monocytegenes surface protein ActA, an important virulence factor, in listeriae- infected mammalian cells. These results contradict to our recent study in human. The deduced amino acid sequence of RB1CC1 contains a nuclear localization signal, a leucine zipper motif and a coiled-coil structure, indicating RB1CC1 is a nuclear protein; Immunoblot and immunocy- tochemical analyses have demonstrated nuclear localization of the human RB1CC1 protein (Chano et al., 2002). It remains to be determined whether the contradiction may result from species difference, or multiple function of RB1CC1; however, clarification of the molecular roles of RB1CC1 is hampered by scarcity of information about the Gene 291 (2002) 29–34 0378-1119/02/$ - see front matter q 2002 Elsevier Science B.V. All rights reserved. PII: S0378-1119(02)00585-1 www.elsevier.com/locate/gene Abbreviations: RB1CC1, RB1-inducible coiled-coil 1; RB1, retinoblas- toma 1; DNA, deoxyribonucleic acid; cDNA, DNA complementary to RNA; mRNA, messenger ribonucleic acid; PCR, polymerase chain reac- tion; RT, reverse transcription; RACE, rapid amplification of cDNA ends; FISH, fluorescence in situ hybridization; BAC, bacterial artificial chromo- some; SDS, sodium dodecyl sulfate; PVDF, polyvinylidine difluoride; dCTP, deoxycytidine triphosphate * Corresponding author. Tel.: 181-77-548-2600; fax: 181-77-548-2407. E-mail address: chano@belle.shiga-med.ac.jp (T. Chano).