Neuroscience Research 68 (2010) 131–136 Contents lists available at ScienceDirect Neuroscience Research journal homepage: www.elsevier.com/locate/neures Genetic background and gender effects on gross phenotypes in congenic lines of ALS2/alsin-deficient mice Shinji Hadano a,b,c,∗ , Yasuhiro Yoshii d , Asako Otomo b , Ryota Kunita b , Kyoko Suzuki-Utsunomiya b , Lei Pan b , Shigeru Kakuta e , Yasuo Iwasaki d , Yoichiro Iwakura e , Joh-E Ikeda a,b,f a Neurodegenerative Diseases Research Centre, Tokai University Graduate School of Medicine, Isehara, Kanagawa 259-1193, Japan b Department of Molecular Life Sciences, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan c The Institute of Medical Sciences, Tokai University, Isehara, Kanagawa 259-1193, Japan d Department of Neurology, Toho University Omori Hospital, Ota-ku, Tokyo 143-8451, Japan e Center for Experimental Medicine and Systems Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan f Apoptosis Research Centre, Children Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada article info Article history: Received 30 April 2010 Received in revised form 1 June 2010 Accepted 7 June 2010 Available online 14 June 2010 Keywords: Amyotrophic lateral sclerosis Motor neuron disease ALS2/alsin Als2 knockout mouse Genetic background Gender abstract Loss-of-function mutations in human ALS2 account for several juvenile recessive motor neuron diseases (MNDs). To understand the molecular basis underlying motor dysfunction in ALS2-linked MNDs, several lines of Als2 -/- mice with a mixed genetic background were thus far generated, and their phenotypes were thoroughly characterized. However, several phenotypic discrepancies among different Als2-deficient lines became evident. To investigate whether genetic backgrounds are associated with such discrep- ancies, we here generated congenic lines of Als2 -/- mice on two different genetic backgrounds; C57BL/6 (B6) and FVB/N (FVB), and investigated their gross phenotypes. Both B6 and FVB congenic lines were viable and fertile with no evidences for obvious abnormalities. There were no differences in growth curves between wild-type and Als2 -/- mice on each genetic background. Remarkably, Als2 -/- mice on a FVB, but not a B6, background exhibited a shorter life span than wild-type litters. Further, B6 female, but not male, Als2 -/- mice showed a significantly lower spontaneous rearing activity than wild-type litters. These genetic background- and/or gender-specific findings suggest the presence of modifiers for life span and motor activities in Als2 -/- mice. These congenic mice should provide a useful means to understand the molecular and genetic basis for variable expression of pathological phenotypes in MNDs. © 2010 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved. 1. Introduction ALS2 is a causative gene for a number of juvenile autosomal recessive motor neuron diseases (MNDs), including amyotrophic lateral sclerosis 2 (ALS2), juvenile primary lateral sclerosis (PLSJ), and infantile-onset ascending hereditary spastic paralysis (IAHSP) (Hadano et al., 2001, 2007). The ALS2-coded protein, ALS2 (aka alsin), is a guanine nucleotide exchange factor for Rab5 small GTPase, and involves in macropinocytosis-associated endosome fusion, regulation of endolysosomal protein degradation, and neu- rite outgrowth (Otomo et al., 2003, 2008; Kunita et al., 2007; Hadano et al., 2010). ALS2 mutations are predicted to result in either premature termination of translation or substitution of an evolu- tionarily conserved amino acid. Thus, a loss of functions in ALS2 ∗ Corresponding author at: Neurodegenerative Diseases Research Centre, Tokai University Graduate School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259- 1193, Japan, Tel.: +81 463 93 1121x2567; fax: +81 463 91 4993. E-mail address: shinji@is.icc.u-tokai.ac.jp (S. Hadano). accounts for motor dysfunction and/or degeneration in the ALS2- linked MNDs (Hadano et al., 2007). However, the molecular basis for phenotype variations among the ALS2-deficient patients with different ALS2 mutations; e.g., onset of disease and lower motor neuron involvement, remains unclarified. To understand the pathogenesis for the ALS2-linked MNDs, a total of 6 independent lines of Als2 -/- (KO) mice have thus far been generated, and their phenotypes were thoroughly charac- terized (Cai et al., 2005, 2008; Hadano et al., 2006; Devon et al., 2006; Yamanaka et al., 2006; Deng et al., 2007; Gros-Louis et al., 2008). Although none of Als2-KO mice represents the complex dis- ease phenotypes, the subclinical levels of motor dysfunction and axonal degeneration emerged in aged animals (Hadano et al., 2006; Yamanaka et al., 2006; Deng et al., 2007). Nonetheless, the discrep- ancies in a number of neuropathological features among different Als2-KO lines also became evident (Cai et al., 2008). At this stage, the possibility that these variables are due to the different muta- tion introduced in each knockout mouse strain cannot be excluded (Hadano et al., 2007; Cai et al., 2008). However, as previously sug- gested (Cai et al., 2008), it is equally likely that they are due to a 0168-0102/$ – see front matter © 2010 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved. doi:10.1016/j.neures.2010.06.004