Netrin G1: its downregulation in the nucleus accumbens of cocaine-conditioned mice and genetic association in human cocaine dependence
ADDICTION BIOLOGY
Authors: Kelai, Sabah; Ramoz, Nicolas; Moalic, Jean-Marie; Noble, Florence; Mechawar, Naguib; Imbeaud, Sandrine; Turecki, Gustavo; Simonneau, Michel; Gorwood, Philip; Maussion, Gilles
Abstract
Netrin G1 is a presynaptic ligand involved in axonal projection. Although molecular mechanisms underlying cocaine addiction are still poorly understood, Netrin G1 might have a role as a regulator of anxiety, fear and spatial memory, behavioural traits impaired in the context of cocaine exposure. In this study, the Netrin G1 (Ntng1) expression was investigated in the nucleus accumbens of mice primarily conditioned to cocaine using a place preference paradigm. A genetic association study was then conducted on 146 multiplex families of the Collaborative study on Genetics of Alcoholism, in which seven single nucleotide polymorphisms located in the NTNG1 gene were genotyped. NTNG1 expression levels were also quantified in BA10, BA46 and the cerebellum of healthy controls (with no Axis 1 psychopathology). Decreased Ntng1 expression was initially observed in the nucleus accumbens of mice conditioned to cocaine. Significant genetic family-based associations were detected between NTNG1 polymorphisms and cocaine dependence. NTNG1 expression in BA10, BA46 and the cerebellum, however, were not significantly associated with any allele or haplotype of this gene. These results confirm that Ntng1 expression is disturbed in the nucleus accumbens of mice, after cocaine conditioning. A haplotype of NTNG1 was found to constitute a vulnerability factor for cocaine use disorder in patients, although none of its single nucleotide polymorphisms were associated with a differential expression pattern in healthy controls. The data suggest that change in the Ntng1 expression is a consequence of cocaine exposure, and that some of its genetic markers are associated with a greater risk for cocaine use disorder.
NTNG1 mutations are a rare cause of Rett syndrome
AMERICAN JOURNAL OF MEDICAL GENETICS PART A
Authors: Archer, HL; Evans, JC; Millar, DS; Thompson, PW; Kerr, AM; Leonard, H; Christodoulou, J; Ravine, D; Lazarou, L; Grove, L; Verity, C; Whatley, SD; Pitz, DT; Sampson, JR; Clarke, AJ
Abstract
A translatin that disrupted the netrin G1 gene (NTNG1) was recently reported in a patient with an early seizure variant of Rett syndrome (RTT). The Netrin G1 protein (NTNG1) has an important in the developing central nervous system, particularly in axonal guidance, signalling and NMDA receptor function and awas a good candidate gene for RTT. We recruited 115 patients with RTT (females: 25 classic and 84 atypical; 6 males) but no mutation in the MECP2 gene. For those 52 patienta with epileptic seizure onset in the first 6 months of life. CDKL5 mutations were also excluded. We aimed to determine whether mutations in NTNG1 accounted for a sifgnificant subset of patients with RTT, particularly those with the early onset seizure variant and other atypical presentations. We sequenced the nine coding exons of NTNG1 and identified four sequence variants, none of which were likely to be pathogenic. Mutations in the NTNG1 function demands further investigation in relation to the central nervous system pathophysiology of the disorder. (c) 2006 Wiley-Liss, Inc.