title: Complete or partial reduction of the Met receptor tyrosine kinase in distinct circuits differentially impacts mouse behavior.
abstract: BACKGROUND
  Our laboratory discovered that the gene encoding the receptor tyrosine kinase, MET, contributes to autism risk. Expression of MET is reduced in human postmortem temporal lobe in autism and Rett Syndrome. Subsequent studies revealed a role for MET in human and mouse functional and structural cortical connectivity. To further understand the contribution of Met to brain development and its impact on behavior, we generated two conditional mouse lines in which Met is deleted from select populations of central nervous system neurons. Mice were then tested to determine the consequences of disrupting Met expression.
  
  
  METHODS
  Mating of Emx1 (cre) and Met (fx/fx) mice eliminates receptor signaling from all cells arising from the dorsal pallium. Met (fx/fx) and Nestin (cre) crosses result in receptor signaling elimination from all neural cells. Behavioral tests were performed to assess cognitive, emotional, and social impairments that are observed in multiple neurodevelopmental disorders and that are in part subserved by circuits that express Met.
  
  
  RESULTS
  Met (fx/fx) /Emx1 (cre) null mice displayed significant hypoactivity in the activity chamber and in the T-maze despite superior performance on the rotarod. Additionally, these animals showed a deficit in spontaneous alternation. Surprisingly, Met (fx/fx; fx/+) /Nestin (cre) null and heterozygous mice exhibited deficits in contextual fear conditioning, and Met (fx/+) /Nestin (cre) heterozygous mice spent less time in the closed arms of the elevated plus maze.
  
  
  CONCLUSIONS
  These data suggest a complex contribution of Met in the development of circuits mediating social, emotional, and cognitive behavior. The impact of disrupting developmental Met expression is dependent upon circuit-specific deletion patterns and levels of receptor activity.
authors.affiliation: Chan Division of Occupational Science and Occupational Therapy, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90089 USA ; Institute for the Developing Mind, Children's Hospital of Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027 USA ; Department of Pediatrics, Children's Hospital of Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027 USA.
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Thompson
authors.affiliation: Institute for the Developing Mind, Children's Hospital of Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027 USA ; Department of Pediatrics, Children's Hospital of Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027 USA.
authors.forename: Pat
authors.initials: P
authors.lastname: Levitt
keywords: Autism; Behavior; Fear learning; Gene dose; Met; Mouse; Phenotype