Loss of GABAergic neurons in the hippocampus and cerebral cortex of Engrailed-2 null mutant mice: implications for autism spectrum disorders.
The homeobox-containing transcription factor Engrailed-2 (En2) is involved in patterning and neuronal differentiation of the midbrain/hindbrain region, where it is prominently expressed. En2 mRNA is also expressed in the adult mouse hippocampus and cerebral cortex, indicating that it might also function in these brain areas. Genome-wide association studies revealed that En2 is a candidate gene for autism spectrum disorders (ASD), and mice devoid of its expression (En2(-/-) mice) display anatomical, behavioral and clinical "autistic-like" features. Since reduced GABAergic inhibition has been proposed as a possible pathogenic mechanism of ASD, we hypothesized that the phenotype of En2(-/-) mice might include defective GABAergic innervation in the forebrain. Here we show that the Engrailed proteins are present in postnatal GABAergic neurons of the mouse hippocampus and cerebral cortex, and adult En2(-/-) mice show reduced expression of GABAergic marker mRNAs in these areas. In addition, reduction in parvalbumin (PV), somatostatin (SOM) and neuropeptide Y (NPY) expressing interneurons is detected in the hippocampus and cerebral cortex of adult En2(-/-) mice. Our results raise the possibility of a link between altered function of En2, anatomical deficits of GABAergic forebrain neurons and the pathogenesis of ASD.
Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento, Italy.
Paola
P
Sgadò
Sacha
S
Genovesi
Anna
A
Kalinovsky
Giulia
G
Zunino
Francesca
F
Macchi
Manuela
M
Allegra
Elisa
E
Murenu
Giovanni
G
Provenzano
Prem Prakash
PP
Tripathi
Simona
S
Casarosa
Alexandra L
AL
Joyner
Yuri
Y
Bozzi
D000818:Animals; D001321:Autistic Disorder / Q000235:genetics* / Q000473:pathology*; D002540:Cerebral Cortex / Q000166:cytology*; D004195:Disease Models, Animal; D059330:GABAergic Neurons / Q000473:pathology*; D006624:Hippocampus / Q000166:cytology*; D018398:Homeodomain Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency*; D009478:Neuropeptide Y / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D013004:Somatostatin / Q000378:metabolism; D000099266:Engrailed 2 Protein
D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D009478:Neuropeptide Y; D010320:Parvalbumins; D013004:Somatostatin; D000099266:Engrailed 2 Protein
ASD; CALB; CCK; DG; En2; Engrailed-2; GABA; GAD; Homeobox transcription factor; Inhibition; Interneuron; NPY; Neurodevelopmental disorder; PV; Parvalbumin; RT-PCR; SNP; SOM; VIP; autism spectrum disorders; calbindin 28kD; cholecystokin; dentate gyrus; glutamic acid decarboxylase; neuropeptide Y; parvalbumin; reverse transcription polymerase chain reaction; single-nucleotide polymorphism; somatostatin; vGAT; vGLUT; vasointestinal peptide; vesicular GABA transporter; vesicular glutamate transporter; γ-aminobutyric acid