title: Dissociation of frontotemporal dementia-related deficits and neuroinflammation in progranulin haploinsufficient mice.
abstract: Frontotemporal dementia (FTD) is a neurodegenerative disease with hallmark deficits in social and emotional function. Heterozygous loss-of-function mutations in GRN, the progranulin gene, are a common genetic cause of the disorder, but the mechanisms by which progranulin haploinsufficiency causes neuronal dysfunction in FTD are unclear. Homozygous progranulin knock-out (Grn(-/-)) mice have been studied as a model of this disorder and show behavioral deficits and a neuroinflammatory phenotype with robust microglial activation. However, homozygous GRN mutations causing complete progranulin deficiency were recently shown to cause a different neurological disorder, neuronal ceroid lipofuscinosis, suggesting that the total absence of progranulin may have effects distinct from those of haploinsufficiency. Here, we studied progranulin heterozygous (Grn(+/-)) mice, which model progranulin haploinsufficiency. We found that Grn(+/-) mice developed age-dependent social and emotional deficits potentially relevant to FTD. However, unlike Grn(-/-) mice, behavioral deficits in Grn(+/-) mice occurred in the absence of gliosis or increased expression of tumor necrosis factor-α. Instead, we found neuronal abnormalities in the amygdala, an area of selective vulnerability in FTD, in Grn(+/-) mice. Our findings indicate that FTD-related deficits resulting from progranulin haploinsufficiency can develop in the absence of detectable gliosis and neuroinflammation, thereby dissociating microglial activation from functional deficits and suggesting an important effect of progranulin deficiency on neurons.
authors.affiliation: Center for Neurodegeneration and Experimental Therapeutics, Departments of Neurology and Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Filiano
authors.forename: Lauren Herl
authors.initials: LH
authors.lastname: Martens
authors.forename: Allen H
authors.initials: AH
authors.lastname: Young
authors.forename: Brian A
authors.initials: BA
authors.lastname: Warmus
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
authors.forename: Grisell
authors.initials: G
authors.lastname: Diaz-Ramirez
authors.forename: Jian
authors.initials: J
authors.lastname: Jiao
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Zhang
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Huang
authors.forename: Fen-Biao
authors.initials: FB
authors.lastname: Gao
authors.forename: Robert V
authors.initials: RV
authors.lastname: Farese
authors.forename: Erik D
authors.initials: ED
authors.lastname: Roberson
mesh_terms: D000679:Amygdala / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003213:Conditioning, Psychological / Q000502:physiology; D004195:Disease Models, Animal; D004644:Emotions / Q000502:physiology; D004660:Encephalitis; D005260:Female; D057180:Frontotemporal Dementia / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology*; D005911:Gliosis; D000077155:Granulins; D057895:Haploinsufficiency / Q000502:physiology; D006720:Homozygote; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000473:pathology / Q000502:physiology; D010641:Phenotype; D000077153:Progranulins; D012919:Social Behavior; D013037:Spatial Behavior / Q000502:physiology
chemical_list: D000077155:Granulins; C120204:Grn protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D000077153:Progranulins