A SLC33A1/AT-1 Tg mouse model that selectively overexpresses human AT-1 in neurons exhibited cognitive deficits, autistic-like social behavior, aberrations in synaptic plasticity, an increased number of dendritic spines and branches, and widespread proteomic changes (Hullinger et al., 2016).
Molecular Function
The protein encoded by this gene is a probable acetyl-CoA transporter required for the formation of O-acetylated (Ac) gangliosides. A heterozygous missense variant in SLC33A1 was identified in a Chinese family presenting with spastic paraplegia (SPG42; OMIM 612539), whereas biallelic variants in SLC33A1 are associated with congenital cataracts, hearing loss, and neurodegeneration (CCHLND; OMIM 614482).
External Links
References
Type
Title
Type of Disorder
Associated Disorders
Author, Year
Primary
Increased expression of AT-1/SLC33A1 causes an autistic-like phenotype in mice by affecting dendritic branching and spine formation.
Chromosomal duplications affecting the 3q25.31 locus harboring AT-1/ SLC33A1 have been associated with autism spectrum disorder (ASD) and intellectual disability (SFARI Autism Database; http://sfari.org/; Sanders et al., 2011; Prasad et al., 2012; Krumm et al., 2013).
References
Type
Title
Author, Year
Primary
Increased expression of AT-1/SLC33A1 causes an autistic-like phenotype in mice by affecting dendritic branching and spine formation.
Model Type:
Genetic
Model Genotype:
Heterozyous
Mutation:
Human SLC33A1 cDNA isolated and subcloned into pTRE-Tight vector was linearized and injected into the pronucleus of fertilized eggs from FVB mice; monogenic pTRE-AT-1 mice were backcrossed to WT C57BL/6 mice for five generations, and then bred to CamK2a-tTA mice; the inducible neuron-specific overexpression Tet-Off system is driven by the CamK2 promoter; the transgenic animals maintained in the absence of doxycycline (Dox) overexpressed human SLC33A1 in forebrain neurons during development and after birth.
Allele Type: Targeted (marker); Transgenic
Strain of Origin: FVB
Genetic Background: C57BL/6
ES Cell Line: FVB
Mutant ES Cell Line: FVB
Model Source: Jackson Laboratory
Description: Hippocampal tissue from 6 month old slc33a1 tg mice displayed a drastic increase in the number of dendritic branches and spines compared to wt controls;
Exp Paradigm: Confocal images of cultured neurons were uploaded and analyzed in imaris 8 (oxford instruments) using filament tracer module; filaments and spines were traced, segmented, and assigned using semiautomatic and manual detection methods; two-dimensional rendering of cells was created based on filament tracer analysis in imaris, using cylinder display; brains were harvested from 6 month old mice and golgi stained using the fd neurotech golgi kit;
Description: Slc33a1 tg mice display increased levels of hippocampal ltp elicited by theta burst stimulation when compared with nontg wt controls;
Exp Paradigm: For ltp, 3x theta burst consisted of a total of three trains of 10 bursts (each burst consisting of four stimulations at a frequency of 100 hz) with an interburst interval of 200 ms;
Description: Slc33a1 tg mice display reduced ltd induced by paired pulse low-frequency facilitation when compared with nontg wt controls;
Exp Paradigm: For ltd, paired pulse low frequency stimulation consisted of 900 pairs of stimuli with a 50 ms paired pulse interval
Description: Slc33a1 tg mice displayed decreased repetitive behavior in the marble burying task compared to wt controls
Exp Paradigm: Each mouse was placed into a clean cage with extra bedding and 20 black marbles arranged in a grid pattern; after 30 min of exploration in the cage, the number of marbles completely buried in the bedding and the number of marbles buried greater than 50 percent were counted;
Description: Slc33a1 tg mice failed to show a preference for investigating the novel mouse when compared to wt mice
Exp Paradigm: The test consisted of three trials, each 10 min in length, run consecutively; in the first trial, the experimental mouse was exposed to an empty arena and allowed to explore freely; in the second trial, a male juvenile mouse was placed in a mesh cup in one side chamber of the box and an identical empty mesh cup was placed in the opposite side chamber of the box to provide a neutral object control; the mesh cup allowed for visual and scent cues, but prevented aggressive behavior between the mice; during the third trial, the juvenile stimulus mouse from trial two was kept in the test arena, and a novel juvenile male mouse was placed in a cup in the opposite chamber; all trials were videotaped and used for subsequent analysis; investigation time was scored by
Description: Wt mice spent greater than 40 percent of their total investigation time exploring the novel object, whereas slc33a1 tg mice displayed no preference for the novel object relative to the trained objects
Exp Paradigm: Each mouse received five sequential 6-min trials, with a 3-min inter-trial interval
Cued or contextual fear conditioning: context discrimination1
Decreased
Description: Although during the training phase the slc33a1 tg mice did not show any difference in the percentage of freezing time compared to wildtype controls, during the context testing phase slc33a1 tg mice showed significant reduction in the percentage of freezing time compared to wildtype controls
Exp Paradigm: The shock stimulus consisted of a 1.5s 0.7 ma shock, with an inter-trial interval of 2 min
Description: Slc33a1 tg mice showed a decreased capacity to recall spatial location information in the probe trail phase of the mwm test compared to controls
Exp Paradigm: The morris water maze test consisted of eight blocks of testing over 4 days, followed by a probe trial
Description: Slc33a1 tg mice swam greater distances before locating the hidden platform than wt controls during the training phase of the mwm test
Exp Paradigm: The morris water maze test consisted of eight blocks of testing over 4 days, followed by a probe trial
Description: Majority of these protein markers (synaptogyrin1, rap2a, neurexin1, rab12, mglur5, ampa2,3,4) were significantly up-regulated in postsynaptic densities of tg animals compared with controls; increased acetylation of proteins may have consequences for neuronal outgrowth and adhesion, synaptic activity and structure, cell surface transporters, and protein synthesis pathways; analysis identified 395 acetylation sites on 152 proteins;
Exp Paradigm: Expression levels of selected target proteins known to be involved in neuronal outgrowth and synaptic plasticity, were compared in the hippocampi of slc33a1 tg and wt mice; neurexin1, neuroligin3, and rap2a were selected as indicators of dendritic branching and synapse formation; ampa2/3/4, mglur5, synaptogyrin1, synapsin3, and rab12 were selected as markers of pre and postsynaptic plasticity; panther classification system; string analysis;- mass spectrometry (ms)
Description: Direct assessment of both mrna and protein levels in neurons isolated from the adult brain confirmed successful up-regulation of slc33a1 in tg mice
Exp Paradigm: Markers, iba1 for microglia; s100 for astrocytes; iii tubulin, l1cam, and nfl 160 for neurons; controls included wildtype, camk2-tta, tre-slc33a1;-western blot
Description: There is significant increase in the acetylation of h3k27 accompanied by a significant decrease in h3k27 methylation, indicative of increased transcriptional activation in slc33a1-tg animals
Exp Paradigm: Assessment of h3k27acetyl and h3k-27trimethyl levels by immunoblotting- liquid chromatography-mass spectrometry (lc-ms)
Description: Slc25a1 and acly transcripts showed significant up-regulation, whereas acss2 did not; increased h3k27 acetylation of slc25a1 and acly, when compared with wt mice; h3k27 modification might serve as a sensor to rapidly respond to changes in cytosolic levels of acetyl-coa by activating key mitochondria genes;
Exp Paradigm: Quantitative pcr (qrt-pcr); chromatin immunoprecipitation (chip);
Description: Direct assessment of both mrna and protein levels in neurons isolated from the adult brain confirmed successful up-regulation of slc33a1 in tg mice
Exp Paradigm: Markers, iba1 for microglia; s100 for astrocytes; iii tubulin, l1cam, and nfl 160 for neurons; controls included wildtype, camk2-tta, tre-slc33a1;- quantitative pcr (qrt-pcr)
Description: Slc33a1 tg mice displayed significant reduction of acetyl-coa levels in the cytosol of total hippocampus and adult cortical neurones, when compared with wt mice;
Exp Paradigm: Cytosol recovered from total hippocampus and cortical neurones;
Description: In hippocampal tissue, 476 proteins were up-regulated in slc33a1 tg mice compared with camk2 controls; globally, the acetylome and proteome data identified four major biological functions: protein translation and quality control; transport of synaptic vesicles, assembly of synaptic connections, and regulation of synaptic activity; neuronal migration, outgrowth and adhesion; mitochondria activity, specifically electron transport chain, tricarboxylate acid cycle, and acetyl-coa metabolism; 163 out of 476 proteins up-regulated in slc33a1 tg mice were either membrane or secreted proteins that are normally translated on the er surface and inserted into the secretory pathway; two proteins that allow crosstalk between mitochondria and cytosolic acetyl-coa were fou
Exp Paradigm: Camk2 mice were selected as the control group to correct for possible nonspecific variations in protein expression;
Description: Majority of these protein markers (synaptogyrin1, rap2a, neurexin1, rab12, mglur5, ampa2,3,4) were significantly up-regulated in postsynaptic densities of tg animals compared with controls; increased acetylation of proteins may have consequences for neuronal outgrowth and adhesion, synaptic activity and structure, cell surface transporters, and protein synthesis pathways; analysis identified 395 acetylation sites on 152 proteins;
Exp Paradigm: Expression levels of selected target proteins known to be involved in neuronal outgrowth and synaptic plasticity, were compared in the hippocampi of slc33a1 tg and wt mice; neurexin1, neuroligin3, and rap2a were selected as indicators of dendritic branching and synapse formation; ampa2/3/4, mglur5, synaptogyrin1, synapsin3, and rab12 were selected as markers of pre and postsynaptic plasticity; panther classification system; string analysis;-western blot
Description: There is significant increase in the acetylation of h3k27 accompanied by a significant decrease in h3k27 methylation, indicative of increased transcriptional activation in slc33a1-tg animals
Exp Paradigm: Assessment of h3k27acetyl and h3k-27trimethyl levels by immunoblotting-western blot
