Fig 1.
Schematic of DNM1 protein showing the domain locations of eight human variants [1–3] and the fitful mutation ([5]; in red) within an alternatively spliced exon in the middle domain. The exon structure shows the location of the fitful mutation in the alternatively spliced exon 10a. Dnm1a, containing exon 10a, and Dnm1b, containing exon10b, can functionally compensate for each other.
Table 1.
Dynamin 1 mutant genotypes referenced in this study.
Fig 2.
Schematic of the Dnm1 transcript and the conditional EE genotype strategy.
(Top) The Dnm1Ftfl allele is shown with the mutation in alternatively spliced exon 10a. (Middle) The Dnm1flox allele is shown with location of the loxP sites flanking exons 2–4 [7]. (Bottom) After cre recombinase activity, exons 2–4 are deleted resulting in a frameshift and the Dnm1null allele. Thus, the genotypes in the present studies are compound heterozygous, Dnm1Ftfl/null, where the null (deleted allele) is present only in cells that express cre recombinase.
Fig 3.
Tomato reporter expression in brain sections from gene specific cre strains.
(A) Vibratome sections from the hippocampus, cortex and cerebellum of Gad2-cre, Pvalb-cre, Sst-cre, Cort-cre, Dlx5/6-cre and Emx1-cre mice crossed to mice carrying the conditional red fluorescent protein variant tdTomato. tdTomato is expressed only in cells expressing the cre (red), nuclei are counterstained with DAPI (blue). (B) Vibratome sections from the cortex of Gad2-cre (top images) or Pvalb-cre (bottom images) expressing animals crossed with the tomato reporter and counterstained with Gad65 antibody (top) or parvalbumin antibody (bottom) demonstrating the overlap of the cre expression with inhibitory neurons (Gad65 or Pvalb).
Table 2.
Expression patterns associated with cre recombinase mouse lines used in this study.
Fig 4.
Reduced lifespan of Dnm1Ftfl/flox mice crossed to different Cre driver lines.
Survival curves of Dnm1Ftfl/flox mice in conjunction with specific cre driver lines from postnatal day 0 until day 180. 100% of the Gad2-cre;Dnm1Ftfl/flox mice, 100% of the Dlx5/6-cre;Dnm1Ftfl/flox mice and 91% of the Pvalb-cre;Dnm1Ftfl/flox mice die before weaning. The Emx1-cre;Dnm1Ftfl/flox mice do not have a reduced lifespan.
Fig 5.
Variety of EEG seizures in different Dnm1Ftfl conditional mutants.
Differential EEG traces from three different conditional models. (A) EEG analysis of one Pvalb-cre;Dnm1Ftfl/flox mouse that lived long enough for recording displayed remarkably frequent and synchronous spike-wave discharges when awake; two independent episodes are shown following each other, n = 1. (B) EEG analysis of a Sst-cre;Dnm1Ftfl/flox mouse shows high amplitude poly-spike and slow spike-waves that end abruptly, followed by a quiet baseline. This is suggestive of an aborted tonic-clonic seizure, of the type that when more severe or prolonged, is lethal. Shown are two independent examples of traces, n = 4. (C) EEG analysis of a Emx1-cre;Dnm1Ftfl/flox mouse showing normal EEG activity; two traces are shown. n = 2. RF, right-front; LF, left-front; LB, left-back.
Fig 6.
Emx1-cre; Dnm1Ftfl/flox mice are smaller than littermates and have postural differences.
(Top) Adult mice were weighed at the onset of behavioral testing. Shown are male (left) and female (right) adult mice body weights. (Bottom) Dynamic weight bearing assay in freely moving animals measuring hindpaw surface area normalized to body weight. One-way ANOVA with Dunnett’s post hoc analysis (****P<0.0001, **P<0.01, v sex-matched WT control).
Table 3.
Summary of the effects of each cre line in combination with the Dnm1Ftfl/flox genotype.
Fig 7.
Emx1-cre;Dnm1Ftfl/flox mice demonstrate hyperactivity, stereotypical and altered activity.
(A) Total distance traveled in the open field test, males on left, females on right. ****P<0.0001; two-way repeated measures ANOVA, Bonferroni post hoc analysis. (B) Vertical activity (rearing) in the open field test; males on left, females on right. One Way ANOVA with Dunnett’s post hoc test (***P<0.001, **P<0.01; vs WT control). (C) Repetitive behavior as measured by rotational behavior in the open field; males on left, females on right. One-way ANOVA (within sex) with Dunnett’s post-hoc test (****P<0.0001 vs WT control). (D) Activity measured in the wheel running assay. Total distance traveled (RPMs) was measured in 60 min time bins over a 48 hour period. Light/dark cycle is indicated below; males on left, females on right.
Fig 8.
Anxiety- and depression-related behaviors of Emx1-cre;Dnm1Ftfl/flox mice.
(A) Amount of time spent at the perimeter was measured in the open field for 30 min; males on left, females on right. (B) Immobility time (sec) was measured in the tail suspension test; males on left, females on right. One-way ANOVA (within sex) with Dunnett’s post hoc analysis (****P<0.0001, **P<0.01, *P<0.05; v WT control).
Fig 9.
Altered dopaminergic and glutamatergic response.
Hyperactivity induced by amphetamine (top graphs; males left, females right) or by challenge with MK-801 (bottom graphs; males left, females right) as measured by total distance traveled in the open field after administration of drug. Two-way repeated measures ANOVA (time x same sex genotype) with Bonferroni post-hoc comparisons (***P<0.001, *P<0.05).