Genetic restoration of Emc10 levels in adulthood rescues SM performance in Df(16)A+I–mice.
(A) Emc10 ‘knockout-first’ conditional allele. The ‘knockout-first’ allele (tm1a) contains an IRES:lacZ trapping cassette and a floxed promoter-driven neo cassette inserted into the intron of Emc10 gene, disrupting gene function. Flp converts the ‘knockout-first’ allele to a conditional allele (tm1c), restoring gene activity. Cre deletes the promoter-driven selection cassette and floxed exon of the tm1a allele to generate a lacZ-tagged allele (tm1b) or deletes the floxed exon of the tm1c allele to generate a frameshift mutation (tm1d), triggering NMD of the deleted transcript. (B) Expression levels of Emc10-1 mRNA transcript in PFC of Emc10tm1c+I-; UBC-creIERT2; Df(16)A+I+ and Emc10tm1c+I-; UBC-creIERT2; Df(16)A+/- mice [referred to as WT and Df(16)A+/-] following adult TAM treatment. qRT-PCR analysis shows TAM-mediated normalization of Emc10-1 mRNA levels in the PFC of Df(16)+I- mice. Significant upregulation of Emc10-1 mRNA expression level seen in corn oil-treated Df(16)A+I- compared to corn oil-treated WT mice [one-way ANOVA, F(3, 12)=22.58, P<0.0001; post hoc Tukey, P=0.0013]. Following TAM treatment, Emc10-1 expression is normalized to near WT levels in TAM-treated Df(16)A+I- compared to corn oil-treated Df(16)A+I- mice (post hoc Tukey, P=0.0098). Emc10-1 reduction is also observed in TAM-treated WT compared to corn oil-treated WT mice (post hoc Tukey, P=0.0131). Corn oil-treated WT mice: n=5, corn oil-treated Df(16)A+I- mice: n=3, TAM-treated WT mice: n=4, and TAM-treated Df(16)A+I- mice: n=4. (C) Emc10 protein levels in PFC of WT and Df(16)A+/- mice following adult TAM treatment. Left panel: Emc10 protein levels are significantly elevated in corn oil-treated Df(16)A+- compared to corn oil-treated WT mice [one-way ANOVA, F(2, 7)=6.216, P=0.0281, post hoc Tukey, P=0.0300]. Emc10 protein level is reduced in TAM-treated Df(16)A+I- compared to corn oil-treated Df(16)A+I- mice (post hoc Tukey, P=0.0634). Corn oil-treated WT mice: n=4, corn oil-treated Df(16)A+I- mice: n=3, TAM-treated Df(16)A+I- mice: n=3. Right panel: Representative Western Blot. Tubulin was used as loading control. (D-E) Emc10 mRNA expression levels of both Emc10 isoforms: Emc10-1 (D) and Emc10-2 (E), with or without a TMD respectively (7), as assayed by qRT-PCRs in the HPC of the Emc10tm1c+I-; UBC-creIERT2; Df(16)A+I+ and Emc10tm1c+I-; UBC-creIERT2; Df(16)A+/- mice [referred to as WT and Df(16)A+/-] following adult TAM treatment. (D) qRT-PCR analysis shows TAM-mediated restoration of Emc10-1 mRNA levels in the HPC of Df(16)A+I- mice. Significant upregulation of Emc10-1 mRNA expression level seen in corn oil-treated Df(16)A+I- compared to corn oil-treated WT mice [one-way ANOVA, F(3, 11)=16.77, P<0.001; post hoc Tukey, P=0.0027]. Following TAM treatment, Emc10-1 expression is restored to near WT levels in Df(16)A+I- compared to corn oil-treated Df(16)A+I- mice (post hoc Tukey, P=0.0132). Emc10-1 reduction is also observed in TAM-treated WT compared to corn oil-treated WT mice (post hoc Tukey, P=0.0485). (E) qRT-PCR analysis shows TAM-mediated restoration of Emc10-2 mRNA levels in the HPC of Df(16)A+I- mice. Significant upregulation of Emc10-2 mRNA expression level seen in corn oil-treated Df(16)A+I- compared to corn oil-treated WT mice [one-way ANOVA, F(3, 11)=28.28, P<0.0001; post hoc Tukey, P=0.0284]. Following TAM treatment, Emc10-2 expression is restored to near WT levels in Df(16)A+I- compared to corn oil-treated Df(16)A+I- mice (post hoc Tukey, P=0.0002). Emc10-2 reduction is also observed in TAM-treated WT compared to corn oil-treated WT mice (post hoc Tukey, P=0.0005). Corn oil-treated WT mice: n=5, corn oil-treated Df(16)A+I- mice: n=3, TAM-treated WT mice: n=3, and TAM-treated Df(16)A+I- mice: n=4. (F) Expression levels of Emc10-1 mRNA transcript in cerebellum (CB) of WT and Df(16)A+/- mice following adult TAM treatment. qRT-PCR analysis shows TAM mediated normalization of Emc10-1 mRNA levels in the PFC of Df(16)A+I- mice. Significant upregulation of Emc10-1 mRNA expression level seen in corn oil-treated Df(16)A+I- compared to corn oil-treated WT mice [one-way ANOVA, F(3, 10)=37.43, P<0.0001; post hoc Tukey, P<0.0001]. Following TAM treatment, Emc10-1 expression is normalized to WT levels in TAM-treated Df(16)A+I- compared to corn oil-treated Df(16)A+I- mice (post hoc Tukey, P=0.0003). Emc10-1 downregulation is also observed in TAM-treated WT compared to corn-oil-treated WT mice (post hoc Tukey, P=0.0122). Corn oil-treated WT mice: n=5, corn oil-treated Df(16)A+I- mice: n=2, TAM-treated WT mice: n=3, and TAM-treated Df(16)A+I- mice: n=4. (G) Corn oil-treated Df(16)A+I- mice show a robust SM deficit compared to corn oil-treated WT mice as indicated by the significant difference in trial 2 interaction time upon reintroduction of a familiar juvenile mouse [three-way ANOVA for Trial X Genotype X Treatment Interaction matching by trial: F (1, 35) = 8.823 P=0.0053; post hoc Tukey, P= 0.0047]. A reduction in trial 2 interaction time indicates rescue of the SM deficit in TAM-treated Df(16)A+I- compared to corn oil-treated Df(16)A+I- mice (post hoc Tukey, P= 0.0082). (H) A negative difference score (trial 1-trial 2) confirms the SM deficit in corn oil-treated adult Df(16)A+I- mice compared to WT littermates [two-way ANOVA for Genotype X Treatment interaction: F (1, 35) =8.823, P=0.0053; post hoc Tukey, P= 0.0048]. Increase in the difference score of Df(16)A+I- mice in TAM-vs corn oil-treated group demonstrates rescue of SM performance (post hoc Tukey, P= 0.0181). Corn oil-treated WT mice: n=12 (7 males, 5 females), corn oil-treated Df(16)A+I- mice: n=7 (3 males, 4 females), TAM-treated WT mice: n=11 (6 males, 5 females), and TAM-treated Df(16)A+I- mice: n=9 (4 males, 5 females). (I) Tamoxifen (TAM) mediated Emc10 down-regulation does not rescue hyperactivity in Df(16)A+/− mice in the open field (OF) assay as demonstrated in the total distance traveled. In a 1-h exposure to a novel OF arena Df(16)A+/−+ TAM mice compared with WT + TAM mice remain as hyperactive [one-way ANOVA, F(3, 31)= 8.052, P=0.0004; post hoc Tukey, P= 0.0222] as Df(16)A+/− + oil mice compared with WT + oil mice [one-way ANOVA, F(3, 31)= 8.052, P=0.0004; post hoc Tukey, P= 0.0047]. Corn-oil treated WT mice: n= 10, TAM-treated WT mice: n= 9, corn-oil treated Df(16)A+/− mice: n= 10, TAM-treated Df(16)A+/−mice: n= 6. Data are presented as mean ± SEM, *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001.