Fig 1.
Queuine integration into tRNAs.
In eukaryotic cells, the tRNA guanine transglycosylase (TGT) enzyme exchanges guanine (G) with the nucleobase queuine (q) at the wobble position (position 34, first base of the anticodon) of tRNAs that contain a GUN anticodon sequence (N = any base) and are specific to tRNA isoacceptors for tyrosine (tRNATyr), asparagine (tRNAAsn), aspartic acid (tRNAAsp) and histidine (tRNAHis). Queuosine (Q) is the corresponding nucleoside of q and Q-tRNA base-pairing with NAY codons (Y = C or U) impacts speed and fidelity of mRNA translation [14, 20–22].
Fig 2.
STL-101 decreases α-syn pSer129 in an in vitro model of synucleinopathy and protects dopaminergic (DA) neurons from MPP+ injury.
(A) IF of human α-syn (labelled in red with syn211 antibody) and the phosphorylated/aggregated form of α-syn (α-syn pSer129, labelled in green with EP1536Y antibody) on control and huPFFs-treated mouse cortical neurons. Scale bar = 200μm. (B) IF of α-syn pSer129 (EP1536Y antibody) three weeks after huPFFs exposure in untreated (-) and treated mouse cortical neurons with STL-101 at 0.1μM. Scale bar = 200μm. (C) Quantification of α-syn pSer129 as shown in B. in control (no huPFFs) and huPFFs-exposed mouse cortical neurons treated with STL-101 diluted in PBS at 0, 0.1, 1 and 10μM. Data is expressed as mean +/- SEM and analyzed using two-way ANOVA followed by Dunnett’s multiple comparison; ***p<0.001 cf. huPFFs + [STL-101] = 0μM. (D) STL-101 diluted in culture medium was added at the indicated concentrations to rat DA neuron cultures 1 day before MPP+ intoxication at 10μM. 48h after MPP+ injury DA neuron survival was assessed by TH+ neurons counting. Statistical significance was calculated using one-way ANOVA, Dunnett’s multiple comparison test (*p<0.05, ****p<0.0001 in comparison to MPP+ treatment only). n = 3 biological replicates. Dimethyl fumarate (DMF) was used at 10μM as a positive control.
Fig 3.
STL-101 protects against acute injury with Aβ1–42 in rat cortical neurons.
(A) Representative IF of MAP2 (red) and p-tau (AT100, green) in control (-), Aβ1–42 injured neurons, Aβ1–42 injured neurons pretreated with STL-101 at 0.3μM for 24h and Aβ1–42 injured neurons treated with BDNF at 50ng/mL. Aβ1–42 was used at 20μM. Scale bar = 100μm. (B) Quantification of p-tau in MAP2/AT100 IFs as shown in A. and with STL-101 pretreatment at the indicated concentrations. (C) Measurement of neurite network as shown in A. (D) Neuron survival quantification after Aβ1–42 injury. STL-101 pretreatments were performed at the indicated concentrations and the neurotrophic factor BDNF was used as a positive control at 50ng/mL. Control (Ctrl) = culture medium with 0.1% DMSO. Results are expressed as a percentage of control condition and mean +/- SEM (n = 4–6 wells/condition) is shown. Statistical analysis was performed using one-way ANOVA followed by Dunnett’s multiple comparison test (*p<0.05, **p<0.01, ***p<0.001, ****p<0.0001 in comparison with Aβ1–42).
Fig 4.
Queuine level in plasma does not vary with age but is higher in women than men.
(A) Measurement of queuine level was performed by LC-MS/MS in plasma samples of 80 neurologically healthy women and 80 neurologically healthy men from 50 to 90 years old. (B) Comparison of queuine level between men and women as shown in A. **p<0.01 (Mann Whitney test).