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Advanced Neurology Drosophila Sirtuin 1 and Alzheimer’s disease

Tau /+;+/+ AD model flies compared to control flies 3.6. Overexpression/downregulation of Bsk
WT
(1.0) (Figure 5H). In addition, downregulation of Bsk modulates Sirt1 expression in AD model flies
(homozygous) in GMR-GAL4-UAS-Tau /+;UAS-Bsk RNAi / To further validate the above observations and investigate
WT
UAS-Bsk RNAi flies significantly reduced Grim, Reaper, and the association between Sirt1 and JNK, we analyzed the
Hid expression to 0.22-, 0.58-, and 1.89-fold, respectively. expression levels of Sirt1 in the heads of 10-day-old AD
In the AD genetic background, Sirt1 overexpression along model flies with Bsk overexpression and downregulation
with Bsk downregulation further decreased the expression from both control and experimental groups using qRT-
levels of Grim, Reaper, and Hid to 0.17-, 0.39-, and 0.78-
fold, respectively, in GMR-GAL4-UAS-Tau /UAS- PCR. The expression level of Sirt1 was significantly
WT
Sirt1;UAS-Bsk RNAi /UAS-Bsk RNAi flies. decreased to 0.47-fold in GMR-GAL4-UAS-Tau /+;+/+
WT
and 0.45-fold in GMR-Aβ k52 /+;GMR-Aβ k53 /+ flies
42
42
To further verify these results, we examined DIAP1 compared to control flies (1.0) (Figure 6). Our study
expression by conducting qRT-PCR on the heads of suggests that overexpression of Bsk in an AD genetic
10-day-old adult flies from both control and experimental background increases Sirt1 expression levels to 0.8-fold
groups. As shown in Figure 5I, DIAP1 expression was in GMR-GAL4-UAS-Tau /UAS-Bsk;+/+ and 0.65-fold in
WT
significantly decreased to 0.19 in AD model flies (GMR- GMR-Aβ k52 /UAS-Bsk;GMR-Aβ k53 /+ flies compared to
42
42
GAL4-UAS-Tau /+;+/+) compared to the experimental AD model flies (Figure 6). In contrast, Bsk downregulation
WT
control group (1.0). Downregulation of Bsk in an AD significantly increased Sirt1 expression levels to 1.6-fold in
genetic background increased DIAP1 expression up GMR-GAL4-UAS-Tau /+;UAS-Bsk RNAi /+ and 1.13-fold in
WT
to 2.9-fold in GMR-GAL4-UAS-Tau /+;UAS-Bsk RNAi / GMR-Aβ k52 /+;GMR-Aβ k53 /UAS-Bsk RNAi flies compared to
WT
42
42
UAS-Bsk RNAi flies (Figure 5I). Moreover, we observed that AD model flies (Figure 5).
Sirt1 overexpression alongside Bsk downregulation in an
AD genetic background significantly increased DIAP1 3.7. Sirt1 regulates the Notch signaling in Drosophila
expression to 5.3-fold in GMR-GAL4-UAS-Tau /UAS- We further explored the potential genetic interaction
WT
Sirt1;UAS-Bsk RNAi /UAS-Bsk RNAi flies (Figure 5I). This finding between Notch, Sirt1, and AD-associated genes (Tau ) in
supports our observations. WT
Drosophila. The rough eye phenotype, abnormal bristles,
and ommatidial disarrangement observed in GMR-GAL4-
UAS-Tau /+;+/+ AD model flies (Figure 7A) improved
WT
when Notch was downregulated using UAS-Notch RNAi
(single or double copy) in GMR-GAL4-UAS-Tau /+;UAS-
WT
Notch RNAi /TM6B and GMR-GAL4-UAS-Tau /+;UAS-
WT
Notch RNAi /UAS-Notch RNAi , respectively (Figure 7B and C).
Furthermore, these pathologies significantly improved
when Sirt1 was overexpressed and Notch was downregulated
(single or double copy) in AD genetic backgrounds (i.e.,
GMR-GAL4-UAS-Tau /UAS-Sirt1;UAS-Notch RNAi /TM6B
WT
and GMR-GAL4-UAS-Tau /UAS-Sirt1;UAS-Notch RNAi /
WT
UAS-Notch RNAi ,respectively) (Figure 7D and E).
Notch has been reported as a substrate of presenilin/γ-
secretase and plays an essential role in memory and learning
processes. 56,57 Thus, to examine the effect of Notch signaling
Figure 6. qRT-PCR analysis showing expression of Sirt1 in Bsk
overexpression/downregulation in Alzheimer’s disease model flies. along with Sirt1 overexpression on behavioral changes in
The histogram above illustrates the expression level of Sirt1 quantified AD model flies, we conducted behavioral assays (phototaxis
by RT-qPCR real-time PCR in the heads of 10-day-old adult flies: and climbing activity) in 10-day-old AD model flies with
GMR-GAL4/+;+/+, GMR-GAL4-UAS-Tau /+;+/+, GMR-GAL4- Sirt1 overexpression alongside Notch downregulation. We
WT
UAS-Tau /UAS-Bsk;+/+, GMR-GAL4-UAS-Tau /+;UAS-Bsk RNAi /+, found that the light preference index in 10-day-old AD
WT
WT
GMR-GAL4/+;+/+, GMR-Aβ 42 k52 /+;GMR-Aβ 42 k53 /+, GMR-Aβ 42 k52 /UAS-
Bsk;GMR-Aβ 42 k53 /+, and GMR-Aβ 42 k52 /+;GMR-Aβ 42 k53 /UAS-Bsk RNAi flies. model flies (GMR-GAL4-UAS-Tau /+;+/+) significantly
WT
RP49 (an endogenous control) was used for normalization. Error bars decreased to 10.13 compared to GMR-GAL4/+;+/+control
indicate mean ± standard error of the mean. Significance was calculated flies with a light preference index of 18.50 (Figure 7F). The
by one-way analysis of variance with Tukey’s test in GraphPad Prism 5.0 light preference index of GMR-GAL4-UAS-Tau /+;+/+
and is indicated as ns: non-significant, *P < 0.05, **P < 0.01, ***P < 0.0001 WT
Abbreviation: qRT-PCR: Quantitative reverse transcription- polymerase flies (10.13) increased to 13.33 and 14.85 when Notch was
chain reaction downregulated (homozygous/heterozygous condition)
Volume 3 Issue 4 (2024) 11 doi: 10.36922/an.4291