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Author Spotlight: Establishing a Reliable Distal MCA Occlusion Model in Mice for Stroke Research
Published on: December 15, 2023
RETRACTED: Molecular Investigation of DKK3 in Cerebral Ischemic/Reperfusion Injury
Maria Caffo1, Roberta Fusco2, Rosalba Siracusa2
1Department of Biomedical, Dental and Morphological and Functional Imaging, University of Messina, Via Consolare Valeria, 98125 Messina, Italy.
Abstract:
Dickkopf-3 (Dkk3) is an atypical member of the Dkk family of Wnt inhibitors, which has been implicated in the pathophysiology of neurodegenerative disorders. Its role in the mechanisms of cellular degeneration and protection is still unknown. The aim of our work is to investigate the endogenous activation of the DKK3 pathway in a model of transient occlusion of the middle cerebral artery in rats. In particular, the animals were subjected to 1 h of ischemia followed by different reperfusion times (1 h, 6 h, 12 h and 24 h) to evaluate the downstream pathway and the time course of its activation. Western blot analysis showed increased Dkk3 expression in animals with the highest time of reperfusion. The increased levels of Dkk3 were accompanied by reduced Wnt3a, Frz1 and PIWI1a expression in the cytosol while FOXM1 and β-catenin decreased in the nucleus. These molecular changes led to an increase in the apoptotic pathway, as showed by the increased expression of Caspase 3 and Bax and the reduced levels of Bcl-2, and to a decrease in neurogenesis, as shown by the decreased expression of Tbr2, Ngn2 and Pax6. In the second part of the study, we decided to employ curcumin, an activator of the Wnt/β-catenin signaling, to investigate its effect on Dkk3. In particular, curcumin was administered 1 and 6 h after ischemia, and animals were sacrificed 24 h later when the expression of Dkk3 was higher. Our data displayed that curcumin administration decreased Dkk3 expression, and increased Wnt3a, Frz1 and PIWI1a levels. Well in line with these data, curcumin administration increased nuclear β-catenin and FOXM1 expression. The down-regulation of Dkk3 by curcumin led to reduced apoptosis and increased neurogenesis. Summarizing, our results showed that Dkk3 acts as an inhibitor of Wnt/β-catenin signaling during cerebral ischemia. Additionally, its inhibition and the contextual activation of the Wnt/β-catenin pathway are protective against ischemic stroke.
Insights
Dickkopf-3 (Dkk3) inhibits Wnt/β-catenin signaling after stroke, increasing apoptosis and reducing neurogenesis. Curcumin treatment reduced Dkk3, promoting neuroprotection and recovery in a rat model.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Dickkopf-3 (Dkk3) is a Wnt inhibitor implicated in neurodegenerative disorders, but its role in stroke pathophysiology is unclear.
- Investigating Dkk3's endogenous activation and downstream effects in a cerebral ischemia model is crucial for understanding stroke mechanisms.
Purpose of the Study:
- To investigate the endogenous activation of the Dickkopf-3 (Dkk3) pathway following transient middle cerebral artery occlusion in rats.
- To evaluate the impact of Dkk3 on Wnt/β-catenin signaling, apoptosis, and neurogenesis post-ischemia.
- To examine the neuroprotective effects of curcumin, a Wnt/β-catenin activator, on Dkk3-mediated pathways.
Main Methods:
- Transient middle cerebral artery occlusion (tMCAO) model in rats with varying reperfusion times.
- Western blot analysis to assess protein expression levels (Dkk3, Wnt3a, Frz1, PIWI1a, FOXM1, β-catenin, Caspase 3, Bax, Bcl-2, Tbr2, Ngn2, Pax6).
- Administration of curcumin at different time points post-ischemia to evaluate its therapeutic potential.
Main Results:
- Dkk3 expression significantly increased with longer reperfusion times post-ischemia.
- Elevated Dkk3 correlated with reduced Wnt pathway activation, increased apoptosis (Caspase 3, Bax), and decreased neurogenesis (Tbr2, Ngn2, Pax6).
- Curcumin administration reduced Dkk3 levels, restored Wnt/β-catenin signaling, decreased apoptosis, and enhanced neurogenesis.
Conclusions:
- Dkk3 acts as an inhibitor of the Wnt/β-catenin signaling pathway during cerebral ischemia.
- Inhibition of Dkk3 and concurrent activation of the Wnt/β-catenin pathway demonstrate neuroprotective effects against ischemic stroke.
- Targeting the Dkk3 pathway with agents like curcumin holds therapeutic potential for stroke treatment.
