Dickkopf 3 (Dkk3) Improves Amyloid-β Pathology, Cognitive Dysfunction, and Cerebral Glucose Metabolism in a Transgenic Mouse Model of Alzheimer’s Disease

Article type: Research Article

Authors: Zhang, Li^{a; b} | Sun, Caixian^a | Jin, Yaxi^a | Gao, Kai^a | Shi, Xudong^a | Qiu, Wenying^{b; c} | Ma, Chao^{b; c; *} | Zhang, Lianfeng^{a; b; *}

Affiliations: [a] Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Institute of Laboratory Animal Sciences, Chinese Academy of Medical Sciences and Comparative Medical Center, Peking Union Medical College, Beijing, China | [b] Neuroscience Center, Chinese Academy of Medical Sciences, Beijing, China | [c] Department of Human Anatomy, Histology and Embryology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China

Correspondence: [*] Correspondence to: Dr. Lianfeng Zhang, Building 5, Panjiayuan Nanli, Chaoyang District, Beijing 100021, China. Tel.: +86 10 87778442; E-mail: [email protected] and Dr. Chao Ma, E-mail: [email protected].

Abstract: Dysfunctional Wnt signaling is associated with Alzheimer’s disease (AD), and activation of the Wnt signaling pathway inhibits AD development. Dickkopf 3 (Dkk3) is a modulator of the Wnt signaling pathway and is physiologically expressed in the brain. The role of Dkk3 in the pathogenesis of AD has not been evaluated. In the present study, we determined that Dkk3 expression was significantly decreased in brain tissue from AD patients and the AD transgenic mouse model APPswe/PS1dE9 (AD mice). Transgenic mice with brain tissue-specific Dkk3 expression were generated or crossed with AD mice to study the effects of Dkk3 on AD. In AD mice, transgenic expression of Dkk3 improved abnormalities in learning, memory, and locomotor activity, reduced the accumulation of amyloid-β, and ameliorated glucose uptake deficits. Furthermore, we determined that Dkk3 downregulated GSK-3β, a central negative regulator in canonical Wnt signaling, and upregulated PKCβ1, a factor implicated in noncanonical Wnt signaling. This indicates that increased activation of GSK-3β and the inhibition of PKCβ1 in AD patients may be responsible for the dysfunctional Wnt signaling in AD. In summary, our data suggest that Dkk3 is an agonist of Wnt signaling, and the ability of transgenic expression of Dkk3 to compensate for the decrease in Dkk3 expression in AD mice, reverse dysfunctional Wnt signaling, and partially inhibit the pathological development of AD suggests that Dkk3 could serve as a therapeutic target for the treatment of AD.

Keywords: Alzheimer’s disease, cognition, Dkk3, transgenic mice, Wnt signaling pathway

DOI: 10.3233/JAD-161254

Journal: Journal of Alzheimer's Disease, vol. 60, no. 2, pp. 733-746, 2017