DEF8 and Autophagy-Associated Genes Are Altered in Mild Cognitive Impairment, Probable Alzheimer’s Disease Patients, and a Transgenic Model of the Disease

Issue title: Translational Research and Drug Discovery for Neurodegeneration: Challenges for Latin America

Guest editors: K.S. Jagannatha Rao, Gabrielle B. Britton, Luisa Lilia Rocha Arrieta, Norberto Garcia-Cairasco, Alberto Lazarowski, Adrián Palacios, Antoni Camins Espuny and Ricardo B. Maccioni

Article type: Research Article

Authors: Leyton, Esteban^{a; b; c; 1} | Matus, Diego^{a; b; c; 1} | Espinoza, Sandra^a | Benitez, José Matías^{a; d} | Cortés, Bastián I.^a | Gomez, Wileidy^a | Arévalo, Nohela B.^b | Murgas, Paola^{b; e} | Manque, Patricio^{b; f} | Woehlbier, Ute^{b; d} | Duran-Aniotz, Claudia^g | Hetz, Claudio^{h; i; j; k} | Behrens, María Isabel^{l; m; n; o} | SanMartín, Carol D.^{b; c; d; l; *} | Nassif, Melissa^{a; b; d; *}

Affiliations: [a] Laboratory of Neuroprotection and Autophagy, Center for Integrative Biology, Faculty of Science, Universidad Mayor, Santiago, Chile | [b] Center for Integrative Biology, Faculty of Science, Universidad Mayor, Santiago, Chile | [c] Escuela de Tecnología Médica, Facultad de Ciencias, Universidad Mayor, Santiago, Chile | [d] Escuela de Biotecnología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile | [e] Immunology Laboratory, Center for Integrative Biology, Faculty of Science, Universidad Mayor, Santiago, Chile | [f] Center for Genomics and Bioinformatics, Faculty of Science, Universidad Mayor, Santiago, Chile | [g] Center for Social and Cognitive Neuroscience (CSCN), School of Psychology, Universidad Adolfo Ibañez, Santiago, Chile | [h] Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile | [i] Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile | [j] Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile | [k] Buck Institute for Research on Aging, Novato, CA, USA | [l] Departamento de Neurociencia, Facultad de Medicina, Universidad de Chile, Santiago, Chile | [m] Departamento de Neurología y Neurocirugía, Hospital Clínico Universidad de Chile, Santiago, Chile | [n] Centro de Investigación Clínica Avanzada (CICA), Hospital Clínico Universidad de Chile, Santiago, Chile | [o] Departamento de Neurología y Psiquiatría, Clínica Alemana de Santiago

Correspondence: [*] Correspondence to: Carol D. SanMartín, PhD, Center for Integrative Biology, Faculty of Sciences, Universidad Mayor, Camino La Piramide 5750, Huechuraba, 8580000, Santiago de Chile. Tel.: +56 2 25189245; E-mail: [email protected]; ORCID: 0000-0003-3733-5448; and Melissa Nassif, Tel.: +56 2 25189242; E-mail: [email protected]; ORCID: 0000-0002-5039-5245

Note: [1] These authors contributed equally to this work.

Abstract: Background:Disturbances in the autophagy/endolysosomal systems are proposed as early signatures of Alzheimer’s disease (AD). However, few studies are available concerning autophagy gene expression in AD patients. Objective:To explore the differential expression of classical genes involved in the autophagy pathway, among them a less characterized one, DEF8 (Differentially expressed in FDCP 8), initially considered a Rubicon family member, in peripheralblood mononuclear cells (PBMCs) from individuals with mild cognitive impairment (MCI) and probable AD (pAD) and correlate the results with the expression of DEF8 in the brain of 5xFAD mice. Method:By real-time PCR and flow cytometry, we evaluated autophagy genes levels in PBMCs from MCI and pAD patients. We evaluated DEF8 levels and its localization in brain samples of the 5xFAD mice by real-time PCR, western blot, and immunofluorescence. Results:Transcriptional levels of DEF8 were significantly reduced in PBMCs of MCI and pAD patients compared with healthy donors, correlating with the MoCA and MoCA-MIS cognitive tests scores. DEF8 protein levels were increased in lymphocytes from MCI but not pAD, compared to controls. In the case of brain samples from 5xFAD mice, we observed a reduced mRNA expression and augmented protein levels in 5xFAD compared to age-matched wild-type mice. DEF8 presented a neuronal localization. Conclusion:DEF8, a protein proposed to act at the final step of the autophagy/endolysosomal pathway, is differentially expressed in PBMCs of MCI and pAD and neurons of 5xFAD mice. These results suggest a potential role for DEF8 in the pathophysiology of AD.

Keywords: Alzheimer’s disease, autophagy, DEF8, lymphocytes, lysosome, mild cognitive impairment, Rubicon

DOI: 10.3233/JAD-201264

Journal: Journal of Alzheimer's Disease, vol. 82, no. s1, pp. S163-S178, 2021