2020
Acta Med Okayama. 2020 Jun;74(3):199-208. doi: 10.18926/AMO/59950.
Dkk3/REIC, an N-glycosylated Protein, Is a Physiological Endoplasmic Reticulum Stress Inducer in the Mouse Adrenal Gland
Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan. Division of Molecular Biology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan. Department of Basic Science, School of Veterinary Nursing and Technology, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-8602, Japan. Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan. Innovation Center Okayama for Nanobio-Targeted Therapy, Okayama University, Okayama 700-8558, Japan. Niimi University, Niimi, Okayama 718-8585, Japan.
Service type: Knockout mice
Abstract
Dickkopf 3 (Dkk3) is a secreted protein belonging to the Dkk family and encoded by the orthologous gene of REIC. Dkk3/REIC is expressed by mouse and human adrenal glands, but the understanding of its roles in this organ is still limited. To determine the functions of Dkk3 in the mouse adrenal gland, we first identified that the mouse Dkk3 protein is N-glycosylated in the adrenal gland as well as in the brain. We performed proteome analysis on adrenal glands from Dkk3-null mice, in which exons 5 and 6 of the Dkk3 gene are deleted. Twodimensional polyacrylamide gel electrophoresis of adrenal proteins from wild-type and Dkk3-null mice revealed 5 protein spots whose intensities were altered between the 2 genotypes. Mass spectrometry analysis of these spots identified binding immunoglobulin protein (BiP), an endoplasmic reticulum (ER) chaperone. To determine whether mouse Dkk3 is involved in the unfolded protein response (UPR), we carried out a reporter assay using ER-stress responsive elements. Forced expression of Dkk3 resulted in the induction of distinct levels of reporter expression, showing the UPR initiated by the ER membrane proteins of activating transcription factor 6 (ATF6) and inositol-requring enzyme 1 (IRE1). Thus, it is possible that Dkk3 is a physiological ER stressor in the mouse adrenal gland. Keywords: Dkk3 knockout mouse; adrenal gland; endoplasmic reticulum stress; glucose-regulated protein 78; proteome.
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