Spatiotemporal Protein Expression Profiles of QSOX1 in the Murine Uterus, Placenta, and Embryo during Pregnancy

Hung-Shih Lin,Tsung-Hsien Yang,Sheng-Hsiang Li,Robert Kuo-Kuang Lee,Hsu-Wei Fang

doi:10.3390/app112110151

Abstract

Quiescin Q6 sulfhydryl oxidase 1 (QSOX1) catalyzes the oxidation of the sulfhydryl group to disulfide bond and is widely expressed in various tissues. This study focuses on investigating QSOX1′s spatiotemporal and cellular protein expression profile of the pregnant uterus, placenta, and developing embryo during mouse pregnancy. Immunohistochemical staining was used to reveal the localization of QSOX1 protein, and HistoQuest was applied to quantify protein levels. The expression level of QSOX1 in the decidua and muscle cells of the pregnant uterus fluctuated dramatically during pregnancy. QSOX1 was ubiquitously expressed in the labyrinth, junction zone, and chorionic plate in the placenta. The quantitative analysis found that this protein was highly expressed in the spinal cord, lens, midbrain, cerebellum, medulla oblongata, and tooth of mouse embryos, followed by the heart, intercostal muscle, diaphragm, intermediate zone, extrinsic ocular muscle, spine, pons, epidermis, tongue, ganglion, vomeronasal organ, thoracic vertebrae, and thymus. Interestingly, QSOX1 was also markedly expressed in olfactory system tissues. This comprehensive spatiotemporal study of QSOX1 protein expression will provide a basis for further investigations of the QSOX1 physiological function in the pregnant uterus, placenta, and developing embryo.

Highlights

Quiescin Q6 sulfhydryl oxidase 1 (QSOX1), a flavin adenine dinucleotide (FAD)dependent sulfhydryl oxidase, was first purified from the rat seminal vesicle secretion and characterized to catalyze the oxidation of low molecular thiol compounds such as glutathione and 2-mercaptoethanol to disulfide bonds [1]
Sequence analyses and biochemical studies revealed that QSOX1 and egg white sulfhydryl oxidase belong to the FAD-dependent sulfhydryl oxidases [2]
Two forms of QSOX1 were detected from thousands of protein components in the uterine tissue extract collected from the cycling

Summary

Introduction

Quiescin Q6 sulfhydryl oxidase 1 (QSOX1), a flavin adenine dinucleotide (FAD)dependent sulfhydryl oxidase, was first purified from the rat seminal vesicle secretion and characterized to catalyze the oxidation of low molecular thiol compounds such as glutathione and 2-mercaptoethanol to disulfide bonds [1]. Sequence analyses and biochemical studies revealed that QSOX1 and egg white sulfhydryl oxidase belong to the FAD-dependent sulfhydryl oxidases [2]. Hoober et al demonstrated that chicken egg white sulfhydryl oxidase utilizes an internal redox-active cysteine bridge and a FAD moiety, the same in the QSOX1, to oxidize low molecular weight thiols; the oxidase exhibits a high catalytic activity toward a range of reduced peptides and proteins in vitro [3]. QSOX1 has two main isoforms, i.e., long-form (~82 kDa) and short-form (~65 kDa) [4]. The short form is the main QSOX1 form [6,8,9]

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Discussion

Conclusion