Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland.
Department of Ecology and Vertebrate Zoology, Faculty of Biology and Environmental Protection, University of Łódź, 90-237 Łódź, Poland.
Molecules. 2022 Apr 6;27(7):2371. doi: 10.3390/molecules27072371.
Proteins are ubiquitous macromolecules that display a vast repertoire of chemical and enzymatic functions, making them suitable candidates for chemosignals, used in intraspecific communication. Proteins are present in the skin gland secretions of vertebrates but their identity, and especially, their functions, remain largely unknown. Many lizard species possess femoral glands, i.e., epidermal organs primarily involved in the production and secretion of chemosignals, playing a pivotal role in mate choice and intrasexual communication. The lipophilic fraction of femoral glands has been well studied in lizards. In contrast, proteins have been the focus of only a handful of investigations. Here, we identify and describe inter-individual expression patterns and the functionality of proteins present in femoral glands of male sand lizards () by applying mass spectrometry-based proteomics. Our results show that the total number of proteins varied substantially among individuals. None of the identified femoral gland proteins could be directly linked to chemical communication in lizards, although this result hinges on protein annotation in databases in which squamate semiochemicals are poorly represented. In contrast to our expectations, the proteins consistently expressed across individuals were related to the immune system, antioxidant activity and lipid metabolism as their main functions, showing that proteins in reptilian epidermal glands may have other functions besides chemical communication. Interestingly, we found expression of the Major Histocompatibility Complex (MHC) among the multiple and diverse biological processes enriched in FGs, tentatively supporting a previous hypothesis that MHC was coopted for semiochemical function in sand lizards, specifically in mate recognition. Our study shows that mass spectrometry-based proteomics are a powerful tool for characterizing and deciphering the role of proteins secreted by skin glands in non-model vertebrates.
蛋白质是无处不在的大分子，具有广泛的化学和酶功能，使它们成为化学信号的合适候选者，用于种内通讯。蛋白质存在于脊椎动物的皮肤腺分泌物中，但它们的身份，尤其是它们的功能，在很大程度上仍然未知。许多蜥蜴物种都有股腺，即表皮器官，主要参与化学信号的产生和分泌，在配偶选择和种内通讯中起着关键作用。蜥蜴的股腺的亲脂性部分已经得到了很好的研究。相比之下，蛋白质只受到少数几项研究的关注。在这里，我们通过应用基于质谱的蛋白质组学来鉴定和描述雄性沙蜥股腺中存在的个体间表达模式和蛋白质的功能。我们的结果表明，个体之间的蛋白质总数差异很大。在鉴定出的股腺蛋白中，没有一种可以直接与蜥蜴的化学通讯联系起来，尽管这一结果取决于数据库中蛋白质的注释，而数据库中鳞翅目动物的信息化学物质代表性很差。与我们的预期相反，个体间一致表达的蛋白质与免疫系统、抗氧化活性和脂质代谢有关，其主要功能是蛋白质在爬行动物的表皮腺中可能具有除化学通讯以外的其他功能。有趣的是，我们发现主要组织相容性复合体 (MHC) 在丰富的 FG 中多种和多样化的生物学过程中表达，这暂时支持了 MHC 在前沙蜥中被用于化学信号功能的假设，特别是在配偶识别中。我们的研究表明，基于质谱的蛋白质组学是一种强大的工具，可用于描述和破译由皮肤腺分泌的蛋白质在非模型脊椎动物中的作用。
