Ziegler Andreas, Santos Pablo Sandro Carvalho, Kellermann Thomas, Uchanska-Ziegler Barbara
Institut für Immungenetik; Charité-Universitätsmedizin Berlin; Campus Benjamin Franklin; Freie Universität Berlin; Berlin, Germany.
Self Nonself. 2010 Jul;1(3):176-191. doi: 10.4161/self.1.3.12736. Epub 2010 Jun 21.
Self/nonself perception governs mate selection in most eukaryotic species. It relies on a number of natural barriers that act before, during and after copulation. These hurdles prevent a costly investment into an embryo with potentially suboptimal genetic and immunological properties and aim at discouraging fertilization when male and female gametes exhibit extensive sharing of alleles. Due to the fact that several genes belonging to the extended major histocompatibility complex (xMHC) carry out crucial immune functions and are the most polymorphic within vertebrate genomes, it is likely that securing heterozygosity and the selection of rare alleles within this gene complex contributes to endowing the offspring with an advantage in fighting infections. Apart from MHC class I and II antigens, the products of several other genes within the xMHC are candidates for participating in mate choice, especially since the respective loci are subject to long-range linkage disequilibrium which may aid to preserve functionally connected alleles within a given haplotype. Among these loci are polymorphic odorant receptor genes that are expressed not only in the olfactory epithelium, but also within male reproductive tissues. They may thus not only be of importance in olfaction-influenced mate choice, by recognizing MHC-dependent individual-specific olfactory signals, but could also guide spermatozoa along chemical gradients to their target, the oocyte. By focusing on the human HLA complex and genes within its vicinity, we show here that the products of several xMHC-specified molecules might be involved in self/nonself perception during reproduction. Although the molecular details are often unknown, the existence of highly diverse, yet intertwined pre- and post-copulatory barriers suggests that xMHC-encoded proteins may be important for various stages of mate choice, germ cell development, as well as embryonic and foetal life in mammals and other vertebrates. Many of these genes should thus be regarded as crucial not only within the immune system, but also in reproduction.
自我/非自我认知在大多数真核生物物种的配偶选择中起主导作用。它依赖于许多在交配前、交配期间和交配后起作用的天然屏障。这些障碍可防止对具有潜在次优遗传和免疫特性的胚胎进行代价高昂的投入，并旨在当雄配子和雌配子表现出广泛的等位基因共享时抑制受精。由于属于扩展主要组织相容性复合体（xMHC）的几个基因执行关键的免疫功能，并且在脊椎动物基因组中是多态性最高的，因此确保该基因复合体内的杂合性和稀有等位基因的选择可能有助于赋予后代在抵抗感染方面的优势。除了MHC I类和II类抗原外，xMHC内其他几个基因的产物也可能参与配偶选择，特别是因为各自的基因座存在长距离连锁不平衡，这可能有助于在给定单倍型内保留功能相关的等位基因。这些基因座中包括多态性气味受体基因，它们不仅在嗅觉上皮中表达，也在雄性生殖组织中表达。因此，它们不仅可能通过识别依赖MHC的个体特异性嗅觉信号在受嗅觉影响的配偶选择中起重要作用，还可能沿着化学梯度引导精子到达其靶标——卵母细胞。通过关注人类HLA复合体及其附近的基因，我们在此表明，几种xMHC指定分子的产物可能参与生殖过程中的自我/非自我认知。尽管分子细节通常未知，但高度多样且相互交织的交配前和交配后屏障的存在表明，xMHC编码的蛋白质可能对哺乳动物和其他脊椎动物配偶选择、生殖细胞发育以及胚胎和胎儿生命的各个阶段都很重要。因此，这些基因中的许多不仅在免疫系统中，而且在生殖过程中都应被视为至关重要的。
