Zettergren Anna, Karlsson Sara, Studer Erik, Sarvimäki Anna, Kettunen Petronella, Thorsell Annika, Sihlbom Carina, Westberg Lars
Department of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, POB 431, 405 30, Göteborg, Sweden.
Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.
BMC Neurosci. 2017 Jan 5;18(1):9. doi: 10.1186/s12868-016-0332-1.
It is well-established that organizational effects of sex steroids during early development are fundamental for sex-typical displays of, for example, mating and aggressive behaviors in rodents and other species. Male and female brains are known to differ with respect to neuronal morphology in particular regions of the brain, including the number and size of neurons, and the density and length of dendrites in nuclei of hypothalamus and amygdala. The aim of the present study was to use global proteomics to identify proteins differentially expressed in hypothalamus/amygdala during early development (postnatal day 8) of male, female and conditional androgen receptor knockout (AR) male mice, lacking androgen receptors specifically in the brain. Furthermore, verification of selected sexually dimorphic proteins was performed using targeted proteomics.
Our proteomic approach, iTRAQ, allowed us to investigate expression differences in the 2998 most abundantly expressed proteins in our dissected tissues. Approximately 170 proteins differed between the sexes, and 38 proteins between AR and control males (p < 0.05). In line with previous explorative studies of sexually dimorphic gene expression we mainly detected subtle protein expression differences (fold changes <1.3). The protein MARCKS (myristoylated alanine rich C kinase substrate), having the largest fold change of the proteins selected from the iTRAQ analyses and of known importance for synaptic transmission and dendritic branching, was confirmed by targeted proteomics as differentially expressed between the sexes.
Overall, our results provide solid evidence that a large number of proteins show sex differences in their brain expression and could potentially be involved in brain sexual differentiation. Furthermore, our finding of a sexually dimorphic expression of MARCKS in the brain during development warrants further investigation on the involvement in sexual differentiation of this protein.
众所周知，性类固醇在早期发育过程中的组织效应对于啮齿动物和其他物种中典型的性行为表现（例如交配和攻击行为）至关重要。已知雄性和雌性大脑在大脑特定区域的神经元形态方面存在差异，包括神经元的数量和大小，以及下丘脑和杏仁核细胞核中树突的密度和长度。本研究的目的是使用全局蛋白质组学来鉴定在雄性、雌性和条件性雄激素受体敲除（AR）雄性小鼠（大脑中特异性缺乏雄激素受体）早期发育（出生后第8天）期间下丘脑/杏仁核中差异表达的蛋白质。此外，使用靶向蛋白质组学对选定的性二态性蛋白质进行了验证。
我们的蛋白质组学方法iTRAQ使我们能够研究解剖组织中2998种表达最丰富的蛋白质的表达差异。两性之间约有170种蛋白质存在差异，AR雄性小鼠和对照雄性小鼠之间有38种蛋白质存在差异（p < 0.05）。与先前对性二态性基因表达的探索性研究一致，我们主要检测到细微的蛋白质表达差异（倍数变化<1.3）。蛋白质MARCKS（肉豆蔻酰化富含丙氨酸的C激酶底物）在iTRAQ分析中选择的蛋白质中具有最大的倍数变化，并且对突触传递和树突分支具有已知的重要性，通过靶向蛋白质组学证实其在两性之间差异表达。
总体而言，我们的结果提供了确凿的证据，表明大量蛋白质在大脑表达中存在性别差异，并可能参与大脑性分化。此外，我们发现在发育过程中大脑中MARCKS的性二态性表达值得进一步研究该蛋白质在性分化中的作用。
