Distribution of Smad mRNA and proteins in the rat brain
Distribution of Smad mRNA and proteins in the rat brain
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DOI：
10.1016/j.jchemneu.2017.11.012
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发表时间：
2018-07-01
影响因子：
2.8
通讯作者：
Kondo, Tomohiro
中科院分区：
文献类型：
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作者：
Nakajima, Takayuki;Hata, Ryusuke;Kondo, Tomohiro
已知Smad蛋白转导转化生长因子-β超家族蛋白的作用，包括转化生长因子-βS、激活素和骨形态发生蛋白。在本研究中，我们用RT-PCR和原位杂交的方法检测了Smad1、-2、-3、-4、-5和-8mRNA在大鼠脑内的表达。此外，我们还用免疫组织化学方法检测了侧脑室注射转化生长因子-β1、激活素A或Bmp6后Smad1、-2、-3、-5和-8蛋白的核积聚，以探讨转化生长因子-β、激活素和/或骨形态发生蛋白是否激活了大鼠脑内的Smads。RT-PCR分析表明，Smad1、-2、-3、-4、-5和-8在脑内均有表达，Smad3和Smad8在不同脑区的表达水平存在差异。例如，Smad3mRNA在大脑皮层、尾壳核/苍白球和小脑中高水平表达，在丘脑和中脑中低水平表达。Smad8在中脑、小脑、脑桥/延髓的表达高于嗅球、大脑皮层、尾壳核/苍白球、海马/齿状回和丘脑。除嗅结节、下丘脑后部和小脑核等少数区域外，Smadl mRNA的ISH信号广泛存在于脑内。在嗅球、梨状皮质、基底节、扣带回、松果体和内侧缰核、下丘脑、中脑下丘等脑区，以及桥脑、小脑皮质和脉络丛的部分核团中均可观察到Smad2的ISH信号。Smad3mRNA的ISH信号在几个脑区也有丰富的观察到。Smad3基因在嗅结节、梨状皮质、基底节、齿状回和扣带回有较强的表达。Smad5和Smad8基因的ISH信号仅局限于少数脑区，信号强度较弱。在检测的所有区域均检测到Smad4mRNA的ISH信号。脑室注射激活素A可诱导神经元内Smad2和Smad3免疫反应。相反，侧脑室注射转化生长因子-β1或Bmp6不会引起任何Smad免疫反应在神经元中的核积聚。这些结果表明激活素-Smad信号在脑内稳态中起重要作用。
Smad proteins are known to transduce the action of TGF-beta superfamily proteins including TGF-beta s, activins, and bone morphogenetic proteins (BMPs). In this study, we examined the expression of Smadl,-2,-3,-4,-5, and-8 mRNA in the rat brain by means of RT-PCR and in situ hybridization (ISH). In addition, we examined the nuclear accumulation of Smadl,-2,-3,-5, and -8 proteins after intracerebroventricular injection of TGF-beta 1, activin A, or BMP6 with immunohistochemistry to investigate whether TGF-beta, activin, and/or BMP activate Smads in the rat brain. RT-PCR analysis revealed that Smadl,-2,-3,-4,-5, and-8 mRNA was expressed in the brain and that the Smad3 and Smad8 mRNA differed in the expression level between brain regions. For example, there were high levels of expression of Smad3 mRNA in the cerebral cortex, caudate putamen/globus pallidus, and cerebellum, but low levels in the thalamus and midbrain. Expression of Smad8 mRNA was higher in the midbrain, cerebellum, and pons/medulla oblongata in comparison to the olfactory bulb, cerebral cortex, caudate putamen/globus pallidus, hippocampus/dentate gyrus, and thalamus. ISH signals for Smadl mRNA were widely detected in the brain except for a small number of regions including the olfactory tubercle, posterior region of hypothalamus, and cerebellar nuclei. ISH signals for Smad2 mRNA were abundantly observed in several brain regions including the olfactory bulb, piriform cortex, basal ganglia, cingulate cortex, epithalamus, including the pineal gland and medial habenular nuclei, hypothalamus, inferior colliculi of the midbrain, and some nuclei in the pons, cerebellar cortex, and choroid plexus. ISH signals for Smad3 mRNA were also abundantly observed in several brain regions. Especially strong signals for Smad3 mRNA were observed in the olfactory tubercle, piriform cortex, basal ganglia, dentate gyrus, and cingulate cortex. ISH signals for Smad5 and Smad8 mRNA were restricted to a small number of brain regions, the signal intensity of which was weak. ISH signals for Smad4 mRNA were detected in all regions examined. Intracerebroventricular injection of activin A induced nuclear accumulation of Smad2 and Smad3 immunoreactivity in neurons. In contrast, intracerebroventricular injection of TGF-beta 1 or BMP6 did not induce nuclear accumulation of the immunoreactivity for any Smad in neurons. These results suggest that activin-Smad signaling plays an important role in brain homeostasis.