Pathogenic variants in the gene encoding the small GTPase Ras analogue in Brain 39b (RAB39B) are associated with early-onset parkinsonism. In this study we investigated the expression and localization of RAB39B (RNA and protein) in mouse brain tissue to gain a better understanding of its normal physiological function(s) and role in disease.We developed novel resources, including monoclonal antibodies directed against RAB39B and mice with Rab39b knockout, and performed real-time PCR and western blot analysis on whole brain lysates. To determine the spatial localization of Rab39b RNA and protein, we performed in-situ hybridization and immunohistochemistry on fresh frozen and fixed brain tissue. Our results show that RAB39B is localized throughout the cortex, hippocampus and substantia nigra of mice throughout postnatal life. We found high levels of RAB39B within MAP2 positive cortical and hippocampal neurons, and TH positive dopaminergic neurons in the substantia nigra pars compacta.Our studies support and extend current knowledge of the localization of RAB39B. We validate RAB39B as a neuron-enriched protein and demonstrate that it is present throughout the mouse cortex and hippocampus. Further, we observe high levels in the substantia nigra pars compacta, the brain region most affected in Parkinson's disease pathology. The distribution of Rab39b is consistent with human disease associations with parkinsonism and cognitive impairment. We also describe and validate novel resources, including monoclonal antibodies directed against RAB39B and mice with Rab39b knockout, both of which are valuable tools for future studies of the molecular function of RAB39B.

中文翻译：

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帕金森氏病相关的RAB39B在小鼠脑组织中的分布。

脑39b（RAB39B）中编码小GTPase Ras类似物的基因中的致病变异与早发性帕金森病有关。在这项研究中，我们调查了RAB39B（RNA和蛋白质）在小鼠脑组织中的表达和定位，以更好地了解其正常的生理功能和在疾病中的作用。我们开发了新颖的资源，包括针对RAB39B和Rab39b基因敲除小鼠，并对全脑裂解液进行实时PCR和Western印迹分析。为了确定Rab39b RNA和蛋白质的空间定位，我们在新鲜的冷冻和固定脑组织上进行了原位杂交和免疫组织化学。我们的结果表明，RAB39B在整个出生后的生命中都位于小鼠的皮质，海马和黑质中。我们在黑质致密部中的MAP2阳性皮质和海马神经元以及TH阳性多巴胺能神经元中发现了高水平的RAB39B。我们的研究支持并扩展了当前对RAB39B定位的认识。我们验证RAB39B为一种富含神经元的蛋白质，并证明它存在于整个小鼠皮质和海马体中。此外，我们在黑质致密部（帕金森氏病病理最受影响的大脑区域）中观察到高水平。Rab39b的分布与帕金森氏症和认知障碍的人类疾病相关。我们还描述和验证了新颖的资源，包括针对RAB39B的单克隆抗体和具有Rab39b基因敲除的小鼠，这两者都是未来RAB39B分子功能研究的宝贵工具。