Maurer J A, Wray S
Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Neurosci. 1997 Jun 15;17(12):4552-61. doi: 10.1523/JNEUROSCI.17-12-04552.1997.
Changes in mRNA stability have been shown to regulate critical intracellular processes. In this investigation, we studied tyrosine hydroxylase (TH) mRNA turnover in functionally and anatomically distinct dopaminergic (DA) populations of the rat hypothalamus. To this end, long-term slice explant cultures from postnatal, preoptic area/hypothalami, containing three anatomically discrete DA populations, were generated and maintained under defined conditions. The organotypic cultures were treated with the transcription inhibitors 5,6-dichloro-1-D-ribofuranosylbenzimidazole or actinomycin D and processed for in situ hybridization histochemistry. Relative TH mRNA content per cell was quantitated. Single-cell analysis showed marked differences in basal TH mRNA turnover rates between DA neuronal populations. Anterior and midhypothalamic DA neurons exhibited half-time turnovers of 9-12 and 11-23 hr, respectively. In contrast, in the caudal hypothalamus, DA neurons of the arcuate nucleus had a significantly lower baseline level and more rapid turnover (6-7 hr) of TH mRNA. This investigation shows that basal turnover of a phenotypic mRNA, TH mRNA in DA neurons, is not an intrinsic property of the phenotypic marker. Furthermore, we found that destabilization of TH mRNA in the caudal hypothalamus corresponds to the known rhythmic output displayed by arcuate DA cells and, as such, may be critical for normal function of this population. We propose that intrinsic differences in the post-transcriptional regulation of TH permits neuronal subpopulations, which subserve different physiological functions, an additional mechanism to control DA biosynthesis in response to their unique needs.
mRNA稳定性的变化已被证明可调节关键的细胞内过程。在本研究中，我们研究了大鼠下丘脑功能和解剖学上不同的多巴胺能（DA）群体中酪氨酸羟化酶（TH）mRNA的周转情况。为此，我们从出生后的视前区/下丘脑制备了长期切片外植体培养物，其中包含三个解剖学上离散的DA群体，并在特定条件下进行培养和维持。将器官型培养物用转录抑制剂5,6-二氯-1-D-呋喃核糖基苯并咪唑或放线菌素D处理，并进行原位杂交组织化学处理。对每个细胞的相对TH mRNA含量进行定量分析。单细胞分析显示，DA神经元群体之间的基础TH mRNA周转率存在显著差异。下丘脑前部和中部的DA神经元的半衰期周转率分别为9-12小时和11-23小时。相比之下，在下丘脑尾部，弓状核的DA神经元的TH mRNA基线水平显著较低，周转速度更快（6-7小时）。本研究表明，表型mRNA（DA神经元中的TH mRNA）的基础周转率不是表型标记的固有特性。此外，我们发现下丘脑尾部TH mRNA的去稳定化与弓状DA细胞显示的已知节律输出相对应，因此可能对该群体的正常功能至关重要。我们提出，TH转录后调控的内在差异使具有不同生理功能的神经元亚群有了另一种机制，可根据其独特需求控制DA生物合成。
