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Clustering of single-cell RNA sequencing data is often used to show what states and subtypes cells have. Using this technique, striatal cells were clustered into subtypes using different clustering algorithms. Previously known subtypes were confirmed and new subtypes were found. One of them is a third medium spiny neuron subtype. Using the observed heterogeneity, as a second task, this project questions whether or not differences in individual neurons have an impact on the network dynamics. By clustering spiking activity from a neural network model, inconclusive results were found. Both algorithms indicating low heterogeneity, but by altering the quantity of a subtype between a low and high number, and clustering the network activity in each case, results indicate that there is an increase in the heterogeneity. This project shows a list of potential striatal subtypes and gives reasons to keep giving attention to biologically observed heterogeneity.

蛋白激酶CK2（Casine kinase 2）為四單體所構成，針對配受質蛋白之絲胺酸或蘇胺酸位置進行磷酸化，先前研究已經發現在紋狀體腦區之CK2的表現量與活性皆高於大腦中其餘腦區，而紋狀體腦區主要神經細胞為-氨基丁酸神經元（GABAergic neurons）的medium spiny neuron（MSN），會受到來自黑質多巴胺神經細胞（dopaminergic neurons）的調控。此外，DARPP-32（dopamine- and cAMP-regulated phosphoprotein, Mr 32 kDA）蛋白亦被發現大量表現於在MSN細胞中，且為CK2之受質蛋白質。雖然CK2已被證實參與多巴胺神經元的神經保護機制，但是否參與MSN細胞對運動行為調控之生理機制仍未清楚。由於已有研究發現施予1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）藥物處理造成黑質-紋狀體腦區受損之老鼠腦內-氨基丁酸（GABA）的生合成酵素─麩胺酸脫羧酵素67（GAD67）表現量與正常老鼠不同，因此本論文研究的主題擬在大鼠實驗模式中利用MPP+造成投射至紋狀體之多巴胺神經細胞受損，探討當多巴胺調控紋狀體神經細胞能力缺失的狀態下，MSN細胞之CK2、DARPP-32和GAD蛋白表現與動物運動行為之相關性。 實驗結果發現，直接於紋狀體給予1-甲基-4-苯基碘化啶 （MPP+ Iodide）皆會造成CK2、DARPP-32以及GAD67之蛋白質含量的減少，多巴胺及其代謝物和GABA等神經化學傳遞物質亦有減少的現象；另外，在MPP+給予前分別操弄CK2或DARPP-32 胺基酸Ser102磷酸化的表現，皆會改變GAD67蛋白質含量與黑質酪胺酸羥化酶（Tyrosine Hydroxylase, TH）蛋白質含量，同時神經化學傳遞物質的含量或代謝亦有改變。由現有之結果推測CK2/DARPP-32/GAD67細胞訊息傳遞機制可能參與巴金森氏症運動行為失常之細胞層面的調控。 / Protein kinase CK2 is a heterotetrameric and serine/threonine protein kinase. Its protein levels and activity are found to be elevated in the striatum when compared to other brain areas. CK2 is known to involve in the neuroprotective effects of dopaminergic neurons, whether it also regulates the neuronal function relative to motor behaviors is still unclear. DARPP-32 protein is known as one of the substrates for CK2 and is highly expressed in the GABAergic medium spiny neurons (MSN) responsible for dopamine stimulation in the striatum. Furthermore, other studies have indicated that the expression of glutamic acid decarboxylase 67 (GAD67) mRNA and protein was different in the striatum of MPTP vs. naïve animals, which is one of the enzymes responsible for the synthesis of neurotransmitter GABA. In the present study, we observed that the parallel changes in protein levels of CK2, DARPP-32 and GAD67 in the striatum and TH in the substantia nigra of MPP+-treated. We also found that manipulation of CK2 or DARPP-32 gene expression aggravated the MPP+-induced neuropathological dificts. The present results suggest that CK2/DARPP-32/GAD67 signaling pathway might involve in the cellular mechanism of motor-deficit in Parkinson’s disease.