探討VPS13C基因和巴金森病的關聯性:針對粒線體的功能研究

Abstract

巴金森病(PD)是一種老年人的常見神經退行性疾病。PD的病理特徵包括黑質中含有α-突觸核蛋白組成的路易體積累和多巴胺能神經元(Dopaminergic neuron)的選擇性缺失。根據先前的研究，環境、衰老和遺傳是PD的危險因素。近期遺傳學的研究已經確定了幾個基因是罕見單基因形式PD的原因，這表明錯誤折疊蛋白質的積累、線粒體功能障礙、氧化應激增加、蛋白酶體降解和自噬/線粒體自噬受損以及突觸小泡運輸缺陷，參與了發病機制。VPS13C屬於對囊泡轉運至關重要的大型VPS13蛋白家族。VPS13C有保護粒線體功能的作用。VPS13C耗竭導致線粒體膜電位降低和線粒體超氧化物增加，引發不可逆的線粒體損傷。本研究探討八種中草藥提取物，在線粒體氧化磷酸化解偶聯劑(FCCP)處理的SH-SY5Y細胞中，增強線粒體功能的作用。其中鉤藤、山梔子、蘇木、黃芩和何首烏等五種中草藥提取物，在FCCP處理的SH-SY5Y細胞中，可增加細胞存活率、提升線粒體膜電位，及/或減少線粒體超氧化物。RNA干擾中介的VPS13C基因敲低，亦導致SH-SY5Y細胞存活率降低、線粒體膜電位下降和線粒體超氧化物增加。在TPA誘導多巴胺能分化、VPS13C敲低的SH-SY5Y細胞中，鉤藤、山梔子、黃芩提取物的處理，減少了乳酸脫氫酶的釋放和凋亡蛋白酶-3活性，並促進了神經突生長。此外，這三種中草藥提取物逆轉了VPS13C敲低導致的線粒體膜電位下降和線粒體超氧化物上升。該研究結果將證實VPS13C在PD發病機制中的作用，並為PD治療提供治療策略。Parkinson’s disease (PD) is a common neurodegenerative disorder affecting the elderly. The pathological features of PD include the accumulation of α-synuclein-containing Lewy bodies and selected loss of dopaminergic neurons in the substantia nigra. Environment, aging and genetics are reported risk factors of PD. Recently, genetic studies have identified several genes as the cause of rare monogenic forms of PD, suggesting that accumulation of misfolded proteins, mitochondrial dysfunction, increased oxidative stress, impaired proteasome degradation and autophagy/mitophagy, and deficits in synaptic vesicle trafficking are involved in the pathogenesis of PD. Vacuolar protein sorting 13 homolog C (VPS13C) belongs to a family of large VPS13 proteins crucial for vesicular transport. VPS13C also plays a role in mitochondrial maintenance. VPS13C depletion led to the reduction of mitochondrial membrane potential and increase of mitochondrial superoxide, triggering the irreversible mitochondrial damage. In this study, eight Chinese herbal extracts were examined for enhancing mitochondrial function in SH-SY5Y cells treated with carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), a potent mitochondrial oxidative phosphorylation uncoupler. Among them, five herbal extracts, U. rhynchophylla, G. jasminoides, C. sappan L., S. baicalensi and P. multiflorum, increased cell viability, elevated mitochondrial membrane potential, and/or reduced mitochondrial superoxide in FCCP-treated SH-SY5Y cells. Reduced cell viability, decreased mitochondrial membrane potential and increased mitochondrial superoxide were established in SH-SY5Y cells via RNA interference-directed VPS13C gene knockdown. In TPA-induced dopaminergic differentiation of SH-SY5Y cells with VPS13C knockdown, treatments of U. rhynchophylla, G. jasminoides and S. baicalensi reduced lactate dehydrogenase release and caspase-3 activity, and promoted neurite growth. In addition, these three herbal extracts reversed the impairment of decreased mitochondrial membrane potential and increased mitochondrial superoxide in VPS13C knockdown SH-SY5Y cells. The study results confirm the role of VPS13C in PD pathogenesis and provide a therapeutic strategy for PD treatment.