| 摘要: | 中風(stroke)為全球第二大死因，可分為兩種類型，分別是缺血性中風以及出血性中風。其中缺血性中風約占所有中風患者的87%，發生原因是供應腦部的血流受到血液凝塊阻塞，導致局部的腦缺血。根據動物研究指出，阻斷Glutamate receptor的活化或抑制Glutamate的釋放皆可有效減少缺氧所誘發的神經受損。然而這種治療方式往往缺乏良好的專一性，進而干擾神經的再生並且誘發細胞凋亡，因而限制了在臨床上的應用。
先前文獻指出，不同品系的小鼠對於缺氧的耐受性也有所不同。因此我們提出了一個假說，是否有其他突觸的molecular targets比Glutamate receptor更能決定小鼠個體間缺氧耐受性差異。我們選擇了依缺氧耐受性由小到大的三種不同品系小鼠，分別為FVB, C57BL/6, BALB/c。我們發現了一個突觸骨架蛋白，Shank3，它可能是造成小鼠個體間，缺氧耐受性差異的因素。根據我們的實驗結果指出，不同品系的小鼠，其Shank3的表現量也有所不同，且Shank3的表現量與缺氧所造成的表象具有正相關。當缺氧發生時，Shank3的表現量越高，其腦梗塞面積、腦水腫程度，也就越嚴重，而神經發炎因子，像是：COX2, iNOS, IL-6, IL-10, 以及TNF-α的表現量也相對增加。同時，小鼠個體間Shank3表現量也與缺氧後所導致的神經功能性受損呈正相關。此外，在in vitro的loss-of-function實驗中，我們藉由lentiviruses表現shRNA或CrispR，進而抑制Shank3在primary culture neurons表現，我們進一步確認了Shank3在缺氧所導致的神經受損中扮演調控的角色。綜合以上結果，我們證實Shank3在小鼠個體間的缺氧耐受性中扮演重要的角色，並且此研究結果有將助於了解Shank3是否能做為新的中風治療標的。
Stroke, is the second leading cause of death in the world. There are two types of stroke which are ischemic stroke and hemorrhagic stroke. Ischemic stroke, which contributes to 87% of cases, is caused by the interruption or reduction of blood supply to the brain by blood clots and lead to lacking of regional blood flow. Accumulating evidence by experiments in rodents has indicated that blockade of glutamate receptors or inhibition in releasing of glutamate can significantly reduce the hypoxia induced neuronal damage. However, lack of target specificity is always the major concern of such therapeutic approach and it is usually followed by decrease in neurogenesis and increase in apoptotic cell death afterwards, which limits their practical application in clinic.
Since clinical experience indicated that everyone responses differently to the hypoxic challenge. We hypothesized that there might be some synaptic molecular targets other than glutamate receptors that could decide individual susceptibility to develop hypoxic phenotypes? By using three different strains of inbred mice which displayed increasing levels of hypoxic susceptibility from FVB, C57BL/6, to BALB/c, we identified a synaptic scaffolding protein: Shank3 may be a critical determining factor that decides individual hypoxic susceptibility. Our data indicated that Shank3 is differentially expressed in three distinct species of mice and there is a significant positive correlation between the Shank3 expression levels with the severity of hypoxia induced phenotypes. Specifically, the size of infarct area, cerebral edema and neuro-inflammatory molecules, such as COX2, iNOS, IL-6, IL-10, and TNF-α were profoundly increased in the animals with higher expression levels of Shank3. Meanwhile, individual expression level of Shank3 also correlated well with the functional neurological changes after hypoxic insults.
Furthermore, by in vitro loss-of-function studies with lentiviruses expressing shRNA or CrispR to silence Shank3 expression in primary culture neurons, we further confirmed the functional significance of Shank3 in hypoxia mediated neuronal damage. Our current study has validated the critical role of Shank3 in determining individual hypoxic susceptibility and may have the potential to provide a promising therapeutic strategy for ischemic stroke by targeting Shank3. |
