Spinal Müsküler Atrofi Hastalarının Fibroblast Kültürlerinde Mikrotübül Stabilitesinin Araştırılması

Abstract

Spinal muscular atrophy (SMA), which is characterized by motor neuron loss and muscle atrophy, is a neurodegenerative disease primarily in childhood. In SMA, Survival of motor neuron 1 (SMN1) gene mutations lead to the absence of functional SMN protein. SMN deficiency causes dysregulations in microtubule cytoskeleton in terms of polymerization and architecture, however, molecular mechanisms have not been clearly described. Previously, we showed reduced microtubule stability in an in-vitro SMA model, however, it has not been investigated in SMA patient samples so far. In this thesis, microtubule stability was investigated in fibroblast cells of SMA patients. For this purpose, we analyzed acetylated and detyrosinated α tubulin levels as stability markers in clinically different SMA patients. Western blot studies demonstrated a significant reduction in acetylated α tubulin level in SMA type I cells compared to controls. Similarly, immunofluorescence analysis also showed a reduction in the fluorescence intensity of acetylated α tubulin levels in patient cells. Additionally, the acetylated stable microtubule network has been shown to be impaired in type I patients cells. Considering that these alterations may affect cellular morphology and microtubule functions, detailed morphometric analyses were performed. Our results showed that patient cells, especially type I, were smaller both in width, height and area than controls. Besides, cell proliferation rates of patient cells were found to be increased compared to controls by MTS assay. In the light of all findings, it was concluded that the microtubule stability is reduced, especially in SMA type I patient cells. Functional consequences of reduced microtubule stability in SMA should be addressed in further studies.