High-throughput Screening for Novel Compounds Which Increase the SMN2 mRNA Exon7 Inclusion in Spinal Muscular Atrophy Cells
| Autor: | Wei-Ling Cheng, 鄭惟齡 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 Spinal muscular atrophy (SMA) is an autosomal recessive disorder that is one of the leading hereditary causes of infantile mortality in the world. SMA is characterized by the degeneration of moton neurons in the anterior horn of spinal cord, resulting in progressive muscle atrophy and paralysis. SMA is caused by reduced levels of SMN (survival motor neuron) full-length (FL) protein as a result of deletion or mutation of the SMN1 gene. SMN protein can be expressed from two nearly identical genes, SMN1 and SMN2. An important difference between these two genes is a single nucleotide change on exon 7. As a result, the majority of the transcript from SMN2 lacks exon 7, thus producing an SMN truncated (TR) mRNA and protein. Because SMA patients carry at least one SMN2 gene, drug stimulation of SMN2 gene to produce more FL SMN protein is a feasible treatment for SMA. Increase of FL SMN protein expression can be achieved by promoting SMN2 gene transcription or by modulating SMN2 mRNA splicing. Several compounds were described to increase SMN protein levels in cells derived from SMA patients, but most of these compounds were not suitable for SMA therapy due to their toxicity and side-effects. In order to develop more specific and safe drugs, we have already established a high-throughput HeLa cell system which can be used to screen for drugs that modulate SMN2 mRNA splicing. In addition, we have also established a similar system in NSC34 motoneuron cells which can be used to screen for drugs that function in motoneurons. Using the above systems, we have already screened 248 compounds, including synthetic chemicals and compounds extracted from Chinese herbal medicine. Three potential compounds, #39, #49 and #91, have been selected and further tested in the lymphoid cell lines from SMA patients. One of these compounds, #91, can increase the expression of SMN FL mRNA and protein, and also the number of gems in SMA cells. The compound #91 was identified as securinine, an alkaloid extracted from Securinega suffruticosa. Our finding adds a new category to the list of potential SMA drugs. In the future we will analyze similar compounds or derivatives of securinine to develop more SMA drug(s) with less toxicity and better efficacy. These potential drugs will then be tested in SMA mouse model and human clinical trial. We hope the new drugs will amend the quality of SMA patients’ lives and successfully provide therapeutics for SMA. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|