本文選題：Mitf-M基因　切入點：基因突變　出處：《中國人民解放軍醫(yī)學(xué)院》2013年博士論文　論文類型：學(xué)位論文

【摘要】：小眼畸形相關(guān)轉(zhuǎn)錄因子（Mitf）是由Mitf基因編碼的一個擁有堿性螺旋-環(huán)-螺旋拉鏈（basic helix-loop-helix zipper，bHLH-Zip)結(jié)構(gòu)的轉(zhuǎn)錄因子[1]。Mitf調(diào)控著許多細(xì)胞的分化，如黑色素細(xì)胞，視杯來源的視網(wǎng)膜色素上皮細(xì)胞（RPE）以及許多類型的骨髓來源的細(xì)胞[2]。根據(jù)氨基末端的不同，Mitf包含至少5種基因亞型，每種亞型的啟動子以及起始外顯子都不同，，并且表達在不同的組織中，而Mitf-M特異性表達在黑色素細(xì)胞和黑色素瘤細(xì)胞中[3-7]。 人類的Waardenburg綜合征是一種以聽覺-色素異常為特點的常染色體顯性遺傳疾病，占先天性耳聾的2%[8]。按臨床特征和遺傳標(biāo)準(zhǔn)共分為四種亞型。其中Waardenburg綜合征2A型及其嚴(yán)重類型Tietz綜合征是由MITF-M基因突變引起的，表現(xiàn)為感音神經(jīng)性耳聾、虹膜異色和白色額發(fā)[9]。盡管大量研究已經(jīng)證明Mitf-M基因突變將導(dǎo)致神經(jīng)嵴來源的黑色素細(xì)胞缺失，最終產(chǎn)生耳聾等癥狀，但是Mitf基因?qū)β犛X系統(tǒng)的作用及其分子病理機制至今未明[10]。因此，仔細(xì)研究此亞型Mitf基因的結(jié)構(gòu)和功能對于耳聾的基因診斷和分子病理機制研究是很重要的。 本研究通過建立正常榮昌豬內(nèi)耳解剖、手術(shù)方式以及形態(tài)、聽功能數(shù)據(jù)庫，發(fā)現(xiàn)豬的內(nèi)耳和人類及其他動物相比在功能和形態(tài)上既具有相似性又存在差異，為下一步研究白化耳聾榮昌豬奠定了基礎(chǔ)；通過對白化耳聾榮昌豬進行家系構(gòu)建和基因分析，確定精確的致病基因為Mitf-M基因，使得此耳聾動物家系遺傳背景清楚，可以作為耳聾疾病的大型哺乳動物模型應(yīng)用于耳科領(lǐng)域的研究；利用從胚胎到出生后不同發(fā)育階段的自發(fā)突變型白化榮昌豬（Mitf-/-）和正常野生型榮昌豬（Mitf+/+）內(nèi)耳形態(tài)學(xué)和聽功能的比較分析，發(fā)現(xiàn)白化榮昌豬的耳聾是由Mitf-M基因突變導(dǎo)致內(nèi)耳血管紋病理變化引起的，最終引發(fā)血管紋中間細(xì)胞消失，內(nèi)耳鉀離子濃度和耳蝸內(nèi)電位的變化，導(dǎo)致ABR異常，聽功能喪失，闡述了Mitf-M基因突變引發(fā)耳聾的病理機制。使我們進一步明確了胚胎發(fā)育過程中Mitf-M對血管紋和黑色素細(xì)胞發(fā)生作用的關(guān)鍵時間點和變化規(guī)律。這可能也是人類Waardenburg綜合征2A型及Tietz綜合征所致耳聾癥狀的原因。為研究人類Waardenburg綜合征2A型感音神經(jīng)性耳聾的早期基因干預(yù)治療、人工聽力重建、毛細(xì)胞再生等提供了重要的基礎(chǔ)數(shù)據(jù)，為人類Waardenburg綜合征2A型耳聾的研究提供了理想的大型哺乳動物模型。 本研究的重要發(fā)現(xiàn)及其意義： 1.首次報道了正常榮昌豬內(nèi)耳超微結(jié)構(gòu)； 2.首次發(fā)現(xiàn)了白化榮昌豬的耳聾表型與人類Waardenburg綜合征2A型Mitf-M基因突變導(dǎo)致的耳聾表型一致； 3.首次報道了Mitf-M基因突變與白化榮昌豬內(nèi)耳血管紋病理變化的關(guān)系； 4.揭示了Waardenburg綜合征2A型發(fā)病的分子病理機制。
[Abstract]:Microocular deformation-associated transcription factor (Mitf) is a transcription factor with basic helix-loop-helix zipperbHLH-Zipp structure encoded by the Mitf gene. [1] .Mitf regulates the differentiation of many cells, such as melanocytes. Retinal pigment epithelial cells (RPEs) and many types of bone marrow-derived cells [2]. Different amino terminal mitf contains at least five gene subtypes, each of which has different promoters and initial exons. And expressed in different tissues, while Mitf-M was specifically expressed in melanocytes and melanoma cells [3-7]. Human Waardenburg syndrome is an autosomal dominant genetic disease characterized by acoustic-pigment abnormalities. 2% patients with congenital deafness were divided into four subtypes according to clinical characteristics and genetic criteria. Type 2A of Waardenburg syndrome and its severe type Tietz syndrome were caused by mutation of MITF-M gene and presented as sensorineural deafness. Iris heterochromatic and white frontalis [9] .Although a large number of studies have shown that mutations in the Mitf-M gene can lead to the deletion of melanocytes from neural crest, resulting in deafness and other symptoms, However, the role of Mitf gene in the auditory system and its molecular pathological mechanism have not been clarified. Therefore, it is important to study the structure and function of this subtype of Mitf gene for gene diagnosis and molecular pathological mechanism of deafness. In this study, we established the normal Rong Chang pig inner ear anatomy, operation method and shape, auditory function database, found that pig inner ear compared with human and other animals in the function and morphology of both similarities and differences. It lays a foundation for the further study of Rongchang pig with albino deafness, and through the family construction and gene analysis of Rongchang pig with albino deafness, it is determined that the exact pathogenic gene is Mitf-M gene, which makes the genetic background of this deafness animal family clear. It can be used as a large mammal model of deafness disease in the field of otology. The inner ear morphology and auditory function of Mitf-r / -) and Mitf /) of spontaneous mutant Rongchang albino from embryo to postnatal development stage were compared and analyzed. It was found that the deafness of Rongchang pig was caused by the pathological changes of the vascular stria of the inner ear caused by the mutation of Mitf-M gene, and the disappearance of the middle cell of the stria vascularis, the change of the concentration of potassium ion in the inner ear and the change of the potential in the cochlea, which resulted in the abnormality of ABR and the loss of auditory function. The pathological mechanism of deafness caused by mutation of Mitf-M gene was expounded. The key time point and change rule of Mitf-M on stria vascularis and melanocytes during embryonic development were further clarified. This may also be the ensemble of human Waardenburg. In order to study the early gene intervention therapy of human Waardenburg syndrome type 2A sensorineural deafness, the causes of deafness caused by type 2A syndromes and Tietz syndrome were studied. Artificial hearing reconstruction and hair cell regeneration provide important data for the study of human Waardenburg syndrome type 2A deafness and provide an ideal large mammal model. The important findings of this study and its significance:. 1. The ultrastructure of the inner ear of the normal Rongchang pig was reported for the first time. 2. The deafness phenotype of Rongchang albino pig was found to be consistent with the deafness phenotype caused by the mutation of Mitf-M gene of human Waardenburg syndrome type 2A for the first time. 3. The relationship between the mutation of Mitf-M gene and the pathological changes of vascular stria in the inner ear of Rongchang pig was reported for the first time. 4. The molecular pathological mechanism of type 2A of Waardenburg syndrome was revealed.
【學(xué)位授予單位】：中國人民解放軍醫(yī)學(xué)院
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：R764.43

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