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首页> 外文学位 >Essential roles for transcription factor AP-2alpha and cadherin-mediated cell adhesion in lens vesicle separation and maintenance of the lens epithelial cell phenotype.
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Essential roles for transcription factor AP-2alpha and cadherin-mediated cell adhesion in lens vesicle separation and maintenance of the lens epithelial cell phenotype.

机译：转录因子AP-2alpha和钙黏着蛋白介导的细胞粘附在晶状体囊泡分离和维持晶状体上皮细胞表型中的重要作用。

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摘要

Our lab has previously implicated transcription factor, activating protein-2alpha (AP-2alpha), in the some of the key events leading to vertebrate lens morphogenesis. However, as a result of the overt craniofacial defects that these mice also possess, the possibility of secondary effects arising from these defects could not be ruled out. Thus, the focus of this study is to determine the cell-autonomous requirement(s) for AP-2alpha during lens development.;Thus, the data presented here demonstrate that AP-2alpha-mediated disregulation of cadherin molecules negatively impacts lens vesicle separation and leads to an alteration in the lens epithelial cell phenotype.;To address this specific aim, I have conditionally inactivated AP-2alpha in the developing mouse surface ectoderm (Le-AP-2alpha mutants) using the Cre/loxP recombination approach. Embryonic and adult Le-AP-2alpha mutants exhibited defects confined to presumptive lens ectoderm derivatives, including a persistent adhesion of the lens to the overlying corneal epithelium (or lens stalk). This failure in lens vesicle separation from the embryonic surface ectoderm was correlated with reduced expression of the calcium dependent cell adhesion molecule, E-cadherin. Microarray analysis confirmed this finding and also suggested that AP-2alpha also plays an important role in maintaining the lens epithelial cell phenotype. Furthermore, other cadherin molecules expressed within the developing lens (N and P) were found to be misexpressed in the lens stalk of Le-AP-2alpha mice. In order to implicate a loss of E-cadherin with a deregulation in cell sorting leading to failure in lens vesicle separation, E-cadherin was also conditionally inactivated within the developing embryonic mouse lens. Embryonic and adult E-cadherin conditional mutant mice failed to exhibit any corneal-lenticular adhesions, suggesting that E-cadherin alone does not mediate lens vesicle separation. However, these conditional mutants did exhibit severe structural deficits, including microphthalmia, persistent vacuolization within the fibre cell region, and eventual deterioration of the anterior lens epithelium. Additionally, an abnormal disruption in zonula occludens-1 expression and an increase in alpha-smooth muscle actin expression were observed indicative of defects in cell polarity and differentiation. These studies indicate that a loss of E-cadherin alone does not disregulate lens vesicle separation during development but does have an impact on the differentiative state of lens epithelial cells. Considering, N-cadherin was still expressed in the E-cadherin conditional knockout mice, the possibility of cadherin compensation during lens separation could not be ruled out. To determine the co-requirement of both E-cadherin and N-cadherin within the developing lens, a double conditional knockout of these cadherins was performed. These mice possessed distinct defects in lens separation characterized by the retention of P-cadherin expression within the cells lining the lens stalk region. These double mutant lenses also exhibited severe defects in lens epithelial cell adhesion and survival, as lens epithelial cells underwent detachment-induced apoptosis (anoikis). The data presented in this study suggest that both E- and N-cadherin are required for normal lens vesicle separation and that the number of functional cadherin alleles has a significant impact on the growth of the lens.
机译：在导致脊椎动物晶状体形态发生的一些关键事件中，我们的实验室先前牵涉到转录因子激活蛋白2alpha（AP-2alpha）。但是，由于这些小鼠也存在明显的颅面缺陷，因此不能排除由这些缺陷引起的继发效应的可能性。因此，本研究的重点是确定晶状体发育过程中AP-2alpha的细胞自主需求。因此，此处提供的数据证明AP-2alpha介导的钙黏着蛋白分子失调对晶状体囊泡分离产生负面影响。导致晶状体上皮细胞表型的改变。为了解决这一特定目标，我使用Cre / loxP重组方法在发育中的小鼠表面外胚层（Le-AP-2alpha突变体）中有条件地灭活了AP-2alpha。胚胎和成年Le-AP-2alpha突变体表现出局限在推测的晶状体外胚层衍生物中，包括晶状体与上层角膜上皮（或晶状体柄）的持久粘附。从胚表面外胚层分离晶状体囊泡的失败与钙依赖性细胞粘附分子E-钙粘蛋白的表达降低有关。微阵列分析证实了这一发现，并且还表明AP-2alpha在维持晶状体上皮细胞表型中也起着重要作用。此外，发现在发育中的晶状体（N和P）中表达的其他钙黏着蛋白分子在Le-AP-2alpha小鼠的晶状体茎中表达不正确。为了暗示E-钙粘着蛋白的丧失与细胞分选中的失调导致晶状体囊泡分离失败，在发育中的胚胎小鼠晶状体中也有条件地使E-钙粘着蛋白失活。胚胎和成年E-钙粘蛋白条件突变小鼠均未表现出任何角膜-透镜粘附，提示仅E-钙粘蛋白不能介导晶状体囊泡分离。然而，这些条件突变体确实表现出严重的结构缺陷，包括小眼症，纤维细胞区域​​内持续的空泡化以及最终的前晶状体上皮退化。此外，观察到小带咬合蛋白-1表达的异常破坏和α-平滑肌肌动蛋白表达的增加表明细胞极性和分化的缺陷。这些研究表明，单独的E-钙粘蛋白的损失不会在发育过程中使晶状体囊泡分离失调，但会影响晶状体上皮细胞的分化状态。考虑到，在钙粘蛋白条件性敲除小鼠中仍表达N-钙粘蛋白，因此不能排除在晶状体分离过程中钙粘蛋白补偿的可能性。为了确定显影透镜中E-钙粘着蛋白和N-钙粘着蛋白的共同需求，对这些钙粘着蛋白进行了双重条件剔除。这些小鼠在晶状体分离中具有明显的缺陷，其特征在于在晶状体茎区域内衬的细胞内保留了P-钙粘着蛋白表达。这些双突变体晶状体还表现出晶状体上皮细胞粘附和存活方面的严重缺陷，因为晶状体上皮细胞经历了脱离诱导的凋亡（凋亡）。这项研究中提供的数据表明正常晶状体囊泡分离需要E-和N-钙粘蛋白，而功能性钙粘蛋白等位基因的数量对晶状体的生长有重要影响。

著录项

  • 作者

    Pontoriero, Giuseppe.;

  • 作者单位

    McMaster University (Canada).;

  • 授予单位 McMaster University (Canada).;
  • 学科 Biology Genetics.;Health Sciences Human Development.;Health Sciences Ophthalmology.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 150 p.
  • 总页数 150
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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