Function of LIM-domain Transcriptional Regulators in Inner Ear Development

LIM 结构域转录调节因子在内耳发育中的功能

• 批准号: 7826716
• 负责人: Lin Gan
• 金额: $ 32.4万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-03-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7826716
• 关键词: Abbreviations; Adult; Affect; Apoptosis; Cell Differentiation process; Cells; Cochlea; Color; Competence; Data; Development; Disease; Distal; Ectopic Expression; Embryo; Epithelial; Epithelium; Figs - dietary; Ganglia; Genes; Hair Cells; Helix-Turn-Helix Motifs; Inner Hair Cells; Knock-in Mouse; Knockout Mice; Knowledge; LIM Domain; Labyrinth; LacZ Genes; Lead; Maintenance; Medial; Modeling; Molecular; Mouse Strains; Mus; Myxoid cyst; Natural regeneration; Neurons; Organ; Organ of Corti; Outer Hair Cells; Pattern; Primordium; Process; Proteins; Regulation; Relative (related person); Reporter Genes; Rhombotin 2; Role; Sensory; Staging; Supporting Cell; Testing; Tissues; Transcriptional Regulation; United States; Utricular macula; Vestibule; base; competence factor; deafness; ganglion cell; hair cell regeneration; hearing impairment; homeodomain; insight; neuron development; novel strategies; null mutation; prevent; programs; protein function; public health relevance; stem; transcription factor

DESCRIPTION (provided by applicant): A major cause of deafness disorders stem from the degeneration of hair cells within the inner ear although in many cases the mechanisms underlying these disorders is not understood. By defining the mechanisms controlling normal hair cell development, we will gain a better understanding of how these processes are disrupted in pathological situations and how the hair cells can be regenerated. The central hypothesis of this proposal is that the expression of the LIM-homeodomain transcription factor Isl1 provides the ventral cochlear epithelium with a competence to form the sensory organ and that the negative regulation of Isl1 function by the LIM-domain-only transcriptional regulators LMO3 and LMO4 restricts the competence to the presumptive OC (OC) region. In our preliminary studies, we have shown that during the sensory development in the cochlea at E12.5 to E16.5, Isl1 is expressed in a broad domain in the ventral cochlear epithelium, including the presumptive OC. Interestingly, the expression of LMO3 is detected in the lesser epithelial ridge (LER), whereas LMO4 expression is confined to the greater epithelial ridge (GER) and to the distal LER (dLER). The combined LMO3 and LMO4 expression domain overlaps with that of Isl1 except in the presumptive OC region where Isl1 is expressed alone. Consistent with our hypothesis, we have shown that loss of LMO4 results in the formation of supernumerary hair cells in the dLER, confirming a role for LMO4 as a negative regulator of sensory organ development. Thus, based on the established roles of LMO proteins in inhibiting LIM-HD proteins' function in transcriptional regulation, the combined action of Isl1, LMO3 and LMO4 could determine the formation of the OC region. In order to test this hypothesis and investigate the roles of LIM-domain factors in the inner ear development, we propose the following three specific aims: 1). To determine the requirement for LMO4 in the sensory and neuronal development in the cochlea and vestibule by targeted disruption of LMO4; 2). To determine whether the ectopic expression of LMO4 in the presumptive prosensory region represses the sensory development by the conditional activation of LMO4 expression in the Isl1-expressing cells; and 3). To determine the role of Isl1 in the sensory and neuronal development of the inner ear by the conditional deletion of Isl1. PUBLIC HEALTH RELEVANCE Loss of the inner ear hair cells in the organ of Corti is the leading cause of hearing loss that affects 278 million people worldwide, including 28 million in the United States. However, since the loss of hair cells is an irreversible process and mammalian inner ear lacks the capability to regenerate hair cells, effective remedies to replace hair cells remain elusive. The studies proposed in this application will provide new insights into the molecular mechanisms underlying the sensory organ formation in the inner ear and could lead to novel approaches in the treatment and eventual cure of deafness by de novo hair cell regeneration. The central hypothesis of this proposal is that the expression of the LIM-homeodomain transcription factor provides the ventral cochlear epithelium with the competence to form the sensory organ and that the LIM-domain-only transcriptional regulators suppress the role of LIM-homeodomain factor in the ventral cochlea except the presumptive organ of Corti region. Thus, the combined function of LIM-homeodomain and LIM-domain-only factors regulates the competence in the ventral cochlear epithelium and determines the region of the presumptive organ of Corti.

描述（由申请人提供）：聋哑疾病的主要原因源于内耳内部毛细胞的变性，尽管在许多情况下，这些疾病的机制尚不清楚。通过定义控制正常毛细胞发育的机制，我们将更好地理解这些过程在病理情况下如何破坏这些过程以及如何再生毛细胞。该提议的核心假设是，林 - 美分域转录因子ISL1的表达为腹侧耳蜗上皮提供了形成感觉器官的能力，并且由唯一的单粒转录调节剂对ISL1功能的负调控限制了lmo4和LMO4的能力LMO4和LMO 4限制了Parsumptive oc（Ocumptive oc）。在我们的初步研究中，我们表明，在耳蜗的感官发育期间，E12.5至E16.5，ISL1在腹侧人工耳蜗上皮的一个宽区域中表达，包括推定OC。有趣的是，在较小的上皮脊（LER）中检测到LMO3的表达，而LMO4表达局限于更大的上皮脊（GER）和远端LER（DLER）。除了单独表达ISL1的推定OC区域外，LMO3和LMO4表达域与ISL1的表达结构域重叠。与我们的假设一致，我们表明LMO4的丧失导致DLER中的超毛细胞形成，这证实了LMO4作为感觉器官发育的负调节剂的作用。因此，基于LMO蛋白在抑制LIM-HD蛋白在转录调控中的功能中的确定作用，ISL1，LMO3和LMO4的合并作用可以确定OC区域的形成。为了检验这一假设并研究Lim域因子在内耳发育中的作用，我们提出以下三个特定目的：1）。通过针对LMO4的靶向破坏来确定耳蜗和前庭的感觉和神经元发育中LMO4的需求； 2）。确定LMO4在假设区域中的异位表达是否通过在表达ISL1表达细胞中的LMO4表达的条件激活来抑制感觉发育；和3）。确定ISL1通过ISL1的条件缺失在内耳的感觉和神经元发展中的作用。 Corti器官内耳毛细胞的公共卫生相关性丧失是听力损失的主要原因，影响了全球2.78亿人，其中包括美国的2800万。但是，由于毛细胞的丧失是一个不可逆的过程，哺乳动物的内耳缺乏再生毛细胞的能力，因此有效替代毛细胞的有效疗法仍然难以捉摸。本应用中提出的研究将为内耳中感觉器官形成的分子机制提供新的见解，并可能导致从头毛细胞再生对耳聋的治疗和最终治愈的新方法。该提案的中心假设是，林 - 整合域转录因子的表达提供了腹侧人工耳蜗的上皮，具有形成感觉器官的能力，并且仅由lim域的仅转录调节剂抑制了lim骨共构域因子在腹侧耳蜗中的作用。因此，Lim-Homeodomain和仅限域域的组合功能调节腹侧耳蜗上皮的能力，并确定Corti推定器官的区域。