Genetic analysis of a spontaneous mutation in a rat with a novel hind limb defect

新型后肢缺陷大鼠自发突变的遗传分析

• 批准号: 7658476
• 负责人: DEBASISH SINHA
• 金额: $ 24.6万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7658476
• 关键词: Accounting; Action Potentials; Affect; Afferent Neurons; Age; Animal Model; Animals; Apoptosis; Appearance; Atrophic; Axon; Birth; Body Weight; Brain; Breeding; Bromodeoxyuridine; Candidate Disease Gene; Cell Communication; Cell Nucleolus; Cerebral Ventricles; Chromosome Mapping; Chromosomes; Chromosomes, Human, Pair 1; Chromosomes, Human, Pair 10; Comorbidity; Crystallins; Cytoplasm; Data; Databases; Defect; Denervation; Development; Disease; Dorsal; Electron Microscopy; Evaluation; Exhibits; Exons; Eye; Female; Fibroblast Growth Factor Receptor 2; Gait; Gene Mutation; Genes; Genetic; Genome; Genotype; Health; Heterozygote; Homozygote; Human; In Situ Nick-End Labeling; Inherited; Label; Laboratories; Limb structure; Lod Score; Maps; Measures; Molecular; Motor; Motor Neurons; Muscle; Mutation; Names; Nature; Neural Conduction; Neurodevelopmental Disorder; Neuroglia; Neurologic; Neurons; Newborn Infant; Online Mendelian Inheritance In Man; Parents; Partner in relationship; Pathology; Pattern; Peripheral Nervous System Diseases; Phenotype; Poly-A Addition Site; RNA Splicing; Rana; Rattus; Relative (related person); Reverse Transcriptase Polymerase Chain Reaction; Rodent; Rotation; Schwann Cells; Site; Sprague-Dawley Rats; Structure of phrenic nerve; Study models; Techniques; Ventral Roots; Weight; Work; autosomal recessive trait; base; disability; gene function; genetic analysis; genetic linkage analysis; genome wide association study; interest; juvenile animal; mRNA Expression; male; mouse genome; mutant; novel; public health relevance; rat genome; sciatic nerve; spinal nerve posterior root; sural; sural nerve; tool

DESCRIPTION (provided by applicant): We describe here a novel rat mutant that arose spontaneously from a mating of two Sprague Dawley rats in a colony that we maintain to study another mutation, Nuc1. Nuc1 is an eye-specific phenotype with developmental abnormalities that we have been investigating for several years. Hind limbs of the new mutant animals are extended and abducted so severely that they do not effectively support the animal's weight. Because of this unusual appearance and gait anomaly, we have named the mutant strain frogleg. The brain of a frogleg rat is smaller in size and weight relative to normal littermates; however body weight, which is typically lower in the affected newborn rats, does catch up to normal after several months. Histological analysis of frogleg sciatic nerve revealed some abnormal changes in Schwann cells. Neurometric studies also showed that sciatic compound muscle action potential is significantly reduced in frogleg rats. Attempts to breed frogleg animals with each other or with phenotypically normal males and females were unsuccessful. Carrying the line was complicated by the absence of a heterozygote phenotype. We were able to perpetuate the frogleg line by breeding unaffected littermates of frogleg rats in random combination until specific matings produced frogleg progeny, thereby identifying the parents as heterozygotes. We have established that the condition is inherited in a Mendelian fashion as a single autosomal recessive trait, and have used genetic linkage analysis to map the gene to rat chromosome 1q36-37. This disease interval has been reduced to a chromosomal region of 2.7 Mbp. Based on the Reference Sequence annotation database for the most current rat genome assembly, there are 8 potential frogleg gene candidates. However, augmentation of this number by alignment with syntenic portions of the human and mouse genomes increases the total number of genes in the interval to approximately 19. In the current application, we seek to identify the gene and the specific mutation responsible for the frogleg phenotype. In addition we will better characterize the neurological abnormalities of frogleg rats. Knowing the gene's identity and the nature of the mutation will help us to further understand the molecular and cellular mechanisms responsible for this interesting phenotype. Our working hypothesis is that identification of the mutation and the gene responsible for the frogleg phenotype will provide a novel model for studying cellular and molecular mechanisms of neurodevelopmental disorders. Therefore, we propose the following aims: SPECIFIC AIM 1: To refine the linkage map of the frogleg locus. SPECIFIC AIM 2: To identify the frogleg gene and mutation. SPECIFIC AIM 3: To characterize the pathology that underlies the phenotype of the frogleg rat. The identification of the gene responsible for frogleg would be a major step toward defining the potential value of the model for the study of mechanisms involved in neurodevelopmental disorders. PUBLIC HEALTH RELEVANCE: The frogleg rat is a novel spontaneous mutant with a well-defined hind limb disability. This defect is neurological in origin. With the identification of the gene and specific mutation, the frogleg rat will become a valuable animal model for the study of neurodevelopmental disorders.

描述（由申请人提供）：我们在这里描述了一种新型的大鼠突变体，该突变体是由两只sprague dawley大鼠在一个菌落中自发产生的，我们维持研究另一个突变，nuc1。 NUC1是一种具有发育异常的眼科特异性表型，我们已经研究了几年。新型突变动物的后肢被延伸并绑架了，以至于它们没有有效地支持动物的体重。由于这种不寻常的外观和步态异常，我们将突变菌株的菌群命名为Frogleg。相对于正常同窝仔的大鼠的大脑的大小和重量较小。但是，在受影响的新生大鼠中通常较低的体重确实会在几个月后赶上正常。 Frogleg坐骨神经的组织学分析显示，雪旺细胞的一些异常变化。神经计量学研究还表明，菌群大鼠的坐骨神经能复合肌肉作用电位显着降低。试图彼此或表型正常的男性和女性繁殖蛙血动物的尝试失败了。由于没有杂合子表型，携带这条线很复杂。我们能够通过随机组合繁殖未受影响的Frogleg大鼠的同窝窝来使Frogleg系列永久化，直到特定的分配产生了Frogleg后代，从而将父母识别为杂合子。我们已经确定，这种情况是以孟德尔的方式遗传为单个常染色体隐性特征，并使用遗传链接分析将基因映射到大鼠1q36-37染色体。该疾病间隔已减少为2.7 Mbp的染色体区域。基于最新大鼠基因组组装的参考序列注释数据库，有8个潜在的蛙基因候选物。但是，通过与人类和小鼠基因组的同步部分对齐来增加该数量的数量会使间隔中的基因总数增加到大约19个。在当前应用中，我们试图识别造成Frogleg表型的基因和特定的突变。此外，我们将更好地表征蛙leg大鼠的神经系统异常。了解该基因的身份和突变的性质将有助于我们进一步理解负责这种有趣表型的分子和细胞机制。我们的工作假设是，鉴定突变和负责Frogleg表型的基因将为研究神经发育障碍的细胞和分子机制提供新的模型。因此，我们提出以下目的：特定目的1：完善Frogleg基因座的链接图。特定目的2：识别蛙基因和突变。特定目的3：表征基础蛙大鼠表型的病理。鉴定负责Frogleg的基因将是定义模型研究中涉及神经发育疾病机制的潜在价值的主要步骤。 公共卫生相关性：Frogleg大鼠是一种新型自发突变体，具有明确的后肢残疾。这种缺陷是神经系统的。通过鉴定基因和特异性突变，Frogleg大鼠将成为研究神经发育疾病的宝贵动物模型。