Developmental Dyslexia (DD) refers to a reading disorder affecting individuals that possess otherwise normal intelligence. Having demonstrated by familial and twin studies, genetic factors are found to be of major significance to DD development. A strong dyslexia susceptibility gene KIAA0319 (K), of which crucial role in DD had been revealed by various linkage and association studies, was found to have 40% reduction in expression in the DD risk haplotype. Besides, both up- and down-regulation of K would result in impaired neuronal migration in rat. Despite the undoubtedly strong linkage of K to DD, biological and molecular knowledge of K is still lacking. Consequently, how K plays its role in DD remains unclear. To address this question, investigations of human K protein and its interactions in molecular level were performed. K protein is a large transmembrane protein which consists of four main parts, including the N-terminus of K which has a MANSC domain downstream of the signal peptide, a large cluster of five PKD domains in the middle of the protein sequence, a Cysteine -rich C6 region together with a transmembrane domain which had been demonstrated to be critical for forming K protein homodimer, and the only cytoplasmic C-terminus of K. Having shown that no gross effect on gene expression at both mRNA and protein level was found with overexpressing K by DNA microarray and two-dimensional gel electrophoresis, protein interactions involving K were targeted for investigation. Towards this goal, a monoclonal antibody against K was raised, which is capable for recognizing native full-length K proteins in immunoblotting, indirect immunofluorescence staining, as well as in immunoprecipitation. A novel K interaction partner protein KIAA0319-Like (KL), which is a homologous protein of K with high sequence similarity (59%), has been found and confirmed by co-immunoprecipitation. No interaction was shown for truncation mutants of Cysteine-rich C6 region in either K or KL proteins, cuing that the interaction of K and KL at C6 region is a mimic of K homodimer, and led to a hypothesis that the function of K is regulated by KL, which serves as a molecular control of neuronal migration by regulating the formation of K dimer. Another known interaction partner of K protein, the mu---subunit of Adaptor protein 2 complex (AP2M1) which binds to cytoplasmic C-terminus of K (55% similarity to that of KL), was found to have similar binding behaviour towards K as well as KL by co-immunoprecipitation and molecular docking. In addition to AP2M1, two adaptor proteins FEM and SH2 were also confirmed to be interacting with cytoplasmic C-terminus of K, suggested that cytoplasmic region of K is responsible for interactions of downstream cellular pathways. Interaction of K with adaptor proteins also suggested that K might be a membrane receptor that mediates signalling via various adapter proteins. The N-terminus of K protein which has the least sequence similarity to KL (31%) is hence thought to confer to the specificity of the receptor and is critical to the function of K in DD. / Chan, Hoi Ling. / Adviser: Mary M. Y. Waye. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 164-170). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344549 |
| Date | January 2010 |
| Contributors | Chan, Hoi Ling., Chinese University of Hong Kong Graduate School. Division of Life Sciences. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xv, 188 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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