Although early studies on HCR provided valuable information for its characterization, the functions of HCR remain unclear. / In addition, we also isolated HCR partners in keratinocyte using a yeast two-hybrid screening. Two novel HCR partners, keratin 17 and nm23-H2, were identified. Since the expression of keratin 17 in epidermis has been recognized as a hallmark of psoriatic plaques, our findings support HCR as a candidate gene for psoriasis susceptibility. We speculate that nm23-H2 is involved in endocytosis together with HCR because nm23 also participated in endocytotic pathways. / In this study, we attempted to relate the function of HCR gene to its role in the pathogenesis of psoriasis. We first examined the subcellular localization of HCR. From a series of co-localization experiments, we eventually localized HCR in early endosomes because almost completely overlapped with active Rab4 which regulates vesicle traffic from early endosomes to perinuclear recycling endosomes and to the plasma membrane indicating that HCR may regulate sorting of internalized cargo from early endosomes to the recycling endosomes or back to the cytoplasm. / Psoriasis is a common chronic skin disorder affecting approximately 1-2% of the Caucasian population. A genetic basis for psoriasis susceptibility has been determined, however, the genetic influence of psoriasis is complex. Several genetic linkage studies have been identified. PSORS1 at 6p21.3 which has been narrowed down to a few hundred kilobase intervals around the HLA-C is the most consistently observed susceptibility locus for psoriasis in both linkage analyses and genome wide scans. HCR is a candidate gene lying within the HLA region which was previously named PG8 for 'putative gene 8' and is now more commonly called HCR for 'alpha-helix coiled-coil rod homolog'. The HCR gene is highly polymorphic. SNP association analysis showed that one SNP haplotype, named HCR*WWCC (corresponding to SNPs at nucleotides 307, 325, 1723, 2327, and involving amino acids 103, 109, 575 and 776, respectively), was associated with psoriasis. Early studies showed that the protein was confined to basal keratinocytes in healthy and non-lesional skin, whereas, it was expressed above the tips of basal and suprabasal dermal papillae in psoriatic lesional skin. / Li, Chunman. / "November 2005." / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 0810. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 137-149). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / School code: 1307.