Ubiquitin C-terminal hydrolase L1 (UCHL1) is a multifunctional protein primarily expressed in neuronal cells and involved in numerous cellular processes. UCHL1 has been linked with neurodegenerative diseases and a wide range of cancers but its specific role remains unknown. Previous UCHL1 knockdown studies have shown that UCHL1 controls the expression of pro- and anti-apoptotic genes as well as genes involved in cell cycle regulation but it is unknown how UCHL1 regulates these genes. We have shown that UCHL1 is cross-linked to DNA in DU145 but not in LNCaP or PC3 prostate cancer cells. Therefore, we hypothesized that UCHL1 regulates the expression of pro- or anti-apoptotic genes as well as the genes involved in the cell cycle through its interaction with DNA. By utilizing ChIP and ChIP-seq analyses it is possible to determine the UCHL1 target sequences on the genomic DNA. It was shown that UCHL1 is only expressed in DU145 but not in LNCaP, PC3 or C4-2 prostate cancer cell lines. Additionally, UCHL1 is expressed and cross-linked to DNA in HEK293T cells. It is believed that UCHL1 is silenced by upstream promoter methylation when it is not expressed. However, treatment with the epigenetic drugs 5-aza-2′-deoxycytidine and trichostatin A (TSA) did not result in induction of UCHL1 expression in LNCaP, PC3 or C4-2 prostate cancer cell lines. UCHL1 is also associated with p53. However, ChIP assay results have shown that UCHL1 and p53 do not bind to genomic DNA of upstream promoter regions CDKN1A and BAX genes. Additionally, through UCHL1 ChIP-seq analyses in DU145 and HEK293T cells, we discovered that UCHL1 co-localizes to the DNA with the shelterin complex shedding light on a new role of UCHL1 that has never been described before. / October 2014

<p>The Deubiquitinating (DUB) enzymes, LotA and UCHL1 R178Q, were examined biochemically and also structurally in the case of UCHL1 R178Q. LotA is a bacterial effector of <i>Legionella pneumophila</i> that enables the pathogen to establish a replicative niche. LotA has two Deubiquitinase (DUB) domains specific to different substrates. Here, I report biochemical examinations the first DUB domain that is specific to Lys6-linked di-ubiquitin. Michaelis- Menten kinetic parameters were determined for this domain. Through activity assays of various truncations a series of residues were discerned that contribute to interaction of the distal binding site of ubiquitin chain.</p> UCHL1 mutant R178Q displays enhanced activity when compared to wild type (WT). The mutant was crystallized for structural analysis to gain insights into the higher catalytic activity of the mutant. The structure revealed that the catalytic histidine maintains a misaligned orientation similar to the WT enzyme. Biochemical analysis was done to ascertain the role of key residues that interact with the catalytic histidine. The residue type at position 178 in the structure plays a key role in enhancing the enzyme activity.

Ubiquitin C-terminal hydrolase L1 is a deubiquitinating enzyme that salvages ubiquitin from substrates and maintains intracellular ubiquitin pools. While the role of ubiquitin C-terminal hydrolase L1 is well characterized in neurons, there is an increasing scope of evidence to suggest that ubiquitin C-terminal hydrolase L1 also plays a role in renal function and glomerular disease, however, its specific role in these settings remains incompletely elucidated. In the present thesis we explored the role of ubiquitin C-terminal hydrolase L1 in a mouse model of glomerular disease, ACTN4-associated focal segmental glomerulosclerosis and the role of ubiquitin C-terminal hydrolase L1 in renal function. Deletion of ubiquitin C-terminal hydrolase L1 in a mouse model of ACTN4-associated focal segmental glomerulosclerosis significantly improved indices of podocyte injury, a likely result of ubiquitin pool attenuation and sustained α-actinin-4 levels. However, global ablation of ubiquitin C-terminal hydrolase L1 in mice led to altered renal hemodynamics, namely glomerular hyperfiltration, most likely attributed to nerve dysfunction and loss of arterial resistance. Finally, mice lacking ubiquitin C-terminal hydrolase L1 exhibited perturbations in phosphate homeostasis as these showed evidence of hyperphosphatemia and phosphaturia, indicating altered renal phosphate balance. Altogether, these data show that while ubiquitin C-terminal hydrolase L1 plays a maladaptive role in glomerular disease, it also functions as a crucial regulator of renal hemodynamics and renal phosphate handling, suggesting that it may have distinct functions in diseased and non-diseased kidneys.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18883号 / 医博第3994号 / 新制||医||1009(附属図書館) / 31834 / 京都大学大学院医学研究科医学専攻 / (主査)教授 岩井 一宏, 教授 野田 亮, 教授 藤田 潤 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

Doctor of Philosophy(PhD) / Hyperparathyroidism, a disease of the parathyroid glands, is one of the most common endocrinopathies, having a prevalence of 1 – 3 per 1000 individuals. It is characterised by calcium insensitive hypersecretion of parathyroid hormone, and increased cell proliferation. While the treatment for familial as well as many sporadic tumours associated with hyperparathyroidism includes parathyroidectomy, the extent of surgery and the follow-up monitoring regime, are dependent on accurate clinical and histopathological classification of the lesion. However, overlaps in histopathological and morphological features confound distinctions between the three main classifications of adenoma, hyperplasia and carcinoma and differential diagnosis of these lesions remains challenging. At the start of this candidature in January 2002, the genes associated with two familial syndromes in which hyperparathyroidism may feature, Multiple Endocrine Neoplasia (MEN) 1 and 2 had been identified, respectively MEN1 and RET. In addition, overexpression or translocation of cyclin D1 had been identified in both benign and malignant sporadic lesions, indicating a role for cyclin D1 in parathyroid tumorigenesis. However, the underlying events leading either directly, or indirectly, to the development of a large proportion of parathyroid lesions are still largely unknown. The work described in this thesis has contributed to the understanding of parathyroid lesions and the diagnosis and prognosis of affected individuals. During this candidature, constitutive mutation of HRPT2 was associated with Hyperparathyroidism–Jaw Tumour syndrome (HPT-JT). HRPT2 mutation analysis and loss of heterozygosity studies at 1q24-32 in parathyroid tumours presented in this thesis identified the strong association of HRPT2 mutation with sporadic parathyroid malignancy. In addition, 2-hits affecting HRPT2 were identified in several tumours suggestive of a role for HRPT2 as a tumour suppressor gene in sporadic parathyroid tumorigenesis. Microarray analysis of parathyroid tumours presented in this thesis identified three broad clusters of tumours. Cluster 1 comprised predominantly hyperplastic specimens and also included the normal tissue. Cluster 2, the most robust of the clusters, consisted of tumours harbouring HRPT2 mutations. The HPT-JT-associated tumours, both benign and malignant, and sporadic carcinomas, comprised this cluster. Cluster 3 contained the majority of the sporadic adenoma specimens, some hyperplasia, as well as all of the MEN 1-associated tumours. The cluster data is strongly suggestive that parathyroid tumours with somatic HRPT2 mutation, or tumours developing on a background of germline HRPT2 mutation, follow pathways distinct from those involved in mutant MEN 1-related parathyroid tumours. The results of this work provide strong evidence for an adenoma to carcinoma progression model for parathyroid tumorigenesis in the presence of a germline HRPT2 mutation. With the knowledge that both HRPT2 and MEN1 have significant roles in familial as well as sporadic parathyroid tumorigenesis, assays for mutation screening of these two genes have been developed as part of this thesis. These assays will facilitate a rapid molecular diagnosis for patients with one of these familial syndromes. Furthermore, novel putative biomarkers for different parathyroid tumour subtypes have also been identified. VCAM1 and UCHL1 (PGP9.5) were found to be significantly overexpressed in tumours harbouring an HRPT2 mutation at both the transcript and protein level. These two molecules are suggested as putative biomarkers for the discrimination of sporadic carcinoma or HPT-JT-associated tumours. RALDH2 transcript and protein were highly significantly overexpressed in the hyperplasia class relative to the adenoma class, and this molecule is suggested as a putative biomarker for discrimination of these classes of parathyroid tumours. These biomarkers may assist in the accurate diagnosis and prognosis of hyperparathyroidism. Large cohort studies of these putative biomarkers will be required to determine their robustness in discriminating parathyroid tumour subtypes. Further studies of their putative role in parathyroid tumorigenesis may identify them as novel molecular targets for future therapeutics to treat both hyperplastic and neoplastic parathyroid lesions.

Doctor of Philosophy(PhD) / Hyperparathyroidism, a disease of the parathyroid glands, is one of the most common endocrinopathies, having a prevalence of 1 – 3 per 1000 individuals. It is characterised by calcium insensitive hypersecretion of parathyroid hormone, and increased cell proliferation. While the treatment for familial as well as many sporadic tumours associated with hyperparathyroidism includes parathyroidectomy, the extent of surgery and the follow-up monitoring regime, are dependent on accurate clinical and histopathological classification of the lesion. However, overlaps in histopathological and morphological features confound distinctions between the three main classifications of adenoma, hyperplasia and carcinoma and differential diagnosis of these lesions remains challenging. At the start of this candidature in January 2002, the genes associated with two familial syndromes in which hyperparathyroidism may feature, Multiple Endocrine Neoplasia (MEN) 1 and 2 had been identified, respectively MEN1 and RET. In addition, overexpression or translocation of cyclin D1 had been identified in both benign and malignant sporadic lesions, indicating a role for cyclin D1 in parathyroid tumorigenesis. However, the underlying events leading either directly, or indirectly, to the development of a large proportion of parathyroid lesions are still largely unknown. The work described in this thesis has contributed to the understanding of parathyroid lesions and the diagnosis and prognosis of affected individuals. During this candidature, constitutive mutation of HRPT2 was associated with Hyperparathyroidism–Jaw Tumour syndrome (HPT-JT). HRPT2 mutation analysis and loss of heterozygosity studies at 1q24-32 in parathyroid tumours presented in this thesis identified the strong association of HRPT2 mutation with sporadic parathyroid malignancy. In addition, 2-hits affecting HRPT2 were identified in several tumours suggestive of a role for HRPT2 as a tumour suppressor gene in sporadic parathyroid tumorigenesis. Microarray analysis of parathyroid tumours presented in this thesis identified three broad clusters of tumours. Cluster 1 comprised predominantly hyperplastic specimens and also included the normal tissue. Cluster 2, the most robust of the clusters, consisted of tumours harbouring HRPT2 mutations. The HPT-JT-associated tumours, both benign and malignant, and sporadic carcinomas, comprised this cluster. Cluster 3 contained the majority of the sporadic adenoma specimens, some hyperplasia, as well as all of the MEN 1-associated tumours. The cluster data is strongly suggestive that parathyroid tumours with somatic HRPT2 mutation, or tumours developing on a background of germline HRPT2 mutation, follow pathways distinct from those involved in mutant MEN 1-related parathyroid tumours. The results of this work provide strong evidence for an adenoma to carcinoma progression model for parathyroid tumorigenesis in the presence of a germline HRPT2 mutation. With the knowledge that both HRPT2 and MEN1 have significant roles in familial as well as sporadic parathyroid tumorigenesis, assays for mutation screening of these two genes have been developed as part of this thesis. These assays will facilitate a rapid molecular diagnosis for patients with one of these familial syndromes. Furthermore, novel putative biomarkers for different parathyroid tumour subtypes have also been identified. VCAM1 and UCHL1 (PGP9.5) were found to be significantly overexpressed in tumours harbouring an HRPT2 mutation at both the transcript and protein level. These two molecules are suggested as putative biomarkers for the discrimination of sporadic carcinoma or HPT-JT-associated tumours. RALDH2 transcript and protein were highly significantly overexpressed in the hyperplasia class relative to the adenoma class, and this molecule is suggested as a putative biomarker for discrimination of these classes of parathyroid tumours. These biomarkers may assist in the accurate diagnosis and prognosis of hyperparathyroidism. Large cohort studies of these putative biomarkers will be required to determine their robustness in discriminating parathyroid tumour subtypes. Further studies of their putative role in parathyroid tumorigenesis may identify them as novel molecular targets for future therapeutics to treat both hyperplastic and neoplastic parathyroid lesions.

Neurological disorders affect more than 14% of the population worldwide and together with traumatic brain and spinal cord injuries represent major health, public and economic burden of the society. Incidence of inherited and idiopathic neurodegenerative disorders and acute CNS injuries is growing globally while neuroscience society is being challenged by numerous unanswered questions. Therefore, research of the CNS disorders is essential. Since animal models of the CNS diseases and injuries represent the key step in the conversion of the basic research to the clinics, we focused our work on generation of new animal models and on their use in pre-clinical research. We generated and characterized transgenic minipig model of Huntington's disease (HD) which represents the only successful establishment of a transgenic model of HD in minipig which should be valuable for testing of long term safety of HD therapeutics. Next, we crossed the well characterized R6/2 mouse HD model with the gad mouse model which lacks the expression of UCHL1 which led to results that support the theory of "protective" role of mutant huntingtin aggregates and suggest that UCHL1 function(s) may be affected in HD disturbing certain branches of Ubiquitin Proteasome System. Traumatic spinal cord injury and Amyotrophic Lateral...