Glutamic Acid Decarboxylase (GAD) is a rate-limiting enzyme responsible for synthesis of the inhibitory neurotransmitter GABA. Dopaminergic denervation in rodents by unilateral injections of 6-OHDA or MPTP causes an increase in Gad67 mRNA in the striatum, which is further exacerbated by administration of L-Dopa (Horvath et al., 2011; Katz et al., 2005 Bacci et al., 2002). Denervation of nigrostriatal neurons is the key pathological hallmark of Parkinson's disease, which results in hypokinetic movement and rigidity. Medium spiny projection neurons of the striatum comprise 95% of the neuronal population and utilize Gad67 (encoded by the Gad1 gene) for the synthesis of basal levels of GABA. The contribution of Gad67 to GABA signaling in medium spiny projection neurons in the striatum has not been thoroughly understood in normal or Parkinsonian states. Mice with a deletion in Gad67 in Gpr88 expressing neurons were generated by crossing mice with a floxed exon 2 of Gad1 with mice expressing Cre recombinase under the control of the Gpr88 promoter. The aim of this study was first, to characterize mice with a deletion in striatal Gad67 by immunohistochmical, electriophysiological and behavioral examination to determine whether Gad67 expression contributes to sensorimotor and learning tasks. And next, to investigate whether a downregulation in striatal Gad67 would decrease dyskinesia and affect the impaired motor symptoms following dopaminergic denervation with a unilateral 6-OHDA lesion and subsequent treatment with L-Dopa. In this study, neuronal Gpr88 expression was indicated by GFP reporter expression, which resulted from Cre-mediated excision of exon 2 of the Gad1 gene. Gpr88 expression was confirmed in the striatum, olfactory tubercle, cortex and brain stem. Furthermore, Gpr88 was confined to striatonigral and striatopallidal MSNs in the striatum. Additionally, Cre-mediated GFP reporter expression indicated that Gpr88 expression occurs throughout various brain regions, including the motor and visual areas of the cortex, amygdala, hippocampus and cerebellum during development. The developmental expression of Gpr88 seems to be a highly regulated process that occurs throughout the brain. In the conditional knockout mouse, deleting striatal Gad67 resulted in an upregualtion of Gad67 in the globus pallidus and downregulation in the substantia nigra. The changes in Gad67 expression indicate the effects of inactivating GABAergic signaling in striatonigral and striatopallidal MSNs in the direct and indirect pathways. Mice with a deletion in striatal Gad67 demonstrated compromised performance in spatial learning in the Morris water maze, suggesting that GABAergic striatal signaling in the direct and indirect pathways accounts for cue-based learning and spatial memory. However, inactivation of GABAergic signaling in striatonigral and striatopallidal MSNs does not account for motor deficits such as bradykinesia, akinesia or hypokinesia in intact mice; instead it perpetuates hyperkinetic motor activity. In the second experiment of this study, dopaminergic denervation by a unilateral 6-OHDA lesion induced bradykinesia and hypokinetic motor behavior, as demonstrated by impaired performance in the rota-rod and pole test. Additionally, L-Dopa administration to 6-OHDA lesioned mice evoked abnormal involuntary movements (AIMs) to the same degree in all dyskinetic mice. A deletion in striatal Gad67 did not decrease symptoms of dyskinesia, nor cause a lessening of motor impairment caused by dopaminergic denervation. Complete inactivation of the indirect pathway is believed to limit the inhibition of unwanted actions and may perpetuate dyskinesia, even when striatonigral MSNs of the direct pathway are inactive.

Abstract The complete exon-intron organization of the gene coding for the mouse α1(XIII) collagen chain, Col13a1, was characterized from genomic clones and multiple transcription initiation points were determined. Detailed comparison of the human and mouse genes showed that the exon-intron structures are completely conserved between the species, and both genes have their 5' untranslated region preceded by a highly conserved putative promoter region. The chromosomal location of the mouse gene was determined to be at chromosome 10, band B4, between markers D10Mit5 – (2.3 ± 1.6 cM) – Col13a1 – (3.4 ± 1.9 cM) – D10Mit15. The location of the genes for both the catalytically important α-subunit of prolyl 4-hydroxylase (P4HA) and human type XIII collagen (COL13A1) were previously mapped to 10q21.3-23.1. Prolyl-4-hydroxylase catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of peptide-bound proline and plays a crucial role in the synthesis of these proteins. The order and transcriptional orientation of the COL13A1 and P4HA was determined. These two genes were found to lie at tail to tail orientation on chromosome 10 and the distance between these genes was determined to be about 550 kbp. To study the function of type XIII collagen we used gene targeting in ES cells to generate a mouse line that carries a mutated type XIII collagen gene. Instead of normal protein, mutant mice express type XIII collagen with an altered amino-terminus in which the cytosolic and the transmembrane domains have been replaced with an unrelated sequence. The homozygous mice are fertile and viable but they show alterations in skeletal muscles, mainly wavy sarcolemma and increased variation in muscle fiber diameter. Ultrastructural studies revealed additional abnormalities such as streaming of z-disks, accumulation and enlargement of mitochondria, and disorganized myofilaments. The basement membranes of the muscle cells showed areas of detachment from the plasma membrane and the fibrillar matrix of the cells was less compact than in control animals. Fibroblasts cultured from mutant mice had normal levels of type XIII collagen but exhibited decreased adhesion to substratum which might be explained by a reduced anchoring strength of the altered protein.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24669号 / 農博第2552号 / 新制||農||1099(附属図書館) / 学位論文||R5||N5450(農学部図書室) / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 菅瀬 謙治, 教授 小川 順, 教授 森 直樹 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

The aim of the current study was divided into two separate goals, (i) optimization of a number of PCR-based protocols employed for genotyping transgenic mouse lines and (ii) evaluating a protocol for co-detection of mRNA and its correlated protein in the mouse midbrain. The optimization was performed on PCR protocols for genotyping the following transgenic mouse lines; Dat-Cre, Vglut2-Lox, Vglut2-Cre and Vmat2-Lox. Also, two different polymerases were evaluated parallel to each other – KAPA and Maxima Hot Start. One of the main findings from the PCR optimizations were that for the Vglut2-Lox protocol. By decreasing the annealing temp and increasing the MgCl2 the bands appeared brighter.  For the second part of the project, in-situ hybridization (ISH) was used to detect the mRNA expression with a `non-radioactive in situ hybridization´ protocol, using digoxigenin or fluorescein labelled riboprobes (mRNA probes). To detect the correlated protein a basic immunohistochemistry (IHC) protocol with the use of primary and secondary antibodies was implemented. The combined protocol was tested with Nd6 and Grp markers. Before testing to combined the protocols the ISH protocol was performed alone with riboprobes for Girk2, Lpl and Fst. The combined protocol detected mRNA and protein for both the control marker Th and the Nd6 marker. In conclusions, the optimized PCR protocols were optimal when used with the Maxima Hot Start polymerase and the new combined ISH and IHC protocol worked for markers Th and Nd6.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第24505号 / 医博第4947号 / 新制||医||1064(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 渡邉 大, 教授 林 康紀, 教授 井上 治久 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Atrial natriuretic factor (ANF) is a polypeptide hormone produced in heart atria, stored in atrial secretory granules and released into the circulation in response to various stimuli. Proper sorting of ANF at the level of the trans-Golgi network (TGN) is required for the storage of ANF in these specific granules, and this sorting of hormones has been found to be associated with G-proteins. Specifically, the Go protein alpha-subunit (Gαo) was established to participate in the stretch-secretion coupling of ANF, but may also be involved in the transporting of ANF from the TGN into atrial granules for storage and maturation. Based on knowledge of Gαo involvement in hormone production in other endocrine tissues, protein-protein interactions of Gαo and proANF and their immunochemical co-localization in granules, the direct involvement of these two proteins in atrial granule biogenesis is probable. In this study, mice were created using the Cre/lox recombination system with a conditional Gαo knockout in cardiocytes to study and characterize ANF production, secretion and granule formation. Deletion of this gene was successful following standard breeding protocols. Characterization and validation of cellular and molecular content of the knockout mice through mRNA levels, protein expression, peptide content, electron microscopy, and electrocardiography determined that a significant phenotypic difference was observed in the abundance of atrial granules. However, Gαo knockout mice did not significantly alter the production and secretion of ANF and only partially prevented granule biogenesis, likely due to incomplete Gαo knockout. These studies demonstrate an involvement of Gαo in specific atrial granule formation.

Atrial natriuretic factor (ANF) is a polypeptide hormone produced in heart atria, stored in atrial secretory granules and released into the circulation in response to various stimuli. Proper sorting of ANF at the level of the trans-Golgi network (TGN) is required for the storage of ANF in these specific granules, and this sorting of hormones has been found to be associated with G-proteins. Specifically, the Go protein alpha-subunit (Gαo) was established to participate in the stretch-secretion coupling of ANF, but may also be involved in the transporting of ANF from the TGN into atrial granules for storage and maturation. Based on knowledge of Gαo involvement in hormone production in other endocrine tissues, protein-protein interactions of Gαo and proANF and their immunochemical co-localization in granules, the direct involvement of these two proteins in atrial granule biogenesis is probable. In this study, mice were created using the Cre/lox recombination system with a conditional Gαo knockout in cardiocytes to study and characterize ANF production, secretion and granule formation. Deletion of this gene was successful following standard breeding protocols. Characterization and validation of cellular and molecular content of the knockout mice through mRNA levels, protein expression, peptide content, electron microscopy, and electrocardiography determined that a significant phenotypic difference was observed in the abundance of atrial granules. However, Gαo knockout mice did not significantly alter the production and secretion of ANF and only partially prevented granule biogenesis, likely due to incomplete Gαo knockout. These studies demonstrate an involvement of Gαo in specific atrial granule formation.