Regulation of expression of the intestinal actin-binding protein, villin, a marker of intestinal epithelial differentiation, is poorly understood. Activation of the extracellular calcium-sensing receptor (CaSR) on sub-epithelial myofibroblasts stimulated the secretion of Wnt5a, while activation of the CaSR on intestinal epithelia increased expression of Ror2, a Wnt-family co-receptor. Immunocytochemistry has localized Ror2 expression in the epithelia lining the small intestine from the crypt base to the villus tip. The aim of this study was to determine whether Wnt5a binding Ror2 in intestinal epithelia stimulated transient increases in phospho-ERK1/2 (pERK1/2) which lead to increased expression of villin transcript and protein. To examine Wnt5a-Ror2 regulation of villin expression, we transgenically overexpressed wild-type, truncated, or mutant Ror2 constructs in HT-29 adenocarcinoma cells and nontransformed fetally-derived human intestinal epithelial cells (HIECs), added conditioned media containing Wnt5a and measured changes in ERK1/2 phosphorylation, villin amplicons and protein expression by RT-PCR and Western blot techniques. Wnt5a addition caused a transient increase in pERK1/2, which was maximal at 10 min but diminished by 30 min. Transient transfection with a siRNA duplex against Ror2 diminished Ror2 amplicons and protein and reduced the extent of pERK1/2 activation. Structure-function analysis revealed that deletion of the cysteine-rich, kringle, or tyrosine kinase domain or substitution mutations of tyrosine residues in the intracellular Ser/Thr-1 region of Ror2 prevented the Wnt5a-stimulation of pERK1/2. Deletion of the intracellular proline and serine/threonine rich regions of Ror2 had no effect on Wnt5a-stimulation of pERK1/2 in HT29 cells. Western blot analysis demonstrated that villin protein was increased by over-expression of wild-type Ror2 in HT-29 cells and HIECs in the presence of Wnt5a. The increase in villin expression was blocked by pharmacological inhibition of MEK1&2 and casein kinase 1, but not by PKC and p38 inhibitors. Neither Wnt3a nor EGF addition increased villin protein. This work suggested that stromal Wnt5a will stimulate pERK1/2 via the Ror2 tyrosine kinase domain to generate increased villin protein. These findings suggested that Ror2 homeostasis and Wnt5a interaction with Ror2 are important determinants of the regulation of villin expression in the intestine. / Thesis (Master, Physiology) -- Queen's University, 2009-07-14 23:34:39.397

No description available.

The gene PRICKLE1 is important for human brain function, as mutations in PRCKLE1 are associated with progressive myoclonus epilepsy (PME). Mutations in prickle orthologs could cause seizures in flies, zebrafish and mice, suggesting a conserved role of Prickle protein in seizure from fruit flies to humans. The underlying molecular mechanism how PRICKLE1 mutation causes PME is still unknown. Prickle1 is part of the planar cell polarity (PCP) pathway, which regulates cell polarity within plane of cell sheets. In Drosophila, prickle is recruited to one side of the cell by another PCP protein, Van Gogh. This asymmetric protein localization of Van Gogh/prickle establishes cell polarity. In zebrafish and Xenopus, loss of Prickle or Van Gogh like (Vangl) genes causes PCP phenotypes, which seemingly supports the Prickle/Vangl protein interaction and the role of Prickle in PCP pathway. The function of Prickle in mammals has not been analyzed. It is possible that mammalian Prickle also interacts with Vangl to mediate PCP signaling based on the conserved role of prickle from Drosophila to Xenopus. If Prickle1 interacts with Vangl and regulate PCP pathway, the PME we observed in humans might be associated with loss of neuronal polarity and impaired neuron activity. Therefore, to understand whether Prickle1 mediates Vangl signaling in mammals could be a step toward revealing the etiology of PME in human patients. Therefore, I analyzed the function of Prickle1 in three developmental processes, the limb development, the palate development, and the caudal migration of facial branchimotor neurons (FBMs), in which the function of PCP pathway, especially Vangl2, has been described. Supporting the interaction between Prickle1 and Vangl, mutations in either Prickle1 or Vangl2 leads to shorter limbs. However, Prickle1 and Vangl2 only have limited overlap in mRNA expression in the digit tips. This raises the question as to how impaired Prickle1/Vangl2 protein interaction in these cells in the digit tips cause defective growth of the whole limb. It also suggests alternate function of Prickle1 other than mediating Vangl2 function. This interaction between Prickle1 and Vangl2 is further challenged by the limited function of Vangl but the essential role of Prickle1 in palate development, which suggests that the function of Prickle1 is independent of Vangl2. In the caudal migration of FBMs, Prickle1 mutation impairs this migration process dose-dependently. This is different from Vangl2 mutation, which completely blocks the caudal migration and partially impairs the lateral migration of FBMs. More importantly, Prickle1 is expressed by the neurons, while Vangl2 functions in the surrounding cells, which again raises the question as to whether and how the two proteins could interact if they are not expressed in the same cell. These results together question the model that Prickle1 is the intracellular partner of Vangl2, but support Prickle1 function might be independent of Vangl. Actually, it is possible that Prickle1 is part of gene expression regulation machinery: Prickle1 mutation affects Wnt5a expression in the limb and Shh expression in the palate. Although this regulation mechanism is still unknown, it suggests that defective gene expression might be related to PME caused by PRICKLE1 mutation.

No description available.

Nous avons identifié, un ligand de Wnt, Wnt5a, comme faisant partie intégrante du complexe mTORC1, qui régule la fonction lysosomal et favorise le trafic intracellulaire du cholestérol. En diminuant l’activité de mTORC1 et en activant l’axe autophagie-lysosome, Wnt5a adapte les concentration du cholestérol intracellualire aux besoins de la cellule. Wnt5a favorise l’export du cholestérol depuis les endosomal/lysosomal (LELs) vers le réticulum endoplasmique (RE), limite l’accumulation intracellulaire du cholestérol, et protège contre l’athérosclérose. D’un point de vue mécanistique, Wnt5a se lie aux membranes riches en cholestérol et interagit spécifiquement avec la protéine membranaire Niemann-Pick C1 (NPC1), la protéine soluble Niemann-Pick C2 (NPC2), deux protéines lysosomales qui régulent l’export du cholestérol à partir des LELs. En conséquence, l’absence de Wnt5a inhibe la fonction lysosomale et l’autophagie, ainsi que la sortie du cholesterol hors des LELs. Ceci resulte en l’accumulation de larges corps d’inclusion intracellulaires, de larges LELs riches en cholestérol, d’une diminution du cholestérol au niveau du RE. / We identified the Wnt ligand, Wnt5a, as a member of the nutrient/energy/stress sensor, mTORC1 scaffolding complex, which drives lysosomal function and promotes cholesterol trafficking. By decreasing mTORC1 activity and by activating the autophagy-lysosomal axis, Wnt5a senses changes in dietary cholesterol supply, promotes endosomal/lysosomal (LELs) cholesterol egress to the endoplasmic reticulum (ER), and protects against atherosclerosis. Moreover, Wnt5a binds cholesterol-rich membranes and specifically interacts with two lysosomal proteins Niemann–Pick C1 and Niemann–Pick C2 that regulate cholesterol export from LELs. Consequently, absence of Wnt5a decoupled mTORC1 from variations in LELs sterol levels, and this resulted in accumulation of large intracellular inclusion bodies, large LELs and low ER cholesterol.

Made available in DSpace on 2015-07-22T20:49:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-02-27. Added 1 bitstream(s) on 2015-08-11T03:25:42Z : No. of bitstreams: 1 Publico-094.pdf: 903461 bytes, checksum: edf5b6e40862ad70fc99b723417b0669 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivo: Analisar as vias canônica e não-canônicas da família Wnt no ovário normal e na neoplasia benigna e maligna do ovário. Métodos: Obtiveram-se tecidos ovarianos no período entre 1993 e 2004. As pacientes foram divididas em três grupos: Grupo A, neoplasia ovariana epitelial maligna (N = 38); Grupo B, neoplasia ovariana epitelial benigna (N = 28) e Grupo C, ovários normais (N = 26). A imunoexpressão para Wnt1, Frizzled-1 (FZD1), Wnt5a, Frizzled-5 (FZD5) e Betacatenina foi avaliada em cada grupo. Resultados: A proporção de pacientes Wnt1-positivas no grupo A (29,4%) foi significantemente maior do que nos grupos B (4,3%) e C (9,1%) (p = 0,020). A proporção de mulheres FZD1-positivas no grupo C (54,5%) foi significantemente menor do que nos grupos A (97,1%) e B (90,0%) (p < 0,001). A proporção de pacientes wnt5apositivas foi significantemente maior no grupo A (80,0%) comparado aos grupos B (25,0%) e C (27,3%) (p<0,001). A proporção de pacientes Beta-catenina-positivas no grupo C (95,8%) foi significantemente maior do que no grupo B (52,4%) (p = 0,004). A comparação nas curvas de sobrevida no grupo A relacionada à expressão de Wnt5a mostrou diferença significante entre as pacientes positivas e negativas, sendo que as pacientes Wnt5a-positivas apresentaram resultados piores (p=0,050). Conclusão: Os achados demonstram que as vias relacionadas ao Wnt5a têm papel relevante na neoplasia ovariana maligna. Outrossim, a imunoexpressão do Wnt5a revelou ser marcador de mau prognóstico para câncer de ovário. / Objectives: To analize the canonical and noncanonical Wnt pathway in normal ovary, benign ovarian tumor and ovarian cancer. Methods: Ovarian specimens were obtained from surgeries performed between 1993 and 2004. The patients were divided in three groups: Group A, epithelial ovarian cancer (N = 38); Group B, benign epithelial neoplasia (N = 27) and Group C, normal ovaries (N = 26). Immunoreactivity for Wnt1, FZD1, Wnt5a, FZD5 and -catenin was scored for each group. Results: The proportion of Wnt1 positive women at the group A (29.4%) was significantly higher than the group B (4.3%) and C (9.1%) (p = 0.020). The proportion of FZD1 positive patients in group C (54.5%) was significantly lower than the group A (97.1%) and B (90.0%) (p < 0.001). The proportion of Wnt5a positive women was significantly higher for group A (80.0%) compared to the group B (25.0%) and C (27.3%) (p<0.001). The proportion of ß-catenin positive patients in the group C (95.8%) was significantly higher than the group B (52.4%) (p = 0.004). Comparison of the survival curves in group A according to Wnt5a expression showed a significant difference between positive and negative patients, whereas the Wnt5a positive women showed worse results (p=0.050). Conclusion: Our findings suggest that the pathways related to Wnt5a have an important role in ovarian malignant neoplasia. Furthermore, Wnt5a was found to be a predictor of poor prognosis for ovarian cancer. / FAPESP: 06/51401-1 / TEDE / BV UNIFESP: Teses e dissertações

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21953号 / 医博第4495号 / 新制||医||1037(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 柳田 素子, 教授 斎藤 通紀, 教授 近藤 玄 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Maternal immune activation (MIA) disrupts the central innate immune system during a critical neurodevelopmental period. Microglia are the primary innate immune cells in the brain and can mediate neurodevelopment, but the direct influence of microglia on the MIA phenotype remains largely unknown. Here, we show that MIA can lead to long-lasting effects on microglial phenotype, neuronal circuitry, and behaviors. Transcriptomic analysis revealed aberrant expression of neurogenic genes in MIA microglia. We found that microglia repopulation by colony-stimulating factor receptor 1 (CSF1R) inhibition reversed MIA-induced social deficits and corrected expression of the newly identified MIA-associated neuritogenic molecules in microglia. In vitro whole-cell patch-clamp recording and immunohistochemistry revealed that microglia repopulation restored MIA-induced changes in intrinsic excitability, dendritic spine density, and microglia-neuron interactions of layer V intrinsically bursting pyramidal neurons in the prefrontal cortex. Maternal inflammation therefore alters microglial phenotypes and changes neuronal functions by mediating microglia-neuron interactions. We found that Wingless-related MMTV integration site 5a (WNT5a) is a critical regulator of this microglia-neuron communication. Studies have shown that the neurotrophic factor WNT5a plays a critical role in neurodevelopment, and here we demonstrate that WNT5a is one of the neuritogenic genes significantly upregulated in embryonic MIA microglia. We showed using microarray analysis that the microglial secretome can promote neural stem cell differentiation through various pathways, including Wnt pathways. Live imaging of neuron-microglia co-culture demonstrated that microglia enhanced neurite development and dendritic spine density and that this was diminished by microglial Wnt5a silencing using siRNA transfection. Multi-electrode array recordings revealed that microglia co-culture increased spontaneous neuronal firing rate. Thus, microglia can secrete WNT5a and regulate dendritic spine development, maintenance, and neural circuitry. These results indicate that altered expression of microglial WNT5a due to pathogenic states such as inflammation can lead to abnormal neuronal activity. To further elucidate microglia biology, we developed an inducible immortalized murine microglial cell line using a tetracycline expression system. The addition of doxycycline can induce rapid cell proliferation for the expansion of cell colonies. Upon withdrawal of doxycycline, this monoclonal microglial cell line can differentiate and resemble in vivo microglia physiology as assessed by expression of microglial genes, innate immune response, chemotaxis, and phagocytic capabilities. This cell line becomes a convenient and useful method to study microglia in vitro. / 2024-02-03T00:00:00Z

No description available.

L’athérosclérose débute par l’accumulation de cholestérol dans les cellules des parois artérielles, formant des plaques d’athéromes. LRP1 protège contre la maladie en inhibant l’accumulation intracellulaire de cholestérol et nous avions montré qu’une signalisation Wnt5a était impliquée dans cette inhibition. Le projet de thèse consistait à caractériser les mécanismes moléculaires de cette inhibition et à vérifier l’effet athéroprotecteur de Wnt5a. Nous avons montré in vitro et in vivo que Wnt5a inhibe l’accumulation de cholestérol via la stimulation de son export et l’inhibition de sa synthèse endogène. Nous avons ensuite observé que l’invalidation de Wnt5a spécifiquement dans les CMLv de souris LDLR-/- conduit à une augmentation des lésions athéromateuses après un régime riche en cholestérol, confirmant alors son rôle athéroprotecteur. Nos travaux ont ainsi permis de révéler le potentiel de Wnt5a en tant que cible thérapeutique dans le traitement contre l’athérosclérose. / Protects against intracellular cholesterol accumulation and we identified the secreted protein Wnt5a as a partner of this inhibitory effect of LRP1. The aim of this thesis is to determine the molecular mechanisms by which the LRP1/Wnt5a signaling pathway prevents cholesterol accumulation in cells and to study the antiatherogenic potential of Wnt5a. We first showed in vitro and in vivo that Wnt5a decreases cellular cholesterol content by stimulating its efflux through the induction of cholesterol transporters expression and by down-regulating the expression of HMGCoA-reductase. Then we used mice deleted for Wnt5a specifically in smooth muscle cells, which present more atherosclerotic lesions than control mice after a high cholesterol diet. This confirms that Wnt5a protects against atherosclerosis and could be an interesting therapeutic target in the treatment of the disease.