Thesis (M.A.) -- Central Connecticut State University, 2007. / Thesis advisor: James P. Mulrooney "... in partial fulfillment of the requirements for the degree of Master of Arts in Biomolecular Science" Includes bibliographical references (leaves 42-45). Also available via the World Wide Web.

Thesis (M.S.) -- Central Connecticut State University, 2005. / Thesis advisor: James Mulrooney. "... in partial fulfillment of the requirements for the degree of Master of Biomolecular Sciences." Includes bibliographical references. Also available via the World Wide Web.

Collective cell migration is an important feature of wound healing, as well as embryonic and tumor development. The origin of collective cell migration is mainly intercellular interactions through effects such as a line tension preventing cells from detaching from the boundary. In contrast, in this study, we show for the first time that the formation of a constant cell front of a monolayer can also be maintained by the dynamics of the underlying migrating single cells. Ballistic motion enables the maintenance of the integrity of the sheet, while a slowed down dynamics and glass-like behavior cause jamming of cells at the front when two monolayers—even of the same cell type—meet. By employing a velocity autocorrelation function to investigate the cell dynamics in detail, we found a compressed exponential decay as described by the Kohlrausch–William–Watts function of the form C(δx)t ∼ exp (−(x/x0(t))β(t)), with 1.5 6 β(t) 6 1.8. This clearly shows that although migrating cells are an active, non-equilibrium system, the cell monolayer behaves in a glass-like way, which requires jamming as a part of intercellular interactions. Since it is the dynamics which determine the integrity of the cell sheet and its front for weakly interacting cells, it becomes evident why changes of the migratory behavior during epithelial to mesenchymal transition can result in the escape of single cells and metastasis.

Cells of the stratified adult corneal epithelium undergo centripetal migration throughout adult life from the edge of the cornea to the centre. To date nothing is known about the mechanism underpinning the oriented cellular migration. Failure to replenish apoptotic cells lost by desquamation from the superficial layer of the corneal epithelium leads to severe pathological conditions that may result in blindness. In this study we investigated the role of planar cell polarity (PCP) core proteins as the guidance cue for centripetal migration in the cornea. Cre-mediated conditional deletion of floxed alleles of the core PCP gene Vangl2 in the corneal epithelium and lens of adult mice was achieved. The effect of this deletion was studied by microscopic and immunohistological observation of the cornea compared to littermate controls, showing defects consistent with disrupted apical-basal polarity in mutant mice. Planar behaviour of the corneal epithelial cells was assayed by breeding the mutant alleles (Le-CreTg/-; Vangl2flox/flox) and the Looptail mouse (Vangl2Lp/+) onto an X-linked LacZ reporter transgene (XLacZ) background, demonstrating the importance of PCP core components for normal cell migration. In vitro directional migration studies were performed on Vangl2 and Frizzled6 knock-down human corneal epithelial cells following the application of direct current electric fields (DC-EFs), resulting in the reduction of directional migratory response to the DC-EF. This study showed for the first time roles for the planar cell polarity (PCP) signalling in orchestrating and coordinating cellular cues that drive oriented migration in the unwounded adult corneal epithelium. It is likely that mutations in PCP genes could lead to ocular surface abnormalities in humans.

No description available.

No description available.

No description available.

"Cell and process migration are critical to the establishment of neural circuitry. The study of these processes is facilitated through use of model organisms with simple nervous systems, such as C. elegans. Research in this nematode has defined the cytoplasmic adaptor MIG-10 as a key regulator of these processes. Mutation of mig-10 disrupts neuronal and axonal migration and outgrowth of the ‘canals’, or processes, of the excretory cell. MIG-10 directs the localization of UNC-34, which remodels actin filaments at the leading edge of a migrating cell or process to modify the direction or rate of its protrusion. An interactor of MIG-10 identified in a yeast two- hybrid analysis, ABI-1, has several roles in actin remodeling, such as targeting Ena/VASP members for phosphorylation by Abl kinase. Mutation of abi-1 in the nematode produces phenotypes that resemble those of mig-10 mutants, including disrupted outgrowth of the excretory canals, a developmental process in which ABI-1 is known to function cell autonomously. To test the hypothesis that the ABI-1/MIG-10 interaction contributes to cell migration and outgrowth, both in vivo and in vitro analyses were performed. Expression of either MIG-10A or MIG-10B exclusively in the excretory cell partially rescued the canal truncation characteristic of mig-10 mutants, suggesting MIG-10 functions autonomously in this cell during canal outgrowth. Physical interaction between MIG-10 and ABI-1 was confirmed using a co-immunoprecipitation system. Both MIG-10A and MIG-10B interact with ABI-1 through a mechanism that likely involves the SH3 domain of ABI-1 and sites in either the central region or C-terminus of MIG-10. These results suggest that MIG-10 and ABI-1 function together in a cell autonomous manner to promote cell or process migration. A possible consequence of this interaction is modulation of the MIG-10 binding to UNC-34 through Abl-mediated phosphorylation of MIG-10."

No description available.

神經元定向遷移是中樞神經系統發育必須進行的過程，遷移中的神經元極化細胞支架和分途徑，以達到神經元兩極性。小腦是腦部的運動神經中心，負責調整身體的平衡和肌肉的協調。蒲金氏細胞 (Purkinje cell)是小腦主要的輸出路線，為小腦必不可少的一員。可是，蒲金氏細胞遷移過程的分子機制和細胞機制仍然認知多。高爾基器(Golgi apparatus)是蛋白分途徑中的早期細胞器，它的再定位移動在大腦和小腦神經元的遷移過程中有發生。但是，高爾基器極性在蒲金氏細胞定向遷移中究竟發揮什麼作用仍然未知。在這文研究，我目標研究高爾基器定位和蒲金氏細胞早期遷移的關係。 / 透過免疫熒光成像分析，我發現在蒲金氏細胞早期遷移過程中，高爾基器重新定位於前導突起頂端的底部，將前導突起頂端突化成軸突。透過超表達一種高爾基器重組蛋白，培養中的蒲金氏細胞失去高爾基器極性和軸突，證明高爾基器的定位對於蒲金氏細胞突化軸突是必要的。在條件性 Smad1/5雙基因剔除小鼠的小腦，一群蒲金氏細胞未能遷移，顯示出隨機和分散的高爾基器定位，並失去軸突突出。總括來說，我的結果顯示出當蒲金氏細胞在進行早期遷移過程時，高爾基器的定位突化蒲金氏細胞的軸突，這可能對蒲金氏細胞遷移有重要作用。此發現揭開蒲金氏細胞遷移過程中的細胞機制，豐富我們對小腦發展過程中其中一件重要事件的認知。 / Neuronal migration is a fundamental process for central nervous system development during which migrating neurons polarize their cytoskeleton and secretory pathway to establish polarity. Cerebellum is the motor center, tuning body balance and muscle coordination. Purkinje cells, as the major output in the cerebellum, play an indispensable role for cerebellar function. However, the migration of Purkinje cells during early embryonic stages with respect to molecular and cellular mechanisms is largely unknown. Golgi apparatus is an early subcellular compartment in the protein secretory pathway. Recent studies show that Golgi reorientates during neocortical and cerebellar neuronal migration. Nevertheless, it is still not clear what role Golgi polarization plays during Purkinje cell migration. Therefore, in my study, I aim to address how Golgi polarization relates to Purkinje cell migration. / By immunofluorescence study, I showed that Golgi located at the base of leading processes during early Purkinje cell migration, which specifies the leading processes into axons. Disruption of Golgi orientation by overexpressing a Golgi stacking protein suppressed axon specification in cultured Purkinje cells, which suggests that Golgi polarization may be necessary for Purkinje cell axon specification. Conditional inactivation of Smad1/5 in the mouse cerebellum resulted in ectopic Purkinje cells which failed to migrate displayed random and dispersed Golgi positioning and an absence of axon protrusions. Overall, the results suggest that Golgi orientation specified axons of Purkinje cells, which may be important for further Purkinje cell migration. This finding identifies the cellular process during Purkinje cell migration and enriches our understanding of one of the critical events during cerebellar development. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Au, Sin Man June. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 98-109). / Abstracts also in Chinese. / Abstract --- p.iii / Acknowledgements --- p.v / Abbreviations --- p.vi / List of Figures --- p.x / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Cerebellum --- p.1 / Chapter 1.1.1 --- Cerebellum development --- p.1 / Chapter 1.1.2 --- Anatomy and cellular components --- p.4 / Chapter 1.2 --- Neuronal polarization and migration --- p.6 / Chapter 1.2.1 --- Axon specification and axon guidance --- p.7 / Chapter 1.3 --- Cerebellar Purkinje cells --- p.8 / Chapter 1.3.1 --- Physiological and morphological development --- p.8 / Chapter 1.3.2 --- Migration of Purkinje cells. --- p.9 / Chapter 1.3.2.1 --- Settling pattern of Purkinje cell populations --- p.9 / Chapter 1.3.2.2 --- Migration before E13.5 --- p.9 / Chapter 1.3.2.3 --- Interaction with radial glia --- p.10 / Chapter 1.3.2.4 --- Molecular mechanisms --- p.11 / Chapter 1.4 --- Golgi in neurons --- p.17 / Chapter 1.4.1 --- Polarized trafficking --- p.17 / Chapter 1.4.2 --- Golgi motility during cell polarization and migration --- p.19 / Chapter 1.4.2.1 --- Golgi/centrosome positioning in non-neuronal cell polarization and migration --- p.21 / Chapter 1.4.2.2 --- Golgi/centrosome positioning in neuronal polarization --- p.23 / Chapter 1.4.2.3 --- Golgi’s role in dendrite development --- p.26 / Chapter 1.4.2.4 --- Golgi/centrosome positioning in neuronal migration --- p.26 / Chapter 1.4.2.5 --- Opposite views on Golgi/centrosome positioning in cell polarization and migration --- p.28 / Chapter 1.4.3 --- Golgi’s role in microtubule cytoskeleton organization --- p.31 / Chapter 1.4.4 --- Other factors determining Golgi positioning --- p.32 / Chapter 1.5 --- Aims of the study --- p.34 / Chapter Chapter 2 --- Characterization of Lhx1{U+1D33}{U+A7F1}{U+1D3E}, a Lhx1-driven tau-eGFP knock-in transgenic mouse line / Chapter 2.1 --- Introduction --- p.35 / Chapter 2.2 --- Materials --- p.36 / Chapter 2.2.1 --- Tissue preparation --- p.36 / Chapter 2.2.2 --- Immunofluorescence --- p.36 / Chapter 2.3 --- Methods --- p.36 / Chapter 2.4 --- Results --- p.39 / Chapter 2.4.1 --- GFP expression in Lhx1{U+1D33}{U+A7F1}{U+1D3E} mice --- p.39 / Chapter 2.4.2 --- Purkinje cell markers specifically stain GFP-positive cells in Lhx1{U+1D33}{U+A7F1}{U+1D3E} mice --- p.42 / Chapter 2.5 --- Discussion --- p.44 / Chapter Chapter 3 --- Purkinje cell morphology and migration in early embryonic stages / Chapter 3.1 --- Introduction --- p.46 / Chapter 3.2 --- Materials and Methods --- p.47 / Chapter 3.3 --- Results --- p.48 / Chapter 3.3.1 --- Confocal imaging of Lhx1{U+1D33}{U+A7F1}{U+1D3E} embryos --- p.48 / Chapter 3.4 --- Discussion --- p.52 / Chapter Chapter 4 --- Specification of axon by localization of Golgi in Purkinje cells / Chapter 4.1 --- Introduction --- p.54 / Chapter 4.2 --- Materials --- p.57 / Chapter 4.3 --- Methods --- p.59 / Chapter 4.4 --- Results --- p.63 / Chapter 4.4.1 --- Golgi orientation from E12 to E15.5, in postnatal and in adult Lhx1{U+1D33}{U+A7F1}{U+1D3E} mice --- p.63 / Chapter 4.4.2 --- Anteriorly-orientated Golgi locates at the base of axon --- p.70 / Chapter 4.4.3 --- Golgi locates at the base of axon in cultured Purkinje cells at --- p.1DIV.71 / Chapter 4.4.4 --- Purkinje cells with Golgi orientation loss abrogate axon specification --- p.72 / Chapter 4.5 --- Discussion --- p.76 / Chapter Chapter 5 --- Purkinje cells with migration defect lose Golgi polarization and axon specification in Smad1/5 dKO mutants / Chapter 5.1 --- Introduction --- p.79 / Chapter 5.2 --- Materials and Methods --- p.81 / Chapter 5.3 --- Results --- p.83 / Chapter 5.3.1 --- Purkinje cells with migration defect lose Golgi polarization, normal morphology and axon differentiation --- p.83 / Chapter 5.4 --- Discussion --- p.89 / Chapter Chapter --- 6 General discussion, future perspectives and conclusions / Chapter 6.1 --- General discussion --- p.92 / Chapter 6.2 --- Future perspectives --- p.95 / Chapter 6.2.1 --- Golgi polarization in directing Purkinje cell migration --- p.95 / Chapter 6.2.2 --- The signal mediating Purkinje cell early migration and axonogenesis --- p.96 / Chapter 6.3 --- Conclusions --- p.97 / References --- p.98