Planar cell polarity (PCP) refers to the coordinated orientation, movement, or structure of cells within the plane of a tissue. Zebrafish PCP mutants such as the vangl2 mutant exhibit defects in convergent extension, neural tube morphogenesis, and ciliary positioning. Tmem14a is a putative tetraspanin protein that was identified as an potential interactor of Vangl2 in a membrane yeast-two hybrid screen. GFP-tagged versions of Tmem14a are localized to the trans-Golgi network in zebrafish neuroepithelial cells. Knockdown of Tmem14a activity results in convergent extension defects, an ectopic accumulation of cells in the neural tube, and disorganized cilia. The localization of GFP-tagged Tmem14a to the trans-Golgi network suggested that Tmem14a plays a role in the trafficking of core PCP components to the cell membrane. Indeed, the membrane localization of GFP-Vangl2 was disrupted in Tmem14a morphants. Thus, Tmem14a is an interactor of Vangl2 and a novel regulator of vertebrate planar cell polarity signaling.

Heidelberg, Univ., Diss., 2007.

Stuttgart, Univ., Diss., 2006.

Thesis (Ph.D.). / Written for the Dept. of Biochemistry. Title from title page of PDF (viewed 2009/06/09). Includes bibliographical references.

Techn. University, Diss., 2002--Berlin.

Universiẗat, Diss., 2000--Kiel.

ABSTRACT The Golgi apparatus has always been an interesting organelle of study because of its unique morphology as well as the critical roles it plays in cell biology. It is situated next to the endoplasmic reticulum and secreted proteins must pass through the Golgi vesicular pathway for modifications and targeting. In addition, the Golgi apparatus plays an essential role in establishing cellular polarity. Cell polarity refers to difference in orientation of cell structures spatially, and is involved in establishing functionality. The Golgi apparatus establishes cell polarity in various ways including orienting itself spatially, biasing vesicular trafficking within the cell, and most importantly through its role as a microtubule organizing center. The cytoskeleton provides the structural framework for cells. Microtubules nucleated from the Golgi-dependent microtubule organizing center result in an asymmetric cytoskeleton. An asymmetric cytoskeleton is essential to establishing cell polarity. Neurons require cell polarity to establish the essential structures such as the axon and dendrites. The Golgi apparatus establishes neuronal polarity through its extensive network of associated proteins. In this review, we will discuss the growing evidence supporting the role of the Golgi apparatus in establishing neuronal polarity.

xii, 45 p. : col. ill. / Regulated acidification of intercellular organelles and vesicles is essential for many cellular processes, from basic metabolism and protein sorting to synapse function and developmental signaling. These diverse processes are driven by spatiotemporal regulation of the V-ATPase, the cellular H + -pump. In yeast and higher eukaryotes V-ATPase localization is directed by the 100-kDa "a" subunit, and many human diseases are linked to mutations in "a". Saccharomyces cerevisiae contains two "a" isoforms, VPH1 and STV1, with all other V-ATPase subunits encoded for by single genes. The V-ATPase contains only one "a" subunit per complex. Complexes that contain Vph1p localize to the vacuole (lysosome), and Stv1p-containing complexes localize to the late Golgi/endosome. Here I present a set of STV1 mutants that are disrupted for Golgi retention but not V-ATPase assembly or enzymatic function. Using a forward genetic screen I defined multiple residues within a 39 amino-acid region of Stv1p that are necessary for Stv1p retention to the Golgi. The residues most strongly affecting Golgi localization are present in a small STV1 -specific insertion of eight residues, suggesting they may bind directly to sorting machinery. However, I also find that Stv1p/Vph1p chimeras containing the STV1 -specific insertion are not sufficient to direct Golgi retention in both minimal (13AA) and expanded (49AA) contexts. I conclude that the Stv1p Golgi retention signal is composed of a complex binding surface, of which the central element is a short peptide rich in amino acids with aromatic side chains. / Committee in charge: Bruce Bowerman, Chairperson; Tom H. Stevens, Advisor; Karen Guillemin, Member; George F. Sprague Jr., Member Kenneth E. Prehoda Outside Member

Formins are proteins involved in regulation and construction of actin filaments of eucaryotic organism. They parcipitate in regulating cytokinesis, polar tip growth, and thus participate in development of whole organisms. There are 2 classes of formins in Arabidopsis thaliana. Both classes include FH1 and FH2 domains (formin homology 1 a 2). Class I formins have N-terminal transmembrane domain, unlike class II formins. Some formins of class II have a N-terminal PTEN domain (Phosphatase and Tensin Homolog). Sequence analyses predicted membrane binding via phosphatase or C2 subdomain of PTEN. This thesis was focused on the formin AtFH14, specifically its PTEN domain. Based on predicted sequence, a DNA fragment encoding the PTEN domain was amplified, sequenced and cloned to destination vectors for YFP and EOS phusions. Marked protein was visualized by transient expression in Nicotiana benthamiana. Stably transformed Arabidopsis lines were prepared for stably expression of protein. The tagged protein was localized in cortical cytoplasm, cytoplasmatical strands, probably in nuclear membrane or perinuclear cytoplasm, as well as in peculiar "folicle-like" structures that might be due to binding of PTEN at the periphery of some membrane organelles. Also were seen filament structures, maybe caused by PTEN binding...

Neurons of the nucleus reuniens thalami stained with Golgi methods are compared to cells in this nucleus labelled in retrograde fashion after hippocampal injections of horseradish peroxidase. The cellular morphology ranges from fusiform to multiangular with most cells showing radiating processes characteristic of neurons in the reticular core. Dendrites are long and relatively smooth, with a few sparsely distributed spinous processes. These cells are comparable to the cholinergic cells of the median septal/diagonal band area which also project into the hippocampal formation.