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Spatial Regulation (spatial + regulation)
Selected AbstractsTemporal and Spatial Regulation of CRE Recombinase Expression in Gonadotrophin-Releasing Hormone Neurones in the MouseJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2008A. Wolfe Gonadotrophin-releasing hormone (GnRH) neurones located within the brain are the final neuroendocrine output regulating the reproductive hormone axis. Their small number and scattered distribution in the hypothalamus make them particularly difficult to study in vivo. The Cre/loxP system is a valuable tool to delete genes in specific cells and tissues. We report the production of two mouse lines that express the CRE bacteriophage recombinase in a GnRH-specific manner. The first line, the GnRH-CRE mouse, contains a transgene in which CRE is under the control of the murine GnRH promoter and targets CRE expression specifically to GnRH neurones in the hypothalamus. The second line, the GnRH-CRETeR mouse, uses the same murine GnRH promoter to target CRE expression to GnRH neurones, but is modified to be constitutively repressed by a tetracycline repressor (TetR) expressed from a downstream tetracycline repressor gene engineered within the transgene. GnRH neurone-specific CRE expression can therefore be induced by treatment with doxycycline which relieves repression by TetR. These GnRH-CRE and GnRH-CRETeR mice can be used to study the function of genes expressed specifically in GnRH neurones. The GnRH-CRETeR mouse can be used to study genes that may have distinct roles in reproductive physiology during the various developmental stages. [source] AKAP-independent localization of type-II protein kinase A to dynamic actin microspikesCYTOSKELETON, Issue 9 2009Robert L. Rivard Abstract Regulation of the cyclic AMP-dependent protein kinase (PKA) in subcellular space is required for cytoskeletal dynamics and chemotaxis. Currently, spatial regulation of PKA is thought to require the association of PKA regulatory (R) subunits with A-kinase anchoring proteins (AKAPs). Here, we show that the regulatory RII, subunit of PKA associates with dynamic actin microspikes in an AKAP-independent manner. Both endogenous RII, and a GFP-RII, fusion protein co-localize with F-actin in microspikes within hippocampal neuron growth cones and the leading edge lamellae of NG108-15 cells. Live-cell imaging demonstrates that RII,-associated microspikes are highly dynamic and that the coupling of RII, to actin is tight, as the movement of both actin and RII, are immediately and coincidently stopped by low-dose cytochalasin D. Importantly, co-localization of RII, and actin in these structures is resistant to displacement by a cell-permeable disrupter of PKA-AKAP interactions. Biochemical fractionation confirms that a substantial pool of PKA RII, is associated with the detergent-insoluble cytoskeleton and is resistant to extraction by a peptide inhibitor of AKAP interactions. Finally, mutation of the AKAP-binding domain of RII, fails to disrupt its association with actin microspikes. These data provide the first demonstration of the physical association of a kinase with such dynamic actin structures, as well as the first demonstration of the ability of type-II PKA to localize to discrete subcellular structures independently of canonical AKAP function. This association is likely to be important for microfilament dynamics and cell migration and may prime the investigation of novel mechanisms for localizing PKA activity. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] The acyltransferase gene bus-1 exhibits conserved and specific expression in nematode rectal cells and reveals pathogen-induced cell swellingDEVELOPMENTAL DYNAMICS, Issue 12 2008Maria J. Gravato-Nobre Abstract Susceptibility to the rectal pathogen Microbacterium nematophilum provides a means of examining hindgut differentiation in C. elegans. Mutants of bus - 1 are resistant to infection with this pathogen. We show here that bus - 1 encodes a predicted acyltransferase expressed in rectal epithelial cells (K, F, and U), suggesting its involvement in regional surface modification. bus - 1 reporter genes were used to show spatial regulation by hindgut developmental control genes: egl - 38, mab - 9, and mab - 23. A bus - 1::GFP reporter reveals the conspicuous rectal epithelial swelling induced by M. nematophilum. The C. briggsae ortholog of bus - 1 exhibits conserved function and rectal expression, but it is expressed in vulval as well as rectal cells, correlated with pathogen adhesion to both vulval and rectal cells in this species. Another acyltransferase affecting bacterial adhesion, bus - 18/acl - 10, was also identified, which also shows strong rectal expression, but it is expressed in additional epithelial tissues and is required for general surface integrity. Developmental Dynamics 237:3762,3776, 2008. © 2008 Wiley-Liss, Inc. [source] Temporal and spatial regulation of bone morphogenetic protein signaling in late lung developmentDEVELOPMENTAL DYNAMICS, Issue 10 2007Miguel A. Alejandre-Alcázar Abstract Bone morphogenetic proteins (BMPs) play important roles in early lung development. No study to date has addressed a role for BMP signaling in late lung development. We describe changes in the expression and localization of BMP receptors (Bmpr1a, Bmpr1b, and Bmpr2) and Smad (Smad1, Smad4, Smad5, and Smad8) intracellular signaling proteins during the saccular and alveolarization stages of late lung development. BMP signaling, assessed by Smad1/5 phosphorylation, nuclear translocation, and induction of id1, id2, and id3 gene expression, was evident throughout late lung development. Our data indicate that BMP signaling is active during late lung development, and points to roles for the BMP system in septal and vascular development, and in the homeostasis of the epithelial layer of large conducting airways in the mature lung. Developmental Dynamics 236:2825,2835, 2007. © 2007 Wiley-Liss, Inc. [source] Comparative ontogeny and phylogeny of the upper jaw skeleton in amniotesDEVELOPMENTAL DYNAMICS, Issue 5 2006Joy M. Richman Abstract The morphology, position, and presence of the upper jaw bones vary greatly across amniote taxa. In this review, we compare the development and anatomy of upper jaw bones from the three living amniote groups: reptiles, birds, and mammals. The study of reptiles is particularly important as comparatively little is known about the embryogenesis of the jaw in this group. Our review covers the ontogeny and phylogeny of membranous bones in the face. The aim is to identify conserved embryonic processes that may exist among the three major amniote groups. Finally, we discuss how temporal and spatial regulation of preosseous condensations and ossification centers can lead to variation in the morphology of amniote upper jaw bones. Developmental Dynamics 235:1230,1243, 2006. © 2006 Wiley-Liss, Inc. [source] MAP kinase activation in avian cardiovascular developmentDEVELOPMENTAL DYNAMICS, Issue 4 2004Christine M. Liberatore Abstract Signaling pathways mediated by receptor tyrosine kinases (RTK) and mitogen-activated protein kinase (MAPK) activation have multiple functions in the developing cardiovascular system. The localization of diphosphorylated extracellular signal regulated kinase (dp-ERK) was monitored as an indicator of MAPK activation in the forming heart and vasculature of avian embryos. Sustained dp-ERK expression was observed in vascular endothelial cells of embryonic and extraembryonic origins. Although dp-ERK was not detected during early cardiac lineage induction, MAPK activation was observed in the epicardial, endocardial, and myocardial compartments during heart chamber formation. Endocardial expression of dp-ERK in the valve primordia and heart chambers may reflect differential cell growth associated with RTK signaling in the heart. dp-ERK localization in the epicardium, subepicardial fibroblasts, myocardial fibroblasts, and coronary vessels is consistent with MAPK activation in epicardial-derived cell lineages. The complex temporal,spatial regulation of dp-ERK in the heart supports diverse regulatory functions for RTK signaling in different cell populations, including the endocardium, myocardium, and epicardial-derived cells during cardiac organogenesis. Developmental Dynamics 230:773,780, 2004. © 2004 Wiley-Liss, Inc. [source] Cathepsin X cleaves the ,2 cytoplasmic tail of LFA-1 inducing the intermediate affinity form of LFA-1 and ,-actinin-1 bindingEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2009Zala Jevnikar Abstract The motility of T cells depends on the dynamic spatial regulation of integrin-mediated adhesion and de-adhesion. Cathepsin X, a cysteine protease, has been shown to regulate T-cell migration by interaction with lymphocyte function associated antigen-1 (LFA-1). LFA-1 adhesion to the ICAM-1 is controlled by the association of actin-binding proteins with the cytoplasmic tail of the ,2 chain of LFA-1. Cleavage by cathepsin X of the amino acid residues S769, E768 and A767 from the C-terminal of the ,2 cytoplasmic tail of LFA-1 is shown to promote binding of the actin-binding protein ,-actinin-1. Furthermore, cathepsin X overexpression reduced LFA-1 clustering and induced an intermediate affinity LFA-1 conformation that is known to associate with ,-actinin-1. Increased levels of intermediate affinity LFA-1 resulted in augmented cell spreading due to reduced attachment of T cells to the ICAM-1-coated surface. Gradual cleavage of LFA-1 by cathepsin X enables the transition between intermediate and high affinity LFA-1, an event that is crucial for effective T-cell migration. [source] How Drosophila change their combs: the Hox gene Sex combs reduced and sex comb variation among Sophophora speciesEVOLUTION AND DEVELOPMENT, Issue 1 2008Neel B. Randsholt SUMMARY Identification of the events responsible for rapid morphological variation during evolution can help understand how developmental processes are changed by genetic modifications and thus produce diverse body features and shapes. Sex combs, a sexually dimorphic structure, show considerable variation in morphology and numbers among males from related species of Sophophora, a subgenus of Drosophila. To address which evolutionary changes in developmental processes underlie this diversity, we first analyzed the genetic network that controls morphogenesis of a single sex comb in the model D. melanogaster. We show that it depends on positive and negative regulatory inputs from proximo-distal identity specifying genes, including dachshund, bric à brac, and sex combs distal. All contribute to spatial regulation of the Hox gene Sex combs reduced (Scr), which is crucial for comb formation. We next analyzed the expression of these genes in sexually dimorphic species with different comb numbers. Only Scr shows considerable expression plasticity, which is correlated with comb number variation in these species. We suggest that differences in comb numbers reflect changes of Scr expression in tarsus primordia, and discuss how initial comb formation could have occurred in an ancestral Sophophora fly following regulatory modifications of developmental programs both parallel to and downstream of Scr. [source] Evaluation of potential regulatory elements identified as DNase I hypersensitive sites in the CFTR geneFEBS JOURNAL, Issue 2 2002Marios Phylactides The cystic fibrosis transmembrane conductance regulator (CFTR) gene shows a complex pattern of expression, with temporal and spatial regulation that is not accounted for by elements in the promoter. One approach to identifying the regulatory elements for CFTR is the mapping of DNase I hypersensitive sites (DHS) within the locus. We previously identified at least 12 clusters of DHS across the CFTR gene and here further evaluate DHS in introns 2, 3, 10, 16, 17a, 18, 20 and 21 to assess their functional importance in regulation of CFTR gene expression. Transient transfections of enhan- cer/reporter constructs containing the DHS regions showed that those in introns 20 and 21 augmented the activity of the CFTR promoter. Structural analysis of the DNA sequence at the DHS suggested that only the one intron 21 might be caused by inherent DNA structures. Cell specificity of the DHS suggested a role for the DHS in introns 2 and 18 in CFTR expression in some pancreatic duct cells. Finally, regulatory elements at the DHS in introns 10 and 18 may contribute to upregulation of CFTR gene transcription by forskolin and mitomycin C, respectively. These data support a model of regulation of expression of the CFTR gene in which multiple elements contribute to tightly co-ordinated expression in vivo. [source] Cellular engineering in a minimal microbe: structure and assembly of the terminal organelle of Mycoplasma pneumoniaeMOLECULAR MICROBIOLOGY, Issue 4 2004Duncan C. Krause Summary Mycoplasma pneumoniae is a minimal microbe with respect to cell envelope composition, biosynthetic and regulatory capabilities and genome size, yet it possesses a remarkably complex, multifunctional terminal organelle. This membrane-bound extension of the mycoplasma cell is defined by the presence of an electron-dense core that appears as paired, parallel bars oriented longitudinally and enlarging at the distal end to form a terminal button. Most non-cytadhering mutants of M. pneumoniae isolated to date exhibit defects in the architecture of the terminal organelle. Detailed characterization of those mutants has revealed the identities of many component proteins of the terminal organelle as well as the likely order in which some of those components are required. Additional questions regarding the composition of the electron-dense core, the means by which the terminal organelle is duplicated during cell division and the manner in which this process is regulated remain to be answered. Thus, it seems that there is much to be learned about cellular engineering and spatial regulation in these ,simple' cell wall-less bacteria. [source] The tomato ethylene receptor gene family: Form and functionPHYSIOLOGIA PLANTARUM, Issue 3 2002Harry Klee Phytohormones are essential for integrating many aspects of plant development and responses to the environment. Regulation of hormonally controlled events occurs at multiple levels: synthesis, catabolism and perception (Trewavas 1983, Bradford and Trewavas 1994). At the level of perception, sensitivity to hormones can be regulated both spatially and temporally during the life cycle. An example of spatial regulation is the differential response to a hormone that occurs during organ abscission. Temporally, sensitivity of an organ to a hormone may change during maturation, as occurs during fruit ripening. In this review, we will focus on the initial event in recognition of one hormone, ethylene. The ethylene receptor was the first plant hormone receptor to be unambiguously identified. Over the last few years, great progress has been made in elucidating the genes involved in ethylene action. Nonetheless, the mechanisms of signal transduction remain to be established. Here, we will address the status of the tomato receptor gene family and the evidence that regulation of receptor gene expression can influence the response of the plant to the hormone. [source] Temporal and spatial regulation of ,6 integrin expression during the development of the cochlear-vestibular ganglionTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2007Dawn Davies Abstract The neurons of the cochlear-vestibular ganglion (CVG) that innervate the sensory hair cells of the inner ear are derived from the otic epithelium early in development. Neuroblasts detach from neighboring cells, migrate into the mesenchyme where they coalesce to form the ganglion complex, then send processes back into the epithelium. Cell migration and neuronal process formation involve changes in cellular interactions with other cells and proteins in the extracellular matrix that are orchestrated by cell surface-expressed adhesion molecules, including the integrins. I studied the expression pattern of the ,6 integrin subunit during the early development of the CVG using immunohistochemistry and reverse-transcriptase polymerase chain reaction (RT-PCR) in murine tissue sections, otocyst, and ganglion explants. At embryonic day (E)10.5 ,6 integrin was expressed in the otic epithelium but not in migrating neuroblasts. Importantly, the loss of ,6 was associated with exit from the epithelium, not neuronal determination, revealing differentiation cues acutely associated with the cellular environment. Markers of glial and neuronal phenotype showed that ,6-expressing cells present in the CVG at this stage were glia of neural crest origin. By E12.5 ,6 expression in the ganglion increased alongside the elaboration of neuronal processes. Immunohistochemistry applied to otocyst cultures in the absence of glia revealed that neuronal processes remained ,6-negative at this developmental stage and confirmed that ,6 was expressed by closely apposed glia. The spatiotemporal modulation of ,6 expression suggests changing roles for this integrin during the early development of inner ear innervation. J. Comp. Neurol. 502:673,682, 2007. © 2007 Wiley-Liss, Inc. [source] | |||||||||||||