Browsing by Subject "Somatostatin receptor 3"

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    An inducible CiliaGFP mouse model for in vivo visualization and analysis of cilia in live tissue
    (BMC, 2013-07-03) O’Connor, Amber K.; Malarkey, Erik B.; Berbari, Nicolas F.; Croyle, Mandy J.; Haycraft, Courtney J.; Bell, P. Darwin; Hohenstein, Peter; Kesterson, Robert A.; Yoder, Bradley K.; Biology, School of Science
    Background: Cilia are found on nearly every cell type in the mammalian body, and have been historically classified as either motile or immotile. Motile cilia are important for fluid and cellular movement; however, the roles of non-motile or primary cilia in most tissues remain unknown. Several genetic syndromes, called the ciliopathies, are associated with defects in cilia structure or function and have a wide range of clinical presentations. Much of what we know about the formation and maintenance of cilia comes from model systems like C. elegans and Chalmydomonas. Studies of mammalian cilia in live tissues have been hampered by difficulty visualizing them. Results: To facilitate analyses of mammalian cilia function we generated an inducible CiliaGFP mouse by targeting mouse cDNA encoding a cilia-localized protein somatostatin receptor 3 fused to GFP (Sstr3::GFP) into the ROSA26 locus. In this system, Sstr3::GFP is expressed from the ubiquitous ROSA26 promoter after Cre mediated deletion of an upstream Neo cassette flanked by lox P sites. Fluorescent cilia labeling was observed in a variety of live tissues and after fixation. Both cell-type specific and temporally regulated cilia labeling were obtained using multiple Cre lines. The analysis of renal cilia in anesthetized live mice demonstrates that cilia commonly lay nearly parallel to the apical surface of the tubule. In contrast, in more deeply anesthetized mice the cilia display a synchronized, repetitive oscillation that ceases upon death, suggesting a relationship to heart beat, blood pressure or glomerular filtration. Conclusions: The ability to visualize cilia in live samples within the CiliaGFP mouse will greatly aid studies of ciliary function. This mouse will be useful for in vivo genetic and pharmacological screens to assess pathways regulating cilia motility, signaling, assembly, trafficking, resorption and length control and to study cilia regulated physiology in relation to ciliopathy phenotypes.
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    Bardet–Biedl syndrome proteins are required for the localization of G protein-coupled receptors to primary cilia
    (National Academy of Science, 2008) Berbari, Nicolas F.; Lewis, Jacqueline S.; Bishop, Georgia A.; Askwith, Candice C.; Mykytyn, Kirk; Biology, School of Science
    Primary cilia are ubiquitous cellular appendages that provide important yet not well understood sensory and signaling functions. Ciliary dysfunction underlies numerous human genetic disorders. However, the precise defects in cilia function and the basis of disease pathophysiology remain unclear. Here, we report that the proteins disrupted in the human ciliary disorder Bardet–Biedl syndrome (BBS) are required for the localization of G protein-coupled receptors to primary cilia on central neurons. We demonstrate a lack of ciliary localization of somatostatin receptor type 3 (Sstr3) and melanin-concentrating hormone receptor 1 (Mchr1) in neurons from mice lacking the Bbs2 or Bbs4 gene. Because Mchr1 is involved in the regulation of feeding behavior and BBS is associated with hyperphagia-induced obesity, our results suggest that altered signaling caused by mislocalization of ciliary signaling proteins underlies the BBS phenotypes. Our results also provide a potential molecular mechanism to link cilia defects with obesity.
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    Monitoring endosomal trafficking of the G protein-coupled receptor somatostatin receptor 3
    (Elsevier, 2014) Tower-Gilchrist, Cristy; Styers, Melanie L.; Yoder, Bradley K.; Berbari, Nicolas F.; Sztul, Elizabeth; Biology, School of Science
    Endocytic trafficking of G protein-coupled receptors (GPCRs) regulates the number of cell surface receptors available for activation by agonists and serves as one mechanism that controls the intensity and duration of signaling. Deregulation of GPCR-mediated signaling pathways results in a multitude of diseases, and thus extensive efforts have been directed toward understand the pathways and molecular events that regulate endocytic trafficking of these receptors. The general paradigms associated with internalization and recycling, as well as many of the key regulators involved in endosomal trafficking of GPCRs have been identified. This knowledge provides goalposts to facilitate the analysis of endosomal pathways traversed by previously uncharacterized GPCRs. Some of the most informative markers associated with GPCR transit are the Rab members of the Ras-related family of small GTPases. Individual Rabs show high selectivity for distinct endosomal compartments, and thus co-localization of a GPCR with a particular Rab informs on the internalization pathway traversed by the receptor. Progress in our knowledge of endosomal trafficking of GPCRs has been achieved through advances in our ability to tag GPCRs and Rabs with fluorescent proteins and perform live cell imaging of multiple fluorophores, allowing real-time observation of receptor trafficking between subcellular compartments in a cell culture model.