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  1. Article ; Online: Cortactin knockdown results in disruption of basal TBCs and alters turnover of Sertoli cell ESs in Rattus norvegicus†.

    Palia, Prunveer / Adams, Arlo / Sriram, Aarati / Vogl, A Wayne

    Biology of reproduction

    2021  Volume 105, Issue 5, Page(s) 1330–1343

    Abstract: Here we explore the prediction that long-term knockdown of cortactin (CTTN), a component of tubulobulbar complexes (TBCs), disrupts TBCs in Sertoli cells and alters the turnover of basal ectoplasmic specializations (ESs). In rats, intratesticular ... ...

    Abstract Here we explore the prediction that long-term knockdown of cortactin (CTTN), a component of tubulobulbar complexes (TBCs), disrupts TBCs in Sertoli cells and alters the turnover of basal ectoplasmic specializations (ESs). In rats, intratesticular injections of siRNA targeting CTTN (siCTTN) in one testis and nontargeting siRNA (siControl) in the contralateral testis were done on days 0, 2, 4, 6, and 8. The experiment was terminated on day 9 and testes were analyzed by either western blotting, or by stimulated emission depletion (STED), electron and/or conventional fluorescence microscopy. Levels of CTTN were successfully knocked down in experimental testes compared to controls. When cryo-sections were labeled for actin filaments, or CTTN, and oxysterol binding protein-related protein 9 (ORP9) and analyzed by STED microscopy, TBCs were "less distinct" than in tubules of the same stages from control testes. When analyzed by electron microscopy, redundant clumps of basal actin filament containing ESs were observed in experimental sections. Using labeling of actin filaments in ESs, thresholding techniques were used to calculate the number of pixels above threshold per unit length of tubule wall in seminiferous tubules at Stage VII. Median values were higher in experimental testes relative to controls in the four animals analyzed. Although we detected subtle differences in ES turnover, we were unable to demonstrate changes in spermatocyte translocation or in the levels of junction proteins at the sites. Our results are the first to demonstrate that perturbation of basal TBCs alters the turnover of actin-related junctions (ESs).
    MeSH term(s) Actin Cytoskeleton/metabolism ; Animals ; Cortactin/deficiency ; Intercellular Junctions/metabolism ; Male ; RNA Interference ; RNA, Small Interfering/pharmacology ; Rats ; Sertoli Cells/metabolism ; Testis/metabolism
    Chemical Substances Cortactin ; Cttn protein, rat ; RNA, Small Interfering
    Language English
    Publishing date 2021-08-23
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1118-6
    ISSN 1529-7268 ; 0006-3363
    ISSN (online) 1529-7268
    ISSN 0006-3363
    DOI 10.1093/biolre/ioab161
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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  2. Article ; Online: Internalization of Intact Intercellular Junctions in the Testis by Clathrin/Actin-Mediated Endocytic Structures: Tubulobulbar Complexes.

    Adams, Arlo / Sriram, Aarati / Wayne Vogl, A

    Anatomical record (Hoboken, N.J. : 2007)

    2018  Volume 301, Issue 12, Page(s) 2080–2085

    Abstract: Sertoli cells of the mammalian seminiferous epithelium form unique subcellular actin-related structures at intercellular junctions. The appearance of these so called "tubulobulbar complexes" (TBCs) precedes both sperm release at the apex of the ... ...

    Abstract Sertoli cells of the mammalian seminiferous epithelium form unique subcellular actin-related structures at intercellular junctions. The appearance of these so called "tubulobulbar complexes" (TBCs) precedes both sperm release at the apex of the epithelium and the movement of early spermatogenic cells out of the spermatogonial stem cell niche at the base of the epithelium. TBCs are considered to be part of the mechanism of junction endocytosis by Sertoli cells. The structures contain junction proteins and morphologically identifiable junctions, and are associated with markers of endocytosis. Here we review the current state of knowledge about the structure and function of TBCs. As the complexes form, they morphologically resemble and have the molecular signature of clathrin-coated pits with extremely long necks. As they mature, the actin filament networks around the "necks" of the structures progressively disassemble and the membrane cores expand or swell into distinct "bulbs". These bulbs acquire extensive membrane contact sites with associated cisternae of endoplasmic reticulum. Eventually the bulbs undergo scission and continue through endosomal compartments of the Sertoli cells. The morphology and composition of TBC indicates to us that the structures likely evolved from the basic clathrin-mediated endocytosis mechanism common to cells generally, and along the way they incorporated unique features to accommodate the cyclic turnover of massive and "intact" intercellular junctions that occurs during spermatogenesis. Anat Rec, 301:2080-2085, 2018. © 2018 Wiley Periodicals, Inc.
    MeSH term(s) Actins/analysis ; Actins/metabolism ; Animals ; Clathrin/analysis ; Clathrin/metabolism ; Endocytosis/physiology ; Humans ; Intercellular Junctions/chemistry ; Intercellular Junctions/metabolism ; Male ; Seminiferous Epithelium/chemistry ; Seminiferous Epithelium/cytology ; Seminiferous Epithelium/metabolism ; Sertoli Cells/chemistry ; Sertoli Cells/metabolism ; Testis/chemistry ; Testis/cytology ; Testis/metabolism
    Chemical Substances Actins ; Clathrin
    Language English
    Publishing date 2018-11-09
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2269667-2
    ISSN 1932-8494 ; 1932-8486
    ISSN (online) 1932-8494
    ISSN 1932-8486
    DOI 10.1002/ar.23963
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

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  3. Article ; Online: Actin Disruption Results in Altered Morphology of Basal Tubulobulbar Complexes in Rat Seminiferous Epithelium.

    Sriram, Aarati / Lyon, Kevin R P / Ho, Clement Dallas / Huynh, Nghi / Vogl, A Wayne

    Anatomical record (Hoboken, N.J. : 2007)

    2016  Volume 299, Issue 10, Page(s) 1449–1455

    Abstract: Basal tubulobulbar complexes (TBCs) that occur at attachment sites between neighboring Sertoli cells are subcellular machines that internalize intercellular junctions during movement of spermatocytes from basal to adluminal compartments of the ... ...

    Abstract Basal tubulobulbar complexes (TBCs) that occur at attachment sites between neighboring Sertoli cells are subcellular machines that internalize intercellular junctions during movement of spermatocytes from basal to adluminal compartments of the seminiferous epithelium. Each complex consists of an elongate tubular extension of two attached plasma membranes, and is capped at its distal end by a clathrin-coated pit. The tubular region is surrounded by a cuff of actin arranged in a dendritic network. Near the end of the complex, a bulbous region forms that lacks the actin cuff but is closely associated with cisternae of endoplasmic reticulum. The bulb eventually buds from the complex and enters endocytic compartments of the Sertoli cell. Previous research has shown that when the actin network is perturbed using the actin filament-disruptor, cytochalasin D, apical tubulobulbar complexes that are associated with spermatids were associated with lower levels of actin, patchy actin networks and swollen tubular regions. Here we explored the effects of actin network perturbation on the morphology of basal tubulobulbar complexes in stage V seminiferous tubules. Isolated rat testes were perfused ex vivo for one hour with oxygenated Krebs-Henseleit buffer (with BSA) containing either 40 μM cytochalasin D or control solution containing DMSO and perfusion-fixed for electron microscopy. Compared to control, actin cuffs in drug-treated TBCs appeared less uniform and patchy. In addition, the tubular regions of the complexes appeared swollen. Our results are consistent with the conclusion that intact networks of actin filaments are required for maintaining the structural integrity of basal TBCs. Anat Rec, 299:1449-1455, 2016. © 2016 Wiley Periodicals, Inc.
    MeSH term(s) Actins/metabolism ; Animals ; Intercellular Junctions/metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Seminiferous Epithelium/cytology ; Seminiferous Epithelium/metabolism ; Sertoli Cells/metabolism
    Chemical Substances Actins
    Language English
    Publishing date 2016-10
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2269667-2
    ISSN 1932-8494 ; 1932-8486
    ISSN (online) 1932-8494
    ISSN 1932-8486
    DOI 10.1002/ar.23394
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: IglC and PdpA are important for promoting Francisella invasion and intracellular growth in epithelial cells.

    Law, H T / Sriram, Aarati / Fevang, Charlotte / Nix, Eli B / Nano, Francis E / Guttman, Julian Andrew

    PloS one

    2014  Volume 9, Issue 8, Page(s) e104881

    Abstract: The highly infectious bacteria, Francisella tularensis, colonize a variety of organs and replicate within both phagocytic as well as non-phagocytic cells, to cause the disease tularemia. These microbes contain a conserved cluster of important virulence ... ...

    Abstract The highly infectious bacteria, Francisella tularensis, colonize a variety of organs and replicate within both phagocytic as well as non-phagocytic cells, to cause the disease tularemia. These microbes contain a conserved cluster of important virulence genes referred to as the Francisella Pathogenicity Island (FPI). Two of the most characterized FPI genes, iglC and pdpA, play a central role in bacterial survival and proliferation within phagocytes, but do not influence bacterial internalization. Yet, their involvement in non-phagocytic epithelial cell infections remains unexplored. To examine the functions of IglC and PdpA on bacterial invasion and replication during epithelial cell infections, we infected liver and lung epithelial cells with F. novicida and F. tularensis 'Type B' Live Vaccine Strain (LVS) deletion mutants (ΔiglC and ΔpdpA) as well as their respective gene complements. We found that deletion of either gene significantly reduced their ability to invade and replicate in epithelial cells. Gene complementation of iglC and pdpA partially rescued bacterial invasion and intracellular growth. Additionally, substantial LAMP1-association with both deletion mutants was observed up to 12 h suggesting that the absence of IglC and PdpA caused deficiencies in their ability to dissociate from LAMP1-positive Francisella Containing Vacuoles (FCVs). This work provides the first evidence that IglC and PdpA are important pathogenic factors for invasion and intracellular growth of Francisella in epithelial cells, and further highlights the discrete mechanisms involved in Francisella infections between phagocytic and non-phagocytic cells.
    MeSH term(s) Animals ; Cell Line ; Epithelial Cells/microbiology ; Francisella/genetics ; Francisella/growth & development ; Francisella/pathogenicity ; Francisella tularensis/genetics ; Francisella tularensis/growth & development ; Francisella tularensis/pathogenicity ; Genes, Bacterial ; Genomic Islands ; Hepatocytes/microbiology ; Host-Pathogen Interactions ; Humans ; Lung/cytology ; Lung/microbiology ; Lysosomal Membrane Proteins/metabolism ; Mice ; Vacuoles/metabolism ; Vacuoles/microbiology ; Virulence/genetics
    Chemical Substances Lamp1 protein, mouse ; Lysosomal Membrane Proteins
    Language English
    Publishing date 2014-08-12
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2267670-3
    ISSN 1932-6203 ; 1932-6203
    ISSN (online) 1932-6203
    ISSN 1932-6203
    DOI 10.1371/journal.pone.0104881
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: An Accessory Agonist Binding Site Promotes Activation of α4β2* Nicotinic Acetylcholine Receptors.

    Wang, Jingyi / Kuryatov, Alexander / Sriram, Aarati / Jin, Zhuang / Kamenecka, Theodore M / Kenny, Paul J / Lindstrom, Jon

    The Journal of biological chemistry

    2015  Volume 290, Issue 22, Page(s) 13907–13918

    Abstract: Neuronal nicotinic acetylcholine receptors containing α4, β2, and sometimes other subunits (α4β2* nAChRs) regulate addictive and other behavioral effects of nicotine. These nAChRs exist in several stoichiometries, typically with two high affinity ... ...

    Abstract Neuronal nicotinic acetylcholine receptors containing α4, β2, and sometimes other subunits (α4β2* nAChRs) regulate addictive and other behavioral effects of nicotine. These nAChRs exist in several stoichiometries, typically with two high affinity acetylcholine (ACh) binding sites at the interface of α4 and β2 subunits and a fifth accessory subunit. A third low affinity ACh binding site is formed when this accessory subunit is α4 but not if it is β2. Agonists selective for the accessory ACh site, such as 3-[3-(3-pyridyl)-1,2,4-oxadiazol-5-yl]benzonitrile (NS9283), cannot alone activate a nAChR but can facilitate more efficient activation in combination with agonists at the canonical α4β2 sites. We therefore suggest categorizing agonists according to their site selectivity. NS9283 binds to the accessory ACh binding site; thus it is termed an accessory site-selective agonist. We expressed (α4β2)2 concatamers in Xenopus oocytes with free accessory subunits to obtain defined nAChR stoichiometries and α4/accessory subunit interfaces. We show that α2, α3, α4, and α6 accessory subunits can form binding sites for ACh and NS9283 at interfaces with α4 subunits, but β2 and β4 accessory subunits cannot. To permit selective blockage of the accessory site, α4 threonine 126 located on the minus side of α4 that contributes to the accessory site, but not the α4β2 sites, was mutated to cysteine. Alkylation of this cysteine with a thioreactive reagent blocked activity of ACh and NS9283 at the accessory site. Accessory agonist binding sites are promising drug targets.
    MeSH term(s) Acetylcholine/chemistry ; Animals ; Azetidines/chemistry ; Binding Sites ; Cytosine/chemistry ; DNA, Complementary/metabolism ; Electrophysiology ; HEK293 Cells ; Humans ; Mutation ; Oocytes/cytology ; Oocytes/metabolism ; Oxadiazoles/chemistry ; Protein Binding ; Protein Structure, Tertiary ; Pyridines/chemistry ; Receptors, Nicotinic/metabolism ; Structure-Activity Relationship ; Xenopus laevis
    Chemical Substances 3-(3-(pyridine-3-yl)-1,2,4-oxadiazol-5-yl)benzonitrile ; Azetidines ; DNA, Complementary ; Oxadiazoles ; Pyridines ; Receptors, Nicotinic ; nicotinic receptor alpha3beta2 ; nicotinic receptor alpha4beta2 ; sazetidine-A ; Cytosine (8J337D1HZY) ; Acetylcholine (N9YNS0M02X)
    Language English
    Publishing date 2015-04-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2997-x
    ISSN 1083-351X ; 0021-9258
    ISSN (online) 1083-351X
    ISSN 0021-9258
    DOI 10.1074/jbc.M115.646786
    Database MEDical Literature Analysis and Retrieval System OnLINE

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