A W Vogl

University of British Columbia - Vancouver, Vancouver, British Columbia, Canada

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Publications (94)280.93 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: There is a growing body of evidence that exposure to endocrine disrupting chemicals and to estrogenic compounds in particular can affect the testis and male fertility. In the present study, the constitutive expression of steroidogenic and non-steroidogenic cytochrome P450 (CYP) and related enzymes in adult rat testis, and their regulation by estradiol and bisphenol A, were investigated. CYP1B1, CYP2A1, NADPH-cytochrome P450 oxidoreductase (POR) and microsomal epoxide hydrolase (mEH) proteins, together with CYP17A1 and 3β-hydroxysteroid dehydrogenase (3HSD), were detected by immunoblot analysis in testicular microsomes prepared from untreated adult Sprague-Dawley rats. In contrast, CYP1A, CYP2B, CYP2E, CYP2D, CYP2C, CYP3A and CYP4A enzymes were not detected. Immunofluorescence staining of cryosections of perfusion-fixed testes showed that CYP1B1, CYP2A1, CYP17A1 and 3HSD were expressed exclusively or mainly in interstitial cells, whereas mEH and POR protein staining was detected both in interstitial cells and in seminiferous tubules. Testicular CYP1B1 and CYP2A1 protein levels were decreased following treatment of adult rats with estradiol benzoate at 0.004, 0.04, 0.4 or 4 μmol/kg/day or bisphenol A at 400 or 800 μmol/kg/day, for 14 days, whereas expression of 3HSD was unaffected. Testicular CYP17A1, POR and mEH protein expression was also down-regulated at the three highest dosages of estradiol benzoate and at both dosages of bisphenol A. The present study is the first to establish the cellular localization of CYP1B1, mEH and POR in rat testis and to demonstrate the suppressive effect of bisphenol A on testicular CYP1B1, CYP2A1, mEH and POR protein levels.
    Toxicological Sciences 04/2014; · 4.33 Impact Factor
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    ABSTRACT: Tubulobulbar complexes are elaborate clathrin/actin related structures that form at sites of intercellular attachment in the seminiferous epithelium of the mammalian testis. Here we summarize what is currently known about the morphology and molecular composition of these structures and review evidence that the structures internalize intercellular junctions both at apical sites of Sertoli cell attachment to spermatids, and at basal sites where Sertoli cells form the blood-testis barrier. We present updated models of the sperm release and spermatocyte translocation mechanisms that incorporate tubulobulbar complexes into their designs.
    Seminars in Cell and Developmental Biology 11/2013; · 6.20 Impact Factor
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    ABSTRACT: The mouse protein phosphatase gene Ppp1cc is essential for male fertility, with mutants displaying a failure in spermatogenesis including a widespread loss of post-meiotic germ cells and abnormalities in the mitochondrial sheath. This phenotype is hypothesized to be attributed to the loss of the testis specific isoform PPP1CC2. To identify PPP1CC2 interacting proteins with a function in spermatogenesis, we performed GST pull down assays in mouse testis lysate. Amongst the identified candidate interactors was the testis specific protein kinase TSSK1, which is also essential for male fertility. Subsequent interaction experiments have confirmed the capability of PPP1CC2 to form a complex with TSSK1 mediated by direct interaction of each with the kinase substrate protein TSKS. Interaction between PPP1CC2 and TSKS is mediated through an RVxF docking motif on the TSKS surface. Phosphoproteomic analysis of the mouse testis identified a novel serine phosphorylation site within the TSKS RVxF motif that appears to negatively regulate binding to PPP1CC2. Immunohistochemical analysis of TSSK1 and TSKS in Ppp1cc mutant testis showed reduced accumulation to distinct cytoplasmic foci and other abnormalities in their distribution consistent with the loss of germ cells and seminiferous tubule disorganization observed in the Ppp1cc mutant phenotype. A comparison of Ppp1cc and Tssk1/2 knockout phenotypes via electron microscopy revealed similar abnormalities in the morphology of the mitochondrial sheath. This data demonstrates a novel kinase/phosphatase complex in the testis that could play a critical role in the completion of spermatogenesis.
    Reproduction 10/2013; · 3.56 Impact Factor
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    ABSTRACT: From puberty and throughout adult spermatogenesis, retinoid signalling is essential for germ cell differentiation and male fertility. The initiation of spermatogonial differentiation and germ cell meiosis occurs under the direction of local retinoid signalling in the testis, and corresponds with the final phase of somatic Sertoli cell differentiation at puberty. Here, we consider the cellular and molecular basis of retinoid actions upon Sertoli cell differentiation. Primary rat Sertoli cells were isolated during the pubertal proliferative and quiescent phases at postnatal days 10- and 20- respectively, and cultured with all-trans-retinoic acid. We show that retinoid signalling can potently suppress activin-induced proliferation by antagonising G1 phase progression and entry into the cell cycle. Retinoid signalling was also found to initiate tight junction formation in primary Sertoli cells, consistent with a pro-differentiative role. This study implicates retinoid signalling in the differentiation of both somatic and germ cells in the testis at puberty.
    Molecular and Cellular Endocrinology 07/2013; · 4.04 Impact Factor
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    ABSTRACT: Tubulobulbar complexes (TBCs) are actin-related endocytic structures that internalize intercellular junctions in the seminiferous epithelium. The structures consist of elongate tubular projections of the attached plasma membranes of two adjacent cells that project into Sertoli cells. This double membrane core is cuffed by a dentritic actin network and is capped at its end by a clathrin-coated pit. Here we explore the possibility that elements of the spectrin cytoskeleton are associated with clusters of tubulobulbar complexes that develop at adhesion junctions between late spermatids and Sertoli cells at the apex of the epithelium, and extend what is known about the distribution of plectin at the sites. Cryo-sections of perfusion-fixed testes and apical processes of Sertoli cells mechanically dissociated from perfusion-fixed testes were probed for spectrin, EPB41, and actin and analyzed using conventional fluorescence microscopy and confocal microscopy. Data sets from confocal microscopy were analyzed further in three-dimensional reconstructions using computer software. Additional apical Sertoli cell processes were probed for plectin and analyzed using conventional fluorescence microscopy. Antibodies generated against elements of the spectrin cytoskeleton react with material around and between the actin cuffs of tubulobulbar complexes, but appear excluded from the actin cuffs themselves. A similar staining pattern occurs with a probe for plectin. Immunoelectron microscopy confirmed the staining patterns observed by fluourescence microscopy. Based on our results, we suggest that a network of spectrin and plectin forms a scaffold around tubulobulbar complexes that may provide support for the actin network that cuffs each complex and also link adjacent complexes together.
    Spermatogenesis. 07/2013; 3(3):e25733.
  • Ni Lan, A Wayne Vogl, Joanne Weinberg
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    ABSTRACT: BACKGROUND: During late prenatal and early postnatal life, the reproductive system in males undergoes an extensive series of physiological and morphological changes. Prenatal ethanol (EtOH) exposure has marked effects on the development of the reproductive system, with long-term effects on function in adulthood. The present study tested the hypothesis that prenatal EtOH exposure will delay the onset of spermatogenesis. METHODS: Development of the seminiferous tubules and the onset of spermatogenesis were examined utilizing a rat model of fetal alcohol spectrum disorder (FASD). Male offspring from ad libitum-fed control (C), pair-fed (PF), and EtOH-fed (prenatal alcohol exposure [PAE]) dams were terminated on postnatal (PN) days 5, 15, 18, 20, 25, 35, 45, and 55, to investigate morphological changes through morphometric analysis of the testes from early neonatal life through young adulthood. RESULTS: PAE males had lower relative (adjusted for body weight) testis weights compared with PF and/or C males from PN15 through puberty (PN45). In addition, fewer gonocytes (primordial germ cells) were located on the basal lamina on PN5, while more of those touching the basal lamina were dividing in PAE compared with PF and C males, suggesting delayed cell division and migration processes. As well, the percentage of tubules with open lumena was lower in PAE compared with PF and C males on PN18 and 20, and PAE males had fewer primary spermatocytes per tubule on PN18 and round spermatids per tubule on PN25 compared with C males. Finally, the percentage of tubules at stages VII and VIII, when mature spermatids move to the apex of the epithelium and are released, was lower in PAE compared with PF and/or C males in young adulthood (PN55). CONCLUSIONS: Maternal EtOH consumption appears to delay both reproductive development and the onset of spermatogenesis in male offspring, with effects persisting at least until young adulthood.
    Alcoholism Clinical and Experimental Research 03/2013; · 3.42 Impact Factor
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    ABSTRACT: During metastatic progression, an aberrant epithelial-to-mesenchymal transformation (EMT) that is most often driven by the loss of the cell-cell adhesion molecule E-cadherin generates non-cohesive tumor cells that are highly invasive. We used mesenchymally-transformed, E-cadherin negative MDA-MB-231 breast carcinoma cells in a natural product screen and determined that the triterpenoid saponin sarasinoside A1 inhibited their invasion and the invasion of a number of other tumor cell lines. Sarasinoside A1 also caused MDA-MB-231 cells to become cohesive in 3-dimensional basement membrane and collagen gel cultures. In 2-dimensional culture, sarasinoside A1 initiated a morphologic re-epithelialization of MDA-MB-231 cells wherein pre-existing non-epithelial cadherins and the junction-associated proteins β-catenin and ZO-1 all re-localized to sites of cell-cell contact. Additionally, the intercellular space between neighboring cells narrowed considerably, the stability of polymerized actin at cell-cell contact sites increased, and there was a recruitment and stabilization of nectin-based adhesion complexes to these sites, all of which strongly suggested that functional cell-cell junctions had formed. Importantly, sarasinoside A1 induced nascent cell-cell junction formation that did not require changes in gene expression and was not associated with an induction of E-cadherin, but resulted in increased activation of Rap GTPases. Therefore, our findings with sarasinoside A1 suggest that it may be possible to re-epithelialize metastatic tumor cells with phenotypic consequence even when E-cadherin is completely absent.
    Molecular Cancer Research 02/2013; · 4.35 Impact Factor
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    ABSTRACT: Tubulobulbar complexes are cytoskeleton-related membrane structures that develop at sites of intercellular attachment in the mammalian seminiferous epithelium. At apical junctions between Sertoli cells and spermatids the structures internalize adhesion junctions and are a component of the sperm release mechanism. Here we explore the possibility that tubulobulbar complexes that form at the "blood-testis barrier" are sub-cellular machines that internalize basal junction complexes. Using electron microscopy we confirm that morphologically identifiable tight and gap junctions are present in basal tubulobulbar complexes in rats. In addition, immunological probes for claudin-11 (CLDN11), connexin-43 (GJA1), and nectin-2 (PVRL2) react with linear structures at the light level that we interpret as tubulobulbar complexes, and probes for early endosome antigen 1 (EEA1) and Rab5 (RAB5A) react in similar locations. Significantly, fluorescence patterns for actin and claudin-11 indicate that the amount of junction present is dramatically reduced over the time period that tubulobulbar complexes are known to be most prevalent during spermatogenesis. We also demonstrate, using electron microscopy and fluorescence microscopy, that tubulobulbar complexes develop at basal junctions in primary cultures of Sertoli cells, and that like their in vivo counterparts, the structures contain junction proteins. We use this culture system together with transfection techniques to show that junction proteins from one transfected cell occur in structures that project into adjacent non-transfected cells as predicted by the junction internalization hypothesis. On the basis of our findings we present a new model for basal junction remodeling as it relates to spermatocyte translocation in the seminiferous epithelium.
    Biology of Reproduction 01/2013; · 4.03 Impact Factor
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    ABSTRACT: We have identified cpna-1 (F31D5.3) as a novel essential muscle gene in the nematode C. elegans. Antibodies specific to CPNA-1, as well as a YFP translational fusion, are localized to integrin attachment sites (M-lines and dense bodies) in the body-wall muscle of C. elegans. CPNA-1 contains an N-terminal predicted transmembrane domain and a C-terminal copine domain, and binds to the M-line/dense body protein PAT-6 (actopaxin) and the M-line proteins UNC-89 (obscurin), LIM-9 (FHL), SCPL-1 (SCP) and UNC-96. Proper CPNA-1 localization is dependent upon PAT-6 in embryonic and adult muscle. Nematodes lacking cpna-1 arrest elongation at the twofold stage of embryogenesis, and display disruption of the myofilament lattice. The thick filament component myosin heavy chain MYO-3, and the M-line component UNC-89, are initially localized properly in cpna-1 null embryos. However, in these embryos, when contraction begins, MYO-3 and UNC-89 become mislocalized into large foci and animals die. We propose that CPNA-1 acts as a linker between an integrin associated protein, PAT-6, and membrane-distal components of integrin adhesion complexes in the muscle of C. elegans.
    Molecular biology of the cell 01/2013; · 5.98 Impact Factor
  • A Wayne Vogl, J'nelle S Young, Min Du
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    ABSTRACT: Tubulobulbar complexes are actin-filament-related structures that form at intercellular junctions in the seminiferous epithelium of mammalian testis. The structures occur both at adhesion junctions between Sertoli cells and the maturing spermatids in apical regions of the epithelium, and at junction complexes between neighboring Sertoli cells near the base of the epithelium. Here, we review the general morphology and molecular composition of tubulobulbar complexes, and also include a description of tubulobulbar complex structure in the human seminiferous epithelium. Although tubulobulbar complexes are unique to the seminiferous epithelium, they have the molecular signature of clathrin-based endocytosis machinery present generally in cells. We review the evidence that tubulobulbar complexes internalize intact intercellular junctions and are significant components of the sperm-release mechanism and the process by which spermatocytes translocate from basal to adluminal compartments of the epithelium.
    International review of cell and molecular biology 01/2013; 303:319-55. · 4.97 Impact Factor
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    ABSTRACT: Tubulobulbar complexes are actin-related endocytic structures that form at sites of intercellular attachment in the seminiferous epithelium and are proposed to internalize intact junctions. In this study, we test the prediction that altering the structure/function of tubulobulbar complexes results in failure to release mature spermatids from Sertoli cells. We used an in vivo knockdown strategy to target cortactin, a component of tubulobulbar complexes, in Sprague Dawley rats. In each animal, one testis was surgically injected with cortactin siRNA reagents and the other testis was injected with non-targeting siRNA. After three days, experimental and control testes were processed for immunoblotting, electron microscopy or immunofluorescence microscopy. In testis sections immunostained for cortactin or labeled for filamentous actin, fluorescence microscopy revealed that tubulobulbar complexes were shorter in siRNA-treated testes relative to controls. Significantly, in the knockdown testes, spermiation was delayed in some tubules and had failed in others. When evaluated by electron microscopy, adhesion complexes (ectoplasmic specializations) remained associated with mature spermatids that failed to be released from Sertoli cells. Immunoblots both of whole testis lysates and of isolated seminiferous epithelial lysates confirmed that cortactin expression was knocked-down in experimental testes and in the seminiferous epithelium respectively, relative to controls. Moreover, in testes injected with siRNA reagents with a dye modification on one of the four targeting siRNA sequences, dye clusters were detected at the base of the epithelium confirming that the reagents entered Sertoli cells. Our results are consistent with the hypothesis that tubulobulbar complexes internalize intercellular junctions and that they are a significant component of the sperm release mechanism.
    Biology open. 11/2012; 1(11):1069-77.
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    ABSTRACT: Cyclic AMP-dependent protein kinase A (PKA) regulates elaboration of the virulence factors melanin and polysaccharide capsule in Cryptococcus neoformans. A mutation in PKA1 encoding the catalytic subunit is known to reduce virulence in mice while a defect in PKR1 encoding the regulatory subunit enhances disease. Here, we constructed strains with galactose-inducible and glucose-repressible versions of PKA1 and PKR1 by inserting the GAL7 promoter upstream of the genes. As expected, no capsule was found in dextrose-containing media for the P(GAL7):PKA1 strain, whereas a large capsule was formed on cells grown in galactose. Along with capsule thickness, high PKA activity also influenced cell size, ploidy and vacuole enlargement, as observed in previous reports of giant/titan cell formation. We employed the regulated strains to test the hypothesis that PKA influences secretion and found that elevated PKA expression positively regulates extracellular protease activity and negatively regulates urease secretion. Furthermore, proper PKA regulation and activity were required for wild-type levels of melanization and laccase activity, as well as correct localization of the enzyme. The latter phenotype is consistent with the discovery that PKA regulates the organization of intracellular membrane compartments. Overall, these results indicate that PKA influences secretion pathways directly related to virulence factor elaboration.
    Molecular Microbiology 06/2012; 85(4):700-15. · 5.03 Impact Factor
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    J'nelle S Young, A Wayne Vogl
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    ABSTRACT: Tubulobulbar complexes (TBCs) are actin-related double-membrane invaginations formed at intercellular junctions in the seminiferous epithelium of mammalian testis. They occur at basal junction complexes between neighboring Sertoli cells and at apical junctions between Sertoli cells and spermatids. They are proposed to internalize intercellular junctions during the translocation of spermatocytes from basal to adluminal compartments of the seminiferous epithelium, and during sperm release from Sertoli cells. Although TBCs are specific to the seminiferous epithelium, they morphologically resemble podosomes in osteoclasts. Previously, we have reported that a key group of proteins consisting of N-WASp, Arp2/3, cortactin and dynamin that occur at podosomes also is present at TBCs. Here we explore the prediction that zyxin, a focal adhesion protein known to be present at podosomes, also is present at apical TBCs. A rabbit polyclonal anti-zyxin antibody (B71) was used to label fixed fragments and frozen sections of testis. In both fragments and sections, B71 labeled tubular regions of TBCs at apical sites of attachment between Sertoli cells and spermatids, in addition to being localized at actin related intercellular adhesion junctions termed ectoplasmic specializations. Although the function of zyxin at TBCs has yet to be determined, the protein is known to interact with the cytoplasmic domain of integrins at focal adhesions, and integrins are known to be present in TBCs.
    Spermatogenesis. 01/2012; 2(1):63-68.
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    ABSTRACT: Enteropathogenic Escherichia coli (EPEC) manipulate the cytoskeleton of host intestinal epithelial cells, producing membrane protrusions termed pedestals that the bacteria reside on throughout the course of their infections. By definition pedestals are actin-based structures, however recent work has identified the spectrin cytoskeleton as a necessary component of EPEC pedestals. Here, we investigated the detailed arrangement of the spectrin and actin cytoskeletons within these structures. Immunofluorescent imaging revealed that the spectrin network forms a peripheral cage around actin at the membranous regions of pedestals. Myosin S1 fragment decorated actin filaments examined by electron microscopy demonstrated that actin filaments orientate with their fast-growing barbed ends toward the lateral membranes of EPEC pedestals. These findings provide a detailed descriptive analysis, which further illustrate the spectrin cytoskeletal organization within these structures.
    The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology 12/2011; 295(2):201-7. · 1.34 Impact Factor
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    ABSTRACT: Tubulobulbar complexes (TBCs) are elaborate cytoskeleton-related structures that are formed in association with intercellular junctions in the seminiferous epithelium. They consist of a cylindrical double-membrane core composed of the plasma membranes of the two attached cells, cuffed by a dendritic network of actin filaments. TBCs are proposed to be subcellular machines that internalize intercellular junctions during the extensive junction remodeling that occurs during spermatogenesis. At the apical sites of attachment between Sertoli cells and spermatids, junction disassembly is part of the sperm release mechanism. In this study, we used immunological probes to explore junction internalization and recycling at apical TBCs in the rat seminiferous epithelium. We demonstrate that β1-integrin and nectin 2 were concentrated at the ends of TBCs and for the first time show that the early endosome marker RAB5A was also distinctly localized at the ends of TBCs that appear to be the 'bulbar' regions of the complexes. Significantly, we also demonstrate that the 'long-loop' recycling endosome marker RAB11A was co-distributed with nectin 2 at junctions with early spermatids deeper in the epithelium. Our results are consistent with the hypothesis that TBCs associated with late spermatids internalize adhesion junctions and also indicate that some of the internalized junction proteins may be recycled to form junctions with the next generation of spermatids.
    Reproduction 12/2011; 143(3):347-57. · 3.56 Impact Factor
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    ABSTRACT: To cause disease, Salmonella enterica serovar Typhimurium requires two type III secretion systems that are encoded by Salmonella pathogenicity islands 1 and 2 (SPI-1 and -2). These secretion systems serve to deliver specialized proteins (effectors) into the host cell cytosol. While the importance of these effectors to promote colonization and replication within the host has been established, the specific roles of individual secreted effectors in the disease process are not well understood. In this study, we used an in vivo gallbladder epithelial cell infection model to study the function of the SPI-2-encoded type III effector, SseL. The deletion of the sseL gene resulted in bacterial filamentation and elongation and the unusual localization of Salmonella within infected epithelial cells. Infection with the ΔsseL strain also caused dramatic changes in host cell lipid metabolism and led to the massive accumulation of lipid droplets in infected cells. This phenotype was directly attributable to the deubiquitinase activity of SseL, as a Salmonella strain carrying a single point mutation in the catalytic cysteine also resulted in extensive lipid droplet accumulation. The excessive buildup of lipids due to the absence of a functional sseL gene also was observed in murine livers during S. Typhimurium infection. These results suggest that SseL alters host lipid metabolism in infected epithelial cells by modifying the ubiquitination patterns of cellular targets.
    Infection and immunity 08/2011; 79(11):4392-400. · 4.21 Impact Factor
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    ABSTRACT: We have identified the gene C28H8.6 (pxl-1) as the Caenorhabditis elegans orthologue of vertebrate paxillin. PXL-1 contains the four C-terminal LIM domains conserved in paxillin across all species and three of the five LD motifs found in the N-terminal half of most paxillins. In body wall muscle, PXL-1 antibodies and a full-length green fluorescent protein translational fusion localize to adhesion sites in the sarcomere, the functional repeat unit in muscle responsible for contraction. PXL-1 also localizes to ring-shaped structures near the sarcolemma in pharyngeal muscle corresponding to podosome-like sites of actin attachment. Our analysis of a loss-of-function allele of pxl-1, ok1483, shows that loss of paxillin leads to early larval arrested animals with paralyzed pharyngeal muscles and eventual lethality, presumably due to an inability to feed. We rescued the mutant phenotype by expressing paxillin solely in the pharynx and found that these animals survived and are essentially wild type in movement and body wall muscle structure. This indicates a differential requirement for paxillin in these two types of muscle. In pharyngeal muscle it is essential for contraction, whereas in body wall muscle it is dispensable for filament assembly, sarcomere stability, and ultimately movement.
    Molecular biology of the cell 06/2011; 22(14):2551-63. · 5.98 Impact Factor
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    ABSTRACT: Autophagy enables cells to degrade and recycle cytoplasmic materials both as a housekeeping mechanism and in response to extracellular stress such as nutrient deprivation. Recent studies indicate that autophagy also functions as a protective mechanism in response to several cancer therapy agents, making it a prospective therapeutic target. Few pharmacological inhibitors suitable for testing the therapeutic potential of autophagy inhibition in vivo are known. An automated microscopy assay was used to screen >3,500 drugs and pharmacological agents and identified one drug, verteporfin, as an inhibitor of autophagosome accumulation. Verteporfin is a benzoporphyrin derivative used in photodynamic therapy, but it inhibits autophagy without light activation. Verteporfin did not inhibit LC3/Atg8 processing or membrane recruitment in response to autophagic stimuli, but it inhibited drug- and starvation-induced autophagic degradation and the sequestration of cytoplasmic materials into autophagosomes. Transient exposure to verteporfin in starvation conditions reduced cell viability whereas cells in nutrient-rich medium were unaffected by drug treatment. Analysis of structural analogs indicated that the activity of verteporfin requires the presence of a substituted cyclohexadiene at ring A of the porphyrin core but that it can tolerate a number of large substituents at rings C and D. The existence of an autophagy inhibitor among FDA-approved drugs should facilitate the investigation of the therapeutic potential of autophagy inhibition in vivo.
    Journal of Biological Chemistry 12/2010; 286(9):7290-300. · 4.65 Impact Factor
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    ABSTRACT: Human male infertility affects approximately 5% of men, with one-third suffering from testicular failure, likely the result of an underlying genetic abnormality that disrupts spermatogenesis during development. Mouse models of male infertility such as the Ppp1cc knockout mouse display very similar phenotypes to humans with testicular failure. Male Ppp1cc mutant mice are sterile due to disruptions in spermatogenesis that begin during prepubertal testicular development, and continue into adulthood, often resulting in loss of germ cells to the point of Sertoli cell-only syndrome. The current study employs light and electron microscopy to identify new morphological abnormalities in Ppp1cc mutant seminiferous epithelium. This study reveals that germ cells become delayed in their development around stages VII and VIII of spermatogenesis. Loss of these cells likely results in the reduced numbers of elongating spermatids and spermatozoa previously observed in mutant animals. Interestingly, Ppp1cc mutants also display reduced numbers of spermatogonia compared with their wild-type counterparts. Using electron microscopy, we have shown that junction complexes in Ppp1cc mutants are ultrastructurally normal, and therefore do not contribute to the breakdown in tissue architecture seen in mutants. Electron microscopy revealed major acrosomal and chromatin condensation defects in Ppp1cc mutants. Our observations are discussed in the context of known molecular changes in Ppp1cc mutant testes.
    Reproduction 04/2010; 139(6):1021-9. · 3.56 Impact Factor
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    ABSTRACT: Neopetrosiamide A (NeoA) is a 28-amino acid tricyclic peptide originally isolated from a marine sponge as a tumor cell invasion inhibitor whose mechanism of action is unknown. We show that NeoA reversibly inhibits tumor cell adhesion, disassembles focal adhesions in pre-attached cells, and decreases the level of beta1 integrin subunits on the cell surface. NeoA also induces the formation of dynamic, membrane-bound protrusions on the surface of treated cells and the release of membrane-bound vesicles into the culture medium. Proteomic analysis indicates that the vesicles contain EGF and transferrin receptors as well as a number of proteins involved in adhesion and migration including: beta1 integrin and numerous alpha integrin subunits; actin and actin-binding proteins such as cofilin, moesin and myosin 1C; and membrane modulating eps15 homology domain (EHD) proteins. Surface labeling, trafficking inhibition, and real-time imaging experiments all suggest that beta1 integrin-containing vesicles are released directly from NeoA-induced cell surface protrusions rather than from vesicles generated intracellularly. The biological activity of NeoA is dependent on its disulfide bond pattern and NMR spectroscopy indicates that the peptide is globular with a continuous ridge of hydrophobic groups flanked by charged amino acid residues that could facilitate a simultaneous interaction with lipids and proteins in the membrane. NeoA is an anti-adhesive peptide that decreases cell surface integrin levels through a novel, yet to be elucidated, mechanism that involves the release of adhesion molecule-containing vesicles from the cell surface.
    PLoS ONE 01/2010; 5(5):e10836. · 3.53 Impact Factor

Publication Stats

2k Citations
280.93 Total Impact Points

Institutions

  • 1985–2013
    • University of British Columbia - Vancouver
      • • Department of Cellular and Physiological Sciences
      • • Faculty of Medicine
      • • Department of Zoology
      Vancouver, British Columbia, Canada
  • 2003
    • University of Alaska Anchorage
      • Department of Biological Sciences
      Anchorage, AK, United States
  • 1999
    • University of California, Davis
      • Department of Environmental Toxicology
      Davis, CA, United States
  • 1986–1988
    • Southern Illinois University Carbondale
      • Department of Physiology
      Carbondale, IL, United States
  • 1983
    • Harvard Medical School
      Boston, Massachusetts, United States