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See detailStudy of intact virus-like particles of human papillomavirus by capillary electrophoresis
Bettonville, Virginie ULg; Nicol, Jérôme ULg; Thelen, Nicolas ULg et al

in Electrophoresis (2016), 37

Virus-like particles of human papillomavirus (HPV-VLP), resulting from the self-assembly of the capsid proteins (L1 or L1 and L2), have been widely used to study HPV as they are similar to the native ... [more ▼]

Virus-like particles of human papillomavirus (HPV-VLP), resulting from the self-assembly of the capsid proteins (L1 or L1 and L2), have been widely used to study HPV as they are similar to the native virion. Moreover, two prophylactic vaccines, Gardasil® and Cervarix®, are based on HPV-VLP L1. Analytical techniques currently used to characterize HPV-VLP, such as SDS-PAGE, Western blot, ELISA, are time-consuming and semi-quantitative. In this study, capillary electrophoresis (CE) was evaluated for the analysis of intact HPV16-VLP. The usefulness of capillary inner wall coating as well as various BGEs, pH and detergent additives were investigated. Reproducible HPV-VLP analysis in CE was achieved using poly(ethylene oxide) coated capillary and a BGE containing high salt concentration and low SDS concentration. The developed method enables HPV-VLP detection in less than 10 min (migration times RSD : 1.6 %). The identity of HPV-VLP peak was confirmed by comparison with a sample obtained from a wild-type baculovirus and with VLP-based vaccine, Gardasil®, after adjuvant dissolution. Finally, we applied the developed methodology to VLP-based vaccines, demonstrating that CE could be successfully used for vaccine quality control. [less ▲]

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See detailDominant amphipods of Posidonia oceanica seagrass meadows display considerable trophic diversity
Michel, Loïc ULg; Dauby, Patrick ULg; Gobert, Sylvie ULg et al

in Marine Ecology (2015), 36(4), 969-981

Gut content examination and trophic markers (fatty acids, stables isotopes of C and N) were combined to delineate the diet of the dominant species of amphipods from Mediterranean Posidonia oceanica ... [more ▼]

Gut content examination and trophic markers (fatty acids, stables isotopes of C and N) were combined to delineate the diet of the dominant species of amphipods from Mediterranean Posidonia oceanica seagrass meadows and to highlight trophic diversity among this community. Our results indicate that, although all dominant species heavily relied on macroalgal epiphytes, considerable interspecific dietary differences existed. Carbon stable isotope ratios notably showed that some of the amphipod species favored grazing on epiphytes from leaves or litter fragments (Apherusa chiereghinii, Aora spinicornis, Gammarus aequicauda), while others like Dexamine spiniventris preferred epiphytes from rhizomes. The remaining amphipods (Caprella acanthifera, Ampithoe helleri and Gammarella fucicola) readily consumed both groups. In addition, SIAR modeling suggested that most species had a mixed diet, and relied on several food items. Fatty acid analysis and gut contents revealed that contribution of microepiphytic diatoms and of benthic and suspended particulate organic matter to the diet of amphipods were anecdotal. None of the examined species seemed to graze on their seagrass host (low 18:2(n-6) and 18:3(n-3) fatty acids contents), but G. aequicauda partly relied on seagrass leaf detritus, as demonstrated by the lesser 13C-depletion of their tissues. Overall, our findings suggest that amphipods, because of their importance in transfers of organic matter from primary producers and detritus to higher rank consumers, are key-items in P. oceanica associated food webs. [less ▲]

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See detailHypervulnerability to Sound Exposure through Impaired Adaptive Proliferation of Peroxisomes.
Delmaghani, Sedigheh; Defourny, Jean; Aghaie, Asadollah et al

in Cell (2015), 163(4), 894-906

A deficiency in pejvakin, a protein of unknown function, causes a strikingly heterogeneous form of human deafness. Pejvakin-deficient (Pjvk(-/-)) mice also exhibit variable auditory phenotypes ... [more ▼]

A deficiency in pejvakin, a protein of unknown function, causes a strikingly heterogeneous form of human deafness. Pejvakin-deficient (Pjvk(-/-)) mice also exhibit variable auditory phenotypes. Correlation between their hearing thresholds and the number of pups per cage suggest a possible harmful effect of pup vocalizations. Direct sound or electrical stimulation show that the cochlear sensory hair cells and auditory pathway neurons of Pjvk(-/-) mice and patients are exceptionally vulnerable to sound. Subcellular analysis revealed that pejvakin is associated with peroxisomes and required for their oxidative-stress-induced proliferation. Pjvk(-/-) cochleas display features of marked oxidative stress and impaired antioxidant defenses, and peroxisomes in Pjvk(-/-) hair cells show structural abnormalities after the onset of hearing. Noise exposure rapidly upregulates Pjvk cochlear transcription in wild-type mice and triggers peroxisome proliferation in hair cells and primary auditory neurons. Our results reveal that the antioxidant activity of peroxisomes protects the auditory system against noise-induced damage. [less ▲]

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See detailSpatio‑temporal dynamics of β‑tubulin isotypes during the development of the sensory auditory organ in rat
Renauld, Justine ULg; Johnen, Nicolas; Thelen, Nicolas ULg et al

in Histochemistry & Cell Biology (2015)

There are different β-tubulin isoforms in microtubules of vertebrate tissues. However, their functional significance is still largely unknown. In the present study, we investigated the localization of ... [more ▼]

There are different β-tubulin isoforms in microtubules of vertebrate tissues. However, their functional significance is still largely unknown. In the present study, we investigated the localization of five β-tubulin isotypes (β1– 5) within the hearing organ during development in rat. By using confocal microscopy, we showed that with the exception of the β3-tubulin isoform that was specific to nerve fibres, all the different β-tubulin isoforms were mainly present in the supporting cells. Contrary to β1–4-tubulins, we also found that the β5-tubulin isoform appeared only at a key stage of the post-natal development in specific cell types (pillar cells and Deiters’ cells). By using transmission electron microscopy, we revealed further that this developmental stage coincided with the formation of two separate bundles of microtubules from a unique one in these supporting cells. Together, these results suggest that the β5-tubulin isoform might be involved in the generation of new microtubule bundles from a pre-existing one. [less ▲]

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See detailSpatio-temporal dynamics of β-tubulin isotypes and acetyl-alpha tubulin during the development of the sensory auditory organ in rodents.
Renauld, Justine ULg; Thelen, Nicolas ULg; Johnen, Nicolas ULg et al

Poster (2015, June 05)

The auditory organ is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. These ... [more ▼]

The auditory organ is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. These cells are supported by supporting cells. Supporting cells possess a characteristic cytoskeleton in direct relation with their morphological features and their development. There are different β-tubulin isoforms in microtubules of vertebrate tissues. However, their functional significance is still largely unknown. In the present study, we investigated the localization of five β-tubulin isotypes (β 1 to 5) as well as acetyl-α-tubulin within the hearing organ during development in rodents. By using confocal microscopy, we showed that with the exception of the β3-tubulin isoform that was specific to nerve fibres, all the different β-tubulin isoforms and acetyl-α-tubulin were mainly present in the supporting cells. Contrary to β1-4-tubulins, we also found that the β5-tubulin isoform appeared only at a key stage of the postnatal development in specific cell types (pillar cells and Deiters’ cells). By using transmission electron microscopy, we revealed further that this developmental stage coincided with the formation of two separate bundles of microtubules from a unique one in these supporting cells. In conclusion, these results suggest that the β5-tubulin isoform might be involved in the generation of new microtubule bundles from a pre-existing one. [less ▲]

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See detailChange in the protofilamentnumber and β5-tubulin appearance in supporting cells during development of the hearing organ.
Renauld, Justine ULg; Thelen, Nicolas ULg; Johnen, Nicolas ULg et al

Poster (2015, January)

The supporting cells of the hearing organ are characterized by the presence of an abundant cytoskeleton which is mainly composed of microtubules. These supporting cells have also been shown to contain a ... [more ▼]

The supporting cells of the hearing organ are characterized by the presence of an abundant cytoskeleton which is mainly composed of microtubules. These supporting cells have also been shown to contain a minor mammalian tubulin, the β5-tubulin, recently reported as a biomarker of cell proliferation. It was shown that a β-tubulin isoform can specify the microtubule architecture, as seen with the expression of the Moth β2 tubulin in the Drosophila testes which imposes the 16-protofilament (16pf) structure on the corresponding subset of Drosophila microtubules. Moreover, supporting cell microtubules are formed by 15pf instead of the canonical 13, a unique fact among vertebrates. Such a protofilament configuration has been observed in C. elegans’ neurons which are responsible for the mechanosensory sense of touch. It was also shown that these 15pf microtubules were essential to the proper functioning of these neurons. To determine the role of this particular tubulin in the auditory organ and its possible involvement in the formation of the unusual 15pf microtubules of supporting cells, we studied the spatiotemporal localization of β5-tubulin during development in rats from embryonic day 18 until P25 (25th postnatal day). Then we examined the fine structure of microtubules at the transmission electron microscope level (TEM). Our results showed that β5-tubulin, contrary to other β-tubulins, had a unique distribution in the cochlea. This β-tubulin appeared at a postnatal stage, before the opening of the Corti’s tunnel and is restricted to supporting cells, especially in pillar and Deiters’ cells. Our TEM study further indicated that these cells were composed by 13pf microtubules at P2, but by 15pf microtubules at P25. In conclusion, the architecture and composition of microtubules present in the supporting cells change during development of the Corti organ. Further experiments are now required to determine if these changes are related to the appearance of β5-tubulin. [less ▲]

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See detailA dynamic unfolded protein response contributes to the control of cortical neurogenesis
LAGUESSE, Sophie ULg; Creppe, Catherine ULg; Nedialkova, Dany et al

in Developmental Cell (2015)

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See detailMicroRNA-124 Regulates Cell Specification in the Cochlea through Modulation of Sfrp4/5.
Huyghe, Aurelia; Van Den Ackerveken, Priscilla ULg; SACHELI, Rosalie ULg et al

in Cell Reports (2015), 13

The organ of Corti, the auditory organ of the mammalian inner ear, contains sensory hair cells and supporting cells that arise from a common sensory progenitor. The molecular bases allowing the ... [more ▼]

The organ of Corti, the auditory organ of the mammalian inner ear, contains sensory hair cells and supporting cells that arise from a common sensory progenitor. The molecular bases allowing the specification of these progenitors remain elusive. In the present study, by combining microarray analyses with conditional deletion of Dicer in the developing inner ear, we identified that miR-124 controls cell fate in the developing organ of Corti. By targeting secreted frizzled-related protein 4 (Sfrp4) and Sfrp5, two inhibitors of the Wnt pathway, we showed that miR-124 controls the β-catenin-dependent and also the PCP-related non-canonical Wnt pathways that contribute to HC differentiation and polarization in the organ of Corti. Thus, our work emphasizes the importance of miR-124 as an epigenetic safeguard that fine-tunes the expression of genes critical for cell patterning during cochlear differentiation. [less ▲]

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See detailA dynamic Unfolded Protein Response controls cortical neurogenesis
Creppe, Catherine ULg; Laguesse, Sophie; Nedialkova, Dany et al

Poster (2015)

Detailed reference viewed: 7 (1 ULg)
See detailA dynamic Unfolded Protein Response controls cortical neurogenesis
Creppe, Catherine ULg; Laguesse, sophie; Nedialkova, Dany et al

Poster (2015)

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See detailCytoskeletal changes in supporting cells of the auditory organ during development in rodents: the appearance of 15-protofilament microtubules and β5-tubulin isoform.
Renauld, Justine ULg; Thelen, Nicolas ULg; Johnen, Nicolas et al

Poster (2014, December)

A feature of the supporting cells of the organ of Corti is the presence of an abundant cytoskeleton which is mainly composed of microtubules. These supporting cells have also been shown to contain a minor ... [more ▼]

A feature of the supporting cells of the organ of Corti is the presence of an abundant cytoskeleton which is mainly composed of microtubules. These supporting cells have also been shown to contain a minor mammalian tubulin, the β5-tubulin [1], recently reported to be a biomarker for cancer outcome [2] and cell proliferation [3]. It was shown that a β-tubulin isoform can specify the microtubule architecture, as seen with the expression of the Moth β2 tubulin in the Drosophila testes which imposes the 16-protofilament (16pf) structure on the corresponding subset of Drosophila microtubules, which normally contain 13pf [4]. Moreover, supporting cell microtubules are formed by 15pf instead of the canonical 13, a unique fact among vertebrates [5]. Such a protofilament configuration has been observed in C. elegans’ neurons which are responsible for the mechanosensory sense of touch [6]. It was also shown that these 15pf microtubules were essential to the proper functioning of these mechanosensory neurons [6]. To determine the role of this particular tubulin in the auditory organ and its possible involvement in the formation of the unusual 15pf microtubules of supporting cells, we studied the spatiotemporal localization of β5-tubulin during development in rats from embryonic day 18 until P25 (25th postnatal day). Then we examined the fine structure of microtubules at the transmission electron microscope level. Our results showed that β5-tubulin, contrary to other β-tubulins, had a unique distribution in the cochlea. This β-tubulin appeared at a postnatal stage, before the opening of the Corti’s tunnel and are restricted to supporting cells, especially in pillar and Deiters’ cells. Electron microscopy further indicated that pillar and Deiters cells were composed by 13pf microtubules at P2, but by 15pf microtubules at P25. In conclusion, the architecture of microtubules seems to evolve during the development of the organ of Corti. Furthermore, β5-tubulin has the same localization than this structure and could be an interesting target. [less ▲]

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See detailβ 5 tubulin and 15-protofilament microtubules appeared in supporting cells of the Corti’s organ during development in rodents
Renauld, Justine ULg; Thelen, Nicolas ULg; Johnen, Nicolas et al

Conference (2014, August 31)

A feature of the organ of Corti’s supporting cells is the presence of an abundant cytoskeleton which is mainly composed of microtubules. These supporting cells have also been shown to contain a minor ... [more ▼]

A feature of the organ of Corti’s supporting cells is the presence of an abundant cytoskeleton which is mainly composed of microtubules. These supporting cells have also been shown to contain a minor mammalian tubulin, the β5-tubulin [1], recently related as a biomarker for cancer outcome [2] and cell proliferation [3]. It was shown that a β-tubulin isoform can specified the microtubule architecture, such as the expression of the Moth β2 in the Drosophila testes imposed the 16 protofilaments (16pf) structure on the corresponding subset of Drosophila microtubules, which normally contain 13pf [4]. Moreover, supporting cell microtubules are formed by 15pf instead of the canonical 13, a unique fact among vertebrates [5]. Such a protofilament configuration has been observed in C. elegans’ neurons which are responsible for the mechanosensory sense of touch [6]. It was also shown that these 15pf microtubules were essential to the proper functioning of these mechanosensory neurons [6]. To determine the role of this particular tubulin in the auditory organ and its possible involvement in the formation of the unusual 15pf microtubules of supporting cells, we studied the spatiotemporal localization of β5-tubulin during development in rats from embryonic day 18 until P25 (25th postnatal day). We also analyzed the localization of β5-tubulin mRNA expression in the Corti’s organ. Then we examined the fine structure of microtubules at the electron microscope level. For these experiments, we used an early postnatal stage and a late postnatal stage. Our results showed that β5-tubulin, contrary to other β-tubulins, had a unique distribution in the cochlea. This β-tubulin appeared at a postnatal stage, before the opening of the Corti’s tunnel and being restricted to supporting cells, especially in pillar and Deiters cells,. The same localization of β5-tubulin mRNA was observed by in Situ Hybridization. Electron microscopy indicated further that Pillar and Deiters cells were composed by 15-protofilament microtubules at the late postnatal stage (P25). In conclusion, all these data strongly suggest that there is a relationship between the presence of β5-tubulin and 15-protofilament microtubules in the supporting cells of the auditory organ. Further studies are now needed to elucidate their role. [less ▲]

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See detailVaricella-zoster virus induces the formation of dynamic nuclear capsid aggregates.
Lebrun, Marielle ULg; Thelen, Nicolas ULg; Thiry, Marc ULg et al

in Virology (2014), 454-455

The first step of herpesviruses virion assembly occurs in the nucleus. However, the exact site where nucleocapsids are assembled, where the genome and the inner tegument are acquired, remains ... [more ▼]

The first step of herpesviruses virion assembly occurs in the nucleus. However, the exact site where nucleocapsids are assembled, where the genome and the inner tegument are acquired, remains controversial. We created a recombinant VZV expressing ORF23 (homologous to HSV-1 VP26) fused to the eGFP and dually fluorescent viruses with a tegument protein additionally fused to a red tag (ORF9, ORF21 and ORF22 corresponding to HSV-1 UL49, UL37 and UL36). We identified nuclear dense structures containing the major capsid protein, the scaffold protein and maturing protease, as well as ORF21 and ORF22. Correlative microscopy demonstrated that the structures correspond to capsid aggregates and time-lapse video imaging showed that they appear prior to the accumulation of cytoplasmic capsids, presumably undergoing the secondary egress, and are highly dynamic. Our observations suggest that these structures might represent a nuclear area important for capsid assembly and/or maturation before the budding at the inner nuclear membrane. [less ▲]

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See detailDifferentiation of Boettcher's cells during postnatal development of rat cochlea.
Cloes, Marie ULg; Renson, Thomas; Johnen, Nicolas et al

in Cell and tissue research (2013), 354(3), 707716

Contrary to the highly specialized epithelial cells of the mammalian auditory organ, little is known about the surrounding cells and, in particular, Boettcher's cells (BC). Our morphological studies show ... [more ▼]

Contrary to the highly specialized epithelial cells of the mammalian auditory organ, little is known about the surrounding cells and, in particular, Boettcher's cells (BC). Our morphological studies show that, in rats, these cells began their differentiation around postnatal day 8 (P8) reaching maturity around P20, when they are completely covered by Hensen's and Claudius' cells. Tight junctions were noted near the apex of BC, providing that they were in direct contact with the endolymphatic space, between approximately P8 and P16. We observed gap junctions between BC and adjacent cells before the end of the covering process suggesting the additional involvement of BC in potassium recycling into the endolymph. Adherens junctions were also seen between BC throughout their maturation. Importantly, we noticed cytoplasmic secretory granules and an accumulated material, probably a secretion, in the intercellular space, between P8 and P25. These results indicate that BC could basally take part in the secretion of the extracellular matrix of the basilar membrane. Finally, we show that the basolateral interdigitations of BC are longer and more tighlty grouped at maturity and harbour urea transporters as early as P18. Our observations thus support the view that BC perform several functions. [less ▲]

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