scholarly journals A V0-ATPase-dependent apical trafficking pathway maintains the polarity of the intestinal absorptive membrane

2018 ◽  
Author(s):  
Aurélien Bidaud-Meynard ◽  
Ophélie Nicolle ◽  
Markus Heck ◽  
Grégoire Michaux
Keyword(s):  
Brush Border ◽  
Molecular Mechanisms ◽  
Super Resolution ◽  
Structural Defects ◽  
Intestinal Epithelial ◽  
Intestinal Membrane ◽  
Apical Trafficking ◽  
Resolution Imaging ◽  
Trafficking Defects

AbstractIntestine function relies on the strong polarity of intestinal epithelial cells and the array of microvilli forming a brush border at their luminal pole. Combining genetic RNAi screen and in vivo super-resolution imaging in the C. elegans intestine, we uncovered that the V0 sector of the V-ATPase (V0-ATPase) controls a late apical trafficking step, involving RAB-11 endosomes and the SNARE SNAP-29, necessary to maintain the polarized localization of both apical polarity modules and brush border proteins. We show that the V0-ATPase pathway also genetically interacts with glycosphingolipids in enterocyte polarity maintenance. Finally, we demonstrate that depletion of the V0-ATPase fully recapitulates the severe structural, polarity and trafficking defects observed in enterocytes from patients with Microvillus inclusion disease (MVID) and used this new in vivo MVID model to follow the dynamics of microvillus inclusions. Hence, we describe a new function for the V0-ATPase in apical trafficking and epithelial polarity maintenance and the promising use of C. elegans intestine as an in vivo model to better understand the molecular mechanisms of rare genetic enteropathies.Summary statementV0-ATPase controls a late apical trafficking step involved in the maintenance of the apical absorptive intestinal membrane and its depletion phenocopies the trafficking and structural defects of MVID in C. elegans.

scholarly journals Differential FSH Glycosylation Modulates FSHR Oligomerization and Subsequent cAMP Signaling

2021 ◽  
Vol 12 ◽  
Author(s):  
Uchechukwu T. Agwuegbo ◽  
Emily Colley ◽  
Anthony P. Albert ◽  
Viktor Y. Butnev ◽  
George R. Bousfield ◽  
...  
Keyword(s):  
Super Resolution ◽  
Hek293 Cells ◽  
Camp Signaling ◽  
Camp Production ◽  
Functional Roles ◽  
Menopausal Women ◽  
Resolution Imaging ◽  
Post Menopausal

Follicle-stimulating hormone (FSH) and its target G protein-coupled receptor (FSHR) are essential for reproduction. Recent studies have established that the hypo-glycosylated pituitary FSH glycoform (FSH21/18), is more bioactive in vitro and in vivo than the fully-glycosylated variant (FSH24). FSH21/18 predominates in women of reproductive prime and FSH24 in peri-post-menopausal women, suggesting distinct functional roles of these FSH glycoforms. The aim of this study was to determine if differential FSH glycosylation modulated FSHR oligomerization and resulting impact on cAMP signaling. Using a modified super-resolution imaging technique (PD-PALM) to assess FSHR complexes in HEK293 cells expressing FSHR, we observed time and concentration-dependent modulation of FSHR oligomerization by FSH glycoforms. High eFSH and FSH21/18 concentrations rapidly dissociated FSHR oligomers into monomers, whereas FSH24 displayed slower kinetics. The FSHR β-arrestin biased agonist, truncated eLHβ (Δ121-149) combined with asparagine56-deglycosylated eLHα (dg-eLHt), increased FSHR homomerization. In contrast, low FSH21/18 and FSH24 concentrations promoted FSHR association into oligomers. Dissociation of FSHR oligomers correlated with time points where higher cAMP production was observed. Taken together, these data suggest that FSH glycosylation may modulate the kinetics and amplitude of cAMP production, in part, by forming distinct FSHR complexes, highlighting potential avenues for novel therapeutic targeting of the FSHR to improve IVF outcomes.

scholarly journals Protein Kinase C Signaling Mediates a Program of Cell Cycle Withdrawal in the Intestinal Epithelium

2000 ◽  
Vol 151 (4) ◽  
pp. 763-778 ◽  
Author(s):  
Mark R. Frey ◽  
Jennifer A. Clark ◽  
Olga Leontieva ◽  
Joshua M. Uronis ◽  
Adrian R. Black ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Intestinal Epithelium ◽  
Molecular Mechanisms ◽  
Model Systems ◽  
Intestinal Epithelial ◽  
Kinase C

Members of the protein kinase C (PKC) family of signal transduction molecules have been widely implicated in regulation of cell growth and differentiation, although the underlying molecular mechanisms involved remain poorly defined. Using combined in vitro and in vivo intestinal epithelial model systems, we demonstrate that PKC signaling can trigger a coordinated program of molecular events leading to cell cycle withdrawal into G0. PKC activation in the IEC-18 intestinal crypt cell line resulted in rapid downregulation of D-type cyclins and differential induction of p21waf1/cip1 and p27kip1, thus targeting all of the major G1/S cyclin-dependent kinase complexes. These events were associated with coordinated alterations in expression and phosphorylation of the pocket proteins p107, pRb, and p130 that drive cells to exit the cell cycle into G0 as indicated by concomitant downregulation of the DNA licensing factor cdc6. Manipulation of PKC isozyme levels in IEC-18 cells demonstrated that PKCα alone can trigger hallmark events of cell cycle withdrawal in intestinal epithelial cells. Notably, analysis of the developmental control of cell cycle regulatory molecules along the crypt–villus axis revealed that PKCα activation is appropriately positioned within intestinal crypts to trigger this program of cell cycle exit–specific events in situ. Together, these data point to PKCα as a key regulator of cell cycle withdrawal in the intestinal epithelium.

scholarly journals ABHD4-dependent developmental anoikis protects the prenatal brain from pathological insults

2019 ◽  
Author(s):  
Zsófia I. László ◽  
Zsolt Lele ◽  
Miklós Zöldi ◽  
Vivien Miczán ◽  
Fruzsina Mógor ◽  
...  
Keyword(s):  
Progenitor Cells ◽  
Super Resolution ◽  
Loss Of Function ◽  
Fetal Alcohol ◽  
Brain Malformations ◽  
Function Loss ◽  
Resolution Imaging ◽  
Metabolizing Enzyme ◽  
Induced Apoptosis

AbstractIn light of the astronomical number of cell divisions taking place in restricted neurogenic niches, brain malformations caused by ectopic proliferation of misplaced progenitor cells are surprisingly rare. Here, we show that a process we term developmental anoikis distinguishes the abnormal detachment of progenitor cells from the normal delamination of daughter neuroblasts in the developing mouse neocortex. By using in vivo gain-of-function, loss-of-function, and rescue manipulations together with correlated confocal and super-resolution imaging, we identify the endocannabinoid-metabolizing enzyme abhydrolase domain containing 4 (ABHD4) as an essential mediator for the elimination of abnormally detached cells. Consequently, rapid ABHD4 downregulation is necessary for delaminated daughter neuroblasts to escape from anoikis. Moreover, ABHD4 is required for fetal alcohol-induced apoptosis, but not for the well-established form of developmentally controlled programmed cell death. These results suggest that ABHD4-mediated developmental anoikis specifically protects the embryonic brain from the consequences of sporadic delamination errors and teratogenic insults.

scholarly journals Butyrate mediates anti-inflammatory effects of Faecalibacterium prausnitzii in intestinal epithelial cells through Dact3

2020 ◽  
Author(s):  
Marion Lenoir ◽  
Rebeca Martin ◽  
Edgar Torres-Maravilla ◽  
Sead Chadi ◽  
Pamela González-Dávila ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Molecular Mechanisms ◽  
Intestinal Epithelial Cells ◽  
Intestinal Epithelial ◽  
Commensal Bacterium ◽  
Jnk Pathway ◽  
Faecalibacterium Prausnitzii ◽  
Anti Inflammatory

Abstract BackgroundThe commensal bacterium Faecalibacterium prausnitzii plays a key role in inflammatory bowel disease (IBD) pathogenesis and serves as a general health biomarker in humans. However, the host molecular mechanisms that underlie its anti-inflammatory effects remain unknown.MethodsA transcriptomic approach on human intestinal epithelial cells (HT-29) that were stimulated with TNF-α and exposed to F. prausnitzii culture supernatant (SN) was used. Modulation of the most upregulated gene after F. prausnitzii SN contact was validated both in vitro and in vivo.ResultsF. prausnitzii SN upregulates the expression of Dact3, a gene linked to the Wnt/JNK pathway. Interestingly, when we silenced Dact3 expression, the effect of F. prausnitzii SN was lost. Butyrate was identified as the F. prausnitzii effector responsible for Dact3 modulation. Dact3 upregulation was also validated in vivo in both healthy and inflamed mice treated with either F. prausnitzii SN or the live bacteria, respectively. Finally, we demonstrated by colon transcriptomics that gut microbiota directly influences Dact3 expression.ConclusionsOur results provide new clues about the host molecular mechanisms involved in the anti-inflammatory effects of the beneficial commensal bacterium F. prausnitzii.*Contributed equally to this work

scholarly journals Genetically encoded photo-switchable molecular sensors for optoacoustic and super-resolution imaging

2021 ◽  
Author(s):  
Kanuj Mishra ◽  
Juan Pablo Fuenzalida-Werner ◽  
Francesca Pennacchietti ◽  
Robert Janowski ◽  
Andriy Chmyrov ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Fluorescent Protein ◽  
Cultured Cells ◽  
Super Resolution ◽  
Structural Level ◽  
Optoacoustic Imaging ◽  
Molecular Sensors ◽  
The Core ◽  
Resolution Imaging ◽  
G Protein Coupled

AbstractReversibly photo-switchable proteins are essential for many super-resolution fluorescence microscopic and optoacoustic imaging methods. However, they have yet to be used as sensors that measure the distribution of specific analytes at the nanoscale or in the tissues of live animals. Here we constructed the prototype of a photo-switchable Ca2+ sensor based on GCaMP5G that can be switched with 405/488-nm light and describe its molecular mechanisms at the structural level, including the importance of the interaction of the core barrel structure of the fluorescent protein with the Ca2+ receptor moiety. We demonstrate super-resolution imaging of Ca2+ concentration in cultured cells and optoacoustic Ca2+ imaging in implanted tumor cells in mice under controlled Ca2+ conditions. Finally, we show the generalizability of the concept by constructing examples of photo-switching maltose and dopamine sensors based on periplasmatic binding protein and G-protein-coupled receptor-based sensors.

scholarly journals The role of high cholesterol in age-related COVID19 lethality

2020 ◽  
Author(s):  
Hao Wang ◽  
Zixuan Yuan ◽  
Mahmud Arif Pavel ◽  
Robert Hobson ◽  
Scott B. Hansen
Keyword(s):  
Viral Entry ◽  
Super Resolution ◽  
The Elderly ◽  
High Cholesterol ◽  
Entry Site ◽  
Age Related ◽  
Entry Points ◽  
Resolution Imaging ◽  
Tissue Cholesterol

ABSTRACTCoronavirus disease 2019 (COVID19) is a respiratory infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originating in Wuhan, China in 2019. The disease is notably severe in elderly and those with underlying chronic conditions. A molecular mechanism that explains why the elderly are vulnerable and why children are resistant is largely unknown. Here we show loading cells with cholesterol from blood serum using the cholesterol transport protein apolipoprotein E (apoE) enhances the entry of pseudotyped SARS-CoV-2 and the infectivity of the virion. Super resolution imaging of the SARS-CoV-2 entry point with high cholesterol shows almost twice the total number of endocytic entry points. Cholesterol concomitantly traffics angiotensinogen converting enzyme (ACE2) to the endocytic entry site where SARS-CoV-2 presumably docks to efficiently exploit entry into the cell. Furthermore, in cells producing virus, cholesterol optimally positions furin for priming SARS-CoV-2, producing a more infectious virion with improved binding to the ACE2 receptor. In vivo, age and high fat diet induces cholesterol loading by up to 40% and trafficking of ACE2 to endocytic entry sites in lung tissue from mice. We propose a component of COVID19 severity based on tissue cholesterol level and the sensitivity of ACE2 and furin to cholesterol. Molecules that reduce cholesterol or disrupt ACE2 localization with viral entry points or furin localization in the producer cells, may reduce the severity of COVID19 in obese patients.

scholarly journals Super-Resolution Microscopy: Shedding New Light on In Vivo Imaging

2021 ◽  
Vol 9 ◽  
Author(s):  
Yingying Jing ◽  
Chenshuang Zhang ◽  
Bin Yu ◽  
Danying Lin ◽  
Junle Qu
Keyword(s):  
Biological Activities ◽  
Super Resolution ◽  
Spatiotemporal Resolution ◽  
The Past ◽  
Relevant Field ◽  
Living Species ◽  
Resolution Imaging ◽  
Super Resolution Microscopy ◽  
Conventional Light Microscopy

Over the past two decades, super-resolution microscopy (SRM), which offered a significant improvement in resolution over conventional light microscopy, has become a powerful tool to visualize biological activities in both fixed and living cells. However, completely understanding biological processes requires studying cells in a physiological context at high spatiotemporal resolution. Recently, SRM has showcased its ability to observe the detailed structures and dynamics in living species. Here we summarized recent technical advancements in SRM that have been successfully applied to in vivo imaging. Then, improvements in the labeling strategies are discussed together with the spectroscopic and chemical demands of the fluorophores. Finally, we broadly reviewed the current applications for super-resolution techniques in living species and highlighted some inherent challenges faced in this emerging field. We hope that this review could serve as an ideal reference for researchers as well as beginners in the relevant field of in vivo super resolution imaging.

scholarly journals How To Extend The Capabilities Of A Commercial Two-Photon Microscope To Perform Super-Resolution Imaging, Wavelength Mixing And Label-Free Microscopy.

2021 ◽  
Author(s):  
Chiara Peres ◽  
Chiara Nardin ◽  
Guang Yang ◽  
Fabio Mammano
Keyword(s):  
Ex Vivo ◽  
Super Resolution ◽  
Label Free ◽  
Linear Optics ◽  
Non Linear Optics ◽  
Two Photon ◽  
Custom Made ◽  
Non Linear ◽  
Resolution Imaging

Multimodal microscopy combines multiple non-linear techniques that take advantage of different optical processes to generate contrast and increase the amount of information that can be obtained from biological samples. However, the most advanced optical architectures are typically custom-made and require complex alignment procedures, as well as daily maintenance by properly trained personnel for optimal performance. Here, we describe a hybrid system we constructed to overcome these disadvantages by modifying a commercial upright microscope. We show that our multimodal imaging platform can be used to seamlessly perform two-photon STED, wavelength mixing and label-free microscopy in both ex vivo and in vivo samples. The system is highly stable and endowed with remote alignment hardware that ensures simplified operability for non-expert users. This optical architecture is an important step forward towards a wider practical applicability of non-linear optics to bioimaging.

scholarly journals Mechanistic insights into GLUT1 activation and clustering revealed by super-resolution imaging

2018 ◽  
Vol 115 (27) ◽  
pp. 7033-7038 ◽  
Author(s):  
Qiuyan Yan ◽  
Yanting Lu ◽  
Lulu Zhou ◽  
Junling Chen ◽  
Haijiao Xu ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Cell Membranes ◽  
Molecular Mechanisms ◽  
Glucose Transporter ◽  
Super Resolution ◽  
Average Diameter ◽  
Activation Mechanism ◽  
Membrane Expression ◽  
Close Relationship ◽  
Resolution Imaging

The glucose transporter GLUT1, a plasma membrane protein that mediates glucose homeostasis in mammalian cells, is responsible for constitutive uptake of glucose into many tissues and organs. Many studies have focused on its vital physiological functions and close relationship with diseases. However, the molecular mechanisms of its activation and transport are not clear, and its detailed distribution pattern on cell membranes also remains unknown. To address these, we first investigated the distribution and assembly of GLUT1 at a nanometer resolution by super-resolution imaging. On HeLa cell membranes, the transporter formed clusters with an average diameter of ∼250 nm, the majority of which were regulated by lipid rafts, as well as being restricted in size by both the cytoskeleton and glycosylation. More importantly, we found that the activation of GLUT1 by azide or MβCD did not increase its membrane expression but induced the decrease of the large clusters. The results suggested that sporadic distribution of GLUT1 may facilitate the transport of glucose, implying a potential association between the distribution and activation. Collectively, our work characterized the clustering distribution of GLUT1 and linked its spatial structural organization to the functions, which would provide insights into the activation mechanism of the transporter.

Sign in / Sign up

Export Citation Format

Share Document