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Žerovnik Mekuč M, Bohak C, Boneš E, Hudoklin S, Romih R, Marolt M. Automatic segmentation and reconstruction of intracellular compartments in volumetric electron microscopy data. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 223:106959. [PMID: 35763876 DOI: 10.1016/j.cmpb.2022.106959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 02/02/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVES In recent years, electron microscopy is enabling the acquisition of volumetric data with resolving power to directly observe the ultrastructure of intracellular compartments. New insights and knowledge about cell processes that are offered by such data require a comprehensive analysis which is limited by the time-consuming manual segmentation and reconstruction methods. METHOD We present methods for automatic segmentation, reconstruction, and analysis of intracellular compartments from volumetric data obtained by the dual-beam electron microscopy. We specifically address segmentation of fusiform vesicles and the Golgi apparatus, reconstruction of mitochondria and fusiform vesicles, and morphological analysis of the reconstructed mitochondria. RESULTS AND CONCLUSION Evaluation on the public UroCell dataset demonstrated high accuracy of the proposed methods for segmentation of fusiform vesicles and the Golgi apparatus, as well as for reconstruction of mitochondria and analysis of their shapes, while reconstruction of fusiform vesicles proved to be more challenging. We published an extension of the UroCell dataset with all of the data used in this work, to further contribute to research on automatic analysis of the ultrastructure of intracellular compartments.
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Affiliation(s)
- Manca Žerovnik Mekuč
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia.
| | - Ciril Bohak
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia; Visual Computing Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
| | - Eva Boneš
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia.
| | - Samo Hudoklin
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, Ljubljana 1000, Slovenia.
| | - Rok Romih
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, Ljubljana 1000, Slovenia.
| | - Matija Marolt
- Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia; Faculty of Computer and Information Science, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia.
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The Golgi complex: An organelle that determines urothelial cell biology in health and disease. Histochem Cell Biol 2022; 158:229-240. [PMID: 35773494 PMCID: PMC9399047 DOI: 10.1007/s00418-022-02121-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2022] [Indexed: 12/05/2022]
Abstract
The Golgi complex undergoes considerable structural remodeling during differentiation of urothelial cells in vivo and in vitro. It is known that in a healthy bladder the differentiation from the basal to the superficial cell layer leads to the formation of the tightest barrier in our body, i.e., the blood–urine barrier. In this process, urothelial cells start expressing tight junctional proteins, apical membrane lipids, surface glycans, and integral membrane proteins, the uroplakins (UPs). The latter are the most abundant membrane proteins in the apical plasma membrane of differentiated superficial urothelial cells (UCs) and, in addition to well-developed tight junctions, contribute to the permeability barrier by their structural organization and by hindering endocytosis from the apical plasma membrane. By studying the transport of UPs, we were able to demonstrate their differentiation-dependent effect on the Golgi architecture. Although fragmentation of the Golgi complex is known to be associated with mitosis and apoptosis, we found that the process of Golgi fragmentation is required for delivery of certain specific urothelial differentiation cargoes to the plasma membrane as well as for cell–cell communication. In this review, we will discuss the currently known contribution of the Golgi complex to the formation of the blood–urine barrier in normal UCs and how it may be involved in the loss of the blood–urine barrier in cancer. Some open questions related to the Golgi complex in the urothelium will be highlighted.
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Jerman UD, Kreft ME. Reuse of bladder mucosa explants provides a long lasting source of urothelial cells for the establishment of differentiated urothelia. Histochem Cell Biol 2018; 150:567-574. [PMID: 30094468 DOI: 10.1007/s00418-018-1704-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2018] [Indexed: 12/31/2022]
Abstract
Organ explant cultures are well-established in vitro models that are used to study normal cell biological and regeneration processes as well as carcinogenesis. Primary urothelial cultures from bladder mucosa explants are highly differentiated and are thus broadly used as in vitro experimental equivalents of native urothelial tissue. Since experiments on differentiated urothelial cultures from bladder mucosa explants currently allow only a single use of explants, establishment of sufficient quantities of cultures requires large numbers of sacrificed animals. There is thus a great need for a cheaper approach with less ethical dilemmas. Herein, we demonstrate that mouse bladder mucosa explants can be reused. Reused explants produce outgrowths with highly differentiated urothelia, just like primary explants. Even after being recycled ten times, urothelial outgrowths have the supramolecular and ultrastructural features that are comparable to the native urothelium. Ten times reused explants produce superficial urothelial cells that express uroplakins in the apical plasma membrane, claudin-8 in the tight junctions, and have a subapical network of cytokeratin 20. Basal urothelial cells in urothelial outgrowths of ten times reused explants express p63 which indicates that these urothelial outgrowths have a persistent proliferative capacity. Using our approach, one can perform experiments that were previously not feasible due to low quantities of donor tissue. The method also offers opportunity for effective use of scarce healthy human urothelial tissue.
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Affiliation(s)
- Urška Dragin Jerman
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000, Ljubljana, Slovenia.
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Gallo LI, Dalghi MG, Clayton DR, Ruiz WG, Khandelwal P, Apodaca G. RAB27B requirement for stretch-induced exocytosis in bladder umbrella cells. Am J Physiol Cell Physiol 2017; 314:C349-C365. [PMID: 29167152 DOI: 10.1152/ajpcell.00218.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Umbrella cells, which must maintain a tight barrier, modulate their apical surface area during bladder filling by exocytosis of an abundant, subapical pool of discoidal- and/or fusiform-shaped vesicles (DFVs). Despite the importance of this trafficking event for bladder function, the pathways that promote DFV exocytosis remain to be identified. We previously showed that DFV exocytosis depends in part on a RAB11A-RAB8A-MYO5B network, but RAB27B is also reported to be associated with DFVs, and knockout mice lacking RAB27B have fewer DFVs. However, the RAB27B requirements for DFV exocytosis and the relationship between RAB27B and the other umbrella cell-expressed RABs remains unclear. Using a whole bladder preparation, we observed that filling-induced exocytosis of human growth hormone-loaded DFVs was significantly inhibited when RAB27B expression was downregulated using shRNA. RAB27A was also expressed in rat urothelium; however, RAB27A-specific shRNAs did not inhibit exocytosis, and the combination of RAB27A and RAB27B shRNAs did not significantly affect DFV exocytosis more than treatment with RAB27B shRNA alone. RAB27B and RAB11A showed a small degree of overlap when quantified using Squassh segmentation software, and expression of dominant-active or dominant-negative mutants of RAB11A or RAB8A, or expression of a RAB11A-specific shRNA, had no significant effect on the size, number, or intensity of RAB27B-positive DFVs. Likewise, treatment with RAB27B-specific shRNA had no effect on RAB11A-positive DFV parameters. We conclude that RAB27B, but not RAB27A, regulates DFV exocytosis in bladder umbrella cells in a manner that may be parallel to the previously described RAB11A-RAB8A-MYO5B pathway.
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Affiliation(s)
- Luciana I Gallo
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Marianela G Dalghi
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Dennis R Clayton
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Wily G Ruiz
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Puneet Khandelwal
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania
| | - Gerard Apodaca
- Department of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania.,Department of Cell Biology, University of Pittsburgh , Pittsburgh, Pennsylvania
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Višnjar T, Chesi G, Iacobacci S, Polishchuk E, Resnik N, Robenek H, Kreft M, Romih R, Polishchuk R, Kreft ME. Uroplakin traffic through the Golgi apparatus induces its fragmentation: new insights from novel in vitro models. Sci Rep 2017; 7:12842. [PMID: 28993693 PMCID: PMC5634464 DOI: 10.1038/s41598-017-13103-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 09/20/2017] [Indexed: 11/10/2022] Open
Abstract
Uroplakins (UPs) play an essential role in maintaining an effective urothelial permeability barrier at the level of superficial urothelial cell (UC) layer. Although the organization of UPs in the apical plasma membrane (PM) of UCs is well known, their transport in UCs is only partially understood. Here, we dissected trafficking of UPs and its differentiation-dependent impact on Golgi apparatus (GA) architecture. We demonstrated that individual subunits UPIb and UPIIIa are capable of trafficking from the endoplasmic reticulum to the GA in UCs. Moreover, UPIb, UPIIIa or UPIb/UPIIIa expressing UCs revealed fragmentation and peripheral redistribution of Golgi-units. Notably, expression of UPIb or UPIb/UPIIIa triggered similar GA fragmentation in MDCK and HeLa cells that do not express UPs endogenously. The colocalization analysis of UPIb/UPIIIa-EGFP and COPI, COPII or clathrin suggested that UPs follow constitutively the post-Golgi route to the apical PM. Depolymerisation of microtubules leads to complete blockade of the UPIb/UPIIIa-EGFP post-Golgi transport, while disassembly of actin filaments shows significantly reduced delivery of UPIb/UPIIIa-EGFP to the PM. Our findings show the significant effect of the UPs expression on the GA fragmentation, which enables secretory Golgi-outpost to be distributed as close as possible to the sites of cargo delivery at the PM.
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Affiliation(s)
- Tanja Višnjar
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000, Ljubljana, Slovenia
| | - Giancarlo Chesi
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078, Pozzuoli, (NA), Italy
| | - Simona Iacobacci
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078, Pozzuoli, (NA), Italy
| | - Elena Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078, Pozzuoli, (NA), Italy
| | - Nataša Resnik
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000, Ljubljana, Slovenia
| | - Horst Robenek
- Institute for experimental musculoskeletal medicine, University of Münster, Albert-Schweitzer-Campus 1, Domagkstrasse 3, 48149, Münster, Germany
| | - Marko Kreft
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana, Slovenia & LN-MCP, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana & Celica Biomedical Center, Ljubljana, Slovenia
| | - Rok Romih
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000, Ljubljana, Slovenia
| | - Roman Polishchuk
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078, Pozzuoli, (NA), Italy.
| | - Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Vrazov trg 2, SI-1000, Ljubljana, Slovenia.
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Imani R, Veranič P, Iglič A, Kreft ME, Pazoki M, Hudoklin S. Combined cytotoxic effect of UV-irradiation and TiO2 microbeads in normal urothelial cells, low-grade and high-grade urothelial cancer cells. Photochem Photobiol Sci 2015; 14:583-90. [PMID: 25385056 DOI: 10.1039/c4pp00272e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The differentiation of urothelial cells results in normal terminally differentiated cells or by alternative pathways in low-grade or high-grade urothelial carcinomas. Treatments with traditional surgical and chemotherapeutical approaches are still inadequate and expensive, as bladder tumours are generally highly recurrent. In such situations, alternative approaches, using irradiation of the cells and nanoparticles, are promising. The ways in which urothelial cells, at different differentiation levels, respond to UV-irradiation (photolytic treatment) or to the combination of UV-irradiation and nanoparticles (photocatalytic treatment), are unknown. Here we tested cytotoxicity of UV-irradiation on (i) normal porcine urothelial cells (NPU), (ii) human low-grade urothelial cancer cells (RT4), and (iii) human high-grade urothelial cancer cells (T24). The results have shown that 1 minute of UV-irradiation is enough to kill 90% of the cells in NPU and RT4 cultures, as determined by the live/dead viability assay. On the other hand, the majority of T24 cells survived 1 minute of UV-irradiation. Moreover, even a prolonged UV-irradiation for 30 minutes killed <50% of T24 cells. When T24 cells were pre-supplemented with mesoporous TiO2 microbeads and then UV-irradiated, the viability of these high-grade urothelial cancer cells was reduced to <10%, which points to the highly efficient cytotoxic effects of TiO2 photocatalysis. Using electron microscopy, we confirmed that the mesoporous TiO2 microbeads were internalized into T24 cells, and that the cell's ultrastructure was heavily compromised after UV-irradiation. In conclusion, our results show major differences in the sensitivity to UV-irradiation among the urothelial cells with respect to cell differentiation. To achieve an increased cytotoxicity of urothelial cancer cells, the photocatalytic approach is recommended.
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Affiliation(s)
- Roghayeh Imani
- Laboratory of Clinical Biophysics, Faculty of Health Sciences, University of Ljubljana, Zdravstvena 5, Ljubljana, Slovenia
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Carpenter AR, Becknell MB, Ching CB, Cuaresma EJ, Chen X, Hains DS, McHugh KM. Uroplakin 1b is critical in urinary tract development and urothelial differentiation and homeostasis. Kidney Int 2015; 89:612-24. [PMID: 26880456 DOI: 10.1016/j.kint.2015.11.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/12/2015] [Accepted: 09/24/2015] [Indexed: 11/15/2022]
Abstract
Proper development and maintenance of urothelium is critical to its function. Uroplakins are expressed in developing and mature urothelium where they establish plaques associated with the permeability barrier. Their precise functional role in development and disease is unknown. Here, we disrupted Upk1b in vivo where its loss resulted in urothelial plaque disruption in the bladder and kidney. Upk1b(RFP/RFP) bladder urothelium appeared dysplastic with expansion of the progenitor cell markers, Krt14 and Krt5, increased Shh expression, and loss of terminal differentiation markers Krt20 and uroplakins. Upk1b(RFP/RFP) renal urothelium became stratified with altered cellular composition. Upk1b(RFP/RFP) mice developed age-dependent progressive hydronephrosis. Interestingly, 16% of Upk1b(RFP/RFP) mice possessed unilateral duplex kidneys. Our study expands the role of uroplakins, mechanistically links plaque formation to urinary tract development and function, and provides a tantalizing connection between congenital anomalies of the kidney and urinary tract along with functional deficits observed in a variety of urinary tract diseases. Thus, kidney and bladder urothelium are regionally distinct and remain highly plastic, capable of expansion through tissue-specific progenitor populations. Furthermore, Upk1b plays a previously unknown role in early kidney development representing a novel genetic target for congenital anomalies of the kidney and urinary tract.
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Affiliation(s)
- Ashley R Carpenter
- Molecular and Human Genetics, Nationwide Children's Hospital, Columbus, Ohio, USA; College of Medicine, Ohio State University, Columbus, Ohio, USA.
| | | | | | | | - Xi Chen
- Molecular and Human Genetics, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - David S Hains
- Children's Foundation Research Institute at Le Bonheur Children's Hospital, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Kirk M McHugh
- Molecular and Human Genetics, Nationwide Children's Hospital, Columbus, Ohio, USA; Division of Anatomy, Ohio State University, Columbus, Ohio, USA
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Cystitis: from urothelial cell biology to clinical applications. BIOMED RESEARCH INTERNATIONAL 2014; 2014:473536. [PMID: 24877098 PMCID: PMC4022113 DOI: 10.1155/2014/473536] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/15/2014] [Indexed: 12/23/2022]
Abstract
Cystitis is a urinary bladder disease with many causes and symptoms. The severity of cystitis ranges from mild lower abdominal discomfort to life-threatening haemorrhagic cystitis. The course of disease is often chronic or recurrent. Although cystitis represents huge economical and medical burden throughout the world and in many cases treatments are ineffective, the mechanisms of its origin and development as well as measures for effective treatment are still poorly understood. However, many studies have demonstrated that urothelial dysfunction plays a crucial role. In the present review we first discuss fundamental issues of urothelial cell biology, which is the core for comprehension of cystitis. Then we focus on many forms of cystitis, its current treatments, and advances in its research. Additionally we review haemorrhagic cystitis with one of the leading causative agents being chemotherapeutic drug cyclophosphamide and summarise its management strategies. At the end we describe an excellent and widely used animal model of cyclophosphamide induced cystitis, which gives researches the opportunity to get a better insight into the mechanisms involved and possibility to develop new therapy approaches.
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Khandelwal P, Prakasam HS, Clayton DR, Ruiz WG, Gallo LI, van Roekel D, Lukianov S, Peränen J, Goldenring JR, Apodaca G. A Rab11a-Rab8a-Myo5B network promotes stretch-regulated exocytosis in bladder umbrella cells. Mol Biol Cell 2013; 24:1007-19. [PMID: 23389633 PMCID: PMC3608489 DOI: 10.1091/mbc.e12-08-0568] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 01/29/2013] [Accepted: 01/30/2013] [Indexed: 12/03/2022] Open
Abstract
Multiple Rabs are associated with secretory granules/vesicles, but how these GTPases are coordinated to promote regulated exocytosis is not well understood. In bladder umbrella cells a subapical pool of discoidal/fusiform-shaped vesicles (DFVs) undergoes Rab11a-dependent regulated exocytosis in response to bladder filling. We show that Rab11a-associated vesicles are enmeshed in an apical cytokeratin meshwork and that Rab11a likely acts upstream of Rab8a to promote exocytosis. Surprisingly, expression of Rabin8, a previously described Rab11a effector and guanine nucleotide exchange factor for Rab8, stimulates stretch-induced exocytosis in a manner that is independent of its catalytic activity. Additional studies demonstrate that the unconventional motor protein myosin5B motor (Myo5B) works in association with the Rab8a-Rab11a module to promote exocytosis, possibly by ensuring transit of DFVs through a subapical, cortical actin cytoskeleton before fusion. Our results indicate that Rab11a, Rab8a, and Myo5B function as part of a network to promote stretch-induced exocytosis, and we predict that similarly organized Rab networks will be common to other regulated secretory pathways.
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Affiliation(s)
- Puneet Khandelwal
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | | | - Dennis R. Clayton
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Wily G. Ruiz
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Luciana I. Gallo
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Daniel van Roekel
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Stefan Lukianov
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
| | - Johan Peränen
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - James R. Goldenring
- Department of Surgery and Epithelial Biology Center, Vanderbilt University, Nashville, TN 37232
| | - Gerard Apodaca
- Departments of Medicine, University of Pittsburgh, Pittsburgh, PA 15261
- Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261
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Erman A, Resnik N, Romih R. Autophagic activity in the mouse urinary bladder urothelium as a response to starvation. PROTOPLASMA 2013; 250:151-160. [PMID: 22407469 DOI: 10.1007/s00709-012-0387-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 02/08/2012] [Indexed: 05/31/2023]
Abstract
The urinary bladder urothelium is subjected to mechanical forces during cycles of distension and contraction, and its superficial cells are constantly flushed by toxic urine. Yet, the urothelium shows a very slow turnover of cells and superficial cells are extremely long lived. Autophagy has a well-known role in tissue homeostasis and serves as a protective mechanism against cellular stress. Therefore, the presence of autophagy as one of possible processes of survival in an unpleasant environment and during long lifetime of superficial cells was examined in mouse urothelium. We detected and evaluated autophagic activity of superficial urothelial cells under normal and stress conditions, caused by short-term starvation of newborn and 24-h-starved adult mice. Immunolabeling and Western blotting of essential effectors of autophagy, LC3 and Beclin 1, showed a weak signal in superficial urothelial cells. On the other hand, ultrastructural analysis, which proved to be the most reliable method in our study, revealed the presence of autophagic vacuoles, some of them containing specific urothelial structures, fusiform vesicles. Quantitative analysis showed increased autophagy in newborn and starved mice in comparison to a low basic level of autophagy in the urothelium of normal mice. Interestingly, some superficial cells of adults and neonates exhibit intense immunoreactions against LC3 and Beclin 1 and the typical ultrastructural characteristics of autophagy-dependent cell death. We conclude that autophagy, despite low basic activity under physiological conditions, plays an important role in urothelial homeostasis and stability under stress.
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Affiliation(s)
- Andreja Erman
- Institute of Cell Biology, Faculty of Medicine, Lipičeva 2, 1000 Ljubljana, Slovenia.
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Golgi apparatus fragmentation as a mechanism responsible for uniform delivery of uroplakins to the apical plasma membrane of uroepithelial cells. Biol Cell 2012; 102:593-607. [DOI: 10.1042/bc20100024] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Hudoklin S, Jezernik K, Neumüller J, Pavelka M, Romih R. Urothelial plaque formation in post-Golgi compartments. PLoS One 2011; 6:e23636. [PMID: 21887288 PMCID: PMC3161059 DOI: 10.1371/journal.pone.0023636] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 07/21/2011] [Indexed: 11/26/2022] Open
Abstract
Urothelial plaques are specialized membrane domains in urothelial superficial (umbrella) cells, composed of highly ordered uroplakin particles. We investigated membrane compartments involved in the formation of urothelial plaques in mouse umbrella cells. The Golgi apparatus did not contain uroplakins organized into plaques. In the post-Golgi region, three distinct membrane compartments containing uroplakins were characterized: i) Small rounded vesicles, located close to the Golgi apparatus, were labelled weakly with anti-uroplakin antibodies and they possessed no plaques; we termed them "uroplakin-positive transporting vesicles" (UPTVs). ii) Spherical-to-flattened vesicles, termed "immature fusiform vesicles" (iFVs), were uroplakin-positive in their central regions and contained small urothelial plaques. iii) Flattened "mature fusiform vesicles" (mFVs) contained large plaques, which were densely labelled with anti-uroplakin antibodies. Endoytotic marker horseradish peroxidase was not found in these post-Golgi compartments. We propose a detailed model of de novo urothelial plaque formation in post-Golgi compartments: UPTVs carrying individual 16-nm particles detach from the Golgi apparatus and subsequently fuse into iFV. Concentration of 16-nm particles into plaques and removal of uroplakin-negative membranes takes place in iFVs. With additional fusions and buddings, iFVs mature into mFVs, each carrying two urothelial plaques toward the apical surface of the umbrella cell.
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Affiliation(s)
- Samo Hudoklin
- Faculty of Medicine, Institute of Cell Biology, University of Ljubljana, Ljubljana, Slovenia.
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Kreft ME, Hudoklin S, Jezernik K, Romih R. Formation and maintenance of blood-urine barrier in urothelium. PROTOPLASMA 2010; 246:3-14. [PMID: 20521071 DOI: 10.1007/s00709-010-0112-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 01/15/2010] [Indexed: 05/29/2023]
Abstract
Blood-urine barrier, which is formed during differentiation of superficial urothelial cells, is the tightest and most impermeable barrier in the body. In the urinary bladder, the barrier must accommodate large changes in the surface area during distensions and contractions of the organ. Tight junctions and unique apical plasma membrane of superficial urothelial cells play a critical role in the barrier maintenance. Alterations in the blood-urine barrier function accompany most of the urinary tract diseases. In this review, we discuss recent discoveries on the role of tight junctions, dynamics of Golgi apparatus and post-Golgi compartments, and intracellular membrane traffic during the biogenesis and maintenance of blood-urine barrier.
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Affiliation(s)
- Mateja Erdani Kreft
- Institute of Cell Biology, Faculty of Medicine, University of Ljubljana, Lipiceva 2, SI-1000, Ljubljana, Slovenia.
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Khandelwal P, Abraham SN, Apodaca G. Cell biology and physiology of the uroepithelium. Am J Physiol Renal Physiol 2009; 297:F1477-501. [PMID: 19587142 DOI: 10.1152/ajprenal.00327.2009] [Citation(s) in RCA: 261] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The uroepithelium sits at the interface between the urinary space and underlying tissues, where it forms a high-resistance barrier to ion, solute, and water flux, as well as pathogens. However, the uroepithelium is not simply a passive barrier; it can modulate the composition of the urine, and it functions as an integral part of a sensory web in which it receives, amplifies, and transmits information about its external milieu to the underlying nervous and muscular systems. This review examines our understanding of uroepithelial regeneration and how specializations of the outermost umbrella cell layer, including tight junctions, surface uroplakins, and dynamic apical membrane exocytosis/endocytosis, contribute to barrier function and how they are co-opted by uropathogenic bacteria to infect the uroepithelium. Furthermore, we discuss the presence and possible functions of aquaporins, urea transporters, and multiple ion channels in the uroepithelium. Finally, we describe potential mechanisms by which the uroepithelium can transmit information about the urinary space to the other tissues in the bladder proper.
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