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de Caestecker C, Macara IG. A size filter at the Golgi regulates apical membrane protein sorting. Nat Cell Biol 2024:10.1038/s41556-024-01500-0. [PMID: 39237743 DOI: 10.1038/s41556-024-01500-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 08/12/2024] [Indexed: 09/07/2024]
Abstract
Despite decades of research, apical sorting of epithelial membrane proteins remains incompletely understood. We noted that apical cytoplasmic domains are smaller than those of basolateral proteins; however, the reason for this discrepancy is unknown. Here we used a synthetic biology approach to investigate whether a size barrier at the Golgi apparatus might hinder apical sorting of proteins with large cytoplasmic tails. We focused on Crb3, Ace2 and Muc1 as representative apical proteins with short cytoplasmic tails. By incorporating a streptavidin-binding peptide, these proteins can be trapped in the endoplasmic reticulum until addition of biotin, which triggers synchronous release to the Golgi and subsequent transport to the apical cortex. Strikingly, increasing the size of their cytoplasmic domains caused partial mislocalization to the basolateral cortex and significantly delayed Golgi departure. Moreover, N-glycosylation of 'large' Crb3 was delayed, and 'small' Crb3 segregated into spatially distinct Golgi regions. Biologically, Crb3 forms a complex through its cytoplasmic tail with the Pals1 protein, which could also delay departure, but although associated at the endoplasmic reticulum and Golgi, Pals1 disassociated before Crb3 departure. Notably, a non-dissociable mutant Pals1 hampered the exit of Crb3. We conclude that, unexpectedly, a size filter at the Golgi facilitates apical sorting of proteins with small cytoplasmic domains and that timely release of Pals1, to reduce cytoplasmic domain size, is essential for normal Crb3 sorting.
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Affiliation(s)
- Christian de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Ian G Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA.
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Kundu S, Rohokale R, Lin C, Chen S, Biswas S, Guo Z. Bifunctional glycosphingolipid (GSL) probes to investigate GSL-interacting proteins in cell membranes. J Lipid Res 2024; 65:100570. [PMID: 38795858 PMCID: PMC11261293 DOI: 10.1016/j.jlr.2024.100570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/03/2024] [Accepted: 05/04/2024] [Indexed: 05/28/2024] Open
Abstract
Glycosphingolipids (GSLs) are abundant glycolipids on cells and essential for cell recognition, adhesion, signal transduction, and so on. However, their lipid anchors are not long enough to cross the membrane bilayer. To transduce transmembrane signals, GSLs must interact with other membrane components, whereas such interactions are difficult to investigate. To overcome this difficulty, bifunctional derivatives of II3-β-N-acetyl-D-galactosamine-GA2 (GalNAc-GA2) and β-N-acetyl-D-glucosamine-ceramide (GlcNAc-Cer) were synthesized as probes to explore GSL-interacting membrane proteins in live cells. Both probes contain photoreactive diazirine in the lipid moiety, which can crosslink with proximal membrane proteins upon photoactivation, and clickable alkyne in the glycan to facilitate affinity tag addition for crosslinked protein pull-down and characterization. The synthesis is highlighted by the efficient assembly of simple glycolipid precursors followed by on-site lipid remodeling. These probes were employed to profile GSL-interacting membrane proteins in HEK293 cells. The GalNAc-GA2 probe revealed 312 distinct proteins, with GlcNAc-Cer probe-crosslinked proteins as controls, suggesting the potential influence of the glycan on GSL functions. Many of the proteins identified with the GalNAc-GA2 probe are associated with GSLs, and some have been validated as being specific to this probe. The versatile probe design and experimental protocols are anticipated to be widely applicable to GSL research.
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Affiliation(s)
- Sayan Kundu
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Rajendra Rohokale
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Chuwei Lin
- Department of Biology, Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Sixue Chen
- Department of Biology, Genetics Institute, University of Florida, Gainesville, FL, USA; Department of Biology, University of Mississippi, Oxford, MS, USA
| | - Shayak Biswas
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Zhongwu Guo
- Department of Chemistry, University of Florida, Gainesville, FL, USA.
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de Caestecker C, Macara IG. A Size Filter Regulates Apical Protein Sorting. RESEARCH SQUARE 2023:rs.3.rs-3210598. [PMID: 37577471 PMCID: PMC10418535 DOI: 10.21203/rs.3.rs-3210598/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Despite decades of research, apical sorting of epithelial membrane proteins remains incompletely understood. We noted that apical cytoplasmic domains are smaller than those of basolateral proteins; however, the reason for this discrepancy is unknown. We investigated whether a size barrier at the trans-Golgi network (TGN) might hinder apical sorting of proteins with large cytoplasmic tails. We focused on Crb3 and Ace2 as representative apical proteins with short cytoplasmic tails. By incorporating a streptavidin-binding peptide, these proteins can be trapped in the endoplasmic reticulum (ER) until addition of biotin, which triggers synchronous release to the Golgi and subsequent transport to the apical cortex. Strikingly, departure from the Golgi could be significantly delayed simply by increasing cytoplasmic bulk. Moreover, large and small Crb3 segregated into spatially distinct Golgi regions as detected by super resolution imaging. Biologically, Crb3 forms a complex through its cytoplasmic tail with the Pals1 protein, which could also delay departure, but although associated at the ER and Golgi, we found that Pals1 disassociates prior to Crb3 departure. Notably, a non-dissociable mutant Pals1 hampers the exit of Crb3. We conclude that an unexpected mechanism involving a size filter at the TGN facilitates apical sorting of proteins with small cytoplasmic domains and that timely release of Pals1, to reduce cytoplasmic domain size, is essential for the normal kinetics of Crb3 sorting.
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Affiliation(s)
- Christian de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine; Nashville TN 37205, U.S
| | - Ian G. Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine; Nashville TN 37205, U.S
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Klee KMC, Hess MW, Lohmüller M, Herzog S, Pfaller K, Müller T, Vogel GF, Huber LA. A CRISPR screen in intestinal epithelial cells identifies novel factors for polarity and apical transport. eLife 2023; 12:e80135. [PMID: 36661306 PMCID: PMC9889089 DOI: 10.7554/elife.80135] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 01/19/2023] [Indexed: 01/21/2023] Open
Abstract
Epithelial polarization and polarized cargo transport are highly coordinated and interdependent processes. In our search for novel regulators of epithelial polarization and protein secretion, we used a genome-wide CRISPR/Cas9 screen and combined it with an assay based on fluorescence-activated cell sorting (FACS) to measure the secretion of the apical brush-border hydrolase dipeptidyl peptidase 4 (DPP4). In this way, we performed the first CRISPR screen to date in human polarized epithelial cells. Using high-resolution microscopy, we detected polarization defects and mislocalization of DPP4 to late endosomes/lysosomes after knockout of TM9SF4, anoctamin 8, and ARHGAP33, confirming the identification of novel factors for epithelial polarization and apical cargo secretion. Thus, we provide a powerful tool suitable for studying polarization and cargo secretion in epithelial cells. In addition, we provide a dataset that serves as a resource for the study of novel mechanisms for epithelial polarization and polarized transport and facilitates the investigation of novel congenital diseases associated with these processes.
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Affiliation(s)
- Katharina MC Klee
- Institute of Cell Biology, Medical University of InnsbruckInnsbruckAustria
- Institute of Histology and Embryology, Medical University of InnsbruckInnsbruckAustria
| | - Michael W Hess
- Institute of Histology and Embryology, Medical University of InnsbruckInnsbruckAustria
| | - Michael Lohmüller
- Institute of Developmental Immunology, Medical University of InnsbruckInnsbruckAustria
| | - Sebastian Herzog
- Institute of Developmental Immunology, Medical University of InnsbruckInnsbruckAustria
| | - Kristian Pfaller
- Institute of Histology and Embryology, Medical University of InnsbruckInnsbruckAustria
| | - Thomas Müller
- Department of Paediatrics I, Medical University of InnsbruckInnsbruckAustria
| | - Georg F Vogel
- Institute of Cell Biology, Medical University of InnsbruckInnsbruckAustria
- Department of Paediatrics I, Medical University of InnsbruckInnsbruckAustria
| | - Lukas A Huber
- Institute of Cell Biology, Medical University of InnsbruckInnsbruckAustria
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Levic DS, Bagnat M. Polarized transport of membrane and secreted proteins during lumen morphogenesis. Semin Cell Dev Biol 2023; 133:65-73. [PMID: 35307284 PMCID: PMC9481742 DOI: 10.1016/j.semcdb.2022.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 03/09/2022] [Accepted: 03/12/2022] [Indexed: 10/18/2022]
Abstract
A ubiquitous feature of animal development is the formation of fluid-filled cavities or lumina, which transport gases and fluids across tissues and organs. Among different species, lumina vary drastically in size, scale, and complexity. However, all lumen formation processes share key morphogenetic principles that underly their development. Fundamentally, a lumen simply consists of epithelial cells that encapsulate a continuous internal space, and a common way of building a lumen is via opening and enlarging by filling it with fluid and/or macromolecules. Here, we discuss how polarized targeting of membrane and secreted proteins regulates lumen formation, mainly focusing on ion transporters in vertebrate model systems. We also discuss mechanistic differences observed among invertebrates and vertebrates and describe how the unique properties of the Na+/K+-ATPase and junctional proteins can promote polarization of immature epithelia to build lumina de novo in developing organs.
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Affiliation(s)
- Daniel S Levic
- Department of Cell Biology, Duke University, Durham, NC 27710, USA.
| | - Michel Bagnat
- Department of Cell Biology, Duke University, Durham, NC 27710, USA.
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Sun-Wada GH, Wada Y. Exploring the Link between Vacuolar-Type Proton ATPase and Epithelial Cell Polarity. Biol Pharm Bull 2022; 45:1419-1425. [PMID: 36184498 DOI: 10.1248/bpb.b22-00205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vacuolar-type H+-ATPase (V-ATPase) was first identified as an electrogenic proton pump that acidifies the lumen of intracellular organelles. Subsequently, it was observed that the proton pump also participates in the acidification of extracellular compartments. V-ATPase plays important roles in a wide range of cell biological processes and physiological functions by generating an acidic pH; therefore, it has attracted much attention not only in basic research but also in pathological and clinical aspects. Emerging evidence indicates that the luminal acidic endocytic organelles and their trafficking may function as important hubs that connect and coordinate various signaling pathways. Various pharmacological analyses have suggested that acidic endocytic organelles are important for the maintenance of cell polarity. Recently, several studies using genetic approaches have revealed the involvement of V-ATPase in the establishment and maintenance of apico-basal polarity. This review provides a brief overview of the relationship between the polarity of epithelial cells and V-ATPase as well as V-ATPase driven luminal acidification.
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Affiliation(s)
- Ge-Hong Sun-Wada
- Faculty of Pharmaceutical Sciences, Doshisha Women's College of Liberal Arts
| | - Yoh Wada
- Division of Biological Science, Institute of Scientific and Industrial Research, Osaka University
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Francis CR, Kushner EJ. Trafficking in blood vessel development. Angiogenesis 2022; 25:291-305. [PMID: 35449244 PMCID: PMC9249721 DOI: 10.1007/s10456-022-09838-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/03/2022] [Indexed: 02/17/2023]
Abstract
Blood vessels demonstrate a multitude of complex signaling programs that work in concert to produce functional vasculature networks during development. A known, but less widely studied, area of endothelial cell regulation is vesicular trafficking, also termed sorting. After moving through the Golgi apparatus, proteins are shuttled to organelles, plugged into membranes, recycled, or degraded depending on the internal and extrinsic cues. A snapshot of these protein-sorting systems can be viewed as a trafficking signature that is not only unique to endothelial tissue, but critically important for blood vessel form and function. In this review, we will cover how vesicular trafficking impacts various aspects of angiogenesis, such as sprouting, lumen formation, vessel stabilization, and secretion, emphasizing the role of Rab GTPase family members and their various effectors.
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Affiliation(s)
- Caitlin R Francis
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA
| | - Erich J Kushner
- Department of Biological Sciences, University of Denver, Denver, CO, 80210, USA.
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