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Gilder AL, Chapin HC, Padovano V, Hueschen CL, Rajendran V, Caplan MJ. Newly synthesized polycystin-1 takes different trafficking pathways to the apical and ciliary membranes. Traffic 2018; 19:933-945. [PMID: 30125442 PMCID: PMC6237641 DOI: 10.1111/tra.12612] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 08/15/2018] [Accepted: 08/15/2018] [Indexed: 12/26/2022]
Abstract
Mutations in the genes encoding polycystin-1 (PC1) and polycystin 2 (PC2) cause autosomal dominant polycystic kidney disease. These transmembrane proteins colocalize in the primary cilia of renal epithelial cells, where they may participate in sensory processes. PC1 is also found in the apical membrane when expressed in cultured epithelial cells. PC1 undergoes autocatalytic cleavage, producing an extracellular N-terminal fragment that remains noncovalently attached to the transmembrane C-terminus. Exposing cells to alkaline solutions elutes the N-terminal fragment while the C-terminal fragment is retained in the cell membrane. Utilizing this observation, we developed a "strip-recovery" synchronization protocol to study PC1 trafficking in polarized LLC-PK1 renal epithelial cells. Following alkaline strip, a new cohort of PC1 repopulates the cilia within 30 minutes, while apical delivery of PC1 was not detectable until 3 hours. Brefeldin A (BFA) blocked apical PC1 delivery, while ciliary delivery of PC1 was BFA insensitive. Incubating cells at 20°C to block trafficking out of the trans-Golgi network also inhibits apical but not ciliary delivery. These results suggest that newly synthesized PC1 takes distinct pathways to the ciliary and apical membranes. Ciliary PC1 appears to by-pass BFA sensitive Golgi compartments, while apical delivery of PC1 traverses these compartments.
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Affiliation(s)
- Allison L Gilder
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - Hannah C Chapin
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - Valeria Padovano
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - Christina L Hueschen
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Vanathy Rajendran
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Michael J Caplan
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut.,Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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Padovano V, Kuo IY, Stavola LK, Aerni HR, Flaherty BJ, Chapin HC, Ma M, Somlo S, Boletta A, Ehrlich BE, Rinehart J, Caplan MJ. The polycystins are modulated by cellular oxygen-sensing pathways and regulate mitochondrial function. Mol Biol Cell 2016; 28:261-269. [PMID: 27881662 PMCID: PMC5231895 DOI: 10.1091/mbc.e16-08-0597] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 11/10/2016] [Accepted: 11/15/2016] [Indexed: 01/26/2023] Open
Abstract
The polycystin proteins are encoded by the genes mutated in autosomal dominant polycystic kidney disease. A new role for these proteins in oxygen sensing and cell metabolism is proposed. Oxygen regulates the trafficking and channel activity of the polycystin complex, which modulates mitochondrial function by altering mitochondrial calcium uptake. Autosomal dominant polycystic kidney disease is caused by mutations in the genes encoding polycystin-1 (PC1) and polycystin-2 (PC2), which form an ion channel complex that may mediate ciliary sensory processes and regulate endoplasmic reticulum (ER) Ca2+ release. Loss of PC1 expression profoundly alters cellular energy metabolism. The mechanisms that control the trafficking of PC1 and PC2, as well as their broader physiological roles, are poorly understood. We found that O2 levels regulate the subcellular localization and channel activity of the polycystin complex through its interaction with the O2-sensing prolyl hydroxylase domain containing protein EGLN3 (or PHD3), which hydroxylates PC1. Moreover, cells lacking PC1 expression use less O2 and show less mitochondrial Ca2+ uptake in response to bradykinin-induced ER Ca2+ release, indicating that PC1 can modulate mitochondrial function. These data suggest a novel role for the polycystins in sensing and responding to cellular O2 levels.
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Affiliation(s)
- Valeria Padovano
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520
| | - Ivana Y Kuo
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520
| | - Lindsey K Stavola
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520
| | - Hans R Aerni
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520.,Systems Biology Institute, Yale University, West Haven, CT 06516
| | - Benjamin J Flaherty
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520
| | - Hannah C Chapin
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520
| | - Ming Ma
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Stefan Somlo
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520
| | - Alessandra Boletta
- Division of Genetics and Cell Biology, Dibit, San Raffaele Scientific Institute, 20132 Milan, Italy
| | - Barbara E Ehrlich
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520
| | - Jesse Rinehart
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520.,Systems Biology Institute, Yale University, West Haven, CT 06516
| | - Michael J Caplan
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520
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Das S, Majhi PD, Al-Mugotir MH, Rachagani S, Sorgen P, Batra SK. Membrane proximal ectodomain cleavage of MUC16 occurs in the acidifying Golgi/post-Golgi compartments. Sci Rep 2015; 5:9759. [PMID: 26044153 PMCID: PMC4456727 DOI: 10.1038/srep09759] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/13/2015] [Indexed: 12/29/2022] Open
Abstract
MUC16, precursor of the most widely used ovarian cancer biomarker CA125, is up
regulated in multiple malignancies and is associated with poor prognosis. While the
pro-tumorigenic and metastatic roles of MUC16 are ascribed to the cell-associated
carboxyl-terminal MUC16 (MUC16-Cter), the exact biochemical nature of MUC16 cleavage
generating MUC16-Cter has remained unknown. Using different lengths of dual-epitope
(N-terminal FLAG- and C-terminal HA-Tag) tagged C-terminal MUC16 fragments, we
demonstrate that MUC16 cleavage takes place in the juxta-membrane ectodomain stretch
of twelve amino acids that generates a ~17 kDa cleaved product and is
distinct from the predicted sites. This was further corroborated by domain swapping
experiment. Further, the cleavage of MUC16 was found to take place in the
Golgi/post-Golgi compartments and is dependent on the acidic pH in the secretory
pathway. A similar pattern of ~17 kDa cleaved MUC16 was observed in
multiple cell types eliminating the possibility of cell type specific phenomenon.
MUC16-Cter translocates to the nucleus in a cleavage dependent manner and binds to
the chromatin suggesting its involvement in regulation of gene expression. Taken
together, we demonstrate for the first time the oft-predicted cleavage of MUC16 that
is critical in designing successful therapeutic interventions based on MUC16.
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Affiliation(s)
- Srustidhar Das
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Prabin D Majhi
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Mona H Al-Mugotir
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Satyanarayana Rachagani
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Paul Sorgen
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Surinder K Batra
- 1] Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA [2] Department of Pathology, University of Nebraska Medical Center, Omaha, NE 68198, USA [3] Buffett Cancer Center, Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
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A cleavable N-terminal signal peptide promotes widespread olfactory receptor surface expression in HEK293T cells. PLoS One 2013; 8:e68758. [PMID: 23840901 PMCID: PMC3698168 DOI: 10.1371/journal.pone.0068758] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 06/03/2013] [Indexed: 12/21/2022] Open
Abstract
Olfactory receptors (ORs) are G protein-coupled receptors that detect odorants in the olfactory epithelium, and comprise the largest gene family in the genome. Identification of OR ligands typically requires OR surface expression in heterologous cells; however, ORs rarely traffic to the cell surface when exogenously expressed. Therefore, most ORs are orphan receptors with no known ligands. To date, studies have utilized non-cleavable rhodopsin (Rho) tags and/or chaperones (i.e. Receptor Transporting Protein, RTP1S, Ric8b and Gαolf) to improve surface expression. However, even with these tools, many ORs still fail to reach the cell surface. We used a test set of fifteen ORs to examine the effect of a cleavable leucine-rich signal peptide sequence (Lucy tag) on OR surface expression in HEK293T cells. We report here that the addition of the Lucy tag to the N-terminus increases the number of ORs reaching the cell surface to 7 of the 15 ORs (as compared to 3/15 without Rho or Lucy tags). Moreover, when ORs tagged with both Lucy and Rho were co-expressed with previously reported chaperones (RTP1S, Ric8b and Gαolf), we observed surface expression for all 15 receptors examined. In fact, two-thirds of Lucy-tagged ORs are able to reach the cell surface synergistically with chaperones even when the Rho tag is removed (10/15 ORs), allowing for the potential assessment of OR function with only an 8-amino acid Flag tag on the mature protein. As expected for a signal peptide, the Lucy tag was cleaved from the mature protein and did not alter OR-ligand binding and signaling. Our studies demonstrate that widespread surface expression of ORs can be achieved in HEK293T cells, providing promise for future large-scale deorphanization studies.
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Olfactory receptor responding to gut microbiota-derived signals plays a role in renin secretion and blood pressure regulation. Proc Natl Acad Sci U S A 2013; 110:4410-5. [PMID: 23401498 DOI: 10.1073/pnas.1215927110] [Citation(s) in RCA: 756] [Impact Index Per Article: 68.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Olfactory receptors are G protein-coupled receptors that mediate olfactory chemosensation and serve as chemosensors in other tissues. We find that Olfr78, an olfactory receptor expressed in the kidney, responds to short chain fatty acids (SCFAs). Olfr78 is expressed in the renal juxtaglomerular apparatus, where it mediates renin secretion in response to SCFAs. In addition, both Olfr78 and G protein-coupled receptor 41 (Gpr41), another SCFA receptor, are expressed in smooth muscle cells of small resistance vessels. Propionate, a SCFA shown to induce vasodilation ex vivo, produces an acute hypotensive response in wild-type mice. This effect is differentially modulated by disruption of Olfr78 and Gpr41 expression. SCFAs are end products of fermentation by the gut microbiota and are absorbed into the circulation. Antibiotic treatment reduces the biomass of the gut microbiota and elevates blood pressure in Olfr78 knockout mice. We conclude that SCFAs produced by the gut microbiota modulate blood pressure via Olfr78 and Gpr41.
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Chapin HC, Rajendran V, Caplan MJ. Polycystin-1 surface localization is stimulated by polycystin-2 and cleavage at the G protein-coupled receptor proteolytic site. Mol Biol Cell 2010; 21:4338-48. [PMID: 20980620 PMCID: PMC3002387 DOI: 10.1091/mbc.e10-05-0407] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The localization of polycystin (PC)1) to the plasma membrane requires coexpression with PC2 and cleavage at the PC1 G protein-coupled receptor proteolytic site. Neither the PC1 binding capacity of PC2 nor its channel function is required for this effect. Polycystin (PC)1 and PC2 are membrane proteins implicated in autosomal dominant polycystic kidney disease. A physiologically relevant cleavage at PC1's G protein-coupled receptor proteolytic site (GPS) occurs early in the secretory pathway. Our results suggest that PC2 increases both PC1 GPS cleavage and PC1's appearance at the plasma membrane. Mutations that prevent PC1's GPS cleavage prevent its plasma membrane localization. PC2 is a member of the trp family of cation channels and is an important PC1 binding partner. The effect of PC2 on PC1 localization is independent of PC2 channel activity, as tested using channel-inhibiting PC2 mutations. PC1 and PC2 can interact through their C-terminal tails, but removing the C-terminal tail of either protein has no effect on PC1 surface localization in human embryonic kidney 293 cells. Experiments in polarized LLC-PK cells show that apical and ciliary PC1 localization requires PC2 and that this delivery is sensitive to PC2 truncation. In sum, our work shows that PC2 expression is required for the movement of PC1 to the plasma and ciliary membranes. In fibroblast cells this localization effect is independent of PC2's channel activity or PC1 binding ability but involves a stimulation of PC1's GPS cleavage before the PC1 protein's surface delivery.
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Affiliation(s)
- Hannah C Chapin
- Departments of Cell Biology and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA
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