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Matsingos C, Howell LA, McCormick PJ, Fornili A. Elucidating the Activation Mechanism of the Proton-sensing GPR68 Receptor. J Mol Biol 2024; 436:168688. [PMID: 38936694 DOI: 10.1016/j.jmb.2024.168688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 06/08/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024]
Abstract
GPR68 is a proton-sensing G-protein Coupled Receptor (GPCR) involved in a variety of physiological processes and disorders including neoplastic pathologies. While GPR68 and few other GPCRs have been shown to be activated by a decrease in the extracellular pH, the molecular mechanism of their activation remains largely unknown. In this work, we used a combined computational and in vitro approach to provide new insight into the activation mechanism of the receptor. Molecular Dynamics simulations of GPR68 were used to model the changes in residue interactions and motions triggered by pH. Global and local rearrangements consistent with partial activation were observed upon protonation of the inactive state. Selected extracellular histidine and transmembrane acidic residues were found to have significantly upshifted pKa values during the simulations, consistently with their previously hypothesised role in activation through changes in protonation state. Moreover, a novel pairing between histidine and acidic residues in the extracellular region was highlighted by both sequence analyses and simulation data and tested through site-directed mutagenesis. At last, we identified a previously unknown hydrophobic lock in the extracellular region that might stabilise the inactive conformation and regulate the transition to the active state.
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Affiliation(s)
- Christos Matsingos
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
| | - Lesley A Howell
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom
| | - Peter J McCormick
- Centre for Endocrinology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom; Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 7BE, United Kingdom
| | - Arianna Fornili
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
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Yu S, Liu D, Yan C, Yuan C, Zhang C, Zheng S. A novel mutation in GPR68 causes hypomaturation amelogenesis imperfecta. Arch Oral Biol 2024; 164:105991. [PMID: 38761453 DOI: 10.1016/j.archoralbio.2024.105991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/20/2024]
Abstract
OBJECTIVES To identify the genetic cause of a Chinese family with hypomaturation amelogenesis imperfecta (AI) and to characterize the structure of GPR68 mutated enamel in order to develop a deeper understanding of the role of the GPR68 protein during the intricate process of amelogenesis. DESIGN One Chinese family with generalized hypomaturation AI was recruited. Two of the third molars from the proband were subjected to scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Whole exome sequencing (WES) was performed, and the identified mutation was confirmed by Sanger sequencing. Bioinformatics studies were further conducted to analyze the potential deleterious effects of the mutation. RESULTS The proband presented with a hypomaturation AI phenotype, characterized by fragile and discolored enamel surface. The AI enamel showed prismatic structure, which was sporadically obscured by areas of amorphous material and porous structure. EDX analysis showed the proband's enamel demonstrated a significant decrease in calcium and phosphorus content and a significant increase in oxygen compared with normal enamel. A novel homozygous mutation of G protein-coupled receptor 68 (GPR68) (c .149 T > A, p.Ile50Asn) was identified in the proband. Bioinformatics analysis indicated that the mutation site displayed a high level of evolutionary conservation among species, and the mutation might impact the stability and conformation of the protein. CONCLUSION The novel homozygous GPR68 mutation resulted in hypomaturation AI. We first described the effect of GPR68 mutation on enamel structure. Our results provide new genetic evidence that mutations involved in GPR68 contribute to hypomaturation AI.
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Affiliation(s)
- Shunlan Yu
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, Beijing, PR China
| | - Dandan Liu
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, Beijing, PR China
| | - Changqing Yan
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, Beijing, PR China
| | - Chao Yuan
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, Beijing, PR China
| | - Chenying Zhang
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, Beijing, PR China.
| | - Shuguo Zheng
- Department of Preventive Dentistry, Peking University School and Hospital of Stomatology & National Center for Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, Beijing, PR China.
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Using GPCRs as Molecular Beacons to Target Ovarian Cancer with Nanomedicines. Cancers (Basel) 2022; 14:cancers14102362. [PMID: 35625966 PMCID: PMC9140059 DOI: 10.3390/cancers14102362] [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: 03/31/2022] [Revised: 05/03/2022] [Accepted: 05/05/2022] [Indexed: 12/12/2022] Open
Abstract
The five-year survival rate for women with ovarian cancer is very poor despite radical cytoreductive surgery and chemotherapy. Although most patients initially respond to platinum-based chemotherapy, the majority experience recurrence and ultimately develop chemoresistance, resulting in fatal outcomes. The current administration of cytotoxic compounds is hampered by dose-limiting severe adverse effects. There is an unmet clinical need for targeted drug delivery systems that transport chemotherapeutics selectively to tumor cells while minimizing off-target toxicity. G protein-coupled receptors (GPCRs) are the largest family of membrane receptors, and many are overexpressed in solid tumors, including ovarian cancer. This review summarizes the progress in engineered nanoparticle research for drug delivery for ovarian cancer and discusses the potential use of GPCRs as molecular entry points to deliver anti-cancer compounds into ovarian cancer cells. A newly emerging treatment paradigm could be the personalized design of nanomedicines on a case-by-case basis.
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Imenez Silva PH, Wagner CA. Physiological relevance of proton-activated GPCRs. Pflugers Arch 2022; 474:487-504. [PMID: 35247105 PMCID: PMC8993716 DOI: 10.1007/s00424-022-02671-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022]
Abstract
The detection of H+ concentration variations in the extracellular milieu is accomplished by a series of specialized and non-specialized pH-sensing mechanisms. The proton-activated G protein-coupled receptors (GPCRs) GPR4 (Gpr4), TDAG8 (Gpr65), and OGR1 (Gpr68) form a subfamily of proteins capable of triggering intracellular signaling in response to alterations in extracellular pH around physiological values, i.e., in the range between pH 7.5 and 6.5. Expression of these receptors is widespread for GPR4 and OGR1 with particularly high levels in endothelial cells and vascular smooth muscle cells, respectively, while expression of TDAG8 appears to be more restricted to the immune compartment. These receptors have been linked to several well-studied pH-dependent physiological activities including central control of respiration, renal adaption to changes in acid-base status, secretion of insulin and peripheral responsiveness to insulin, mechanosensation, and cellular chemotaxis. Their role in pathological processes such as the genesis and progression of several inflammatory diseases (asthma, inflammatory bowel disease), and tumor cell metabolism and invasiveness, is increasingly receiving more attention and makes these receptors novel and interesting targets for therapy. In this review, we cover the role of these receptors in physiological processes and will briefly discuss some implications for disease processes.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
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Husein D, Alamoudi A, Ohyama Y, Mochida H, Ritter B, Mochida Y. Identification of the C-terminal region in Amelogenesis Imperfecta causative protein WDR72 required for Golgi localization. Sci Rep 2022; 12:4640. [PMID: 35301423 PMCID: PMC8930991 DOI: 10.1038/s41598-022-08719-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 02/28/2022] [Indexed: 11/22/2022] Open
Abstract
Amelogenesis Imperfecta (AI) represents a group of hereditary conditions that manifest tooth enamel defects. Several causative mutations in the WDR72 gene have been identified and patients with WDR72 mutations have brown (or orange-brown) discolored enamel, rough enamel surface, early loss of enamel after tooth eruption, and severe attrition. Although the molecular function of WDR72 is not yet fully understood, a recent study suggested that WDR72 could be a facilitator of endocytic vesicle trafficking, which appears inconsistent with the previously reported cytoplasmic localization of WDR72. Therefore, the aims of our study were to investigate the tissues and cell lines in which WDR72 was expressed and to further determine the sub-cellular localization of WDR72. The expression of Wdr72 gene was investigated in mouse tissues and cell lines. Endogenous WDR72 protein was detected in the membranous fraction of ameloblast cell lines in addition to the cytosolic fraction. Sub-cellular localization studies supported our fractionation data, showing WDR72 at the Golgi apparatus, and to a lesser extent, in the cytoplasmic area. In contrast, a WDR72 AI mutant form that lacks its C-terminal region was exclusively detected in the cytoplasm. In addition, our studies identified a putative prenylation/CAAX motif within the last four amino acids of human WDR72 and generated a WDR72 variant, called CS mutant, in which the putative motif was ablated by a point mutation. Interestingly, mutation of the putative CAAX motif impaired WDR72 recruitment to the Golgi. Cell fractionation assays confirmed subcellular distribution of wild-type WDR72 in both cytosolic and membranous fractions, while the WDR72 AI mutant and CS mutant forms were predominantly detected in the cytosolic fraction. Our studies provide new insights into the subcellular localization of WDR72 and demonstrate a critical role for the C-terminal CAAX motif in regulating WDR72 recruitment to the Golgi. In accordance with structural modelling studies that classified WDR72 as a potential vesicle transport protein, our findings suggest a role for WDR72 in vesicular Golgi transport that may be key to understanding the underlying cause of AI.
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Affiliation(s)
- Dina Husein
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Ahmed Alamoudi
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, MA, USA
- Oral Biology Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Yoshio Ohyama
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Hanna Mochida
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Brigitte Ritter
- Department of Biochemistry, School of Medicine, Boston University, Boston, MA, USA
| | - Yoshiyuki Mochida
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, MA, USA.
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Kadowaki M, Sato K, Kamio H, Kumagai M, Sato R, Nyui T, Umeda Y, Waseda Y, Anzai M, Aoki-Saito H, Koga Y, Hisada T, Tomura H, Okajima F, Ishizuka T. Metal-Stimulated Interleukin-6 Production Through a Proton-Sensing Receptor, Ovarian Cancer G Protein-Coupled Receptor 1, in Human Bronchial Smooth Muscle Cells: A Response Inhibited by Dexamethasone. J Inflamm Res 2021; 14:7021-7034. [PMID: 34955648 PMCID: PMC8694576 DOI: 10.2147/jir.s326964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 12/01/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose Human bronchial smooth muscle cells (BSMCs) contribute to airway obstruction and hyperresponsiveness in patients with bronchial asthma. BSMCs also generate cytokines and matricellular proteins in response to extracellular acidification through the ovarian cancer G protein-coupled receptor 1 (OGR1). Cobalt (Co) and nickel (Ni) are occupational agents, which cause occupational asthma. We examined the effects of Co and Ni on interleukin-6 (IL-6) secretion by human BSMCs because these metals may act as ligands of OGR1. Methods Human BSMCs were incubated in Dulbecco's Modified Eagle Medium (DMEM) containing 0.1% bovine serum albumin (BSA) (0.1% BSA-DMEM) for 16 hours and stimulated for the indicated time by exchanging the medium with 0.1% BSA-DMEM containing any of the metals or pH-adjusted 0.1% BSA-DMEM. IL-6 mRNA expression was quantified via reverse transcription polymerase chain reaction (RT-PCR) using the real-time TaqMan technology. IL-6 was measured using an enzyme-linked immunosorbent assay. Dexamethasone (DEX) was added 30 minutes before each stimulation. To knock down the expression of OGR1 in BSMCs, small interfering RNA (siRNA) targeting OGR1 (OGR1-siRNA) was transfected to the cells and non-targeting siRNA (NT-siRNA) was used as a control. Results Co and Ni both significantly increased IL-6 secretion in human BSMCs at 300 μM. This significant increase in IL-6 mRNA expression was observed 5 hours after stimulation. BSMCs transfected with OGR1-siRNA produced less IL-6 than BSMCs transfected with NT-siRNA in response to either Co or Ni stimulation. DEX inhibited Co- and Ni-stimulated IL-6 secretion by human BSMCs as well as pH 6.3-stimulated IL-6 secretion in a dose-dependent manner. DEX did not decrease phosphorylation of ERK1/2, p38 MAP kinase, and NF-κB p65 induced by either Co or Ni stimulation. Conclusion Co and Ni induce secretion of IL-6 in human BSMCs through activation of OGR1. Co- and Ni-stimulated IL-6 secretion is inhibited by DEX.
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Affiliation(s)
- Maiko Kadowaki
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
| | - Koichi Sato
- Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, Maebeshi, 371-8512, Japan
| | - Hisashi Kamio
- Laboratory of Signal Transduction, Faculty of Pharmaceutical Sciences, Aomori University, Aomori, 030-0943, Japan
| | - Makoto Kumagai
- Laboratory of Signal Transduction, Faculty of Pharmaceutical Sciences, Aomori University, Aomori, 030-0943, Japan
| | - Rikishi Sato
- Laboratory of Signal Transduction, Faculty of Pharmaceutical Sciences, Aomori University, Aomori, 030-0943, Japan
| | - Takafumi Nyui
- Laboratory of Signal Transduction, Faculty of Pharmaceutical Sciences, Aomori University, Aomori, 030-0943, Japan
| | - Yukihiro Umeda
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
| | - Yuko Waseda
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
| | - Masaki Anzai
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
| | - Haruka Aoki-Saito
- Department of Respiratory Medicine, Gunma University Graduate School of Medicine, Maebeshi, 371-8511, Japan
| | - Yasuhiko Koga
- Department of Respiratory Medicine, Gunma University Graduate School of Medicine, Maebeshi, 371-8511, Japan
| | - Takeshi Hisada
- Gunma University Graduate School of Health Sciences, Maebeshi, 371-8514, Japan
| | - Hideaki Tomura
- Laboratory of Cell Signaling Regulation, Division of Life Science, School of Agriculture, Meiji University, Kawasaki, 214-8571, Japan
| | - Fumikazu Okajima
- Laboratory of Signal Transduction, Faculty of Pharmaceutical Sciences, Aomori University, Aomori, 030-0943, Japan
| | - Tamotsu Ishizuka
- Third Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan
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Seymen F, Zhang H, Kasimoglu Y, Koruyucu M, Simmer JP, Hu JCC, Kim JW. Novel Mutations in GPR68 and SLC24A4 Cause Hypomaturation Amelogenesis Imperfecta. J Pers Med 2021; 12:jpm12010013. [PMID: 35055328 PMCID: PMC8781920 DOI: 10.3390/jpm12010013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 11/16/2022] Open
Abstract
Amelogenesis imperfecta (AI) is a rare genetic condition affecting the quantity and/or quality of tooth enamel. Hypomaturation AI is characterized by brownish-yellow discoloration with increased opacity and poorly mineralized enamel prone to fracture and attrition. We recruited three families affected by hypomaturation AI and performed whole exome sequencing with selected individuals in each family. Bioinformatic analysis and Sanger sequencing identified and confirmed mutations and segregation in the families. Family 1 had a novel homozygous frameshift mutation in GPR68 gene (NM_003485.3:c.78_83delinsC, p.(Val27Cysfs*146)). Family 2 had a novel homozygous nonsense mutation in SLC24A4 gene (NM_153646.4:c.613C>T, NP_705932.2:p.(Arg205*)). Family 3 also had a homozygous missense mutation in SLC24A4 gene which was reported previously (c.437C>T, p.(Ala146Val)). This report not only expands the mutational spectrum of the AI-causing genes but also improves our understanding of normal and pathologic amelogenesis.
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Affiliation(s)
- Figen Seymen
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul 34116, Turkey; (F.S.); (Y.K.); (M.K.)
| | - Hong Zhang
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA; (H.Z.); (J.P.S.); (J.C.-C.H.)
| | - Yelda Kasimoglu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul 34116, Turkey; (F.S.); (Y.K.); (M.K.)
| | - Mine Koruyucu
- Department of Pedodontics, Faculty of Dentistry, Istanbul University, Istanbul 34116, Turkey; (F.S.); (Y.K.); (M.K.)
| | - James P. Simmer
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA; (H.Z.); (J.P.S.); (J.C.-C.H.)
| | - Jan C.-C. Hu
- Department of Biologic and Materials Sciences & Prosthodontics, School of Dentistry, University of Michigan, Ann Arbor, MI 48109, USA; (H.Z.); (J.P.S.); (J.C.-C.H.)
| | - Jung-Wook Kim
- Department of Pediatric Dentistry, School of Dentistry & DRI, Seoul National University, Seoul 03080, Korea
- Department of Molecular Genetics, School of Dentistry & DRI, Seoul National University, Seoul 03080, Korea
- Correspondence:
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Ritter M, Bresgen N, Kerschbaum HH. From Pinocytosis to Methuosis-Fluid Consumption as a Risk Factor for Cell Death. Front Cell Dev Biol 2021; 9:651982. [PMID: 34249909 PMCID: PMC8261248 DOI: 10.3389/fcell.2021.651982] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022] Open
Abstract
The volumes of a cell [cell volume (CV)] and its organelles are adjusted by osmoregulatory processes. During pinocytosis, extracellular fluid volume equivalent to its CV is incorporated within an hour and membrane area equivalent to the cell's surface within 30 min. Since neither fluid uptake nor membrane consumption leads to swelling or shrinkage, cells must be equipped with potent volume regulatory mechanisms. Normally, cells respond to outwardly or inwardly directed osmotic gradients by a volume decrease and increase, respectively, i.e., they shrink or swell but then try to recover their CV. However, when a cell death (CD) pathway is triggered, CV persistently decreases in isotonic conditions in apoptosis and it increases in necrosis. One type of CD associated with cell swelling is due to a dysfunctional pinocytosis. Methuosis, a non-apoptotic CD phenotype, occurs when cells accumulate too much fluid by macropinocytosis. In contrast to functional pinocytosis, in methuosis, macropinosomes neither recycle nor fuse with lysosomes but with each other to form giant vacuoles, which finally cause rupture of the plasma membrane (PM). Understanding methuosis longs for the understanding of the ionic mechanisms of cell volume regulation (CVR) and vesicular volume regulation (VVR). In nascent macropinosomes, ion channels and transporters are derived from the PM. Along trafficking from the PM to the perinuclear area, the equipment of channels and transporters of the vesicle membrane changes by retrieval, addition, and recycling from and back to the PM, causing profound changes in vesicular ion concentrations, acidification, and-most importantly-shrinkage of the macropinosome, which is indispensable for its proper targeting and cargo processing. In this review, we discuss ion and water transport mechanisms with respect to CVR and VVR and with special emphasis on pinocytosis and methuosis. We describe various aspects of the complex mutual interplay between extracellular and intracellular ions and ion gradients, the PM and vesicular membrane, phosphoinositides, monomeric G proteins and their targets, as well as the submembranous cytoskeleton. Our aim is to highlight important cellular mechanisms, components, and processes that may lead to methuotic CD upon their derangement.
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Affiliation(s)
- Markus Ritter
- Center for Physiology, Pathophysiology and Biophysics, Institute for Physiology and Pathophysiology, Paracelsus Medical University, Salzburg, Austria
- Institute for Physiology and Pathophysiology, Paracelsus Medical University, Nuremberg, Germany
- Gastein Research Institute, Paracelsus Medical University, Salzburg, Austria
- Ludwig Boltzmann Institute for Arthritis und Rehabilitation, Salzburg, Austria
- Kathmandu University School of Medical Sciences, Dhulikhel, Nepal
| | - Nikolaus Bresgen
- Department of Biosciences, University of Salzburg, Salzburg, Austria
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