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Plazen L, Khadra A. Excitable dynamics in a molecularly-explicit model of cell motility: Mixed-mode oscillations and beyond. J Theor Biol 2023; 564:111450. [PMID: 36868346 DOI: 10.1016/j.jtbi.2023.111450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 02/11/2023] [Accepted: 02/23/2023] [Indexed: 03/05/2023]
Abstract
Mesenchymal cell motility is mainly regulated by two members of the Rho-family of GTPases, called Rac and Rho. The mutual inhibition exerted by these two proteins on each other's activation and the promotion of Rac activation by an adaptor protein called paxillin have been implicated in driving cellular polarization comprised of front (high active Rac) and back (high active Rho) during cell migration. Mathematical modeling of this regulatory network has previously shown that bistability is responsible for generating a spatiotemporal pattern underscoring cellular polarity called wave-pinning when diffusion is included. We previously developed a 6V reaction-diffusion model of this network to decipher the role of Rac, Rho and paxillin (along with other auxiliary proteins) in generating wave-pinning. In this study, we simplify this model through a series of steps into an excitable 3V ODE model comprised of one fast variable (the scaled concentration of active Rac), one slow variable (the maximum paxillin phosphorylation rate - turned into a variable) and a very slow variable (a recovery rate - also turned into a variable). We then explore, through slow-fast analysis, how excitability is manifested by showing that the model can exhibit relaxation oscillations (ROs) as well as mixed-mode oscillations (MMOs) whose underlying dynamics are consistent with a delayed Hopf bifurcation with a canard explosion. By reintroducing diffusion and the scaled concentration of inactive Rac into the model, we obtain a 4V PDE model that generates several unique spatiotemporal patterns that are relevant to cell motility. These patterns are then characterized and their impact on cell motility are explored by employing the cellular potts model (CPM). Our results reveal that wave pinning produces purely very directed motion in CPM, while MMOs allow for meandering and non-motile behaviors to occur. This highlights the role of MMOs as a potential mechanism for mesenchymal cell motility.
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Affiliation(s)
- Lucie Plazen
- Department of Mathematics and Statistics, McGill University, Montreal, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montreal, Canada.
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Li CZ, Ogawa H, Ng SS, Chen X, Kishimoto E, Sakabe K, Fukami A, Hu YC, Mayhew CN, Hellmann J, Miethke A, Tasnova NL, Blackford SJ, Tang ZM, Syanda AM, Ma L, Xiao F, Sambrotta M, Tavabie O, Soares F, Baker O, Danovi D, Hayashi H, Thompson RJ, Rashid ST, Asai A. Human iPSC-derived hepatocyte system models cholestasis with tight junction protein 2 deficiency. JHEP Rep 2022; 4:100446. [PMID: 35284810 PMCID: PMC8904612 DOI: 10.1016/j.jhepr.2022.100446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 02/07/2023] Open
Abstract
Background & Aims The truncating mutations in tight junction protein 2 (TJP2) cause progressive cholestasis, liver failure, and hepatocyte carcinogenesis. Due to the lack of effective model systems, there are no targeted medications for the liver pathology with TJP2 deficiency. We leveraged the technologies of patient-specific induced pluripotent stem cells (iPSC) and CRISPR genome-editing, and we aim to establish a disease model which recapitulates phenotypes of patients with TJP2 deficiency. Methods We differentiated iPSC to hepatocyte-like cells (iHep) on the Transwell membrane in a polarized monolayer. Immunofluorescent staining of polarity markers was detected by a confocal microscope. The epithelial barrier function and bile acid transport of bile canaliculi were quantified between the two chambers of Transwell. The morphology of bile canaliculi was measured in iHep cultured in the Matrigel sandwich system using a fluorescent probe and live-confocal imaging. Results The iHep differentiated from iPSC with TJP2 mutations exhibited intracellular inclusions of disrupted apical membrane structures, distorted canalicular networks, altered distribution of apical and basolateral markers/transporters. The directional bile acid transport of bile canaliculi was compromised in the mutant hepatocytes, resembling the disease phenotypes observed in the liver of patients. Conclusions Our iPSC-derived in vitro hepatocyte system revealed canalicular membrane disruption in TJP2 deficient hepatocytes and demonstrated the ability to model cholestatic disease with TJP2 deficiency to serve as a platform for further pathophysiologic study and drug discovery. Lay summary We investigated a genetic liver disease, progressive familial intrahepatic cholestasis (PFIC), which causes severe liver disease in newborns and infants due to a lack of gene called TJP2. By using cutting-edge stem cell technology and genome editing methods, we established a novel disease modeling system in cell culture experiments. Our experiments demonstrated that the lack of TJP2 induced abnormal cell polarity and disrupted bile acid transport. These findings will lead to the subsequent investigation to further understand disease mechanisms and develop an effective treatment.
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Key Words
- ALB, albumin
- ASGR2, asialoglycoprotein receptor 2
- ATP1a1, ATPases subunit alpha-1
- BMP4, bone morphogenetic protein 4
- BSA-FAF, bovine serum albumin fatty acid-free
- BSEP, bile salt export pump
- Bile acid transport
- CDFDA, 5-(and-6)-carboxy-2′,7′-dichlorofluorescein
- Cellular polarity
- DE, definitive endoderm
- DILI, drug-induced liver injury
- FGF2, fibroblast growth factor 2
- GCA, glycocholate
- GCDCA, glycochenodeoxycholate
- HCM, Hepatocyte Culture Medium
- HE, hepatic endodermal
- HGF, hepatocyte growth factor
- HNF4a, hepatic nuclear factor 4a
- MDCKII, Madin–Darby canine kidney II
- MRP2, multidrug resistance-associated protein 2
- NTCP, Na+-TCA cotransporter
- PFIC (progressive familial intrahepatic cholestasis)
- PFIC, progressive familial intrahepatic cholestasis
- PI, propidium iodide
- RT-qPCR, quantitative reverse transcription PCR
- TCA, taurocholic acid
- TCDCA, taurochenodeoxycholate
- TEER, transepithelial electrical resistance
- TEM, transmission electron microscopy
- TJP1, tight junction protein 1
- TJP2, tight junction protein 2
- iHep, iPSC-derived hepatocytes
- iPSC, induced pluripotent stem cell
- sgRNA, single-guide RNA
- ssODN, single-stranded oligonucleotide-DNA
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Affiliation(s)
- Chao Zheng Li
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Hiromi Ogawa
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Soon Seng Ng
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Xindi Chen
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Eriko Kishimoto
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Kokoro Sakabe
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Aiko Fukami
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Yueh-Chiang Hu
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | | | - Jennifer Hellmann
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Department of Paediatrics, The University of Cincinnati, Cincinnati, OH, USA
| | - Alexander Miethke
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Department of Paediatrics, The University of Cincinnati, Cincinnati, OH, USA
| | - Nahrin L. Tasnova
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | | | - Zu Ming Tang
- Stem Cell Hotel, King’s College London, London, UK
| | - Adam M. Syanda
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Liang Ma
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Fang Xiao
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Melissa Sambrotta
- Institute of Liver Studies King’s College London, London, United Kingdom
| | - Oliver Tavabie
- Institute of Liver Studies King’s College London, London, United Kingdom
| | | | - Oliver Baker
- Genome Editing and Embryology Core Facility, King’s College London, London, UK
| | - Davide Danovi
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Hisamitsu Hayashi
- Graduate School of Pharmaceutical Science, The University of Tokyo, Tokyo, Japan
| | | | - S. Tamir Rashid
- Centre for Stem Cells and Regenerative Medicine, King’s College London, London, UK
| | - Akihiro Asai
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Department of Paediatrics, The University of Cincinnati, Cincinnati, OH, USA
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Lyda JK, Tan ZL, Rajah A, Momi A, Mackay L, Brown CM, Khadra A. Rac activation is key to cell motility and directionality: An experimental and modelling investigation. Comput Struct Biotechnol J 2019; 17:1436-1452. [PMID: 31871589 PMCID: PMC6906685 DOI: 10.1016/j.csbj.2019.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 01/04/2023] Open
Abstract
Cell migration is a tightly-regulated process that involves protein gradients formed by the Rho family of GTPases, including Rho and Rac. The front (rear) of cells is generally characterized by higher active Rac (Rho) and lower active Rho (Rac) concentrations. Protein clusters, called adhesions, that anchor cells to their external environment have been shown to be dynamic and small (stable and large) at the cell front (rear), forming the force-transmission points necessary for persistent movement. Differences in adhesion sizes and dynamics have been linked to gradients in Rac and Rho activity. Here, we study the effects of Rac activation and gradients in Rac and Rho concentrations and activities on cellular polarity and adhesion size using mathematical and experimental approaches. The former is accomplished by expanding an existing reaction-diffusion model to a 2D domain utilizing stochastic dynamics. The model revealed that a hysteresis between the induced/uninduced states (corresponding to higher/lower Rac concentrations, respectively) along with Rac and Rho activation gradients, generated by chemical cues, were vital for forming polarity. Experimentally, the induced state was generated by increasing the cellular βPIX (a Rac-GEF) level and/or decreasing ROCK (a Rac-GAP effector protein) activity with Y-27632 (a ROCK-inhibitor). In agreement with the simulations, our results showed that cells with elevated RacGTP migrated faster, indicating more robust cellular polarization. However, the directionality of cells was not changed significantly, suggesting that external and/or internal physical or chemical cues were needed. Complementing the faster migration observed, adhesions were smaller, generating the phenotype expected with the induced state.
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Affiliation(s)
- Jessica K Lyda
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Zhang L Tan
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Abira Rajah
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Asheesh Momi
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Laurent Mackay
- Department of Physiology, McGill University, Montréal, Québec, Canada
| | - Claire M Brown
- Department of Physiology, McGill University, Montréal, Québec, Canada.,Advanced BioImaging Facility (ABIF), McGill University, Montréal, Québec, Canada.,Cell Information Systems, McGill University, Montréal, Québec, Canada.,Department of Anatomy and Cell Biology, McGill University, Montréal, Québec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montréal, Québec, Canada
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Watanabe T, Bochimoto H, Koga D, Hosaka M, Ushiki T. Functional implications of the Golgi and microtubular network in gonadotropes. Mol Cell Endocrinol 2014; 385:88-96. [PMID: 24121198 DOI: 10.1016/j.mce.2013.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/30/2013] [Accepted: 10/01/2013] [Indexed: 02/01/2023]
Abstract
In contrast to the widely accepted images of the Golgi apparatus as a cup-like shape, the Golgi in pituitary gonadotropes is organized as a spherical shape in which the outer and inner faces are cis- and trans-Golgi elements, respectively. At the center of the spherical Golgi, a pair of centrioles is situated as a microtubule-organizing center from which radiating microtubules isotropically extend toward the cell periphery. This review focuses on the significance of the characteristic organization of the Golgi and microtubule network in gonadotropes, considering the roles of microtubule-dependent membrane transport in the formation and maintenance of the Golgi structure. Because the highly symmetrical organization of the Golgi is possibly perturbed in response to experimental treatments of gonadotropes, monitoring of the Golgi structure in gonadotropes under various experimental conditions will be a novel in vivo approach to elucidate the biogenesis of the Golgi apparatus.
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Affiliation(s)
- Tsuyoshi Watanabe
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa, Japan.
| | - Hiroki Bochimoto
- Department of Microscopic Anatomy and Cell Biology, Asahikawa Medical University, Asahikawa, Japan
| | - Daisuke Koga
- Division of Microscopic Anatomy and Bio-imaging, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masahiro Hosaka
- Laboratory of Molecular Life Sciences, Department of Biotechnology, Akita Prefectural University, Akita, Japan
| | - Tatsuo Ushiki
- Division of Microscopic Anatomy and Bio-imaging, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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