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Baldwin SA, Van Bruggen SM, Koelbl JM, Appalabhotla R, Bear JE, Haugh JM. Microfluidic devices fitted with "flowver" paper pumps generate steady, tunable gradients for extended observation of chemotactic cell migration. BIOMICROFLUIDICS 2021; 15:044101. [PMID: 34290842 PMCID: PMC8282348 DOI: 10.1063/5.0054764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/19/2021] [Indexed: 05/11/2023]
Abstract
Microfluidics approaches have gained popularity in the field of directed cell migration, enabling control of the extracellular environment and integration with live-cell microscopy; however, technical hurdles remain. Among the challenges are the stability and predictability of the environment, which are especially critical for the observation of fibroblasts and other slow-moving cells. Such experiments require several hours and are typically plagued by the introduction of bubbles and other disturbances that naturally arise in standard microfluidics protocols. Here, we report on the development of a passive pumping strategy, driven by the high capillary pressure and evaporative capacity of paper, and its application to study fibroblast chemotaxis. The paper pumps-flowvers (flow + clover)-are inexpensive, compact, and scalable, and they allow nearly bubble-free operation, with a predictable volumetric flow rate on the order of μl/min, for several hours. To demonstrate the utility of this approach, we combined the flowver pumping strategy with a Y-junction microfluidic device to generate a chemoattractant gradient landscape that is both stable (6+ h) and predictable (by finite-element modeling calculations). Integrated with fluorescence microscopy, we were able to recapitulate previous, live-cell imaging studies of fibroblast chemotaxis to platelet derived growth factor (PDGF), with an order-of-magnitude gain in throughput. The increased throughput of single-cell analysis allowed us to more precisely define PDGF gradient conditions conducive for chemotaxis; we were also able to interpret how the orientation of signaling through the phosphoinositide 3-kinase pathway affects the cells' sensing of and response to conducive gradients.
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Affiliation(s)
- Scott A. Baldwin
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, North Carolina 27695, USA
| | - Shawn M. Van Bruggen
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, North Carolina 27695, USA
| | - Joseph M. Koelbl
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, North Carolina 27695, USA
| | - Ravikanth Appalabhotla
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, North Carolina 27695, USA
| | - James E. Bear
- Department of Cell Biology and Physiology, UNC Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA
| | - Jason M. Haugh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, Raleigh, North Carolina 27695, USA
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McGowan SE, McCoy DM. Neuropilin-1 directs PDGFRα-entry into lung fibroblasts and signaling from very early endosomes. Am J Physiol Lung Cell Mol Physiol 2020; 320:L179-L192. [PMID: 33174445 DOI: 10.1152/ajplung.00149.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Platelet-derived growth factor receptor-α (PDGFRα) is absolutely required for the development of secondary pulmonary alveolar septa. Our earlier observations indicated that PDGFRα resides intracellularly as well as on the plasma membrane of murine lung fibroblasts (LF). We have examined how neuropilin-1 (Nrp1), a surface receptor without kinase activity, regulates the intracellular trafficking of PDGFRα in LF obtained from mice, some bearing a targeted deletion of Nrp1 in myofibroblasts. Using the proximity ligation assay, we observed that PDGFRα and Nrp1 colocalized in both early antigen-1 (EEA1) containing sorting endosomes and with adaptor protein containing a pleckstrin homology domain and a phosphotyrosine-binding domain-1 (APPL1) in very early endosomes (VEE). These findings were confirmed using live-cell imaging, which demonstrated that recently internalized PDGFRα was observed in Rab5-containing vesicles residing within 100 nm of the plasma membrane. Nrp1 deletion reduced the phosphorylation of Akt (protein kinase B), the major downstream target of PDGFRα, and limited accumulation of inositol-3 phosphates in APPL1-containing endosomes after exposure to PDGFA. PDGFRα co-immunoprecipitated with APPL1, indicating that PDGFRα enters VEE. Targeted deletion of Nrp1 or APPL1-depletion in control LF reduced the activity of an Akt1 biosensor following stimulation with PDGFA. Our findings demonstrate that Nrp1 enhances the entry of PDGFRα into APPL1 containing VEE and that APPL1 enhances PDGFRα signaling. Therefore, Nrp1 promotes endosomal signaling by PDGFRα offering a potential mechanism to explain our prior observation that Nrp1 supports the formation of alveolar ducts and alveoli during secondary septation in mice.
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Affiliation(s)
- Stephen E McGowan
- Department of Veterans Affairs Research Service and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Diann M McCoy
- Department of Veterans Affairs Research Service and Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa
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Liu SL, Wang ZG, Xie HY, Liu AA, Lamb DC, Pang DW. Single-Virus Tracking: From Imaging Methodologies to Virological Applications. Chem Rev 2020; 120:1936-1979. [PMID: 31951121 PMCID: PMC7075663 DOI: 10.1021/acs.chemrev.9b00692] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
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Uncovering
the mechanisms of virus infection and assembly is crucial
for preventing the spread of viruses and treating viral disease. The
technique of single-virus tracking (SVT), also known as single-virus
tracing, allows one to follow individual viruses at different parts
of their life cycle and thereby provides dynamic insights into fundamental
processes of viruses occurring in live cells. SVT is typically based
on fluorescence imaging and reveals insights into previously unreported
infection mechanisms. In this review article, we provide the readers
a broad overview of the SVT technique. We first summarize recent advances
in SVT, from the choice of fluorescent labels and labeling strategies
to imaging implementation and analytical methodologies. We then describe
representative applications in detail to elucidate how SVT serves
as a valuable tool in virological research. Finally, we present our
perspectives regarding the future possibilities and challenges of
SVT.
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Affiliation(s)
- Shu-Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China.,Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry , China University of Geosciences , Wuhan 430074 , P. R. China
| | - Zhi-Gang Wang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China
| | - Hai-Yan Xie
- School of Life Science , Beijing Institute of Technology , Beijing 100081 , P. R. China
| | - An-An Liu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China
| | - Don C Lamb
- Physical Chemistry, Department of Chemistry, Center for Nanoscience (CeNS), and Center for Integrated Protein Science Munich (CIPSM) and Nanosystems Initiative Munich (NIM) , Ludwig-Maximilians-Universität , München , 81377 , Germany
| | - Dai-Wen Pang
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, and School of Medicine , Nankai University , Tianjin 300071 , P. R. China.,College of Chemistry and Molecular Sciences, State Key Laboratory of Virology, The Institute for Advanced Studies, and Wuhan Institute of Biotechnology , Wuhan University , Wuhan 430072 , P. R. China
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Liu X, Asokan SB, Bear JE, Haugh JM. Quantitative analysis of B-lymphocyte migration directed by CXCL13. Integr Biol (Camb) 2016; 8:894-903. [PMID: 27477203 DOI: 10.1039/c6ib00128a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
B-lymphocyte migration, directed by chemokine gradients, is essential for homing to sites of antigen presentation. B cells move rapidly, exhibiting amoeboid morphology like other leukocytes, yet quantitative studies addressing B-cell migration are currently lacking relative to neutrophils, macrophages, and T cells. Here, we used total internal reflection fluorescence (TIRF) microscopy to characterize the changes in shape (morphodynamics) of primary, murine B cells as they migrated on surfaces with adsorbed chemokine, CXCL13, and the adhesive ligand, ICAM-1. B cells exhibited frequent, spontaneous dilation and shrinking events at the sides of the leading membrane edge, a phenomenon that was predictive of turning versus directional persistence. To characterize directed B-cell migration, a microfluidic device was implemented to generate gradients of adsorbed CXCL13 gradients. Haptotaxis assays revealed a modest yet consistently positive bias of the cell's persistent random walk behavior towards CXCL13 gradients. Quantification of tactic fidelity showed that bias is optimized by steeper gradients without excessive midpoint density of adsorbed chemokine. Under these conditions, B-cell migration is more persistent when the direction of migration is better aligned with the gradient.
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Affiliation(s)
- Xiaji Liu
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Campus Box 7905, 911 Partners Way, Raleigh, NC 27695-7905, USA.
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Johnson HE, King SJ, Asokan SB, Rotty JD, Bear JE, Haugh JM. F-actin bundles direct the initiation and orientation of lamellipodia through adhesion-based signaling. ACTA ACUST UNITED AC 2015; 208:443-55. [PMID: 25666809 PMCID: PMC4332254 DOI: 10.1083/jcb.201406102] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Mesenchymal cells such as fibroblasts are weakly polarized and reorient directionality by a lamellipodial branching mechanism that is stabilized by phosphoinositide 3-kinase (PI3K) signaling. However, the mechanisms by which new lamellipodia are initiated and directed are unknown. Using total internal reflection fluorescence microscopy to monitor cytoskeletal and signaling dynamics in migrating cells, we show that peripheral F-actin bundles/filopodia containing fascin-1 serve as templates for formation and orientation of lamellipodia. Accordingly, modulation of fascin-1 expression tunes cell shape, quantified as the number of morphological extensions. Ratiometric imaging reveals that F-actin bundles/filopodia play both structural and signaling roles, as they prime the activation of PI3K signaling mediated by integrins and focal adhesion kinase. Depletion of fascin-1 ablated fibroblast haptotaxis on fibronectin but not platelet-derived growth factor chemotaxis. Based on these findings, we conceptualize haptotactic sensing as an exploration, with F-actin bundles directing and lamellipodia propagating the process and with signaling mediated by adhesions playing the role of integrator.
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Affiliation(s)
- Heath E Johnson
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695
| | - Samantha J King
- UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599 UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
| | - Sreeja B Asokan
- UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599 UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
| | - Jeremy D Rotty
- UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599 UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
| | - James E Bear
- UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599 UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599 UNC Lineberger Cancer Center, the Department of Cell Biology and Physiology, and Howard Hughes Medical Institute, The University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
| | - Jason M Haugh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695
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