Carbon nanotube porin diffusion in mixed composition supported lipid bilayers

Lipid membranes play a key role in living systems by providing a structural barrier that separates cellular compartments. Bilayer fluidity in the lateral plane is a key property of lipid membranes, that allows the membrane to have sufficient flexibility to accommodate dynamic stresses, shape changes and rearrangements accompanying the cellular lifecycle.*

In the article “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” Kylee Sullivan, Yuliang Zhang, Joseph Lopez, Mary Lowe and Aleksandr Noy describe how they used high-speed atomic force microscopy (HS-AFM) and all-atom molecular dynamics (MD) simulations to study the behavior of CNTPs in a mixed lipid membrane consisting of DOPC lipid with a variable percentage of DMPC lipid added to it. HS-AFM data reveal that the CNTPs undergo diffusive motion in the bilayer plane.*

Motion trajectories extracted from the HS-AFM movies indicate that CNTPs exhibit diffusion coefficient values broadly similar to values reported for membrane proteins in supported lipid bilayers. The data also indicate that increasing the percentage of DMPC leads to a marked slowing of CNTP diffusion. MD simulations reveal a CNTP-lipid assembly that diffuses in the membrane and show trends that are consistent with the experimental observations. *

The above-mentioned study confirms that CNTPs mimic the major features of the diffusive movement of biological pores in lipid membranes and shows how the increase in bilayer viscosity leads to a corresponding slowdown in protein motion. It should be possible to extend this approach to studies of other membrane protein dynamics in supported lipid bilayers. The authors note that those studies, however, will need to be mindful of the challenge of unambiguous visualization of the membrane components, especially in systems that incorporate smaller proteins, such as antimicrobial peptides. Another challenge that could complicate these studies would be microscopic phase separation of the lipid matrix that could lead to complicated pore dynamics in the membrane. *

NanoWorld Ultra-Short AFM cantilevers with high-density carbon/diamond-like carbon (HDC/DLC) AFM tips of the USC-F1.2-k0.15 type were used for the high-speed atomic force microscopy described in the article. *

Figure 2 from “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” by Kylee Sullivan et al.:

CNTP motion in supported lipid bilayers. (a) Representative frames (with times in seconds indicated on each image) from an HS-AFM movie showing a CNTP diffusing in a supported lipid bilayer with 80:20 DOPC-DMPC ratio (see also Supplementary Movie 2). (b) A representative trajectory for CNTP diffusion in the bilayer. The time step between each datapoint is 0.5 s. NanoWorld Ultra-Short AFM Cantilvers USC-F1.2-k0.15 were used for the HS-AFM imaging
Figure 2 a and b from “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” by Kylee Sullivan et al.:

CNTP motion in supported lipid bilayers. (a) Representative frames (with times in seconds indicated on each image) from an HS-AFM movie showing a CNTP diffusing in a supported lipid bilayer with 80:20 DOPC-DMPC ratio (see also Supplementary Movie 2). (b) A representative trajectory for CNTP diffusion in the bilayer. The time step between each datapoint is 0.5 s.
Please refer to the full article cited below for the full figure.

*Kylee Sullivan, Yuliang Zhang, Joseph Lopez, Mary Lowe and Aleksandr Noy
Carbon nanotube porin diffusion in mixed composition supported lipid bilayers
Nature Scientific Reports volume 10, Article number: 11908 (2020)
DOI: https://doi.org/10.1038/s41598-020-68059-2

Please follow this external link to read the full article: https://rdcu.be/b69wj

Open Access : The article “Carbon nanotube porin diffusion in mixed composition supported lipid bilayers” by Kylee Sullivan, Yuliang Zhang, Joseph Lopez, Mary Lowe and Aleksandr Noy is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Intravascular adhesion and recruitment of neutrophils in response to CXCL1 depends on their TRPC6 channels

Representing a central element of the innate immune system, neutrophils are recruited from the blood stream to a site of inflammation. The recruitment process follows a well-defined sequence of events including adhesion to the blood vessel walls, migration, and chemotaxis to reach the inflammatory focus. A common feature of the underlying signalling pathways is the utilization of Ca2+ ions as intracellular second messengers. However, the required Ca2+ influx channels are not yet fully characterized.*

In the article “Intravascular adhesion and recruitment of neutrophils in response to CXCL1 depends on their TRPC6 channels” Otto Lindemann, Jan Rossaint, Karolina Najder, Sandra Schimmelpfennig, Verena Hofschröer, Mike Wälte, Benedikt Fels, Hans Oberleithner, Alexander Zarbock and Albrecht Schwab report a novel role for TRPC6, a member of the transient receptor potential (TRPC) channel family, in the CXCL1-dependent recruitment of murine neutrophil granulocytes.*

The authors describe how they tested whether TRPC6 channels are central elements of the signalling cascade underlying CXCR2-mediated neutrophil recruitment. They combined intravital microscopy, single-cell force spectroscopy with atomic force microscopy, Ca2+ imaging, and microfluidic flow chamber assays to investigate the role of TRPC6 channels in murine neutrophils for their recruitment in renal ischemia-reperfusion and cremaster models as well as in in vitro assays.*

The study reveals that TRPC6 channels in neutrophils are crucial signalling modules in their recruitment from the blood stream in response to CXCL1.*

The single-cell force spectroscopy experiments were performed by using atomic force microscopy (AFM) with NanoWorld Arrow-TL1 tipless cantilevers which were incubated prior to experiments for 30 min in Cell-Tak to make the AFM cantilever sticky for neutrophils.*

NanoWorld Arrow-TL1 Tipless AFM cantilever, single cantilever beam on a silicon support chip
NanoWorld Arrow-TL1
Tipless cantilever,
single cantilever beam on a silicon support chip

*Otto Lindemann, Jan Rossaint, Karolina Najder, Sandra Schimmelpfennig, Verena Hofschröer, Mike Wälte, Benedikt Fels, Hans Oberleithner, Alexander Zarbock and Albrecht Schwab
Intravascular adhesion and recruitment of neutrophils in response to CXCL1 depends on their TRPC6 channels
Journal of Molecular Medicine volume 98, pages349–360(2020)
DOI: https://doi.org/10.1007/s00109-020-01872-4

Please follow this external link to read the full article: https://link.springer.com/article/10.1007/s00109-020-01872-4

Open Access The article “ Intravascular adhesion and recruitment of neutrophils in response to CXCL1 depends on their TRPC6 channels “ by Otto Lindemann, Jan Rossaint, Karolina Najder, Sandra Schimmelpfennig, Verena Hofschröer, Mike Wälte, Benedikt Fels, Hans Oberleithner, Alexander Zarbock and Albrecht Schwab is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy

Stem cell apoptosis exists widely in embryonic development, tissue regeneration, repair, aging and pathophysiology of disease. The molecular mechanism of stem cell apoptosis has been extensively investigated.*

However, alterations in biomechanics and nanomorphology have rarely been studied.*

In the research article “ Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy “ Xuelian Su, Haijing Zhou, Guangjie Bao, Jizeng Wang, Lin Liu, Qian Zheng, Manli Guo and Jinting Zhang establish an apoptosis model for bone marrow mesenchymal stem cells (BMSCs) and investigated in detail the reconstruction of the mechanical properties and nanomorphology of the cells.*

Atomic force microscopy (AFM), scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), flow cytometry and Cell Counting Kit-8 analysis were applied to assess the cellular elasticity modulus, geometry, nanomorphology, cell surface ultrastructure, biological viability and early apoptotic signals (phosphatidylserine,PS).*

The results indicated that the cellular elastic modulus and volume significantly decreased, whereas the cell surface roughness obviously increased during the first 3 h of cytochalasin B (CB) treatment. Moreover, these alterations preceded the exposure of biological apoptotic signal PS.*

These findings suggested that cellular mechanical damage is connected with the apoptosis of BMSCs, and the alterations in mechanics and nanomorphology may be a sensitive index to detect alterations in cell viability during apoptosis. The results contribute to further understanding of apoptosis from the perspective of cell mechanics.*

NanoWorld PNP Silicon Nitride AFM probes of the PNP-DB type were used for the single-cell imaging with Atomic Force Microscopy and nanoindentation experiments described in this research article.*

Figure 4 from “Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy” by Xuelian Su et al.:
Surface topography of BMSCs captured by AFM at different times. Columns A–D indicated the height-measurement images, vertical deflection images, three-dimensional images and cross-sectional images, respectively. The bright area was the elevated part of the cell, where the nucleus was located(A,C). The untreated cells adhered well, and their surface was smooth. The texture of the F-actin bundles is clearly visible (B, 0 h). The surface of treated cells became increasingly rough, the periphery of the cells became irregular and the area of cell extension gradually decreased (A and B, 1 h, 3 h, respectively).
Figure 4 from “Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy” by Xuelian Su et al.:
Surface topography of BMSCs captured by AFM at different times. Columns A–D indicated the height-measurement images, vertical deflection images, three-dimensional images and cross-sectional images, respectively. The bright area was the elevated part of the cell, where the nucleus was located(A,C). The untreated cells adhered well, and their surface was smooth. The texture of the F-actin bundles is clearly visible (B, 0 h). The surface of treated cells became increasingly rough, the periphery of the cells became irregular and the area of cell extension gradually decreased (A and B, 1 h, 3 h, respectively).

*Xuelian Su, Haijing Zhou, Guangjie Bao, Jizeng Wang, Lin Liu, Qian Zheng, Manli Guo and Jinting Zhang
Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy
Biology Open (2020) 9, bio048108.
DOI: 10.1242/bio.048108

Please follow this external link to read the full article: https://bio.biologists.org/content/biolopen/9/3/bio048108.full.pdf

Open Access The article “ Nanomorphological and mechanical reconstruction of mesenchymal stem cells during early apoptosis detected by atomic force microscopy “ by Xuelian Su, Haijing Zhou, Guangjie Bao, Jizeng Wang, Lin Liu, Qian Zheng, Manli Guo and Jinting Zhang is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.