Inherently slow and weak forward forces of neuronal growth cones measured by a drift‐stabilized atomic force microscope

Fuhs, Thomas; Reuter, Lydia; Vonderhaid, Iris; Claudepierre, Thomas; Käs, Josef A.

doi:10.1002/cm.21080

Cited by 18 publications

(20 citation statements)

References 56 publications

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“…Neuronal growth cones in the CNS neurons generate protrusion forces of ~100 pN (Fuhs et al, 2013) and stresses of ~30 Pa that exert strains of 5–10% on polyacrylamide substrata with elastic modulus of 300 Pa (Betz et al, 2011); these strains are comparable to the magnitude applied to OPCs in the present study (10–15%). Engagement of cell processes with multiple axons and myelin wrapping are also likely to exert significant strain on both the oligodendrocyte and the axons.…”

Section: Discussionsupporting

confidence: 72%

Mechanical Strain Promotes Oligodendrocyte Differentiation by Global Changes of Gene Expression

Jagielska

Lowe

Makhija

et al. 2017

Front. Cell. Neurosci.

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Differentiation of oligodendrocyte progenitor cells (OPC) to oligodendrocytes and subsequent axon myelination are critical steps in vertebrate central nervous system (CNS) development and regeneration. Growing evidence supports the significance of mechanical factors in oligodendrocyte biology. Here, we explore the effect of mechanical strains within physiological range on OPC proliferation and differentiation, and strain-associated changes in chromatin structure, epigenetics, and gene expression. Sustained tensile strain of 10–15% inhibited OPC proliferation and promoted differentiation into oligodendrocytes. This response to strain required specific interactions of OPCs with extracellular matrix ligands. Applied strain induced changes in nuclear shape, chromatin organization, and resulted in enhanced histone deacetylation, consistent with increased oligodendrocyte differentiation. This response was concurrent with increased mRNA levels of the epigenetic modifier histone deacetylase Hdac11. Inhibition of HDAC proteins eliminated the strain-mediated increase of OPC differentiation, demonstrating a role of HDACs in mechanotransduction of strain to chromatin. RNA sequencing revealed global changes in gene expression associated with strain. Specifically, expression of multiple genes associated with oligodendrocyte differentiation and axon-oligodendrocyte interactions was increased, including cell surface ligands (Ncam, ephrins), cyto- and nucleo-skeleton genes (Fyn, actinins, myosin, nesprin, Sun1), transcription factors (Sox10, Zfp191, Nkx2.2), and myelin genes (Cnp, Plp, Mag). These findings show how mechanical strain can be transmitted to the nucleus to promote oligodendrocyte differentiation, and identify the global landscape of signaling pathways involved in mechanotransduction. These data provide a source of potential new therapeutic avenues to enhance OPC differentiation in vivo.

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Section: Discussionsupporting

confidence: 72%

Mechanical Strain Promotes Oligodendrocyte Differentiation by Global Changes of Gene Expression

Jagielska

Lowe

Makhija

et al. 2017

Front. Cell. Neurosci.

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“…Lastly, AFM was used to quantify forward pushing forces of mouse retinal ganglion cell and NG108-15 growth cones (35). Using lateral force microscopy, peak forward pushing in addition to retrograde forces were found to be on the order of 10 À1 nN (35). Although lateral force microscopy appears to be an ideal solution for measuring traction force in growth cones, significant technical difficulties exist particularly related to calibrating the torsional response of the AFM cantilever (45).…”

Section: Quantification Of Traction Force Generation During Adhesion-mentioning

confidence: 99%

“…Whereas the optical tweezers approach circumvents the issue of substrate uniformity, the level of force that can be applied with optical and magnetic tweezers to the cell without causing damage is typically below the threshold required to induce adhesion-mediated growth cone advance. Lastly, AFM was used to quantify forward pushing forces of mouse retinal ganglion cell and NG108-15 growth cones (35). Using lateral force microscopy, peak forward pushing in addition to retrograde forces were found to be on the order of 10 À1 nN (35).…”

Section: Quantification Of Traction Force Generation During Adhesion-mentioning

confidence: 99%

“…Different experimental methodologies have been utilized to quantify forces in axons and growth cones including the use of 1) force-calibrated microneedles (3,4,9,(27)(28)(29), 2) traction force microscopy on flexible substrates (11,14,(18)(19)(20)23,30) or fabricated nanowire arrays (31), 3) optical tweezers (16,(32)(33)(34), 4) atomic force microscope (AFM) (35), and 5) microfabricated silicon-based micromechanical force sensors (6,36). Force-calibrated microneedles were employed in the earliest quantitative work and provided a global view of mechanical force at the whole neuron and neurite level, but the details of force generation and distribution at the growth cone level remained unclear (4,5,8,(27)(28)(29)37,38).…”

Section: Introductionmentioning

confidence: 99%

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Substrate Deformation Predicts Neuronal Growth Cone Advance

Athamneh

Cartagena‐Rivera

Raman

et al. 2015

Biophysical Journal

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Although pulling forces have been observed in axonal growth for several decades, their underlying mechanisms, absolute magnitudes, and exact roles are not well understood. In this study, using two different experimental approaches, we quantified retrograde traction force in Aplysia californica neuronal growth cones as they develop over time in response to a new adhesion substrate. In the first approach, we developed a novel method, to our knowledge, for measuring traction forces using an atomic force microscope (AFM) with a cantilever that was modified with an Aplysia cell adhesion molecule (apCAM)-coated microbead. In the second approach, we used force-calibrated glass microneedles coated with apCAM ligands to guide growth cone advance. The traction force exerted by the growth cone was measured by monitoring the microneedle deflection using an optical microscope. Both approaches showed that Aplysia growth cones can develop traction forces in the 10 0 -10 2 nN range during adhesion-mediated advance. Moreover, our results suggest that the level of traction force is directly correlated to the stiffness of the microneedle, which is consistent with a reinforcement mechanism previously observed in other cell types. Interestingly, the absolute level of traction force did not correlate with growth cone advance toward the adhesion site, but the amount of microneedle deflection did. In cases of adhesion-mediated growth cone advance, the mean needle deflection was 1.05 5 0.07 mm. By contrast, the mean deflection was significantly lower (0.48 5 0.06 mm) when the growth cones did not advance. Our data support a hypothesis that adhesion complexes, which can undergo micron-scale elastic deformation, regulate the coupling between the retrogradely flowing actin cytoskeleton and apCAM substrates, stimulating growth cone advance if sufficiently abundant.

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“…Nonetheless, improved substrate stability can still be useful, particularly at physiologically relevant elevated temperature (37°C) where temperature-induced drift may be exacerbated. In one example, Fuhs et al [94] wanted to measure the growth of neurons on hour time scales at 37°C, but substrate drift hindered such experiments. They solved this problem by integrating optical-based stabilization into a modified commercial AFM.…”

Section: Prospects For Ultrastable Afm In Biophysicsmentioning

confidence: 99%

Ultrastable atomic force microscopy: Improved force and positional stability

Churnside

Perkins

2014

FEBS Letters

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a b s t r a c tAtomic force microscopy (AFM) is an exciting technique for biophysical studies of single molecules, but its usefulness is limited by instrumental drift. We dramatically reduced positional drift by adding two lasers to track and thereby actively stabilize the tip and the surface. These lasers also enabled label-free optical images that were spatially aligned to the tip position. Finally, sub-pN force stability over 100 s was achieved by removing the gold coating from soft cantilevers. These enhancements to AFM instrumentation can immediately benefit research in biophysics and nanoscience.Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.

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Inherently slow and weak forward forces of neuronal growth cones measured by a drift‐stabilized atomic force microscope

Cited by 18 publications

References 56 publications

Mechanical Strain Promotes Oligodendrocyte Differentiation by Global Changes of Gene Expression

Mechanical Strain Promotes Oligodendrocyte Differentiation by Global Changes of Gene Expression

Substrate Deformation Predicts Neuronal Growth Cone Advance

Ultrastable atomic force microscopy: Improved force and positional stability

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