Helical arrangement of filaments in microvillar actin bundles

Ohta, Keisuke; Higashi, Ryuhei; Sawaguchi, Akira; Nakamura, Kei‐ichiro

doi:10.1016/j.jsb.2011.10.012

Cited by 29 publications

(19 citation statements)

References 32 publications

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“…Previous studies on the effects of pressure in HPF freezing have suggested, perhaps surprisingly, that few changes due to pressure are observed in frozen samples (Dubochet, 2007), although it has been suggested that chromatin and some phospholipid membranes may exhibit pressure related changes (Leforestier et al., 1996; Semmler et al., 1998). The previous successful preparation of F-actin bundles by HPF (Ohta et al., 2012) would argue against a pressure related effect on actin structure. This argument is supported by the observation that the “tangle” artefact was also present in samples “slam” frozen at ambient pressure.…”

Section: Discussionmentioning

confidence: 99%

Inner ear tissue preservation by rapid freezing: Improving fixation by high-pressure freezing and hybrid methods

Bullen¹,

Taylor²,

Kachar

et al. 2014

Hearing Research

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In the preservation of tissues in as ‘close to life’ state as possible, rapid freeze fixation has many benefits over conventional chemical fixation. One technique by which rapid freeze-fixation can be achieved, high pressure freezing (HPF), has been shown to enable ice crystal artefact-free freezing and tissue preservation to greater depths (more than 40 μm) than other quick-freezing methods. Despite increasingly becoming routine in electron microscopy, the use of HPF for the fixation of inner ear tissue has been limited. Assessment of the quality of preservation showed routine HPF techniques were suitable for preparation of inner ear tissues in a variety of species. Good preservation throughout the depth of sensory epithelia was achievable. Comparison to chemically fixed tissue indicated that fresh frozen preparations exhibited overall superior structural preservation of cells. However, HPF fixation caused characteristic artefacts in stereocilia that suggested poor quality freezing of the actin bundles. The hybrid technique of pre-fixation and high pressure freezing was shown to produce cellular preservation throughout the tissue, similar to that seen in HPF alone. Pre-fixation HPF produced consistent high quality preservation of stereociliary actin bundles. Optimising the preparation of samples with minimal artefact formation allows analysis of the links between ultrastructure and function in inner ear tissues.

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Section: Discussionmentioning

confidence: 99%

Inner ear tissue preservation by rapid freezing: Improving fixation by high-pressure freezing and hybrid methods

Bullen¹,

Taylor²,

Kachar

et al. 2014

Hearing Research

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“…This has the dual effect of increasing the number of putative force-producing elements (i.e., F-actin plus ends) per unit area of membrane and increasing the structural rigidity of the protrusion ( Mogilner and Rubinstein, 2005 ; Claessens et al, 2006 ; Bathe et al, 2008 ). Recent electron tomography studies indicate that microvillar cores are composed of ∼30–40 bundled filaments that exhibit a slight clockwise-oriented twist when viewing distal tips en face ( Ohta et al, 2012 ). Actin filaments within microvilli are bundled by villin ( Bretscher and Weber, 1979 ; Mooseker et al, 1980 ), espin ( Bartles et al, 1998 ), and fimbrin ( Fig.…”

Section: Building Core Actin Bundlesmentioning

confidence: 99%

Shaping the intestinal brush border

Crawley

Mooseker

Tyska

2014

Journal of Cell Biology

226

240

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Epithelial cells from diverse tissues, including the enterocytes that line the intestinal tract, remodel their apical surface during differentiation to form a brush border: an array of actin-supported membrane protrusions known as microvilli that increases the functional capacity of the tissue. Although our understanding of how epithelial cells assemble, stabilize, and organize apical microvilli is still developing, investigations of the biochemical and physical underpinnings of these processes suggest that cells coordinate cytoskeletal remodeling, membrane-cytoskeleton cross-linking, and extracellular adhesion to shape the apical brush border domain.

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“…Although much of what we know comes from studies of intestinal microvilli, factors relevant in this system probably control actin assembly in other types of microvilli as well. A single microvillus is supported by a parallel bundle of 30–40 actin filaments [112], which terminates in a subapical network of intermediate filaments known as the ‘terminal web’ [113]. Microvillus length can be remarkably uniform within and between cells (0.5–3 μm depending on the tissue); recent studies also suggest this parameter might be regulated by intermicrovillar adhesion [81 •• ,82 • ].…”

mentioning

confidence: 99%

MyTH4-FERM myosins in the assembly and maintenance of actin-based protrusions

Weck

Grega-Larson

Tyska

2017

Current Opinion in Cell Biology

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Unconventional myosins are actin-based molecular motors that serve a multitude of roles within the cell, contributing to cell shape and function. One group of myosin motors, MyTH4-FERM myosins, plays an integral part in building and maintaining finger-like protrusions, which allows cells to interact with their external environment. Suggested to act primarily as transporters, these motor proteins enrich adhesion molecules, actin-regulatory proteins and other factors at the tips of filopodia, microvilli, and stereocilia. Below we review data from biophysical, biochemical, and cell biological studies, which implicate these myosins as central players in the assembly, maintenance and function of actin-based protrusions.

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Helical arrangement of filaments in microvillar actin bundles

Cited by 29 publications

References 32 publications

Inner ear tissue preservation by rapid freezing: Improving fixation by high-pressure freezing and hybrid methods

Inner ear tissue preservation by rapid freezing: Improving fixation by high-pressure freezing and hybrid methods

Shaping the intestinal brush border

MyTH4-FERM myosins in the assembly and maintenance of actin-based protrusions

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