Geometric constrains for detecting short actin filaments by cryogenic electron tomography

Kudryashev, Mikhail; Lepper, Simone; Baumeister, Wolfgang; Cyrklaff, Marek; Frischknecht, Friedrich

doi:10.1186/1757-5036-3-6

Cited by 37 publications

(37 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Preservation of large structures such as stress fibers under these conditions provides imperfect evidence of actin integrity, since many of the organelle-interacting actin filaments are likely to be short and labile. Second, short actin filaments might be difficult to detect by cryo-EM tomography even if well preserved, due to their orientation relative to the electron beam or the to fact that they might be just plain short[129, 130]. As evidence for the difficulties in imaging short actin filaments by EM, there has been a 15-year debate on the morphology of actin filaments at the leading edge of motile cells [131], and in this case we actually knew filaments were there!…”

Section: Golgimentioning

confidence: 99%

Connecting the Cytoskeleton to the Endoplasmic Reticulum and Golgi

2014

View full text Add to dashboard Cite

A tendency in cell biology is to divide and conquer. For example, decades of painstaking work have led to an understanding of endoplasmic reticulum (ER) and Golgi structure, dynamics, and transport. In parallel, cytoskeletal researchers have revealed a fantastic diversity of structure and cellular function in both actin and microtubules. Increasingly, these areas overlap, necessitating an understanding of both organelle and cytoskeletal biology. This review addressesconnections between the actin/microtubule cytoskeletons and organelles in animal cells, focusing on threetopics: ER structure/function, ER-to-Golgi transport; and Golgi structure/function. Making these connections has been challenging, due to 1) the small sizes and dynamic characteristics of some components, 2) the fact that organelle-specific cytoskeleton can easily be obscured by more abundant cytoskeletal structures, and 3) the difficulties in imaging membranes and cytoskeleton simultaneously, especially at the ultra-structural level. One major concept is that the cytoskeleton is frequently used to generate force for membrane movement, with two potential consequences: translocation of the organelle, or deformation of the organelle membrane. While initially discussing issues common to metazoan cells in general, we subsequently highlight specific features of neurons, since these highly polarized cells present unique challenges for organellar distribution and dynamics.

show abstract

Section: Golgimentioning

confidence: 99%

Connecting the Cytoskeleton to the Endoplasmic Reticulum and Golgi

2014

View full text Add to dashboard Cite

show abstract

“…Microfilament structures, presumed to be actin, have also been seen lying under the plasma membrane of motile tachyzoites following JAS treatment [28]. Complementing these studies, electron and cryo-electron microscopy studies have observed structures with dimensions consistent with filamentous actin in this pellicular compartment under native conditions [19], [20]. Beyond these encouraging observations, however, no study has unambiguously demonstrated microfilament spatial organisation during zoite movement under native conditions.…”

Section: Introductionmentioning

confidence: 95%

Spatial Localisation of Actin Filaments across Developmental Stages of the Malaria Parasite

et al. 2012

View full text Add to dashboard Cite

Actin dynamics have been implicated in a variety of developmental processes during the malaria parasite lifecycle. Parasite motility, in particular, is thought to critically depend on an actomyosin motor located in the outer pellicle of the parasite cell. Efforts to understand the diverse roles actin plays have, however, been hampered by an inability to detect microfilaments under native conditions. To visualise the spatial dynamics of actin we generated a parasite-specific actin antibody that shows preferential recognition of filamentous actin and applied this tool to different lifecycle stages (merozoites, sporozoites and ookinetes) of the human and mouse malaria parasite species Plasmodium falciparum and P. berghei along with tachyzoites from the related apicomplexan parasite Toxoplasma gondii. Actin filament distribution was found associated with three core compartments: the nuclear periphery, pellicular membranes of motile or invasive parasite forms and in a ring-like distribution at the tight junction during merozoite invasion of erythrocytes in both human and mouse malaria parasites. Localisation at the nuclear periphery is consistent with an emerging role of actin in facilitating parasite gene regulation. During invasion, we show that the actin ring at the parasite-host cell tight junction is dependent on dynamic filament turnover. Super-resolution imaging places this ring posterior to, and not concentric with, the junction marker rhoptry neck protein 4. This implies motor force relies on the engagement of dynamic microfilaments at zones of traction, though not necessarily directly through receptor-ligand interactions at sites of adhesion during invasion. Combined, these observations extend current understanding of the diverse roles actin plays in malaria parasite development and apicomplexan cell motility, in particular refining understanding on the linkage of the internal parasite gliding motor with the extra-cellular milieu.

show abstract

“…For this reason, their presence might be easily overlooked amongst other more abundant actin-based structures. Frustrations over identifying the presence or morphology of actin filaments have been common historically, examples being leading edge actin filament morphology, nuclear actin filaments and actin in Plasmodium (Belin and Mullins, 2013;Kudryashev et al, 2010;Ydenberg et al, 2011). Many imaging techniques, especially electron microscopy, present challenges for imaging short low-abundance filament populations (Kudryashev et al, 2010;Lehrer, 1981;Maupin and Pollard, 1983).…”

Section: Final Thoughtsmentioning

confidence: 99%

Novel roles for actin in mitochondrial fission

Hatch

Gurel

Higgs

2014

Journal of Cell Science

128

130

View full text Add to dashboard Cite

Mitochondrial dynamics, including fusion, fission and translocation, are crucial to cellular homeostasis, with roles in cellular polarity, stress response and apoptosis. Mitochondrial fission has received particular attention, owing to links with several neurodegenerative diseases. A central player in fission is the cytoplasmic dynaminrelated GTPase Drp1, which oligomerizes at the fission site and hydrolyzes GTP to drive membrane ingression. Drp1 recruitment to the outer mitochondrial membrane (OMM) is a key regulatory event, which appears to require a pre-constriction step in which the endoplasmic reticulum (ER) and mitochondrion interact extensively, a process termed ERMD (ER-associated mitochondrial division). It is unclear how ER-mitochondrial contact generates the force required for pre-constriction or why pre-constriction leads to Drp1 recruitment. Recent results, however, show that ERMD might be an actin-based process in mammals that requires the ER-associated formin INF2 upstream of Drp1, and that myosin II and other actinbinding proteins might be involved. In this Commentary, we present a mechanistic model for mitochondrial fission in which actin and myosin contribute in two ways; firstly, by supplying the force for preconstriction and secondly, by serving as a coincidence detector for Drp1 binding. In addition, we discuss the possibility that multiple fission mechanisms exist in mammals.

show abstract

Geometric constrains for detecting short actin filaments by cryogenic electron tomography

Cited by 37 publications

References 66 publications

Connecting the Cytoskeleton to the Endoplasmic Reticulum and Golgi

Connecting the Cytoskeleton to the Endoplasmic Reticulum and Golgi

Spatial Localisation of Actin Filaments across Developmental Stages of the Malaria Parasite

Novel roles for actin in mitochondrial fission

Contact Info

Product

Resources

About