Chapter 1 Roles of F-BAR/PCH Proteins in the Regulation of Membrane Dynamics and Actin Reorganization

Axonal growth cone collapse is accompanied by a reduction in filopodial F-actin. We demonstrate here that semaphorin 3A (Sema3A) induces a coordinated rearrangement of Sema3A receptors and F-actin during growth cone collapse. Differential interference contrast microscopy reveals that some sites of Sema3A-induced F-actin reorganization correlate with discrete vacuoles, structures involved in endocytosis. Endocytosis of FITC-dextran by the growth cone is enhanced during Sema3A treatment, and sites of dextran accumulation colocalize with actin-rich vacuoles and ridges of membrane. Furthermore, the Sema3A receptor proteins, neuropilin-1 and plexin, and the Sema3A signaling molecule, rac1, also reorganize to vacuoles and membrane ridges after Sema3A treatment. These data support a model whereby Sema3A stimulates endocytosis by focal and coordinated rearrangement of receptor and cytoskeletal elements. Dextran accumulation is also increased in retinal ganglion cell (RGC) growth cones, in response to ephrin A5, and in RGC and DRG growth cones, in response to myelin and phorbol-ester. Therefore, enhanced endocytosis may be a general principle of physiologic growth cone collapse. We suggest that growth cone collapse is mediated by both actin filament rearrangements and alterations in membrane dynamics.

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Cloning, purification, crystallization and preliminary X-ray diffraction analysis of mouse PACSIN 3 protein

Acta Crystallographica Section F Structural Biology and Crystallization Communications ◽

10.1107/s1744309111049116 ◽

2012 ◽

Vol 68 (2) ◽

pp. 159-162 ◽

Cited By ~ 1

Author(s):

Xiaoyun Bai ◽

Geng Meng ◽

Xiaofeng Zheng

Keyword(s):

Protein Structures ◽

Membrane Dynamics ◽

X Ray Diffraction ◽

Unit Cell Parameters ◽

Actin Reorganization ◽

X Ray ◽

Cell Parameters ◽

Bar Domain ◽

Cytoplasmic Proteins ◽

Family Protein

PACSIN-family proteins are cytoplasmic proteins that have vesicle-transport, membrane-dynamics, actin-reorganization and microtubule activities. Here, the N-terminal F-BAR domain of mouse PACSIN 3, which contains 341 amino acids, was successfully cloned, purified and crystallized. The crystal of PACSIN 3 (1–341) diffracted to 2.6 Å resolution and belonged to space groupP21, with unit-cell parametersa= 46.9,b= 54.7,c= 193.7 Å, α = 90, β = 96.9, γ = 90°. These data should provide further information on PACSIN-family protein structures.

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Src-mediated Cortactin Phosphorylation Regulates Actin Localization and Injurious Blebbing in Acinar Cells

Molecular Biology of the Cell ◽

10.1091/mbc.e07-11-1130 ◽

2008 ◽

Vol 19 (5) ◽

pp. 2339-2347 ◽

Cited By ~ 30

Author(s):

Vijay P. Singh ◽

Mark A. McNiven

Keyword(s):

Cell Injury ◽

Membrane Dynamics ◽

Actin Binding ◽

Pancreatic Acini ◽

Actin Reorganization ◽

Cell Blebbing ◽

Relevant Role ◽

Bleb Formation ◽

Rapid Activation

Suprastimulation of pancreatic acini is a well-known model for pancreatitis, and it is characterized by actin reorganization and cell blebbing. Currently, however, the mechanisms underlying regulation of these aberrant cytoskeletal and membrane dynamics and how they contribute to cell injury are unclear. We observed that suprastimulation results in a rapid activation of Src and relocalization of the actin-binding protein cortactin from the apical to the basolateral domain at the necks of membrane blebs. Furthermore, Src-mediated cortactin tyrosine phosphorylation was markedly increased after suprastimulation. Pretreatment of acini with Src inhibitors or expression of a cortactin tyrosine phospho-inhibitory mutant reduced actin redistribution and bleb formation induced by suprastimulation in vitro. Importantly, inhibition of Src activity in rat models of suprastimulation-induced pancreatitis substantially reduced disease severity, as indicated by a reduction in serum amylase and pancreatic edema and a striking improvement in tissue histology. These findings indicate a novel, disease-relevant role for Src-mediated cortactin phosphorylation in aberrant reorganization of the actin cytoskeleton, a mechanism that is likely to have implications in other types of cell injury. In addition, they suggest a potential use for Src inhibitors as an approach to reduce cell injury.

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Application of FRAP and digitized fluorescence microscopy to problems in cell membrane dynamics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102675 ◽

1988 ◽

Vol 46 ◽

pp. 118-119

Author(s):

K. Jacobson ◽

A. Ishihara ◽

B. Holifield ◽

F. Zhang

Keyword(s):

Fluorescence Microscopy ◽

Cell Biology ◽

Extended Period ◽

Dynamic Structure ◽

Living Cells ◽

Membrane Dynamics ◽

Molecular Cell Biology ◽

Image Averaging ◽

Single Living Cells ◽

Single Living

Our laboratory is concerned with understanding the dynamic structure of the plasma membrane with particular reference to the movement of membrane constituents during cell locomotion. In addition to the standard tools of molecular cell biology, we employ both fluorescence recovery after photo- bleaching (FRAP) and digitized fluorescence microscopy (DFM) to investigate individual cells. FRAP allows the measurement of translational mobility of membrane and cytoplasmic molecules in small regions of single, living cells. DFM is really a new form of light microscopy in that the distribution of individual classes of ions, molecules, and macromolecules can be followed in single, living cells. By employing fluorescent antibodies to defined antigens or fluorescent analogs of cellular constituents as well as ultrasensitive, electronic image detectors and video image averaging to improve signal to noise, fluorescent images of living cells can be acquired over an extended period without significant fading and loss of cell viability.

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Quick Reference: Chapter 1: The Musculoskeletal System: The Hand and Upper Extremity

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2000.sepoct03 ◽

2000 ◽

Vol 5 (5) ◽

pp. 4-5

Keyword(s):

Dorsal Column ◽

Persistent Pain ◽

Illness Behavior ◽

Abnormal Illness Behavior ◽

Organ Systems ◽

Spinal Cord Dorsal ◽

Objective Basis ◽

Dorsal Column Stimulation ◽

Underlying Pathology

Abstract Spinal cord (dorsal column) stimulation (SCS) and intraspinal opioids (ISO) are treatments for patients in whom abnormal illness behavior is absent but who have an objective basis for severe, persistent pain that has not been adequately relieved by other interventions. Usually, physicians prescribe these treatments in cancer pain or noncancer-related neuropathic pain settings. A survey of academic centers showed that 87% of responding centers use SCS and 84% use ISO. These treatments are performed frequently in nonacademic settings, so evaluators likely will encounter patients who were treated with SCS and ISO. Does SCS or ISO change the impairment associated with the underlying conditions for which these treatments are performed? Although the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) does not specifically address this question, the answer follows directly from the principles on which the AMA Guides impairment rating methodology is based. Specifically, “the impairment percents shown in the chapters that consider the various organ systems make allowance for the pain that may accompany the impairing condition.” Thus, impairment is neither increased due to persistent pain nor is it decreased in the absence of pain. In summary, in the absence of complications, the evaluator should rate the underlying pathology or injury without making an adjustment in the impairment for SCS or ISO.

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Fifth Edition: the New Standard

Guides Newsletter ◽

10.1001/amaguidesnewsletters.2000.novdec01 ◽

2000 ◽

Vol 5 (6) ◽

pp. 1-7

Author(s):

Christopher R. Brigham ◽

James B. Talmage ◽

Leon H. Ensalada

Keyword(s):

Musculoskeletal System ◽

Medical Information ◽

Objective Assessment ◽

Scientific Data ◽

Practical Application ◽

Fourth Edition ◽

Appropriate Use ◽

Medical Evaluation ◽

Single Set

Abstract The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, is available and includes numerous changes that will affect both evaluators who and systems that use the AMA Guides. The Fifth Edition is nearly twice the size of its predecessor (613 pages vs 339 pages) and contains three additional chapters (the musculoskeletal system now is split into three chapters and the cardiovascular system into two). Table 1 shows how chapters in the Fifth Edition were reorganized from the Fourth Edition. In addition, each of the chapters is presented in a consistent format, as shown in Table 2. This article and subsequent issues of The Guides Newsletter will examine these changes, and the present discussion focuses on major revisions, particularly those in the first two chapters. (See Table 3 for a summary of the revisions to the musculoskeletal and pain chapters.) Chapter 1, Philosophy, Purpose, and Appropriate Use of the AMA Guides, emphasizes objective assessment necessitating a medical evaluation. Most impairment percentages in the Fifth Edition are unchanged from the Fourth because the majority of ratings currently are accepted, there is limited scientific data to support changes, and ratings should not be changed arbitrarily. Chapter 2, Practical Application of the AMA Guides, describes how to use the AMA Guides for consistent and reliable acquisition, analysis, communication, and utilization of medical information through a single set of standards.

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