Giant axonal neuropathy alters the structure of keratin intermediate filaments in human hair.

Giant axonal neuropathy (GAN) follows an autosomal recessive genetic inheritance and impedes the peripheral and central nervous system due to axonal swellings that are packed with neurofilaments. The patients display a number of phenotypes, including hypotonia, muscle weakness, decreased reflexes, ataxia, seizures, intellectual disability, pale skin and often curled hair. We used X-ray diffraction and tensile testing to determine potential changes to the structure of keratin intermediate filaments (IFs) in the hair of patients with GAN.

Abnormal intermediate filament organization alters mitochondrial motility in giant axonal neuropathy fibroblasts.

Giant axonal neuropathy (GAN) is a rare disease caused by mutations in the GAN gene, which encodes gigaxonin, an E3 ligase adapter that targets intermediate filament (IF) proteins for degradation in numerous cell types, including neurons and fibroblasts. The cellular hallmark of GAN pathology is the formation of large aggregates and bundles of IFs. In this study, we show that both the distribution and motility of mitochondria are altered in GAN fibroblasts and this is attributable to their association with vimentin IF aggregates and bundles.

Intermediate Filaments Play a Pivotal Role in Regulating Cell Architecture and Function.

Intermediate filaments (IFs) are composed of one or more members of a large family of cytoskeletal proteins, whose expression is cell- and tissue type-specific. Their importance in regulating the physiological properties of cells is becoming widely recognized in functions ranging from cell motility to signal transduction. IF proteins assemble into nanoscale biopolymers with unique strain-hardening properties that are related to their roles in regulating the mechanical integrity of cells.

Inroads into the structure and function of intermediate filament networks.

Although intermediate filaments are one of three major cytoskeletal systems of vertebrate cells, they remain the least understood with respect to their structure and function. This is due in part to the fact that they are encoded by a large gene family which is developmentally regulated in a cell and tissue type specific fashion. This article is in honor of Ueli Aebi.

Vimentin intermediate filaments modulate the motility of mitochondria.

Interactions with vimentin intermediate filaments (VimIFs) affect the motility, distribution, and anchorage of mitochondria. In cells lacking VimIFs or in which VimIF organization is disrupted, the motility of mitochondria is increased relative to control cells that express normal VimIF networks. Expression of wild-type VimIF in vimentin-null cells causes mitochondrial motility to return to normal (slower) rates.

Insights into the mechanical properties of epithelial cells: the effects of shear stress on the assembly and remodeling of keratin intermediate filaments.

The effects of shear stress on the keratin intermediate filament (KIF) cytoskeleton of cultured human alveolar epithelial (A549) cells have been investigated. Under normal culture conditions, immunofluorescence revealed a delicate network of fine tonofibrils containing KIFs, together with many nonfilamentous, keratin-containing "particles," mostly containing either keratin 8 (K8) or 18 (K18), but not both. Triton X-100 extracted approximately 10% of the cellular keratin, and this was accompanied by a loss of the particles but not the KIFs.

Intermediate filaments: versatile building blocks of cell structure.

Cytoskeletal intermediate filaments (IF) are organized into a dynamic nanofibrillar complex that extends throughout mammalian cells. This organization is ideally suited to their roles as response elements in the subcellular transduction of mechanical perturbations initiated at cell surfaces. IF also provide a scaffold for other types of signal transduction that together with molecular motors ferries signaling molecules from the cell periphery to the nucleus.

Preparation and Microinjection of x-Rhodamine-Labeled Vimentin.

INTRODUCTIONIntermediate filaments (IF) are major cytoskeletal systems of vertebrate and many nonvertebrate cells whose expression is cell-type specific and developmentally regulated. This protocol describes the x-rhodamine labeling of one type of IF, vimentin, and a method for microinjection of the labeled vimentin into cultured cells. IF dynamics can then be examined with fluorescence microscopy.

Purification of bovine lens and bacterially expressed human vimentin.

INTRODUCTIONIntermediate filaments (IF) are major cytoskeletal systems of vertebrate and many nonvertebrate cells whose expression is cell-type specific and developmentally regulated. This protocol describes a method for purifying one type of IF, vimentin, from bovine lens tissue. Purification of human vimentin expressed in Escherichia coli is also described.

The nucleoskeleton: lamins and actin are major players in essential nuclear functions.

The nucleoskeleton is composed of many interacting structural proteins that provide the framework for DNA replication, transcription and a variety of other nuclear functions. For example, the type-V intermediate filament proteins, the lamins, and their associated proteins (e.g.