Avian lens spectrin: subunit composition compared with erythrocyte and brain spectrin.

Nelson, W. James; Granger, Bruce L.; Lazarides, Elias

doi:10.1083/jcb.97.4.1271

Cited by 41 publications

(17 citation statements)

References 40 publications

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“…The results of our N-cadherin/cadherin-11 cross-immunoprecipitation experiments have also directly demonstrated intimate complexes of different type-I and type-II cadherins with the plaque proteins mentioned, and experiments are under way to decide whether these are ipso-or heterocellular cadherin complexes. The immunocytochemical results further suggest that the long-side cortex of the fiber cells, at least in the species examined, contains much less of the adherens junction components but is relatively rich in ABPs characteristic of other microfilament-anchorage complexes, including band 4 proteins (Aster et al, 1984;Allen et al, 1987), spectrin (Nelson et al, 1983;Green and Maisel, 1984;Thomas, 2001) and plectin (Weitzer and Wiche, 1987).…”

Section: Discussionmentioning

confidence: 87%

A novel cell-cell junction system: thecortex adhaerensmosaic of lens fiber cells

Straub

Boda

Kühn

et al. 2003

Journal of Cell Science

109

111

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The anucleate prismoid fiber cells of the eye lens are densely packed to form a tissue in which the plasma membranes and their associated cytoplasmic coat form a single giant cell-cell adhesive complex, the cortex adhaerens. Using biochemical and immunoprecipitation methods in various species (cow, pig, rat), in combination with immunolocalization microscopy, we have identified two different major kinds of cortical complex. In one, the transmembrane glycoproteins N-cadherin and cadherin-11 [which also occur in heterotypic (`mixed') complexes] are associated with α- and β-catenin, plakoglobin (proportions variable among species), p120ctn and vinculin. The other complex contains ezrin, periplakin, periaxin and desmoyokin (and so is called the EPPD complex), usually together with moesin, spectrin(s) and plectin. In sections through lens fiber tissue, the short sides of the lens fiber hexagons appear to be enriched in the cadherin-based complexes, whereas the EPPD complexes also occur on the long sides. Moreover, high resolution double-label fluorescence microscopy has revealed, on the short sides, a finer, almost regular mosaicism of blocks comprising the cadherin-based, catenin-containing complexes, alternating with patches formed by the EPPD complexes. The latter, a new type of junctional plaque ensemble of proteins hitherto known only from certain other cell types, must be added to the list of major lens cortex proteins. We here discuss its possible functional importance for the maintenance of lens structure and functions, notably clear and sharp vision.

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Section: Discussionmentioning

confidence: 87%

A novel cell-cell junction system: thecortex adhaerensmosaic of lens fiber cells

Straub

Boda

Kühn

et al. 2003

Journal of Cell Science

109

111

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“…In contrast, full-length ␣-spectrin was more abundant in the membrane pellet (only 15.6 Ϯ 10.0% in S1), as expected (19,35). Similarly, the majority of ␤-spectrin fragments remained in the 30,000 ϫ g supernatant (58.1 Ϯ 3.82% in S1), whereas full-length ␤-spectrin was more abundant in the membrane pellet (only 16.8 Ϯ 2.56% in S1), as shown previously (19,35). However, although all of the ϳ80-kDa ␤-spectrin fragment remained in the supernatant (99.5 Ϯ 1.53% in S1), a significant proportion (ϳ40%) of the ϳ120-kDa ␤-spectrin fragment was pelleted (58.1 Ϯ 3.82% in S1).…”

Section: Figmentioning

confidence: 83%

Caspase Remodeling of the Spectrin Membrane Skeleton during Lens Development and Aging

Lee

Morrow

Fowler

2001

Journal of Biological Chemistry

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Terminal differentiation of lens fiber cells resembles the apoptotic process in that organelles are lost, DNA is fragmented, and changes in membrane morphology occur. However, unlike classically apoptotic cells, which are disintegrated by membrane blebbing and vesiculation, aging lens fiber cells are compressed into the center of the lens, where they undergo cell-cell fusion and the formation of specialized membrane interdigitations. In classically apoptotic cells, caspase cleavage of the cytoskeletal protein ␣-spectrin to ϳ150-kDa fragments is believed to be important for membrane blebbing. We report that caspase(s) cleave ␣-spectrin to ϳ150-kDa fragments and ␤-spectrin to ϳ120-and ϳ80-kDa fragments during late embryonic chick lens development. These fragments continue to accumulate with age so that in the oldest fiber cells of the adult lens, most, if not all, of the spectrin is cleaved to discrete fragments. Thus, unlike classical apoptosis, where caspase-cleaved spectrin is short lived, lens fiber cells contain spectrin fragments that appear to be stable for the lifetime of the organism. Moreover, fragmentation of spectrin results in reduced membrane association and thus may lead to permanent remodeling of the membrane skeleton. Partial and specific proteolysis of membrane skeleton components by caspases may be important for age-related membrane changes in the lens.The spectrin-actin membrane skeleton underlies the plasma membranes of all cells and is important for cellular shape, membrane stability and deformability, as well as the formation of membrane subdomains (1). The major component of the membrane skeleton, spectrin, is composed of an ␣/␤ heterodimer that self-associates head-to-head to form a 200-nm extended tetramer filament. Spectrin cross-links actin filaments into an isotropic meshwork. This spectrin-actin meshwork is attached to the membrane by direct interactions of ␤-spectrin with membrane proteins and indirect interactions of ␤-spectrin with membrane attachment proteins such as ankyrin (2).Proteolysis of ␣-spectrin (␣II-spectrin, non-erythroid spectrin, or fodrin) to discrete fragments is implicated in changes in cell shape and membrane morphology which occur in many cell types. During platelet activation, which includes a cell shape transformation from discs into irregular spheres, spectrin is cleaved to ϳ150-kDa fragments by the calcium-dependent protease, calpain (3). ␣-Spectrin cleavage by calpain has also been implicated in cellular hypoxia (4), neuronal injury and degeneration (5), and neuronal growth cone formation (6). However, in apoptotic cells, ␣-spectrin proteolysis to ϳ150-kDa fragments is mediated by caspases; in these cells, spectrin proteolysis is thought to be important for the disintegration of the plasma membranes via formation of vesicular "apoptotic bodies" (7-12). Although calpain cleavage of spectrin is known to affect its ability to bind membranes or actin filaments (13, 14), the detailed consequences of caspase cleavage of spectrin have not been studied.The terminal ...

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“…Two-dimensional peptide mapping of chymotryptic iodopeptides derived from chicken erythrocyte a spectrin and from this serologically related polypeptide in chicken cerebellum has demonstrated that these polypeptides are structurally indistinguishable, indicating that they share homologous, if not identical, primary structures [31,58]. However, mammalian erythrocyte a spectrin has a different two-dimensional peptide map to the serologically related polypeptide from mammalian brain [ 121, indicating that mammalian erythrocyte a spectrin has diverged structurally during evolution from its counterpart in brain and avian erythrocytes.…”

Section: Identification Of Components Of the Membrane-skeleton In Adumentioning

confidence: 99%

“…Immunoautoradiography of SDS-solubilized extracts of adult chicken cerebellum with a polyclonal antiserum specific for the a subunit of chicken erythrocyte spectrin has revealed the presence of a polypeptide with a apparent molecular weight (M, 240,000) and isoelectric point similar to that of erythrocyte a spectrin [ 12,19,29,62,64]. Two-dimensional peptide mapping of chymotryptic iodopeptides derived from chicken erythrocyte a spectrin and from this serologically related polypeptide in chicken cerebellum has demonstrated that these polypeptides are structurally indistinguishable, indicating that they share homologous, if not identical, primary structures [31,58]. However, mammalian erythrocyte a spectrin has a different two-dimensional peptide map to the serologically related polypeptide from mammalian brain [ 121, indicating that mammalian erythrocyte a spectrin has diverged structurally during evolution from its counterpart in brain and avian erythrocytes.…”

Section: Identification Of Components Of the Membrane-skeleton In Adumentioning

confidence: 99%

Expression and assembly of the erythroid membrane‐skeletal proteins ankyrin (goblin) and spectrin in the morphogenesis of chicken neurons

Lazarides

1985

J of Cellular Biochemistry

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The membrane-skeleton of adult chicken neurons in the cerebellum and optic system is composed of polypeptides structurally and functionally related to the erythroid proteins spectrin and ankyrin, respectively. Neuronal spectrin comprises two distinct complexes that share a common alpha subunit (Mr 240,000) but which have structurally distinct polymorphic subunits (beta' beta spectrin; Mr 220/225,000; gamma spectrin, Mr 235,000); the brain-specific form (alpha gamma spectrin or fodrin) and an erythrocyte-specific form (alpha beta' beta spectrin). Two structurally related isoforms of ankyrin have also been identified and are termed alpha (Mr 260,000) and beta (Mr 237,000) ankyrin. Immunofluorescence demonstrates that the variants of spectrin and ankyrin, respectively, have different distributions within neurons. On the one hand, alpha gamma spectrin and beta ankyrin are present throughout the neuron, in the perikaryon, dendrites, and axon, whereas alpha beta' spectrin and alpha ankyrin are localized exclusively in the perikaryon and dendrites where they are actively segregated from alpha gamma spectrin and other components of axonal transport. This asymmetric distribution of spectrin and ankyrin isoforms is established in distinct stages during neuronal morphogenesis. Early in cerebellar and retinal development, alpha gamma spectrin is expressed in mitotic cells. Subsequently beta ankyrin and alpha gamma spectrin are coexpressed in postmitotic cells and gradually accumulate on the plasma membrane in a uniform pattern throughout the neuron during the phase of cell growth. At the onset of synaptogenesis and the cessation of cell growth, their levels of synthesis decline sharply while the assembled proteins remained as stable membrane components. Concomitantly, there is a dramatic induction in the accumulation of alpha ankyrin and alpha beta' spectrin, whose assembly is limited to the plasma membrane of the perikarya and dendrites. These results demonstrate that two successive, developmentally regulated programs of ankyrin and spectrin expression and patterning on the plasma membrane are involved in the assembly of the spectrin-based asymmetry in the neuronal membrane-skeleton, and that their asymmetric distribution is actively maintained throughout the life of the neuron.

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Avian lens spectrin: subunit composition compared with erythrocyte and brain spectrin.

Cited by 41 publications

References 40 publications

A novel cell-cell junction system: thecortex adhaerensmosaic of lens fiber cells

A novel cell-cell junction system: thecortex adhaerensmosaic of lens fiber cells

Caspase Remodeling of the Spectrin Membrane Skeleton during Lens Development and Aging

Expression and assembly of the erythroid membrane‐skeletal proteins ankyrin (goblin) and spectrin in the morphogenesis of chicken neurons

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