Exposure at the Cell Surface Is Required for Gas3/PMP22 To Regulate Both Cell Death and Cell Spreading: Implication for the Charcot–Marie–Tooth Type 1A and Dejerine–Sottas Diseases

Brancolini, Claudio; Edomi, Paolo; Marzinotto, Stefania; Schneider, Claudio

doi:10.1091/mbc.11.9.2901

Cited by 49 publications

(25 citation statements)

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“…Cell-matrix interactions can influence cell shape, which is profoundly modulated by PMP22 (Brancolini et al, 1999;Roux et al, 2005). In fibroblasts and SCs, the overexpression of PMP22 induces membrane blebbing and regulates cell spreading (Brancolini et al, 2000), whereas in MDCK (Madin-Darby canine kidney) epithelial monolayers it leads to a flattened morphology (Roux et al, 2005). Changes in cells shape, as well as actin remodeling, are prerequisites for myelinogenesis in the PNS Fernandez-Valle et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…The glycosylation consensus sequence at asparagine 41, which bears this epitope, is conserved among members of the PMP22 gene family and across species as distant as zebrafish (Taylor et al, 1995;Wulf et al, 1999). This carbohydrate modification of PMP22 is involved in the stabilization of PMP22 homodimers (Tobler et al, 1999) and in the cell spreading effects (Brancolini et al, 1999(Brancolini et al, , 2000, but not in the trafficking of the protein to the SC membrane (Ryan et al, 2000), or in the interaction with protein zero (Hasse et al, 2004). The L2/HNK-1 epitope can also modulate the heterophilic interaction of some nervous system molecules, including ␣1␤1 integrin and laminin (Pesheva et al, 1987;Lallier and BronnerFraser, 1992).…”

Section: Discussionmentioning

confidence: 99%

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Peripheral Myelin Protein 22 Is in Complex with α6β4 Integrin, and Its Absence Alters the Schwann Cell Basal Lamina

Amici¹,

Dunn²,

Murphy³

et al. 2006

J. Neurosci.

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Peripheral myelin protein 22 (PMP22) is a tetraspan membrane glycoprotein, the misexpression of which is associated with hereditary demyelinating neuropathies. Myelinating Schwann cells (SCs) produce the highest levels of PMP22, yet the function of the protein in peripheral nerve biology is unresolved. To investigate the potential roles of PMP22, we engineered a novel knock-out (Ϫ/Ϫ) mouse line by replacing the first two coding exons of pmp22 with the lacZ reporter. PMP22-deficient mice show strong ␤-galactosidase reactivity in peripheral nerves, cartilage, intestines, and lungs, whereas phenotypically they display the characteristics of tomaculous neuropathy. In the absence of PMP22, myelination of peripheral nerves is delayed, and numerous axon-SC profiles show loose basal lamina, suggesting altered interactions of the glial cells with the extracellular matrix. The levels of ␤4 integrin, a molecule involved in the linkage between SCs and the basal lamina, are severely reduced in nerves of PMP22-deficient mice. During early stages of myelination, PMP22 and ␤4 integrin are coexpressed at the cell surface and can be coimmunoprecipitated together with laminin and ␣6 integrin. In agreement, in clone A colonic carcinoma cells, epitope-tagged PMP22 forms a complex with ␤4 integrin. Together, these data indicate that PMP22 is a binding partner in the integrin/laminin complex and is involved in mediating the interaction of SCs with the extracellular environment.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Peripheral Myelin Protein 22 Is in Complex with α6β4 Integrin, and Its Absence Alters the Schwann Cell Basal Lamina

Amici¹,

Dunn²,

Murphy³

et al. 2006

J. Neurosci.

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“…A recent study by Hasse et al (2002) proposes that another GAS3 family member, PMP22, resides within detergentresistant membranes fractions in neuronal cells (Hasse et al, 2002). Compared with most tetraspan proteins, EMP2 and PMP22 are particularly similar with respect to amino acid identity (ϳ40%) (Taylor and Suter, 1996), functional phenotype (e.g., susceptibility to apoptosis) (Brancolini et al, 2000; Wang Sancho et al, 2001), and intracellular localization Wang et al, 2001). Thus, we speculate that EMP2 and PMP22 (and potentially other members of this tetraspan subfamily) have overlapping and/or similar functions.…”

Section: Discussionmentioning

confidence: 99%

The Tetraspan Protein EMP2 Modulates the Surface Expression of Caveolins and Glycosylphosphatidyl Inositol-linked Proteins

Wadehra

Goodglick

Braun

2004

MBoC

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Caveolae are a subset of lipid rafts enriched in glycosphingolipids and cholesterol-rich domains, but selectively lacking glycosylphosphatidyl inositol-anchored proteins (GPI-APs). Caveolin proteins are the organizing component of caveolae, but the corresponding proteins for other classes of lipid rafts are poorly defined. Epithelial membrane protein-2 (EMP2), a member of the four-transmembrane superfamily, facilitates plasma membrane delivery of certain integrins. In this study, we found by laser confocal microscopy that EMP2 was associated with GPI-APs (detected by the GPI-AP binding bacterial toxin proaerolysin). Biochemical membrane fractionation and methyl-␤-cyclodextrin treatment demonstrated that this association occurred within lipid rafts. EMP2 did not associate with caveolin-bearing membrane structures, and recombinant overexpression of EMP2 in NIH3T3 cells decreased caveolin-1 and caveolin-2 protein levels while increasing the surface expression of GPI-APs. Conversely, a ribozyme construct that specifically cleaves the EMP2 transcript reduced surface GPI-APs and increased caveolin protein expression. These findings suggest that EMP2 facilitates the formation and surface trafficking of lipid rafts bearing GPI-APs, and reduces caveolin expression, resulting in impaired formation of caveolae. INTRODUCTIONAn emerging structural concept for plasma membranes in mammalian cells is the liquid-ordered microdomain. These domains are distinct from the "fluid mosaic" model in that the "liquid-ordered" membranes are more ordered and less fluid than the bulk plasma membrane (Brown and London, 1998b;Brown and London, 2000;Galbiati et al., 2001a). Each domain can be defined by its protein and lipid compositions, and it is becoming increasingly clear that these distinct compartments mediate a number of cellular responses from adhesion and signaling to cellular activation (Brown and London, 1998a;Galbiati et al., 2001a).Lipid rafts, defined as the detergent-resistant fraction of the plasma membrane, are 50-to 350-nm domains rich in cholesterol, glycosphingolipids, sphingolipids, saturated phospholipids, and glycosylphosphatidyl inositol-anchored proteins (GPI-APs) (Gruenberg and Maxfield, 1995;Mukherjee et al., 1997;Melkonian et al., 1999;Abrami et al., 2001;Stuermer et al., 2001). These dynamic structures also include protein components, reflecting a large (Ͼ100) but distinctive set of protein species (Claas et al., 2001). Ubiquitously expressed, lipid rafts have been associated with the sorting of proteins bound for the cell surface and the organizing of signaling molecules for efficient transduction (Robinson, 1997;Schmidt et al., 2001).One important subset of lipid rafts are caveolae (Schnitzer et al., 1995). Caveolae are 50-to 100-nm membrane invaginations comprised of cholesterol, glycosphingolipids, and at least one member of the caveolin family of proteins. To date, three members of the caveolin family have been identified. Caveolin-1 is the principal component of caveolae in the majority of cell types and is r...

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“…PMP-22 is highly expressed in Schwann cells and required for myelin formation (Bronstein 2000). Several forms of human peripheral polyneuropathies arise from PMP22 mutations, deletions, or gene duplications (Brancolini et al 2000) (Table 2). Surprisingly, although PMP22 is only 19% identical to human claudin-1, it has been found in tight junctions in liver, intestine (Notterpek et al 2001), and the blood-brain barrier (Roux et al 2004), and when expressed in MDCK cells, it increases TER (Roux et al 2005).…”

Section: The Claudin Familymentioning

confidence: 99%

Physiology and Function of the Tight Junction

Anderson

Itallie²

2009

Cold Spring Harbor Perspectives in Biology

885

783

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Understanding of tight junctions has evolved from their historical perception as inert solute barriers to recognition of their physiological and biochemical complexity. Many proteins are specifically localized to tight junctions, including cytoplasmic actin-binding proteins and adhesive transmembrane proteins. Among the latter are claudins, which are critical barrier proteins. Current information suggests that the paracellular barrier is most usefully modeled as having two physiologic components: a system of charge-selective small pores, 4 Å in radius, and a second pathway created by larger discontinuities in the barrier, lacking charge or size discrimination. The first pathway is influenced by claudin expression patterns and the second is likely controlled by different proteins and signals. Recent information on claudin function and disease-causing mutations have led to a more complete understanding of their role in barrier formation, but progress is impeded by lack of high resolution structural information.T ight junctions form the continuous intercellular barrier between epithelial cells, which is required to separate tissue spaces and regulate selective movement of solutes across the epithelium. Although there are now .40 proteins (Schneeberger and Lynch 2004;Yamazaki et al. 2008) identified within the tight junction, the claudin family of transmembrane proteins, named from the Latin claudere to close, has emerged as the most critical for defining tight junction selectivity. Here, we review evidence that claudins regulate permselectivity (including size, electrical resistance, and ionic charge preference) derived from studies in cultured epithelial cell models and the phenotypes of knockout mice and human mutants. We highlight the physiologic relevance of selectivity but only briefly discuss how it might be physiologically regulated and altered in pathologic situations. We develop the perspective that the barrier is usefully described as having two pathways: first a system of charge-selective claudin-based pores that are 4 Å in radius and a second pathway created by larger discontinuities in the barrier and that lacks charge and size discrimination. The two pathways may be controlled by different proteins and signals.

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Exposure at the Cell Surface Is Required for Gas3/PMP22 To Regulate Both Cell Death and Cell Spreading: Implication for the Charcot–Marie–Tooth Type 1A and Dejerine–Sottas Diseases

Cited by 49 publications

References 55 publications

Peripheral Myelin Protein 22 Is in Complex with α6β4 Integrin, and Its Absence Alters the Schwann Cell Basal Lamina

Peripheral Myelin Protein 22 Is in Complex with α6β4 Integrin, and Its Absence Alters the Schwann Cell Basal Lamina

The Tetraspan Protein EMP2 Modulates the Surface Expression of Caveolins and Glycosylphosphatidyl Inositol-linked Proteins

Physiology and Function of the Tight Junction

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