RESUMO
Type XVIII collagen is a homotrimeric basement membrane molecule of unknown function, whose COOH-terminal NC1 domain contains endostatin (ES), a potent antiangiogenic agent. The Caenorhabditis elegans collagen XVIII homologue, cle-1, encodes three developmentally regulated protein isoforms expressed predominantly in neurons. The CLE-1 protein is found in low amounts in all basement membranes but accumulates at high levels in the nervous system. Deletion of the cle-1 NC1 domain results in viable fertile animals that display multiple cell migration and axon guidance defects. Particular defects can be rescued by ectopic expression of the NC1 domain, which is shown to be capable of forming trimers. In contrast, expression of monomeric ES does not rescue but dominantly causes cell and axon migration defects that phenocopy the NC1 deletion, suggesting that ES inhibits the promigratory activity of the NC1 domain. These results indicate that the cle-1 NC1/ES domain regulates cell and axon migrations in C. elegans.
Assuntos
Axônios/fisiologia , Caenorhabditis elegans/fisiologia , Movimento Celular , Colágeno/metabolismo , Neurônios/fisiologia , Fragmentos de Peptídeos/metabolismo , Estrutura Terciária de Proteína , Sequência de Aminoácidos , Inibidores da Angiogênese/genética , Inibidores da Angiogênese/metabolismo , Animais , Animais Geneticamente Modificados , Western Blotting , Caenorhabditis elegans/citologia , Caenorhabditis elegans/genética , Colágeno/química , Colágeno/genética , Colágeno Tipo XVIII , Endostatinas , Genes Reporter/genética , Masculino , Microscopia de Fluorescência , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Isoformas de Proteínas , RNA/antagonistas & inibidores , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Alinhamento de SequênciaRESUMO
Collagen XVIII (c18) is a triple helical endothelial/epithelial basement membrane protein whose noncollagenous (NC)1 region trimerizes a COOH-terminal endostatin (ES) domain conserved in vertebrates, Caenorhabditis elegans and Drosophila. Here, the c18 NC1 domain functioned as a motility-inducing factor regulating the extracellular matrix (ECM)-dependent morphogenesis of endothelial and other cell types. This motogenic activity required ES domain oligomerization, was dependent on rac, cdc42, and mitogen-activated protein kinase, and exhibited functional distinction from the archetypal motogenic scatter factors hepatocyte growth factor and macrophage stimulatory protein. The motility-inducing and mitogen-activated protein kinase-stimulating activities of c18 NC1 were blocked by its physiologic cleavage product ES monomer, consistent with a proteolysis-dependent negative feedback mechanism. These data indicate that the collagen XVIII NC1 region encodes a motogen strictly requiring ES domain oligomerization and suggest a previously unsuspected mechanism for ECM regulation of motility and morphogenesis.
Assuntos
Proteínas de Bactérias , Movimento Celular/fisiologia , Colágeno/metabolismo , Endotélio Vascular/citologia , Matriz Extracelular/fisiologia , Fragmentos de Peptídeos/metabolismo , Estrutura Terciária de Proteína , Inibidores da Angiogênese/genética , Inibidores da Angiogênese/metabolismo , Animais , Toxinas Bacterianas/farmacologia , Western Blotting , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Colágeno/química , Colágeno/genética , Colágeno Tipo XVIII , Citotoxinas/farmacologia , Dimerização , Endostatinas , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/crescimento & desenvolvimento , Humanos , Camundongos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Morfogênese , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteína cdc42 de Ligação ao GTP/genética , Proteína cdc42 de Ligação ao GTP/metabolismo , Proteínas rac de Ligação ao GTP/genética , Proteínas rac de Ligação ao GTP/metabolismo , Proteínas rho de Ligação ao GTP/metabolismoRESUMO
Papilin is an extracellular matrix glycoprotein that we have found to be involved in, (1) thin matrix layers during gastrulation, (2) matrix associated with wandering, phagocytic hemocytes, (3) basement membranes and (4) space-filling matrix during Drosophila development. Determination of its cDNA sequence led to the identification of Caenorhabditis and mammalian papilins. A distinctly conserved 'papilin cassette' of domains at the amino-end of papilins is also the carboxyl-end of the ADAMTS subgroup of secreted, matrix-associated metalloproteinases; this cassette contains one thrombospondin type 1 (TSR) domain, a specific cysteine-rich domain and several partial TSR domains. In vitro, papilin non-competitively inhibits procollagen N-proteinase, an ADAMTS metalloproteinase. Inhibiting papilin synthesis in Drosophila or Caenorhabditis causes defective cell arrangements and embryonic death. Ectopic expression of papilin in Drosophila causes lethal abnormalities in muscle, Malpighian tubule and trachea formation. We suggest that papilin influences cell rearrangements and may modulate metalloproteinases during organogenesis.
Assuntos
Proteínas de Drosophila , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Glicoproteínas/metabolismo , Proteínas de Insetos/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Caenorhabditis elegans/genética , Primers do DNA/genética , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento , Glicoproteínas/química , Glicoproteínas/genética , Humanos , Hibridização In Situ , Proteínas de Insetos/química , Proteínas de Insetos/genética , Metaloendopeptidases/genética , Metaloendopeptidases/metabolismo , Dados de Sequência Molecular , Estrutura Terciária de Proteína , RNA Antissenso/genética , RNA Antissenso/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
The recent formulation of guidelines for the management of concussion in sports adopted by the American Academy of Neurology specifically calls for the development of a standardized, systematic sideline evaluation for the immediate assessment of concussion in athletes. The present study involved the preliminary investigation of the feasibility and clinical validity of a standardized version of a brief sideline examination complied in accordance with these guidelines. This examination, intended for use by athletic trainers, was administered by three trainers to 141 nonconcussed high school football players at three separate schools. All players suspected of suffering a concussion (N = 6) during the fall 1995 season were also tested immediately following their injury. The examination was easily administered and scored. The concussed players as a group scored significantly below the nonconcussed controls and below their own baseline (pre-injury) performance, despite their all having been considered by the trainers to have suffered mild, grade 1 concussions. Although preliminary, these data suggest that a standardized sideline examination of this type can be useful in detecting concussion and determining fitness to return to play.
