RESUMO
Fibrillin-1 is a ubiquitous extracellular matrix molecule that sequesters latent growth factor complexes. A role for fibrillin-1 in specifying tissue microenvironments has not been elucidated, even though the concept that fibrillin-1 provides extracellular control of growth factor signaling is currently appreciated. Mutations in FBN1 are mainly responsible for the Marfan syndrome (MFS), recognized by its pleiotropic clinical features including tall stature and arachnodactyly, aortic dilatation and dissection, and ectopia lentis. Each of the many different mutations in FBN1 known to cause MFS must lead to similar clinical features through common mechanisms, proceeding principally through the activation of TGFß signaling. Here we show that a novel FBN1 mutation in a family with Weill-Marchesani syndrome (WMS) causes thick skin, short stature, and brachydactyly when replicated in mice. WMS mice confirm that this mutation does not cause MFS. The mutation deletes three domains in fibrillin-1, abolishing a binding site utilized by ADAMTSLIKE-2, -3, -6, and papilin. Our results place these ADAMTSLIKE proteins in a molecular pathway involving fibrillin-1 and ADAMTS-10. Investigations of microfibril ultrastructure in WMS humans and mice demonstrate that modulation of the fibrillin microfibril scaffold can influence local tissue microenvironments and link fibrillin-1 function to skin homeostasis and the regulation of dermal collagen production. Hence, pathogenetic mechanisms caused by dysregulated WMS microenvironments diverge from Marfan pathogenetic mechanisms, which lead to broad activation of TGFß signaling in multiple tissues. We conclude that local tissue-specific microenvironments, affected in WMS, are maintained by a fibrillin-1 microfibril scaffold, modulated by ADAMTSLIKE proteins in concert with ADAMTS enzymes.
Assuntos
Matriz Extracelular/genética , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Deleção de Sequência/genética , Síndrome de Weill-Marchesani/genética , Proteínas ADAMTS , Adolescente , Adulto , Animais , Sítios de Ligação , Microambiente Celular , Éxons , Matriz Extracelular/metabolismo , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Feminino , Fibrilina-1 , Fibrilinas , Humanos , Proteínas de Ligação a TGF-beta Latente/genética , Proteínas de Ligação a TGF-beta Latente/metabolismo , Masculino , Síndrome de Marfan/genética , Camundongos , Camundongos Transgênicos , Microfibrilas/ultraestrutura , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Transdução de Sinais , Anormalidades da Pele/genética , Anormalidades da Pele/patologia , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismoRESUMO
Collagen IV comprises the predominant protein network of basement membranes, a specialized extracellular matrix, which underlie epithelia and endothelia. These networks assemble through oligomerization and covalent crosslinking to endow mechanical strength and shape cell behavior through interactions with cell-surface receptors. A recently discovered sulfilimine (S=N) bond between a methionine sulfur and hydroxylysine nitrogen reinforces the collagen IV network. We demonstrate that peroxidasin, an enzyme found in basement membranes, catalyzes formation of the sulfilimine bond. Drosophila peroxidasin mutants have disorganized collagen IV networks and torn visceral muscle basement membranes, pointing to a critical role for the enzyme in tissue biogenesis. Peroxidasin generates hypohalous acids as reaction intermediates, suggesting a paradoxically anabolic role for these usually destructive oxidants. This work highlights sulfilimine bond formation as what is to our knowledge the first known physiologic function for peroxidasin, a role for hypohalous oxidants in tissue biogenesis, and a possible role for peroxidasin in inflammatory diseases.
Assuntos
Ácidos/química , Proteínas da Matriz Extracelular/química , Iminas/química , Peroxidase/química , Animais , Catálise , Colágeno Tipo IV/química , Drosophila/química , PeroxidasinaRESUMO
We show that the Drosophila gene rhea, isolated because its wing blister phenotype is typical of mutants affecting integrin function, encodes talin. Embryos deficient in talin have very similar phenotypes to integrin (betaPS) null embryos, including failure in germ band retraction and muscle detachment. We demonstrate that talin is not required for the presence of integrins on the cell surface or their localization at muscle termini. However, talin is required for formation of focal adhesion-like clusters of integrins on the basal surface of imaginal disc epithelia and junctional plaques between muscle and tendon cells. These results indicate that talin is essential for integrin function and acts by stably linking clusters of ECM-linked integrins to the cytoskeleton.
Assuntos
Drosophila/genética , Integrinas/genética , Talina/genética , Animais , Adesão Celular/genética , Citoesqueleto/genética , Drosophila/embriologia , Embrião não Mamífero/embriologia , Embrião não Mamífero/fisiologia , Matriz Extracelular/genéticaRESUMO
Papilins are homologous, secreted extracellular matrix proteins which share a common order of protein domains. They occur widely, from nematodes to man, and can differ in the number of repeats of a given type of domain. Within one species the number of repeats can vary by differential RNA splicing. A distinctly conserved cassette of domains at the amino-end of papilins is homologous with a cassette of protein domains at the carboxyl-end of the ADAMTS subgroup of secreted, matrix-associated metalloproteases. Papilins primarily occur in basement membranes. Papilins interact with several extracellular matrix components and ADAMTS enzymes. Papilins are essential for embryonic development of Drosophila melanogaster and Caenorhabditis elegans.