Carbohydrate self-recognition mediates marine sponge cellular adhesion
AUTOR(ES)
Haseley, Simon R.
FONTE
The National Academy of Sciences
RESUMO
Sponges (Porifera), the simplest and earliest multicellular organisms, are thought to have evolved from their unicellular ancestors about 1 billion years ago by developing cell-recognition and adhesion mechanisms to discriminate against “non-self.” Consequently, they are used as models for investigating recognition phenomena. Cellular adhesion of marine sponges is an event involving adherence of extracellular proteoglycan-like molecules, otherwise known as aggregation factors (AFs). In a calcium-independent process the AFs adhere to the cell surface, and in a calcium-dependent process they exhibit AF self-association. A mechanism which has been implied but not definitely proven to play a role in the calcium-dependent event is self-recognition of defined carbohydrate epitopes. For the red beard sponge, Microciona prolifera, two carbohydrate epitopes, a sulfated disaccharide and a pyruvylated trisaccharide, have been implicated in cellular adhesion. To investigate this phenomenon a system has been designed, by using surface plasmon resonance detection, to mimic the role of carbohydrates in cellular adhesion of M. prolifera. The results show self-recognition of the sulfated disaccharide to be a major force behind the calcium-dependent event. The interaction is not simply based on electrostatic interactions, as other sulfated carbohydrates analyzed by using this procedure did not self-associate. Furthermore, the interaction is completely eradicated on substitution of Ca2+ ions by either Mg2+ or Mn2+ ions. This physiologically relevant recognition mechanism confirms the existence of true carbohydrate self-recognition, and may have significant implications for the role of carbohydrates in cellular recognition of higher organisms.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=55436Documentos Relacionados
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