RESUMO
The stomatin-domain defines a family of proteins that are found in all classes of life. The ubiquity of stomatin-family proteins and their high degree of homology suggest that they have a unifying cellular function, which has yet to be defined. The five stomatin family proteins in mammals show varying expression patterns and different sub-cellular distributions. In surveying the relevant literature, three common themes emerge; stomatin family members are oligomeric; they mostly localise to membrane domains; and in many cases, they have been shown to modulate ion channel activity. How oligomerisation and membrane localisation contribute to the modulation of channel function is unclear to date. Future studies into the precise structure and mechanism of stomatin-like proteins need to address these important questions to clarify the detailed cellular function of stomatin-domain containing proteins.
Assuntos
Proteínas Sanguíneas/química , Proteínas de Caenorhabditis elegans/química , Proteínas de Membrana/química , Proteínas do Tecido Nervoso/química , Homologia de Sequência de Aminoácidos , Animais , Proteínas Sanguíneas/genética , Proteínas de Caenorhabditis elegans/genética , Humanos , Líquido Intracelular/química , Líquido Intracelular/parasitologia , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Estrutura Terciária de Proteína/genéticaRESUMO
In mammals, the osmolality of the extracellular fluid (ECF) is highly stable despite radical changes in salt/water intake and excretion. Afferent systems are required to detect hypo- or hyperosmotic shifts in the ECF to trigger homeostatic control of osmolality. In humans, a pressor reflex is triggered by simply drinking water which may be mediated by peripheral osmoreceptors. Here, we identified afferent neurons in the thoracic dorsal root ganglia (DRG) of mice that innervate hepatic blood vessels and detect physiological hypo-osmotic shifts in blood osmolality. Hepatic sensory neurons are equipped with an inward current that faithfully transduces graded changes in osmolality within the physiological range (~15 mOsm). In mice lacking the osmotically activated ion channel, TRPV4, hepatic sensory neurons no longer exhibit osmosensitive inward currents and activation of peripheral osmoreceptors in vivo is abolished. We have thus identified a new population of sensory neurons that transduce ongoing changes in hepatic osmolality.
