TSPAN5 is a brain enriched protein member of the tetraspanin superfamily, a group of transmembrane proteins some of which have been shown to fundamentally regulate the development of mammalian nervous system. This class of proteins presents the peculiar ability to clusterize forming specialized membrane region called Tetraspanin Enriched Microdomains (TEMs) where they can accumulate other proteins. We found that in developing neurons TSPAN5 was mainly present at the surface membrane while it was concentrated in an intracellular compartment in the postsynapse of mature neurons. We hypothesized that these different localisations could be due to different functions. To deepen the first function of the protein, we knocked down the expression of the protein and found that this led to a dramatic reduction in the number of dendritic spines. We, thus, hypothesized that TSPAN5, through the formation of TEMs, could be responsible of dendritic spines formation. We observed in differential lysis of developing rat hippocampal neurons that two proteins, fundamental for dendritic spines formation, Neuroligin-1 and GluA2 AMPA receptor subunit, were associated with TSPAN5 TEMs. We found that the knockdown of TSPAN5 led to increased mobility of Neuroligin-1 and GluA2 AMPA receptors suggesting the loss of clusterization typical of the first moments of spines formation. To understand the second function of TSPAN5 we identified AP-4 complex as an interactor of the C-terminal intracellular tail of TSPAN5. This complex is known to act on AMPARs trafficking through direct binding of Stargazin, an AMPARs auxiliary subunit. We observed that the knockdown of TSPAN5, carried out after the majority of the synaptogenesis was occurred, caused a strong decrease in surface and total level of GluA2. Different evidences suggested an involvement of TSPAN5 in vesicular transport of GluA2 and we demonstrated that TSPAN5 was necessary for the correct recycling of this receptor. These results highlight multiple roles of TSPAN5 in the regulation of both synapse formation and synaptic functioning in mammalian brain through two distinct mechanisms of action.
|Titolo:||TSPAN5 IS A KEY PLAYER IN DENDRITIC SPINES FORMATION AND AMPA RECEPTORS RECYCLING|
|Relatore:||FORNASARI, DIEGO MARIA MICHELE|
|Data di pubblicazione:||18-feb-2016|
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
Settore BIO/13 - Biologia Applicata
|Citazione:||TSPAN5 IS A KEY PLAYER IN DENDRITIC SPINES FORMATION AND AMPA RECEPTORS RECYCLING ; relatore: D. Fornasari ; correlatore: M. Passafaro. - Milano : Università degli studi di Milano. DIPARTIMENTO DI BIOTECNOLOGIE MEDICHE E MEDICINA TRASLAZIONALE, 2016 Feb 18. ((28. ciclo, Anno Accademico 2015.|
|Appare nelle tipologie:||Tesi di dottorato|