Lack of a-disintegrin-and-metalloproteinase ADAM10 leads to intracellular accumulation and loss of shedding of the cellular prion protein in vivo

Abstract

BackgroundThe cellular prion protein (PrPC) fulfils several yet not completely understood physiological functions. Apart from these functions, it has the ability to misfold into a pathogenic scrapie form (PrPSc) leading to fatal transmissible spongiform encephalopathies. Proteolytic processing of PrPC generates N- and C-terminal fragments which play crucial roles both in the pathophysiology of prion diseases and in transducing physiological functions of PrPC. A-disintegrin-and-metalloproteinase 10 (ADAM10) has been proposed by cell culture experiments to be responsible for both shedding of PrPC and its α-cleavage. Here, we analyzed the role of ADAM10 in the proteolytic processing of PrPC in vivo.ResultsUsing neuron-specific Adam10 knockout mice, we show that ADAM10 is the sheddase of PrPC and that its absence in vivo leads to increased amounts and accumulation of PrPC in the early secretory pathway by affecting its posttranslational processing. Elevated PrPC levels do not induce apoptotic signalling via p53. Furthermore, we show that ADAM10 is not responsible for the α-cleavage of PrPC.ConclusionOur study elucidates the proteolytic processing of PrPC and proves a role of ADAM10 in shedding of PrPC in vivo. We suggest that ADAM10 is a mediator of PrPC homeostasis at the plasma membrane and, thus, might be a regulator of the multiple functions discussed for PrPC. Furthermore, identification of ADAM10 as the sheddase of PrPC opens the avenue to devising novel approaches for therapeutic interventions against prion diseases.

PrPCHomodimerization Stimulates the Production of PrPCCleaved Fragments PrPN1 and PrPC1

“…Taylor et al clearly demonstrated that the ␣-cleavage of PrP C was not affected by the absence of both ADAM10 and ADAM17 in cellulo ). In addition, ADAM10-deficient mice have no alteration in levels of PrPC1 (Altmeppen et al, 2011). Here, we showed that inhibition of ADAM10 and ADAM17 by the general metalloprotease inhibitor marimastat and knockdown of both ADAM10 and ADAM17 expression did not affect the release of PrPN1 in the culture medium under dimerization conditions.…”

“…More evidence is now challenging the implication of ADAM10 and ADAM17 as the principal ␣-PrPases (Vincent et al, 2001;Laffont-Proust et al, 2005;Taylor et al, 2009;Altmeppen et al, 2011). Taylor et al clearly demonstrated that the ␣-cleavage of PrP C was not affected by the absence of both ADAM10 and ADAM17 in cellulo ).…”

“…Dimerization-mediated ␣-cleavage of PrP C is independent of ADAM8, 10, and 17 The two metalloproteases ADAM10 and ADAM17 were initially proposed to be the proteases that are responsible for constitutive and PKC-regulated ␣-cleavage of PrP C , respectively, yet their involvement is currently a matter of debate (Vincent et al, 2001;Taylor et al, 2009;Oliveira-Martins et al, 2010;Altmeppen et al, 2011). Recent results suggest that ADAM8 regulates PrP C ␣-cleavage in skeletal muscle (Liang et al, 2012).…”

“…There is evidence that the metalloproteases ADAM10 (a disintegrin and metalloproteinase) and ADAM17 are responsible for the constitutive and PKC-regulated ␣-cleavage in cultured cells, respectively, and high levels of PrPC1 in the human brain correlates with the presence of active ADAM10 (Vincent et al, 2001;Laffont-Proust et al, 2005;Liang et al, 2012). However, ␣-cleavage occurs normally in neuron-specific ADAM10 knock-out mice and the search for other proteases that have the ability to perform the ␣-cleavage continues (Altmeppen et al, 2011). The hydrophobic domain (HD) (amino acids 111-129) of PrP C is essential for the ␣-cleavage both in cellulo and in vivo (Bremer et al, 2010;Oliveira-Martins et al, 2010).…”

Prion protein “gamma-cleavage”: characterizing a novel endoproteolytic processing event

“…PrP C may be cleaved at its GPI-anchor, allowing shedding of PrP C species from a cell by both protease and phospholipase mediated mechanisms [26][27][28]. PrP C is also subject to two well-described internal cleavage events known as a-and b-cleavage [29].…”