Lysosomal Serine Protease CLN2 Regulates Tumor Necrosis Factor-α-mediated Apoptosis in a Bid-dependent Manner

Abstract

Apoptosis is a highly organized, energy-dependent program by which multicellular organisms eliminate damaged, superfluous, and potentially harmful cells. Although caspases are the most prominent group of proteases involved in the apoptotic process, the role of lysosomes has only recently been unmasked. This study investigated the role of the lysosomal serine protease CLN2 in apoptosis. We report that cells isolated from patients affected with late infantile neuronal ceroid lipofuscinosis (LINCL) having a deficient activity of CLN2 are resistant to the toxic effect of death ligands such as tumor necrosis factor (TNF), CD95 ligand, or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) but not to receptor-independent stress agents. CLN2-deficient cells exhibited a defect in TNF-induced Bid cleavage, release of cytochrome c, and caspase-9 and -3 activation. Moreover, extracts from CLN2-overexpressing cells or a CLN2 recombinant protein were able to catalyze the in vitro cleavage of Bid. Noteworthy, correction of the lysosomal enzyme defect of LINCL fibroblasts using a medium enriched in CLN2 protein enabled restoration of TNF-induced Bid and caspase-3 processing and toxicity. Conversely, transfection of CLN2-corrected cells with small interfering RNA targeting Bid abrogated TNF-induced cell death. Altogether, our study demonstrates that genetic deletion of the lysosomal serine protease CLN2 and the subsequent loss of its catalytic function confer resistance to TNF in non-neuronal somatic cells, indicating that CLN2 plays a yet unsuspected role in TNF-induced cell death.

RNF152, a novel lysosome localized E3 ligase with pro-apoptotic activities

“…Recently, accumulating evidences suggest the existence of a lysosomal pathway for apoptosis (Guicciardi et al, 2004). The lysosomal membrane permeabilization (LMP) that leads to the release of lysosomal proteases into the cytosol may initiate the apoptotic program in several models of apoptosis (Chwieralski et al, 2006;Stoka et al, 2007;Boya and Kroemer, 2008), such as TNFα-induced apoptosis (Autefage et al, 2009). Our studies revealed the first E3 ligase that localizes to lysosmes and exhibits proapoptotic activities at the same time.…”

Lysosomal chymotrypsin B potentiates apoptosis via cleavage of Bid

“…However, the physiological functions of cathepsins have been controversial because the optimum pH for their enzymatic activities is acidic and they are usually autolyzed or denatured under the physiological conditions of the cytosol (pH 7.4) [8]. Thus, there might be other proteases, such as proteases with optimum pH at 7.4, that mediate apoptosis [9][10][11].…”

Effect of acute hypoxic shock on the rat brain morphology and tripeptidyl peptidase I activity

“…As a lysosomal enzyme TPPI has been shown to participate in cell death (apoptosis or necrosis) following lysosomal membrane rupture and release of acid hydrolases in the cell cytosol. Fibroblasts deficient in TPPI activity cannot start tumor necrosis factor-induced apoptosis (Autefage et al, 2009). Moreover, TPPI can activate Bid throughout a proteolytic cleavage thus participating in the receptor-dependent apoptosis.…”

“…Its genetically determined deficiency causes the late infantile neuronal ceroid lipofuscinosis (LINCL)-a recessive neurodegenerative disease leading to an early death of affected individuals (Mole et al, 2005). TPPI is shown to participate in receptor-mediated apoptosis throughout proteolytic cleavage of Bid in isolated fibroblasts (Autefage et al, 2009). On the other hand, it is demonstrated (Van Beersel et al, 2013) that TPPIdeficient fibroblasts exhibit an enhanced BNIP3 (Bcl2/adenovirus E1 B 19 kDa interacting protein 3) activation.…”