ASC, a Novel 22-kDa Protein, Aggregates during Apoptosis of Human Promyelocytic Leukemia HL-60 Cells

Abstract

The cytoskeletal and/or nuclear matrix molecules responsible for morphological changes associated with apoptosis were identified using monoclonal antibodies (mAbs). We developed mAbs against Triton X-100-insoluble components of HL-60 cells pretreated with all-trans retinoic acid. In particular, one mAb recognized a 22-kDa protein that exhibited intriguing behavior by forming an aggregate and appearing as a speck during apoptosis induced by retinoic acid and other anti-tumor drugs. Cloning and sequencing of its cDNA revealed that this protein comprises 195 amino acids and that its Cterminal half has a caspase recruitment domain (CARD) motif, characteristic of numerous proteins involved in apoptotic signaling. We referred to this protein as ASC (apoptosis-associated speck-like protein containing a CARD). The ASC gene was mapped on chromosome 16p11.2-12. The antisense oligonucleotides of ASC were found to reduce the expression of ASC, and consequently, etoposide-mediated apoptosis of HL-60 cells was suppressed. Our results indicate that ASC is a novel member of the CARD-containing adaptor protein family.

A novel glioblastoma cancer gene therapy using AAV-mediated long-term expression of human TERT C-terminal polypeptide

“…Our results indicate that several genes related to apoptosis are differentially expressed in the rAAV-hTERTC27-treated tumor tissues. In particular, TMS1, also known as apoptosis-associated speck-like protein containing a CARD (ASC), 36 is the apoptotic gene which displayed the highest fold change after rAAV-hTERTC27 treatment ( þ 4.6-fold). TMS1 enhances caspase-mediated apoptosis and its proapoptotic activity is mediated through the activation of caspase 9.…”

The estrogen-responsive B box protein: a novel enhancer of interleukin-1β secretion

“…9 It consists of procaspases-1 and -5, Nacht, LRR and Pyrin domain containing protein (NALP)1 10,11 and apoptosis-associated speck-like protein containing a card (Asc). 12 The assembly of this complex relies only on homotypic interactions of the death domain fold family member caspase recruitment domain (CARD) and the recently identified pyrin domain. 11,13,14 The NALP1 protein contains an amino-terminal pyrin domain and a carboxyterminal CARD (Figure 2a).…”

Dual role of TMS1/ASC in death receptor signaling

“…TMS1 was also independently identified by Masumoto et al (1999) as a protein that forms cytoplasmic 'specks' during retinoic acid induced differentiation or drug-induced apoptosis in HL60 cells, and called ASC. Subsequent studies by our lab and others have implicated the epigenetic silencing of TMS1 in a number of other tumor types, including melanomas, glioblastomas, non-small cell lung cancers, gastric and colorectal cancers (Moriai et al, 2002;Guan et al, 2003;Virmani et al, 2003;Yokoyama et al, 2003;Stone et al, 2004).…”

“…There is evidence supporting a role for TMS1 in both of these processes. Evidence from overexpression studies indicates that TMS1 can drive apoptosis in a Bax and caspase-9-dependent manner Ohtsuka et al, 2004), and antisense-mediated knockdown of TMS1 protects cells from apoptosis induced by cytotoxic agents (Masumoto et al, 1999). TMS1 has also been implicated in the extrinsic apoptotic pathway, as forced oligomerization or co-expression with CARD12/Ipaf stimulates caspase-8-dependent apoptosis .…”