Non-erythroid α-spectrin breakdown by calpain and interleukin 1 β-converting-enzyme-like protease(s) in apoptotic cells: contributory roles of both protease families in neuronal apoptosis

Abstract

The cytoskeletal protein non-erythroid alpha-spectrin is well documented as an endogenous calpain substrate, especially under pathophysiological conditions. In cell necrosis (e.g. maitotoxin-treated neuroblastoma SH-SY5Y cells), alpha-spectrin breakdown products (SBDPs) of 150 kDa and 145 kDa were produced by cellular calpains. In contrast, in neuronal cells undergoing apoptosis (cerebellar granule neurons subjected to low potassium and SH-SY5Y cells treated with staurosporine), an additional SBDP of 120 kDa was also observed. The formation of the 120 kDa SBDP was insensitive to calpain inhibitors but was completely blocked by an interleukin 1 beta-converting-enzyme (ICE)-like protease inhibitor, Z-Asp-CH2OC(O)-2,6-dichlorobenzene. Autolytic activation of both calpain and the ICE homologue CPP32 was also observed in apoptotic cells. alpha-Spectrin can also be cleaved in vitro by purified calpains to produce the SBDP doublet of 150/145 kDa and by ICE and ICE homologues [ICH-1, ICH-2 and CPP32(beta)] to produce a 150 kDa SBDP. In addition, CPP32 and ICE also produced a 120 kDa SBDP. Furthermore inhibition of either ICE-like protease(s) or calpain protects both granule neurons and SH-SY5Y cells against apoptosis. Our results suggest that both protease families participate in the expression of neuronal apoptosis.

Multiple death pathways in retina-derived 661W cells following growth factor deprivation: crosstalk between caspases and calpains

“…37 Similarly, fodrin (a-II-spectrin) (240 kDa) undergoes calpain-mediated degradation into 150 and 140 kDa fragments, in addition to the caspase-dependent products of 150 and 120 kDa. 38 In serumstarved 661W photoreceptors, an approximately 40-kDa PARP band and a 140-kDa fodrin band, consequence of calpain activity, were detected by WB (Figure 3c and d). As expected, the above-described caspase products were detected too.…”

Alterations of Extracellular Calcium Elicit Selective Modes of Cell Death and Protease Activation in SH‐SY5Y Human Neuroblastoma Cells

“…The degradation of a-spectrin to BDPs of 150, 145, and 120 kDa is an established marker for the activation of both calpain and caspase-3 (Bahr et al, 1995;Bartus et al, 1995;Nath et al, 1996b). Our laboratory has established that the 120-kDa spectrin BDP is produced solely by caspase-3-like activity (Wang et al, 1998).…”

Emerging roles of caspase-3 in apoptosis

“…19 This is supported by the fact that fodrin (a major component of the cortical cytoskeleton of most eukaryotic cells) has binding sites for microtubules, calmodulin and actin. 17 However, since a-fodrin is also cleaved by calpain in a caspase-independent fashion, 18 further studies are needed to assess the specific function of the caspase-mediated cleavage of a-fodrin in the disassembly of the cell.…”