Procaspase-2S inhibits procaspase-3 processing and activation, preventing ROCK-1-mediated apoptotic blebbing and body formation in human B lymphoma Namalwa cells

Abstract

Procaspase-2S has been reported to selectively prevent membrane blebbing and apoptotic body formation in human monocytic-like leukemic U937 cells after etoposide (VP-16) treatment (Droin et al., Oncogene 20. 260-269, 2001). Here, we show that procaspase-2S overexpressed in human B lymphoma Namalwa cells inhibits procaspase-3 processing and activation, preventing cleavage and activation of Rho GTPase-associated ROCK-1 kinase. Failure of ROCK-1 activation in Namalwa cells correlates with a sustained delay in the appearance of membrane blebbing and apoptotic body formation after VP-16 treatment. Reciprocal coimmunoprecipitation experiments indicate that procaspase-2S binds to procaspase-3, but not procaspase-2L and -9 in untreated and VP-16-treated Namalwa cells. These data suggest that procaspase-2S-mediated anti-apoptotic effects are associated with inhibition of the processing and activation of procaspase-3 in VP-16-treated cells.

Rho kinase in the regulation of cell death and survival

“…This caspase 3-mediated ROCK1 activation is both necessary and sufficient for the formation of membrane blebs through increasing MLC phosphorylation and actomyosin contraction [16,119]. The importance of this pathway in bleb formation was then confirmed by other studies in a variety of cell types, independent of apoptotic stimuli [23,70,86,104,127,155]. In addition, ROCK1-mediated blebbing facilitates cellular fragmentation and/or apoptotic cell clearance as discussed below.…”

“…Caspase 3 is believed to be responsible for activating ROCK1 in apoptotic cells, as evidenced by the absence of ROCK1 cleavage in caspase 3-deficient MCF-7 breast carcinoma cells and the presence of ROCK1 cleavage after restoring procaspase 3 expression [119]. In addition, ROCK1 cleavage by caspase 3 can be inhibited by caspase inhibitors in a variety of apoptotic cells [16,23,70,86,104,119,127,139,140,155]. However, caspase 3-independent cleavage of ROCK1 was observed in extracellular ATP-induced and P2X7 ATP receptor-mediated apoptosis [91] and in cancer cells subjected to combined BGC9331 (a thymidylate synthase inhibitor) and SN-38 (a topoisomerase I inhibitor) treatment [17].…”

Up-regulation of the proapoptotic caspase 2 splicing isoform by a candidate tumor suppressor, RBM5

“…Casp-2L is expressed in a range of tissues, and Casp-2S is expressed predominantly in the heart, brain, and skeletal muscle (14,15). Casp-2L promotes apoptosis, and Casp-2S overexpression protects cells against apoptosis induced by chemotherapeutic drugs such as etoposide (16)(17)(18). Motor neuron death is accelerated in caspase 2-deficient mice during development (19), suggesting that splicing regulation of Casp-2L/Casp-2S may play an important role in neural development.…”

Pharmacological inhibition of Rho-kinase (ROCK) signaling enhances cisplatin resistance in neuroblastoma cells

“…For example, Rho/ROCK signaling has been shown to promote cell survival in melanoma (10,23), gastric (24), and colorectal cancers (25). In contrast, Rho/ROCK signaling promotes apoptosis in prostate cancer (26,27), gastric cancer (28), chronic myelogenous leukemia (29), and lymphoma (30). Moreover, membrane blebbing and nuclear disintegration during apoptosis is dependent on ROCKmediated regulation of the actin myosin cytoskeleton (31,32).…”