Menadione-induced apoptosis and the degradation of lamin-like proteins in tobacco protoplasts

Abstract

Detection of stereotypic hallmarks of apoptosis during cell death induced by menadione, including DNA laddering and the formation of apoptotic bodies, is reported. Comet assay and the TdT-mediated dUTP nick end labelling (TUNEL) procedure were also performed to detect DNA fragmentation. Inhibition of DNA fragmentation by Ac-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO) and phenylmethylsulfosyl (PMSF) implicated the involvement of caspase-like proteases in menadione-induced apoptosis in plants. We further studied the cleavage of lamin-like proteins during apoptosis in menadione-treated tobacco protoplasts. In animals, it has been reported that the solubilization of nuclear lamina and lamin degradation occurs during apoptotic cell death. However, little is known about the fate of lamins in apoptotic plant cells. Our study provided evidence that lamin-like proteins degraded into 35-kDa fragments in tobacco protoplasts induced by menadione, and this preceded DNA fragmentation. The results thus indicated that proteolytic cleavage of nuclear lamins was also conserved in programmed cell death in plants.

Programmed cell death progressively models the development of anther sporophytic tissues from the tapetum and is triggered in pollen grains during maturation

“…However, the formation of nuclear fragments was described in tobacco protoplasts or BY2 cells treated with PCD inducers, respectively, menadione and isopentenyladenosine (Mlejnek and Prochazka, 2002;Sun et al, 1999), which is in accordance with our data.…”

Do Plant Caspases Exist?

“…In this system, some other Cys and Ser protease inhibitors (PMSF and TPCK) also partially suppressed cell death, whereas leupeptin, TLCK, and E64 had no effect (Lam and Del Pozo, 2000). Menadione-induced PCD in tobacco protoplasts, showing typical apoptotic features such as chromatin condensation and nuclear and DNA fragmentation, can be blocked by low concentrations of caspase-3 inhibitor (Ac-DEVD-CHO) and high concentration of PMSF (Sun et al, 1999b).…”

Salt stress induces programmed cell death in Thellungiella halophila suspension-cultured cells

“…Synthetic tetrapeptide inhibitors, such as Ac-DEVD-CHO, are commonly used to block PCD in animal cells and, recently, have been used in plants for in vitro. Sun et al (1999) found that DNA laddering induced by menadione in tobacco cells was completely inhibited by 100 M Ac-DEVD-CHO. Ac-DEVD-CHO has been demonstrated to inhibit pathogenesis in plant cells (del Pozo and Lam, 1998;Richael et al, 2001) and to suppress cell death of pollen tubes in Papaver (Thomas and Franklin-Tong, 2004).…”