Activation of a TRP-like channel and intracellular Ca2+ dynamics during phospholipase-C-mediated cell death.
Bottom Line: Phospholipase C was identified as a pivotal player during cell death, because modulation of the phospholipase C signaling pathway and deletion of PLC-2, which we show to be involved in hyphal development, results in an inability to trigger the characteristic staurosporine-induced Ca(2+) signature.Using Δcch-1, Δfig-1 and Δyvc-1 mutants and a range of inhibitors, we show that extracellular Ca(2+) entry does not occur through the hitherto described high- and low-affinity Ca(2+) uptake systems, but through the opening of plasma membrane channels with properties resembling the transient receptor potential (TRP) family.Partial blockage of the response to staurosporine after inhibition of a putative inositol-1,4,5-trisphosphate (IP3) receptor suggests that Ca(2+) release from internal stores following IP3 formation combines with the extracellular Ca(2+) influx.
Affiliation: IBMC-Instituto de Biologia Molecular e Celular - Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal email@example.com firstname.lastname@example.org.Show MeSH
Mentions: A model illustrating the mechanisms involved in staurosporine-induced and phospholipase-C-mediated cell death is presented in Fig. 7. We propose that the staurosporine-induced increase in the [Ca2+]c is caused by continuous Ca2+ influx from the external medium (through an unidentified TRP-like channel and SOCE) and release of Ca2+ from internal stores by a variety of mechanisms. The action of staurosporine includes the activation of phospholipase C, which leads to the generation of IP3 and possibly to the regulation of the TRP-like channel. The vacuoles readily sequester the excess Ca2+ in an attempt to avoid the associated deleterious effects of Ca2+. This sequestration can occur by means of a Ca2+/H+ antiport system that is indirectly blocked by the disruptive effect of bafilomycin A1 on the proton gradient by inhibiting the vacuolar H+-ATPase (Cordeiro et al., 2011; Cordeiro et al., 2013). Sequestration of Ca2+ through this system seems to eventually saturate because bafilomycin A1 does not block the C phase of the staurosporine-induced Ca2+ signature. Interestingly, recent reports demonstrate that the vacuolar H+/ATPase is a central mediator of cell death in fungal (Kim et al., 2012a; Zhang et al., 2010) and cancer (von Schwarzenberg et al., 2013) cells. In S. cerevisiae, cells lacking vacuolar ATPase activity are very sensitive even to brief elevations in [Ca2+]c (Forster and Kane, 2000). In future studies, it will be interesting to determine the role of the vacuolar H+-ATPase in N. crassa cell death.
Affiliation: IBMC-Instituto de Biologia Molecular e Celular - Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal email@example.com firstname.lastname@example.org.