Abstract
ABSTRACTThe model organism Neurospora crassa undergoes programmed cell death when exposed to staurosporine. Here, we show that staurosporine causes defined changes in cytosolic free Ca2+ ([Ca2+]c) dynamics and a distinct Ca2+ signature that involves Ca2+ influx from the external medium and internal Ca2+ stores. We investigated the molecular basis of this Ca2+ response by using [Ca2+]c measurements combined with pharmacological and genetic approaches. 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 Ca2+ signature. Using Δcch-1, Δfig-1 and Δyvc-1 mutants and a range of inhibitors, we show that extracellular Ca2+ entry does not occur through the hitherto described high- and low-affinity Ca2+ 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 Ca2+ release from internal stores following IP3 formation combines with the extracellular Ca2+ influx.
Highlights
Calcium (Ca2+) is an essential intracellular messenger in all organisms, from prokaryotes to humans
We demonstrate that staurosporine promotes well-defined changes in [Ca2+]c with a distinct Ca2+ signature and that phospholipase C is a pivotal player during the induction of cell death
2-aminoethoxydiphenyl borate (2-APB) might be blocking IP3-receptor-activated Ca2+ release, it is likely that its effects result from the inhibition of transient receptor potential (TRP) channels, as previously claimed (Clapham et al, 2005). This might explain its different effects on the staurosporine-induced Ca2+ signature when compared with the more selective IP3 receptor inhibitor xestospongin C. These results indicate that staurosporine promotes the activity of phospholipase C and that the recruitment of Ca2+ from intracellular stores requires the generation of IP3
Summary
Calcium (Ca2+) is an essential intracellular messenger in all organisms, from prokaryotes to humans. The ion binds to a diverse range of proteins, commonly at EF-hand or EF-hand-like domains, and promotes conformational and electrostatic alterations in these proteins. These interactions modulate their activity and contribute to a cascade of signaling events that defines a Ca2+-mediated cellular response to a stimulus. The high-affinity Ca2+ uptake system (HACS) is the best described fungal Ca2+ uptake system. It comprises the channel Cch and the regulatory proteins Mid and Ecm (Martin et al, 2011; Muller et al, 2001). A glucose-induced Ca2+ influx system was recently proposed (Groppi et al, 2011) but its molecular components are unknown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
