Different Ca2+ signalling cascades manifested by mastoparan in the prothoracic glands of the tobacco hornworm, Manduca sexta, and the silkworm, Bombyx mori.
Application of the tetradecapeptide mastoparan to the prothoracic glands (PGs) of the tobacco hornworm, Manduca sexta, and the silkworm, Bombyx mori, resulted in increases in intracellular Ca(2+) ([Ca(2+)](i)). In M. sexta, Gi proteins are involved in the mastoparan-stimulated increase in [Ca(2+)](i). However, there is no involvement of Gi proteins in the mastoparan-stimulated increase in [Ca(2+)](i) in prothoracic gland cells from B. mori. Unlike in M. sexta prothoracic glands, in B. mori prothoracic glands mastoparan increases [Ca(2+)](i) even in the absence of extracellular Ca(2+). Pharmacological manipulation of the Ca(2+) signalling cascades in the prothoracic glands of both insect species suggests that in M. sexta prothoracic glands, mastoparan's first site of action is influx of Ca(2+) through plasma membrane Ca(2+) channels while in B. mori prothoracic glands, mastoparan's first site of action is mobilization of Ca(2+) from intracellular stores. In M. sexta, the combined results indicate the presence of mastoparan-sensitive plasma membrane Ca(2+) channels, distinct from those activated by prothoracicotropic hormone or the IP(3) signalling cascade, that coordinate spatial increases in [Ca(2+)](i) in prothoracic gland cells. We propose that in B. mori, mastoparan stimulates Ca(2+) mobilization from ryanodine-sensitive intracellular Ca(2+) stores in prothoracic gland cells.
Dedos
Skarlatos G
SG
Saxon Academy of Sciences at Leipzig, Department of Neurohormones, Jena, Germany. sd323@cam.ac.uk
Wicher
Dieter
D
Kaltofen
Sabine
S
Birkenbeil
Heiner
H
D000818:Animals; D012831:Bombyx / Q000502:physiology*; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000032:analysis / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005682:Gadolinium / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D018402:Manduca / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology*; D037342:Pertussis Toxin / Q000494:pharmacology; D012433:Ryanodine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D013997:Time Factors; D014862:Wasp Venoms / Q000494:pharmacology*
D001896:Boron Compounds; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D013873:Thionucleotides; D014862:Wasp Venoms; D006153:Guanosine Diphosphate; D012433:Ryanodine; D019284:Thapsigargin; C023427:guanosine 5'-O-(2-thiodiphosphate); C037500:mastoparan; D005682:Gadolinium; C109986:2-aminoethoxydiphenyl borate; D037342:Pertussis Toxin; D002118:Calcium