Putative regulatory mechanism of prothoracicotropic hormone (PTTH) secretion in the American cockroach, Periplaneta americana as inferred from co-localization of Rab8, PTTH, and protein kinase C in neurosecretory cells.
Small GTPases of the Rab family act as essential regulators of vesicle transport pathways, including the exocytosis of neurohormones. These processes are not well-understood in insects. To address the physiological function of Rab proteins and their phosphorylation in insect neurosecretion, Rab8-like, prothoracicotropic hormone (PTTH)-like, and protein kinase C (PKC)-like immunohistochemical reactivities (-ir) were investigated in the brain of the American cockroach, Periplaneta americana. All the antibodies tested reacted with neurons in the pars intercerebralis, corpora cardiaca, and nervi corporis allati I. Double-labeling experiments demonstrated that all PTTH-ir were colocalized with Rab8-ir and PKC-ir in the pars intercerebralis, although exclusive reactivity was present to antisera against Rab8 or PKC. These findings support the notion that Rab8-like antigen is phosphorylated by PKC, and that this phosphorylation is involved in the axonal transport and secretion of PTTH in this species.
Hiragaki
Susumu
S
Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657 8501, Japan.
Uno
Tomohide
T
Takeda
Makio
M
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000502:physiology; D002478:Cells, Cultured; D007150:Immunohistochemistry; D007301:Insect Hormones / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D009489:Neurosecretion / Q000502:physiology; D010526:Periplaneta / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
D007301:Insect Hormones; C009089:prothoracicotropic hormone; D011493:Protein Kinase C; D020691:rab GTP-Binding Proteins