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Interactions of signaling pathways in ACTH (1-24)-induced cell shape changes in invertebrate immunocytes

D Sassi1, D Kletsas, E Ottaviani

  • 1Department of Animal Biology, University of Modena, Italy.

Peptides
|August 13, 1998
PubMed

Insights

Adrenocorticotropic hormone (ACTH) triggers shape changes in mussel immune cells. This involves the adenylate cyclase/cAMP/protein kinase A pathway and protein kinase C activation, as shown by inhibitor studies.

Area of Science:

  • Marine biology
  • Immunology
  • Cell signaling

Background:

  • Adrenocorticotropic hormone (ACTH) is known to affect vertebrate immune cells.
  • Molluscan immunocytes play a crucial role in invertebrate immunity.
  • Understanding immune cell signaling in bivalves like Mytilus galloprovincialis is vital for marine ecosystem health.

Purpose of the Study:

  • To investigate the signaling pathways involved in ACTH (1-24)-induced cell shape changes in Mytilus galloprovincialis immunocytes.
  • To determine the roles of adenylate cyclase, cAMP, protein kinase A (PKA), and protein kinase C (PKC) in this process.
  • To elucidate the molecular mechanisms underlying immune cell responses in bivalve molluscs.

Main Methods:

  • Computer-assisted microscopic image analysis was used to quantify cell shape changes.
  • Specific inhibitors were employed to block key signaling molecules: suramin sodium (G protein antagonist), 2',5'-dideoxyadenosine (adenylate cyclase inhibitor), staurosporine (broad protein kinase inhibitor), H-89 (PKA inhibitor), and calphostin C (PKC inhibitor).
  • The effects of individual and combined inhibitors on ACTH (1-24)-induced morphological alterations were assessed.

Main Results:

  • ACTH (1-24) induced significant cell shape changes in Mytilus galloprovincialis immunocytes.
  • Suramin sodium, 2',5'-dideoxyadenosine, and staurosporine effectively inhibited these ACTH-induced changes.
  • While H-89 and calphostin C partially inhibited the morphological alterations individually, their simultaneous application completely blocked the changes.
  • These results pinpoint the involvement of both the adenylate cyclase/cAMP/PKA pathway and PKC activation.

Conclusions:

  • ACTH (1-24) mediates cell shape changes in molluscan immunocytes through a dual signaling mechanism.
  • The identified pathways include the adenylate cyclase/cAMP/PKA cascade and protein kinase C activation.
  • This study provides novel insights into the conserved signaling pathways of immune cells across different animal phyla.

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