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RGD-containing molecules induce macropinocytosis in ascidian hyaline amoebocytes

Loriano Ballarin1, Paolo Burighel

  • 1Department of Biology, University of Padova, Via U.Bassi 58/B, 35100 Padova, Italy. loriano.ballarian@unipd.it

Journal of Invertebrate Pathology
|January 13, 2006
PubMed

Insights

Phagocytes in tunicates perform macropinocytosis (MP), a cell-drinking process. This process, enhanced by Arg-Gly-Asp recognition, suggests conserved endocytosis mechanisms across chordates.

Area of Science:

  • Cell Biology
  • Marine Biology
  • Invertebrate Zoology

Background:

  • Phagocytes are crucial immune cells involved in endocytosis.
  • Macropinocytosis (MP) is a form of endocytosis where large amounts of extracellular fluid are non-specifically internalized.
  • The compound ascidian Botryllus schlosseri offers a model for studying fundamental cellular processes in a marine invertebrate.

Purpose of the Study:

  • To investigate the mechanisms of macropinocytosis (MP) in the phagocytes of Botryllus schlosseri.
  • To explore the role of Arg-Gly-Asp (RGD) motif recognition in phagocyte behavior and MP.
  • To determine the metabolic consequences associated with MP induction in these cells.

Main Methods:

  • Observation of phagocyte spreading and vesicle formation.
  • Assessment of MP induction upon exposure to RGD-containing molecules.
  • Measurement of oxygen consumption and superoxide anion production (nitroblue tetrazolium reduction).
  • Evaluation of ATP levels via cytochrome oxidase activity.

Main Results:

  • Botryllus schlosseri phagocytes exhibit constitutive macropinocytosis (MP) at the leading edge.
  • Phagocyte spreading and MP are enhanced by Arg-Gly-Asp (RGD) recognition, indicating integrin involvement.
  • MP is linked to increased oxygen consumption, superoxide anion production, and ATP levels.

Conclusions:

  • Integrin activation likely plays a conserved role in regulating cell spreading and endocytosis in B. schlosseri, similar to mammals.
  • Macropinocytosis in ascidian phagocytes is an active metabolic process.
  • The findings suggest common mechanisms for MP induction are conserved throughout the Chordate phylum.

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