In metastatic B16a murine melanoma cells, α(IIb)β3 integrin was shown to be one of the key adhesion molecules responsible for matrix adhesion and spreading. Upon stimulation, α(IIb)β3 can be upregulated at the cell surface due to translocation of the receptor to the plasma membrane from an intracellular pool. Here we have characterized this integrin pool as a tubulovesicular structure (TVS) corresponding to endosomes. TVS was found to be associated temporarily with microtubules and intermediate filaments especially after protein kinase C (PKC) stimulation with a lipoxygenase metabolite of arachidonic acid, 12-(S)-hydroxyeicosatetraenoic acid [12-(S)-HETE]. After PKC stimulation, the predominantly vesicular TVS became elongated and α(IIb)β3 appeared at the apical plasma membrane and microvilli. Disruption of either the microtubules or intermediate filaments prevented the 12-(S)-HETE effect both on vesicular to tubular transition of TVS as well as on surface expression of this integrin. The connection with the Golgi system of the integrin-containing TVS was proved by a Golgi-inhibitor (brefeldin A) pretreatment, which prevented the PKC-stimulation-induced TVS elongation and subsequent receptor-upregulation at the cell surface. After a soluble ligand binding (mAb to the α(IIb)β3 complex) the surface receptor endocytosed back to the TVS indicating the presence of a dynamic, cytoskeleton associated integrin pool in melanoma cells.
|Number of pages||12|
|Journal||Journal of cell science|
|Publication status||Published - Jan 1 1995|
- Tubulovesicular structure
ASJC Scopus subject areas
- Cell Biology