Brunet-de Carvalho N, Picart R, Van de Moortele S, Tougard C, Tixier-Vidal A. Laminin induces formation of neurite-like processes and potentiates prolactin secretion by GH3 rat pituitary cells.
Differentiation 1989;
40:106-18. [PMID:
2503413 DOI:
10.1111/j.1432-0436.1989.tb00820.x]
[Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tumor-derived GH3 rat pituitary cell lines are widely utilized to study mechanisms of prolactin secretion and responsiveness to secretagogues. These cells served here as a model with which to study relationships between shape and function. When GH3 cells were routinely grown in serum-supplemented medium, they exhibited the polygonal phenotype of epithelial cells, with scarce secretory granules. In contrast, when seeded in a serum-free medium, they attached loosely and contained more secretory granules. In both cases, they released prolactin in a nonpolarized manner. We show in the present work that laminin extracted from Englebreth-Holm-Swarm (EHS) tumors was a potent attachment and spreading factor for GH3/B6 cells seeded in serum-free medium. Moreover, it induced the formation of neurite-like processes, which were increased in number and length by chronic treatment with a specific secretagogue, thyroliberin (TRH). These changes in cell shape were correlated with a potentiation of prolactin secretion, both basal and TRH-stimulated. Furthermore, using immunocytochemistry and electron microscopy, we revealed--at the dilated tip of processes--an accumulation not only of prolactin, but also of synaptophysin, a vesicle membrane marker, and of several organelles, such as secretory granules, smooth vesicles, dense bodies and mitochondria. The cytoplasmic processes contained long parallel bundles of microtubules and showed a strong immunoreactivity for beta 2-tubulin. In addition, we found immunocyto-chemical evidence for the presence of 200-k Da neurofilament protein in GH3/B6 cell processes as well as in neurites of cultured hypothalamic neurons. We conclude that, in GH3/B6 cells, laminin induced the differentiation of neurite-like processes, which were the site of polarized organelle transport and exhibited some neuronal markers.
Collapse