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Induction of tyrosine aminotransferase of primary cultured rat hepatocytes depends on the organization of microtubules
Author(s) -
Ikeda Tatsuru,
Sawada Norimasa,
Satoh Masaaki,
Mori Michio
Publication year - 1998
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199804)175:1<41::aid-jcp5>3.0.co;2-c
Subject(s) - microtubule , tyrosine aminotransferase , primary (astronomy) , microbiology and biotechnology , tyrosine , hepatocyte , tubulin , biology , chemistry , biochemistry , enzyme , in vitro , enzyme inducer , physics , astronomy
We investigated the relationship between the expression of tyrosine aminotransferase (TAT) and cytoskeletal systems of cultured rat hepatocytes by using serum‐free culture conditions and changing three factors: (1) the concentration of calcium, (2) the dish‐coating material, and (3) the cell‐plating density. In hepatocytes in low‐calcium medium, induction of TAT by dexamethasone and glucagon was maintained, although cell‐cell adhesion was lost. Hepatocytes on Matrigel formed a nonspreading, spherical shape that provided them with the full extent of TAT activity without cell‐cell adhesion. Hepatocytes plated on collagen at low cell density spread and changed shape, and the induction of TAT activity was markedly reduced. By using confocal laser‐scanning microscopy, we analyzed the three‐dimensional organization of cytoplasmic microtubules of hepatocytes maintaining the ability of TAT induction. Hepatocytes plated on collagen at low cell density possessed the radial filamentous structure of cytoplasmic microtubules. When the spherical shape of hepatocytes was maintained by cultivating cells on Matrigel, a ring‐like structure of cytoplasmic micotubules beneath the plasma membrane was dominant. Moreover, the induction of TAT activity of hepatocytes in a standard culture system was strongly inhibited by the addition of 1 μM colchicine. These studies suggest that the organization of cytoplasmic microtubules may participate in the shape‐related regulation of cell function. J. Cell. Physiol. 175:41–49, 1998. © 1998 Wiley‐Liss, Inc.