Influence of nidogen complexed or not with laminin on attachment, spreading, and albumin and laminin B2 mRNA levels of rat hepatocytes.
Nidogen/entactin is a Mr = 150,000 glycoprotein which is present within basement membranes in a noncovalent stable complex with laminin. We have studied the effects of nidogen/entactin complexed or not with laminin on attachment, spreading, and functions of adult rat hepatocytes in primary culture. Freshly isolated hepatocytes attached on either recombinant or EHS-derived nidogen, although to a lesser extent than on laminin/nidogen complex, laminin, and E8 and P1 fragments of laminin. Hepatocytes bound on a nidogen fragment bearing the N-terminal and rod-like domains but not on either the N-terminal globules or the rod-like domain which contains a RGD sequence. Attachment of hepatocytes on nidogen and laminin/nidogen complex was inhibited by anti-beta 1 integrin antibodies. Hepatocytes remained rounded on nidogen and laminin, whereas they rapidly spread on laminin/nidogen complex and collagen IV. Nidogen, laminin, and laminin/nidogen complex transiently maintained high steady-state albumin mRNA levels in cultured hepatocytes, but a decrease in albumin mRNA content was observed after 24 h, independently of the substrates. Actinomycin D and cycloheximide treatment indicated that the transient effect of these substrates on albumin expression was related to post-transcriptional mechanisms. Laminin B2 mRNAs were not detectable in freshly isolated hepatocytes but were expressed in 4 h hepatocyte cultures. After 24 h, a dramatic increase in the steady-state level of laminin B2 mRNA was found in hepatocytes cultured on nidogen and laminin/nidogen complex. This effect was slightly prevented in hepatocytes plated on laminin. These results show that interactions of hepatocytes with nidogen/entactin in vitro result only in a transient modulation of hepatocyte functions.
Levavasseur
F
F
Unité de Recherches Hépatologiques, INSERM U-49, Hôpital Pontchaillou, Rennes, France.
Mayer
U
U
Guillouzo
A
A
Clement
B
B
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D001485:Basement Membrane / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects; D016023:Integrins / Q000276:immunology; D007797:Laminin / Q000235:genetics* / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins; D012709:Serum Albumin / Q000235:genetics*
D000906:Antibodies; D016023:Integrins; D007797:Laminin; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012709:Serum Albumin; C029967:nidogen