cAMP-induced morphological changes in an immortalized Schwann cell line: a prelude to differentiation?
Schwann cells (SC), the myelinating cells of the peripheral nervous system, show a remarkable capacity to switch from a differentiated state to a proliferative state both during development and peripheral nerve regeneration. In order to better understand the regulatory mechanisms involved with this change we are studying a Schwann cell line transfected with the SV-40 large T gene (TSC). Serum-free medium combined with elevating intra-cellular cAMP levels produced a slower proliferating TSC whose morphology changed from pleiomorphic to process bearing, reminiscent of primary SC in culture. This change was abrogated by colcemid but was unaltered by cytochalasin D, indicating a major role for microtubules. Ultrastructural studies demonstrated numerous microtubules in the cellular extensions which correlated with strong immunocytochemical staining for tubulin in the processes. Analysis of cytoskeletal fractions from the treated cells revealed a greater proportion of tubulin in the polymerized state compared with untreated cells which closely resembled the distribution in primary SC. The cytoskeletal changes observed in the TSC as a result of elevating the intra-cellular cAMP levels may reflect the earliest cellular changes in the induction of myelination.
De Deyne
P G
PG
Department of Anatomy, Virginia Commonwealth University, Richmond.
De Vries
G H
GH
Bigbee
J W
JW
D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002461:Cell Line, Transformed; D003470:Culture Media / Q000494:pharmacology; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure; D008870:Microtubules / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011108:Polymers; D051381:Rats; D012583:Schwann Cells / Q000187:drug effects* / Q000648:ultrastructure; D014162:Transfection; D014404:Tubulin / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; D003470:Culture Media; D016895:Culture Media, Serum-Free; D009419:Nerve Tissue Proteins; D011108:Polymers; D014404:Tubulin; D015638:Cytochalasin D; D003994:Bucladesine; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases