The expression of a novel Ca2+/CaM stimulated adenylyl cyclase activity in the neuroblastoma cell line Lan-1 is regulated by cell density.
In the human neuroblastoma cell line Lan-1, the mRNA encoding the Ca2+/calmodulin (CaM) sensitive adenylyl cyclase type-1 (AC-1) was detected by reverse transcription-polymerase chain reaction (RT-PCR) as well as by Northern blotting. However, neither Ca2+/CaM stimulated AC activity was found nor could AC-1 type protein be detected by a specific antibody (anti-1Cl). In contrast, when cells were grown to high cell density, Ca2+/CaM stimulated AC-activity could be indeed found in membranes. The large increase in activity was paralleled by the appearance of a 110 kDa protein detected by the monoclonal AC antibody BBC-2. At the same time a 150 kDa adenylyl cyclase species present in growing cells was absent. The 110 kDa protein co-migrated with bovine AC-1 and was slightly larger than the human AC-1. Unexpectedly, however, the antibody anti-1CI was not able to precipitate the newly induced Lan-1 AC. In addition, no increase in type-1 AC mRNA could be detected either by PCR or by Northern blotting. Treatment of Lan-1 cells with 10 microM retinoic acid for 7 days caused growth arrest and morphological differentiation of the cells, yet the induction of the Ca2+/CaM-stimulated AC activity was much lower than in the dense grown control cultures. It is concluded that the Ca2+/CaM-activated AC of M(r) 110 kDa in Lan-1 cells is not related to the previously known Ca2+/CaM stimulated AC isoforms, and might thus represent a novel AC.
Kluxen
F W
FW
Department of Physiological Chemistry II, Heinrich-Heine University Düsseldorf, Germany. kluxen@merck.de
Hülster
A
A
Droste
M
M
Pfeuffer
T
T
D000262:Adenylyl Cyclases / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001932:Brain Neoplasms / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D002417:Cattle; D002452:Cell Count; D005576:Colforsin / Q000494:pharmacology; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D002147:Calmodulin; D005576:Colforsin; D000262:Adenylyl Cyclases; D002118:Calcium