Loss of hepatocyte co-operative activity after inhibition of ganglioside GM1 synthesis and shedding.
Pretreatment of hepatocyte cultures with 1 microM d-l-threo-1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol-HCL (PPPP) for 24 h decreased the ganglioside GM1 content of the cells by approximately 50% and that of the conditioned medium by 90%. No rhythm in the rate of protein synthesis was detected in dense cultures pretreated with PPPP, but was observed in control dense cultures. Conditioned medium from control dense cultures induced synchrony in sparse cultures, which were non-synchronous in their own medium. In contrast, conditioned medium from dense cultures pretreated with PPPP did not synchronize sparse cultures. Since protein synthesis rhythm is a marker of cell synchronization, i.e. their co-operative activity, then non-oscillatory behavior means loss of cell co-operation. The protein synthesis rhythm was restored 24 h after hepatocytes were transferred to PPPP-free medium. Restoration was more rapid when 0.9 microM gangliosides (standard mixture from bovine brain) were added to the medium just after the withdrawal of PPPP. These novel results concerning the loss of rhythm of protein synthesis in low GM1 ganglioside medium support the conclusion that ganglioside is implicated in the regulation of cell co-operative activity.
Institute of Developmental Biology, Russian Academy of Sciences, 26 Vavilov Street, 117808 Moscow, Russia. brodsky@proxima.idb.ac.ru
Vsevolod
V
Brodsky
Natalia
N
Zvezdina
Natalia
N
Nechaeva
Tatjana
T
Novikova
Inessa
I
Gvasava
Valentina
V
Fateeva
Helena
H
Gracheva
D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology*; D002452:Cell Count; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D005677:G(M1) Ganglioside / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D005732:Gangliosides / Q000494:pharmacology; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010507:Periodicity; D011412:Propanolamines / Q000494:pharmacology; D014176:Protein Biosynthesis; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats
C110417:1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol; D017077:Culture Media, Conditioned; D005732:Gangliosides; D011412:Propanolamines; D011759:Pyrrolidines; D005677:G(M1) Ganglioside