N-6-ISOPENTENYLADENOSINE AFFECTS CAMP-DEPENDENT MICROFILAMENT ORGANIZATION IN FRTL-5 THYROID-CELLS

N-6-Isopentenyladenosine (i(6)A), an adenosine and mevalonate derivati ve, inhibits, like adenosine, TSH-induced cAMP increase and its relate d events (I- uptake and DNA synthesis) in FRTL-5 cells, This inhibitio n is dose dependent and is measurable at 10(-8) M. However, unlike ade nosine, i(6)A prevents TSH-promoted microfilament disassembly. The eff ect of i(6)A on cytoskeletal structure is antagonized by pertussis tox in and could be assigned to its N-6 substitution since it can be mimic ked by other synthetic N-6-adenosine derivatives. It is suggested that a step beyond cAMP is involved, since i(6)A prevents also microfilame nt disassembly induced by 8-bromo-cAMP. This is the first demonstratio n that an adenosine derivative, which is also an end-product of the is oprenoid pathway, affects cAMP-dependent microfilament organization. ( C) 1997 Academic Press.