We examined the effects of interleukin-1 beta [IL-1 ] treatment on the distribution and degradation of lamin-B in the nuclear fraction from insulin-secreting RINm5F cells. Western blot analysis indicated that IL-1 beta treatment caused significant alterations in the redistribution of lamin-B, specifically between the triton X-100 soluble [membrane] and insoluble [matrix] fractions of the nucleus. IL-1 treatment also increased the lamin carboxylmethyltransferase [LCMT] activity and the relative abundance of the carboxylmethylated lamin in the nuclear fraction. A significant increase in the relative abundance of lamin-B-degradation products was also observed in the nuclear fraction from the IL-1-treated cells. These findings are compatible with a measurable increase in the lamin-degrading caspase-6 activity in IL-1-treated cells. Confocal microscopy of IL-1-treated cells suggested a significant dissociation of lamin-B from the nuclear lamina and its subsequent association with the DNA-rich elements within the nucleus. N^G-monomethyl-L-arginine [NMMA], a known inhibitor of inducible nitric oxide synthetase [iNOS], markedly inhibited IL-1-induced iNOS gene expression, NO release, caspase-3 and caspase-6 activation, lamin-B degradation and loss in metabolic cell viability, indicating that the observed IL-1-induced effects on nuclear lamin-B involve the intermediacy of NO. Together, our data support the hypothesis that IL-1 treatment results in significant increase in the carboxylmethylation of lamin-B, which would place lamin-B in a strategic location for its degradation mediated by caspases; this could possibly lead to dissolution of nuclear envelope, culminating in the demise of the effete cell.