The CCAAT/enhancer binding protein alpha ( @entity16509 ) and CCAAT/enhancer binding protein beta ( @entity19775 ) mRNAs are templates for the differential translation of several isoforms. Immunoblotting detects C/EBPalphas with molecular masses of 42, 38, 30, and 20 kDa and C/EBPbetas of 35, 20, and approximately 8.5 kDa. The DNA-binding activities and pool levels of @entity18757 ( @entity16509 ) and @entity8919 ( @entity16509 ) in control nuclear extracts decrease significantly whereas the binding activity and protein levels of the 20-kDa isoforms increase dramatically with @entity558 treatment. Our studies suggest that the @entity558 response involves alternative translational initiation at specific in-frame AUGs, producing specific @entity16509 and @entity19775 isoform patterns. We propose that alternative translational initiation occurs by a leaky ribosomal scanning mechanism. We find that nuclear extracts from normal aged @entity19 livers have decreased @entity18757 ( @entity16509 ) levels and binding activity, whereas those of @entity5796 ( @entity16509 ) and @entity5796 ( @entity19775 ) are increased. However, translation of 42-kDa @entity16509 is not down-regulated on polysomes, suggesting that aging may affect its nuclear translocation. Furthermore, recovery of the @entity16509 - and @entity19775 -binding activities and pool levels from an @entity558 challenge is delayed significantly in aged @entity19 livers. Thus, aged livers have altered steady-state levels of @entity16509 and @entity19775 isoforms. This result suggests that normal aging liver exhibits characteristics of chronic stress and a severe inability to recover from an inflammatory challenge.

Effects of age on the posttranscriptional regulation of CCAAT/enhancer binding protein alpha and CCAAT/enhancer binding protein beta isoform synthesis in control and XXXX -treated livers.

@entity558 :: ('MESH:C536528', 'Disease') :: ['LPS'] @entity19775 :: ('12608(Tax:10090)', 'Gene') :: ['C/EBPbeta'] @entity19 :: ('10090', 'Species') :: ['mouse'] @entity5796 :: ('13184(Tax:10090)', 'Gene') :: ['p20'] @entity8919 :: ('15289(Tax:10090)', 'Gene') :: ['p30'] @entity16509 :: ('12606(Tax:10090)', 'Gene') :: ['C/EBPalpha'] @entity18757 :: ('105278(Tax:10090)', 'Gene') :: ['p42']
@entity558 :: (MESH:C536528,Disease) :: ['LPS']
