title: Nucleoplasmic localization of prelamin A: implications for prenylation-dependent lamin A assembly into the nuclear lamina.
abstract: The synthesis of the nuclear lamina protein lamin A requires the prenylation-dependent processing of its precursor protein, prelamin A. Unlike p21ras, which undergoes similar initial posttranslational modifications, maturation of lamin A results in the proteolytic removal of the prenylated portion of the molecule. We have used an in vitro prenylation system to demonstrate the nature of the prenyl substituent on prelamin A to be a farnesyl group. Further, the in vitro farnesylation of prelamin A requires an intact cysteine-aliphatic-aliphatic-other (CAAX) amino acid sequence motif at its carboxyl terminus. The effect of blocking the prenylation of prelamin A on its localization and assembly into the nuclear lamina was investigated by indirect immunofluorescence. Expression of wild-type prelamin A in lovastatin-treated cells showed that nonprenylated prelamin A accumulated as nucleoplasmic particles. Upon addition of mevalonate to lovastatin-treated cells, the wild-type lamin A was incorporated into the lamina within 3 hr. Expression of a mutant lamin A in which the carboxyl-terminal 21 amino acids were deleted resulted in a lamin molecule that was directly assembled into the lamina. These results indicate that the carboxyl-terminal peptide of prelamin A blocks its proper assembly into the nuclear lamina and that the prenylation-initiated removal of this peptide can occur in the nucleus.
authors.affiliation: Eleanor Roosevelt Institute for Cancer Research, Denver, CO 80206.
authors.forename: R J
authors.initials: RJ
authors.lastname: Lutz
authors.forename: M A
authors.initials: MA
authors.lastname: Trujillo
authors.forename: K S
authors.initials: KS
authors.lastname: Denham
authors.forename: L
authors.initials: L
authors.lastname: Wenger
authors.forename: M
authors.initials: M
authors.lastname: Sinensky
mesh_terms: D000818:Animals; D016466:CHO Cells; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000378:metabolism*; D006224:Cricetinae; D005204:Farnesol / Q000378:metabolism; D034904:Lamin Type A; D034882:Lamins; D008148:Lovastatin / Q000494:pharmacology; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship
chemical_list: D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D011498:Protein Precursors; D011994:Recombinant Proteins; D005204:Farnesol; D008148:Lovastatin