Prelamin A and lamin A appear to be dispensable in the nuclear lamina
J. Clin. Invest. Loren G. Fong, et al. 116:743 doi:10.1172/JCI27125 [Go to this article.]

Figure 1
Production of a mutant Lmna allele, Lmna^LCO. (A) A sequence-replacement vector was used to remove intron 11 and the last 150 nucleotides of exon 11. Unexpectedly, this mutation eliminated the splicing event required to produce prelamin A. Exons are shown as boxes. Locations of the PCR primers (i and ii) and the 5′ flanking probe for Southern blots are shown. tk, thymidine kinase gene (for negative selection). (B) Southern blot detection of the Lmna^LCO (LCO/+) allele in EcoRI-cleaved genomic DNA from ES cells. (C) PCR identification of wild-type and Lmna^LCO alleles. Shown are results with wild-type (A10, C12) and Lmna^LCO/+ (B10, B11, B12) ES cell clones from gene-targeting experiments. (D) Northern blot of total RNA from Lmna^+/+ (+/+), Lmna^LCO/+ (LCO/+), and Lmna^+/+ (LCO/LCO) fibroblasts; the blot was hybridized with a mouse Lmna cDNA probe that detects both prelamin A and lamin C transcripts and a mouse Lmnb1 cDNA probe that detects lamin B1, a closely related lamin protein. (E) Western blots of 3 different wild-type, 2 heterozygous, and 1 homozygous primary fibroblast cell lines at the same passage number with a polyclonal antibody against lamin A/C and actin. A minor form of lamin A lacking exon 10 has been reported previously in some human cells (43). It is conceivable that this minor lamin could be synthesized, but this would require splicing from exon 9 to the exon 11–12 fusion. We have not identified this minor splice variant in the lamin C–only fibroblasts.