Hutchinson-Gilford progeria fibroblasts exhibit metabolically normal uridine uptake and RNA synthetic rates

Aggrecan expression is substantially and abnormally upregulated in Hutchinson–Gilford Progeria Syndrome dermal fibroblasts

Hutchinson-Gilford Progeria syndrome (HGPS) is a rare genetic disorder that displays features of segmental aging. It is manifested predominantly in connective tissue, with most prominent histological changes occurring in the skin, cartilage, bone and cardiovascular tissues. Detailed quantitative real time reverse-transcription polymerase chain reaction studies confirmed the previous observation that platelet-derived growth factor A-chain transcripts are consistently elevated 11+/-2- to 13+/-2-fold in two HGPS dermal fibroblast lines compared with age-matched controls. Furthermore, we identified two additional genes with substantially altered transcript levels. Nucleotide pyrophosphatase transcription was virtually shut down with decreased expression of 13+/-3- to 59+/-3-fold in HGPS, whereas aggrecan mRNA was elevated to 24+/-5 times to 41+/-4 times that of chronologically age-matched controls. Aggrecan, normally a component of cartilage and not always detectable in normal fibroblasts cultures, was secreted by HGPS fibroblast lines and was produced as a proteoglycan. This demonstrates that elevated aggrecan expression and its secretion are aberrant features of HGPS. We conclude that HGPS cells can display massively altered transcript levels leading to the secretion of inappropriate protein species.

Hutchinson-Gilford progeria: faithful DNA maintenance, inheritance and allelic transcription of beta(1-4) galactosyltransferase

Hutchinson-Gilford progeria syndrome (HGPS) is a fatal segmental aging disorder affecting children. There is a paucity of prior data at the nucleotide level on DNA maintenance in HGPS. We have examined the specific nucleotide sequences and production of allelic transcripts from the locus GGTB2 encoding beta(1-4) galactosyltransferase. Quantitative Northern blots of mRNA from HGPS and control fibroblasts indicated identical mature beta(1-4) galactosyltransferase transcript sizes and amounts, regardless of their altered glycosylation status. DNA sequencing of cDNA derived from HGPS beta(1-4) galactosyltransferase mRNA populations confirmed the encoded amino acid sequence was unaffected. Population studies of 41 unrelated individuals provided allelic frequency estimates for a novel FokI polymorphism, which was identified in two of six progeria cell strains. The polymorphism was faithfully inherited in a progeria pedigree in a Mendelian manner. Furthermore, the polymorphism provided direct evidence through sequencing of reverse transcription polymerase chain reaction products that both alleles were transcribed and generated mature mRNA. Any defects in transcripts were below detectable levels over the lengths of coding sequences examined, despite multiple replication events from conception leading to the production and maintenance of patient-derived cells. These results indicate faithful transcription in HGPS.