The retinol acid receptor B gene is hypermethylated in patients with familial partial lipodystrophy

Abstract

Mutations in the LMNA gene cause various phenotypes including partial lipodystrophy, muscular dystrophies, and progeroid syndromes. The specific mutation position within the LMNA sequence can partially predict the phenotype, but the underlying mechanisms for the development of these different phenotypes are still unclear. To investigate whether different DNA methylation patterns contribute to the development of different phenotypes caused by LMNA mutations, we analyzed a panel of ten candidate genes related to fat metabolism, aging, and a tendency to different methylation patterns: CSPG2, ESR1, IGF1R, IGFR2, LMNA, MLH1, RANBP1, RARB, ZMPSTE24, and TGFBR1. We studied two independent families each comprising three individuals affected by familial partial lipodistrophy type 2 (FPLD2). Affected members in each family carried two different mutations of the LMNA gene (R482L and R471G respectively). In addition, we analyzed four progeria patients (2!LMNA/C G608G, 1!LMNA/C S143F, and 1!ZMPSTE24 IVS9-Ex10) and seven healthy adults. The gene encoding retinoic acid receptor B (RARB) showed a higher methylation in all six patients with FPLD2 when compared with the progeria patients with other LMNA mutations as well as the healthy controls (P!0 . 05).All other investigated genes showed no difference in the methylation patterns between the groups. A drug-induced inhibition of the retinol pathway is discussed as the key pathway for developing HAART-associated lipodystrophy and our data support a possible role of the retinol pathway in the development of lipodystrophy phenotypes.

The nuclear lamina is mechano-responsive to ECM elasticity in mature tissue

“…Measurements made on proteins in a human lung cancer cell line showed the half-life of A-type lamin to be ,12 hours, roughly in the middle of the span of protein half-lives recorded in the study (Eden et al, 2011). DNA methylation is an epigenetic mechanism by which gene activity can be regulated, but it was discounted as the foremost means of controlling LMNA levels -no consistent changes were observed in the methylation of the LMNA promoter either in a range of cell lines known to express different levels of A-type lamin protein (Swift et al, 2013b) or in tissues from patients with laminopathic disorders (Cortese et al, 2007). LMNA transcription has been reported to be controlled by transcription factors of the retinoic-acid receptor family (RAR and RXR family proteins; Okumura et al, 2004a;Okumura et al, 2004b;Olins et al, 2001;Shin et al, 2013;Swift et al, 2013b), with the resulting mRNA alternatively spliced to give the lamin-A and truncated lamin-C forms.…”