1470-P: Modeling Familial Partial Lipodystropy Type 2 (LMNAp.R482W) Utilizing iPSC-Derived Adipocytes

Familial partial lipodystrophy type 2 (FPLD2) is a genetic syndrome characterized by loss of adipose tissue in the trunk and limbs and accumulation of supraclavicular fat. The most common genetic cause of FPLD2 is a pathogenic variant in the lamin A gene (LMNA; c.1444C>T; p.R482W). Our goal was to model FPLD2 in an induced pluripotent stem cell (iPSC) line. CRISPR/Cas9 gene editing was used to knock-in the heterozygous LMNA p.R482W variant into AN1.1 control iPSCs. Wild type and mutant iPSCs underwent a 2-stage differentiation process, first to mesenchymal cells then to adipocytes. Functional studies included 2-deoxyglucose (2-DG) uptake and mitochondrial stress testing. Adipocytes also underwent flow cytometry, RNA sequencing, and microscopy. We observed that both wild-type and mutant clones successfully differentiated to adipocytes after 26 days in adipogenic differentiation media. Adipogenic differentiation was diminished in mutant cells. Basal and insulin-stimulated uptake of 2-DG was impaired in mutant cells. Mitochondrial stress testing in mutant cells demonstrated decreased oxygen consumption rate (OCR), which was driven by a significant decrease in maximal respiration and coupling efficiency. RNA sequencing showed that the mutant cells had significant reduction in the expression of key adipogenic genes including ADIPOQ, CD36, ITIH5, CHCR7, LIPE, ITGA7, and OMD. Preliminary results from flow cytometry and high content microscopy both demonstrated decreased lipid droplet accumulation in the mutant cell lines. Our results show that an iPSC-based model system can recapitulate the adipose tissue dysfunction seen in FPLD2. We propose that this system is a useful model for studying pharmaceuticals aimed at restoring the metabolic function of adipose tissue in FPLD2. Additionally, our work suggests that iPSC-derived adipocytes may be used to study novel candidate disease genes in individuals with atypical lipodystrophy.