Cell reports

Lack of MTTP Activity in Pluripotent Stem Cell-Derived Hepatocytes and Cardiomyocytes Abolishes apoB Secretion and Increases Cell Stress.

PMID 28514664


Abetalipoproteinemia (ABL) is an inherited disorder of lipoprotein metabolism resulting from mutations in microsomal triglyceride transfer protein (MTTP). In addition to expression in the liver and intestine, MTTP is expressed in cardiomyocytes, and cardiomyopathy has been reported in several ABL cases. Using induced pluripotent stem cells (iPSCs) generated from an ABL patient homozygous for a missense mutation (MTTP(R46G)), we show that human hepatocytes and cardiomyocytes exhibit defects associated with ABL disease,xa0including loss of apolipoprotein B (apoB) secretion and intracellular accumulation of lipids. MTTP(R46G) iPSC-derived cardiomyocytes failed toxa0secrete apoB, accumulated intracellular lipids, and displayed increased cell death, suggesting intrinsic defects in lipid metabolism due to loss of MTTP function. Importantly, these phenotypesxa0were reversed after the correction of the MTTP(R46G) mutation by CRISPR/Cas9 gene editing. Together, these data reveal clear cellular defects in iPSC-derived hepatocytes and cardiomyocytes lacking MTTP activity, including a cardiomyocyte-specific regulated stress response to elevated lipids.