Acquisition and extinction of gene expression programs are separable events in heterokaryon reprogramming.
Although differentiated cells normally retain cell-type-specific gene expression patterns throughout their lifetime, cell identity can sometimes be modified or reversed in vivo by transdifferentiation, or experimentally through cell fusion or by nuclear transfer. To examine the epigenetic changes that are required for the dominant conversion of lymphocytes to muscle, we generated heterokaryons between human B lymphocytes and mouse C2C12 myotubes. We show that within 2 days of heterokaryon formation lymphocyte nuclei adopt an architecture resembling that of muscle and then initiate the expression of muscle-specific genes in the same temporal order as developing muscle. The establishment of this muscle-specific program is coordinated with the shutdown of several lymphocyte-associated genes. Interestingly, erasing lymphocyte identity in reprogrammed cells requires histone deacetylase (HDAC) activity. Inhibition of HDAC activity during reprogramming selectively blocks the silencing of lymphocyte-specific genes but does not prevent the establishment of muscle-specific gene expression. Successful reprogramming is therefore shown to be a multi-step process in which the acquisition and extinction of lineage-specific gene programs are separable events.
Terranova
Rémi
R
Lymphocyte Development Group, MRC, Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
Pereira
Carlos Filipe
CF
Du Roure
Camille
C
Merkenschlager
Matthias
M
Fisher
Amanda G
AG
D000818:Animals; D018951:Antigens, CD20 / Q000096:biosynthesis / Q000235:genetics; D001402:B-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002459:Cell Fusion / Q000379:methods; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D015870:Gene Expression; D020868:Gene Silencing; D022761:Gene Transfer, Horizontal; D006570:Heterochromatin / Q000235:genetics*; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000502:physiology; D009132:Muscles / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D019006:Neural Cell Adhesion Molecules / Q000096:biosynthesis / Q000235:genetics
D018951:Antigens, CD20; D006570:Heterochromatin; D056572:Histone Deacetylase Inhibitors; D019006:Neural Cell Adhesion Molecules; D006655:Histone Deacetylases