PML isoform II plays a critical role in nuclear lipid droplet formation

Y Ohsaki, T Kawai, Y Yoshikawa, J Cheng… - Journal of Cell …, 2016 - rupress.org
Y Ohsaki, T Kawai, Y Yoshikawa, J Cheng, E Jokitalo, T Fujimoto
Journal of Cell Biology, 2016rupress.org
Lipid droplets (LDs) in the nucleus of hepatocyte-derived cell lines were found to be
associated with premyelocytic leukemia (PML) nuclear bodies (NBs) and type I
nucleoplasmic reticulum (NR) or the extension of the inner nuclear membrane. Knockdown
of PML isoform II (PML-II) caused a significant decrease in both nuclear LDs and type I NR,
whereas overexpression of PML-II increased both. Notably, these effects were evident only
in limited types of cells, in which a moderate number of nuclear LDs exist intrinsically, and …
Lipid droplets (LDs) in the nucleus of hepatocyte-derived cell lines were found to be associated with premyelocytic leukemia (PML) nuclear bodies (NBs) and type I nucleoplasmic reticulum (NR) or the extension of the inner nuclear membrane. Knockdown of PML isoform II (PML-II) caused a significant decrease in both nuclear LDs and type I NR, whereas overexpression of PML-II increased both. Notably, these effects were evident only in limited types of cells, in which a moderate number of nuclear LDs exist intrinsically, and PML-II was targeted not only at PML NBs, but also at the nuclear envelope, excluding lamins and SUN proteins. Knockdown of SUN proteins induced a significant increase in the type I NR and nuclear LDs, but these effects were cancelled by simultaneous knockdown of PML-II. Nuclear LDs harbored diacylglycerol O-acyltransferase 2 and CTP:phosphocholine cytidylyltransferase α and incorporated newly synthesized lipid esters. These results corroborated that PML-II plays a critical role in generating nuclear LDs in specific cell types.
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