Roles and origins of leukocyte lipid bodies: proteomic and ultrastructural studies.
Lipid bodies (LBs), multifunctional organelles present in most eukaryotic cells, are sites of eicosanoid formation in leukocytes; but little is known about the composition of leukocyte LBs or the biogenesis and internal structures of LBs from mammalian cells. Proteomic analyses of LBs purified from human monocytic U937 cells detected, common to LBs in other cells, proteins involved in cholesterol and triglyceride metabolism, Rab GTPases, and many membrane and endoplasmic reticulum (ER)-associated proteins. Newly lipid body (LB)-associated proteins included MRP-14, potentially involved in arachidonate transport, and ribosomal subunit proteins and translation regulatory proteins. Ultrastructurally, in U937 cells as well as human neutrophils and eosinophils, ribosomes are attached to and distributed within LBs, and LBs contain extensive ER-like membranes. The presence of ribosomes, ER-like membranes and many membrane-associated and ER luminal proteins within LBs, supports a new model by which enveloped ER-membranes and domains form LBs and indicates that LBs may be sites of protein synthesis.
Wan
Hsiao-Ching
HC
Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave., Boston, MA 02215, USA.
Melo
Rossana C N
RC
Jin
Zhoung
Z
Dvorak
Ann M
AM
Weller
Peter F
PF
D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007962:Leukocytes / Q000378:metabolism* / Q000648:ultrastructure; D008055:Lipids / Q000502:physiology*; D008854:Microscopy, Electron; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D020298:U937 Cells
D008055:Lipids