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Li, Z., Thiel, K., Thul, P.J., Beller, M., Kuhnlein, R.P., Welte, M.A. (2012). Lipid droplets control the maternal histone supply of Drosophila embryos.  Curr. Biol. 22(22): 2104--2113.
FlyBase ID
FBrf0220040
Publication Type
Research paper
Abstract

Histones are essential for chromatin packing, yet free histones not incorporated into chromatin are toxic. While in most cells multiple regulatory mechanisms prevent accumulation of excess histones, early Drosophila embryos contain massive extranuclear histone stores, thought to be essential for development. Excess histones H2A, H2B, and H2Av are bound to lipid droplets, ubiquitous fat storage organelles especially abundant in embryos. It has been proposed that sequestration on lipid droplets allows safe transient storage of supernumerary histones.Here, we critically test this sequestration hypothesis. We find that histones are anchored to lipid droplets via the previously uncharacterized protein Jabba: Jabba localizes to droplets, coimmunoprecipitates with histones, and is necessary to recruit histones to droplets. Jabba mutants lack the maternal H2A, H2B, and H2Av deposits altogether; presumably, these deposits are eliminated unless sequestered on droplets. Jabba mutant embryos compensate for this histone deficit by translating maternal histone mRNAs. However, when histone expression is mildly compromised, the maternal histone protein deposits are essential for proper early mitoses and for viability.A growing number of proteins from other cellular compartments have been found to transiently associate with lipid droplets. Our studies provide the first insight into mechanism and functional relevance of this sequestration. We conclude that sequestration on lipid droplets allows embryos to build up extranuclear histone stores and provides histones for chromatin assembly during times of high demand. This work reveals a novel aspect of histone metabolism and establishes lipid droplets as functional storage sites for unstable or detrimental proteins.

PubMed ID
PubMed Central ID
PMC3513403 (PMC) (EuropePMC)
Related Publication(s)
Supplementary material
Note

Histones: sequestered by jabba in Fatty storehouse.
Marzluff and Tatomer, 2012, Curr. Biol. 22(22): R951--R953 [FBrf0219994]

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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Curr. Biol.
    Title
    Current Biology
    Publication Year
    1991-
    ISBN/ISSN
    0960-9822
    Data From Reference
    Aberrations (1)
    Alleles (7)
    Genes (12)
    Physical Interactions (1)
    Cell Lines (1)
    Insertions (2)
    Transgenic Constructs (2)