Murphy Samantha, Martin Sally, Parton Robert G
Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia.
Biochim Biophys Acta. 2009 Jun;1791(6):441-7. doi: 10.1016/j.bbalip.2008.07.004. Epub 2008 Jul 30.
Lipid droplets (LDs) are key cellular organelles involved in lipid storage and mobilisation. While the major signalling cascades and many of the regulators of lipolysis have been identified, the cellular interactions involved in lipid mobilisation and release remain largely undefined. In non-adipocytes, LDs are small, mobile and interact with other cellular compartments. In contrast, adipocytes primarily contain very large, immotile LDs. The striking morphological differences between LDs in adipocytes and non-adipocytes suggest that key differences must exist in the manner in which LDs in different cell types interact with other organelles. Recent studies have highlighted the complexity of LD interactions, which can be both homotypic, with each other, and heterotypic, with other organelles. The molecules involved in these interactions are also now emerging, including Rab proteins, key regulators of membrane traffic, and caveolin, an integral membrane protein providing a functional link between the cell surface and LDs. Here we summarise recent insights into the cell biology of the LD particularly focussing on the homotypic and heterotypic interactions in both adipocytes and non-adipocytes. We speculate that these interactions may involve inter-organelle membrane contact sites or a hemi-fusion type mechanism to facilitate lipid transfer.
脂滴（LDs）是参与脂质储存和动员的关键细胞器。虽然主要的信号级联反应和许多脂解调节因子已被确定，但脂质动员和释放所涉及的细胞间相互作用在很大程度上仍不明确。在非脂肪细胞中，脂滴较小、可移动，并与其他细胞区室相互作用。相比之下，脂肪细胞主要含有非常大且不移动的脂滴。脂肪细胞和非脂肪细胞中脂滴显著的形态差异表明，不同细胞类型中的脂滴与其他细胞器相互作用的方式必然存在关键差异。最近的研究强调了脂滴相互作用的复杂性，这种相互作用既可以是同型的（脂滴之间相互作用），也可以是异型的（与其他细胞器相互作用）。参与这些相互作用的分子也正在出现，包括Rab蛋白（膜运输的关键调节因子）和小窝蛋白（一种整合膜蛋白，在细胞表面和脂滴之间提供功能联系）。在这里，我们总结了对脂滴细胞生物学的最新见解，特别关注脂肪细胞和非脂肪细胞中的同型和异型相互作用。我们推测，这些相互作用可能涉及细胞器间膜接触位点或半融合型机制以促进脂质转移。
