Motley Alison M, Hettema Ewald H
Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, England, UK.
J Cell Biol. 2007 Jul 30;178(3):399-410. doi: 10.1083/jcb.200702167. Epub 2007 Jul 23.
Peroxisomes can arise de novo from the endoplasmic reticulum (ER) via a maturation process. Peroxisomes can also multiply by fission. We have investigated how these modes of multiplication contribute to peroxisome numbers in Saccharomyces cerevisiae and the role of the dynamin-related proteins (Drps) in these processes. We have developed pulse-chase and mating assays to follow the fate of existing peroxisomes, de novo-formed peroxisomes, and ER-derived preperoxisomal structures. We find that in wild-type (WT) cells, peroxisomes multiply by fission and do not form de novo. A marker for the maturation pathway, Pex3-GFP, is delivered from the ER to existing peroxisomes. Strikingly, cells lacking peroxisomes as a result of a segregation defect do form peroxisomes de novo. This process is slower than peroxisome multiplication in WT cells and is Drp independent. In contrast, peroxisome fission is Drp dependent. Our results show that peroxisomes multiply by growth and division under our assay conditions. We conclude that the ER to peroxisome pathway functions to supply existing peroxisomes with essential membrane constituents.
过氧化物酶体可以通过成熟过程从内质网（ER）重新产生。过氧化物酶体也可以通过分裂进行增殖。我们研究了这些增殖方式如何影响酿酒酵母中过氧化物酶体的数量，以及动力蛋白相关蛋白（Drps）在这些过程中的作用。我们开发了脉冲追踪和交配试验，以追踪现有过氧化物酶体、新形成的过氧化物酶体和内质网衍生的过氧化物酶体前体结构的命运。我们发现，在野生型（WT）细胞中，过氧化物酶体通过分裂进行增殖，而不是重新形成。成熟途径的一个标志物Pex3-GFP从内质网传递到现有的过氧化物酶体。引人注目的是，由于分离缺陷而缺乏过氧化物酶体的细胞确实会重新形成过氧化物酶体。这个过程比野生型细胞中的过氧化物酶体增殖要慢，并且不依赖于Drp。相比之下，过氧化物酶体分裂依赖于Drp。我们的结果表明，在我们的试验条件下，过氧化物酶体通过生长和分裂进行增殖。我们得出结论，内质网到过氧化物酶体的途径起到为现有过氧化物酶体提供必需膜成分的作用。
