3546–3562 Nucleic Acids Research, 2015, Vol. 43, No. 7 Published online 16 March 2015 doi: 10.1093/nar/gkv211 Invadolysin acts genetically via the SAGA complex to modulate chromosome structure Shubha Gururaja Rao†, Michal M. Janiszewski†, Edward Duca, Bryce Nelson, Kanishk Abhinav, Ioanna Panagakou, Sharron Vass and Margarete M.S. Heck*
University of Edinburgh, Queen’s Medical Research Institute, University/BHF Centre for Cardiovascular Science, 47 Little France Crescent, Edinburgh EH16 4TJ, UK
Received December 13, 2012; Revised February 26, 2015; Accepted February 28, 2015 Downloaded from https://academic.oup.com/nar/article/43/7/3546/2414574 by guest on 04 October 2021
ABSTRACT (gcn5, ada2b and sgf11) all suppress an invadolysin- induced rough eye phenotype. We conclude that Identification of components essential to chromo- the abnormal chromosome phenotype of invadolysin some structure and behaviour remains a vibrant mutants is likely the result of disrupting the histone area of study. We have previously shown that in- modification cycle, as accumulation of ubH2B and vadolysin is essential in Drosophila, with roles in cell H3K4me3 is observed. We further suggest that the division and cell migration. Mitotic chromosomes mislocalization of ubH2B to the cytoplasm has ad- are hypercondensed in length, but display an aber- ditional consequences on downstream components rant fuzzy appearance. We additionally demonstrated essential for chromosome behaviour. We therefore that in human cells, invadolysin is localized on the propose that invadolysin plays a crucial role in chro- surface of lipid droplets, organelles that store not mosome organization via its interaction with the only triglycerides and sterols but also free histones SAGA complex. H2A, H2Av and H2B. Is there a link between the storage of histones in lipid droplets and the aber- rantly structured chromosomes of invadolysin mu- INTRODUCTION tants? We have identified a genetic interaction be- The visible changes that chromosomes undergo through the tween invadolysin and nonstop, the de-ubiquitinating cell cycle have been the subject of intense cytological anal- protease component of the SAGA (Spt-Ada-Gcn5- ysis for over a century. Recently, many powerful techniques acetyltransferase) chromatin-remodelling complex. have been brought to bear on the subject of the reversible cy- invadolysin and nonstop mutants exhibit pheno- cle of chromosome condensation and decondensation. Bio- typic similarities in terms of chromosome struc- chemical, physical, genetic and cell biological approaches ture in both diploid and polyploid cells. Further- have all served to identify a myriad of structural and regu- more, IX-141/not1 transheterozygous animals accu- latory components whose detailed roles are still being elu- cidated (1). mulate mono-ubiquitinated histone H2B (ubH2B) and Chromatin condensation is particularly evident during histone H3 tri-methylated at lysine 4 (H3K4me3). mitosis and apoptosis, whereas chromatin relaxation is as- 1/ 1 Whole mount immunostaining of IX-14 not tran- sociated with transcription, replication, repair and recombi- sheterozygous salivary glands revealed that ubH2B nation (2). Post-translational modifications of histones, e.g. accumulates surprisingly in the cytoplasm, rather acetylation, methylation, phosphorylation and ubiquitina- than the nucleus. Over-expression of the Bre1 ubiq- tion, play key roles in chromatin dynamics (3,4). Acetyla- uitin ligase phenocopies the effects of mutating tion of histones is generally associated with ‘relaxing’ or either the invadolysin or nonstop genes. Intrigu- opening chromatin in order to support the access of tran- ingly, nonstop and mutants of other SAGA subunits scriptional machinery to genomic loci (5). In contrast, hi- stone methylation and ubiquitination have been linked to
*To whom correspondence should be addressed. Email: [email protected] †These authors contributed equally to the paper as first authors. Present addresses: Shubha Gururaja Rao, Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA. Michal M. Janiszewski, Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7, 30–387, Krakow 31-007 Krakow, Poland. Edward Duca, University of Malta, Msida, MSD 2080, Malta. Bryce Nelson, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA. Sharron Vass, Edinburgh Napier University, Edinburgh EH11 4BN, UK.