title: Identification of replication-dependent and replication-independent linker histone complexes: Tpr specifically promotes replication-dependent linker histone stability.
abstract: BACKGROUND
  There are 11 variants of linker histone H1 in mammalian cells. Beyond their shared abilities to stabilize and condense chromatin, the H1 variants have been found to have non-redundant functions, the mechanisms of which are not fully understood. Like core histones, there are both replication-dependent and replication-independent linker histone variants. The histone chaperones and other factors that regulate linker histone dynamics in the cell are largely unknown. In particular, it is not known whether replication-dependent and replication-independent linker histones interact with distinct or common sets of proteins. To better understand linker histone dynamics and assembly, we used chromatography and mass spectrometry approaches to identify proteins that are associated with replication-dependent and replication-independent H1 variants. We then used a variety of in vivo analyses to validate the functional relevance of identified interactions.
  
  
  RESULTS
  We identified proteins that bind to all linker histone variants and proteins that are specific for only one class of variant. The factors identified include histone chaperones, transcriptional regulators, RNA binding proteins and ribosomal proteins. The nuclear pore complex protein Tpr, which was found to associate with only replication-dependent linker histones, specifically promoted their stability.
  
  
  CONCLUSIONS
  Replication-dependent and replication-independent linker histone variants can interact with both common and distinct sets of proteins. Some of these factors are likely to function as histone chaperones while others may suggest novel links between linker histones and RNA metabolism. The nuclear pore complex protein Tpr specifically interacts with histone H1.1 and H1.2 but not H1x and can regulate the stability of these replication-dependent linker histones.
authors.affiliation: Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA.
authors.forename: Pei
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, 43210, USA.
authors.forename: Owen E
authors.initials: OE
authors.lastname: Branson
authors.affiliation: Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, 43210, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Freitas
authors.affiliation: Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, 43210, USA. parthun.1@osu.edu.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Parthun
mesh_terms: D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism; D056488:Histone Chaperones / Q000737:chemistry / Q000378:metabolism; D006657:Histones / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008856:Microscopy, Fluorescence; D028861:Nuclear Pore Complex Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D002843:Chromatin; D056488:Histone Chaperones; D006657:Histones; D028861:Nuclear Pore Complex Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C073597:TPR protein, human
keywords: Chromatin; H1; Histone; Histone chaperone; Linker histone; Tpr