Conservation of Mhc Class III Region Synteny Between Zebrafish and Human as Determined by Radiation Hybrid Mapping This information is current as Holger Sültmann, Akie Sato, Brent W. Murray, Naoko of October 2, 2021. Takezaki, Robert Geisler, Gerd-Jörg Rauch and Jan Klein J Immunol 2000; 165:6984-6993; ; doi: 10.4049/jimmunol.165.12.6984 http://www.jimmunol.org/content/165/12/6984 Downloaded from References This article cites 59 articles, 15 of which you can access for free at: http://www.jimmunol.org/content/165/12/6984.full#ref-list-1 http://www.jimmunol.org/ Why The JI? Submit online. • Rapid Reviews! 30 days* from submission to initial decision • No Triage! Every submission reviewed by practicing scientists • Fast Publication! 4 weeks from acceptance to publication *average by guest on October 2, 2021 Subscription Information about subscribing to The Journal of Immunology is online at: http://jimmunol.org/subscription Permissions Submit copyright permission requests at: http://www.aai.org/About/Publications/JI/copyright.html Email Alerts Receive free email-alerts when new articles cite this article. Sign up at: http://jimmunol.org/alerts The Journal of Immunology is published twice each month by The American Association of Immunologists, Inc., 1451 Rockville Pike, Suite 650, Rockville, MD 20852 Copyright © 2000 by The American Association of Immunologists All rights reserved. Print ISSN: 0022-1767 Online ISSN: 1550-6606. Conservation of Mhc Class III Region Synteny Between Zebrafish and Human as Determined by Radiation Hybrid Mapping1 Holger Su¨ltmann,2* Akie Sato,* Brent W. Murray,* Naoko Takezaki,† Robert Geisler,‡ Gerd-Jo¨rg Rauch,‡ and Jan Klein3* In the HLA, H2, and other mammalian Mhc, the class I and II loci are separated by the so-called class III region comprised of ϳ60 genes that are functionally and evolutionarily unrelated to the class I/II genes. To explore the origin of this island of unrelated loci in the middle of the Mhc 19 homologues of HLA class III genes, we identified 19 homologues of HLA class III genes as well as 21 additional non-class I/II HLA homologues in the zebrafish and mapped them by testing a panel of 94 zebrafish-hamster radiation hybrid cell lines. Six of the HLA class III and eight of the flanking homologues were found to be linked to the zebrafish class I (but not class II) loci in linkage group 19. The remaining homologous loci were found to be scattered over 14 zebrafish linkage groups. Downloaded from The linkage group 19 contains at least 25 genes (not counting the class I loci) that are also syntenic on human chromosome 6. This gene assembly presumably represents the pre-Mhc that existed before the class I/II genes arose. The pre-Mhc may not have contained the complement and other class III genes involved in immune response. The Journal of Immunology, 2000, 165: 6984–6993. lthough all jawed vertebrates possess an Mhc, our views tion of peptides acquired in the endoplasmic reticulum (ER),4 and of it have been forged by two mammalian systems, the the class II molecules to the presentation of peptides procured in http://www.jimmunol.org/ A human HLA and the mouse H2 complexes (1, 2). The the endosomal compartment (5). remarkable similarity of the HLA and H2 complexes (3) has kin- However, the presence of the class III genes in the region sep- dled the expectation that the Mhc of all vertebrates would be or- arating the class I and class II parts of the complex has always been ganized in a similar way to those of the human and the mouse. For somewhat puzzling (3, 8). Most of the class III genes are neither some time, this expectation seemed to be borne out by studies of functionally nor evolutionarily related to one another. They are a other species, albeit mostly other mammals (4). Like the HLA and variegated assortment of elements that do not seem to have any the H2 complexes, the Mhcs of these other species could be shown particular reason to be together with one another or with the class to constitute a single chromosomal segment divisible, rather arbi- I and class II loci. A justification for their presence in the vicinity by guest on October 2, 2021 trarily, into three regions, ensconced by three different classes of of class I and II loci has been sought in the involvement of some loci, the class I and class II regions taking up the flanks and the of them in immunity. However, this argument always seemed class III region the center. The class I and II loci comprise the core rather weak for three reasons. First, the class III region contains of the Mhc and, with their involvement in peptide presentation (5), several loci for which there is no evidence for involvement in provide functional and evolutionary identity to the chromosomal immunity. Second, for the loci that are involved in immunity, no segment they occupy. Their organization and sequence, as well as compelling reason has been provided for their linkage to the class the structure of the molecules they encode, leave no doubt that the I and II loci. And third, with the large number of loci involved in genes in each of the two classes are related to one another by their immune responses, it is to be expected that almost any region of origin (6). Nor has there ever been any doubt expressed that the the genome will, by chance, contain some of them. class I and class II genes are derived from a common ancestor (7, The existence and composition of the class III region are not the 8). The existing differences between the genes and their products only seemingly illogical features of the HLA/H2 organization. An- are generally interpreted as being the result of an adaptation to other such feature concerns the genes participating in the produc- slightly different functions, the class I molecules to the presenta- tion of peptides for loading onto the class I molecules. The bulk of these peptides is derived from cytosolic proteins processed by pro- *Max-Planck-Institut fu¨r Biologie, Abteilung Immungenetik, Tu¨bingen, Germany; teasomes (5). The peptides thus produced are then transported †The Graduate University for Advanced Studies, Department of Biosystems Science, across the ER membrane and on the lumenal side loaded into the Hayama, Kanagawa, Japan; and ‡Max-Planck-Institut fu¨r Entwicklungsbiologie, Tu¨- peptide-binding groove of the newly synthesized class I molecules. bingen, Germany Some of the proteasome components, the ER transporters, and the Received for publication July 6, 2000. Accepted for publication September 12, 2000. molecules involved in the loading are encoded in genes (PSMB, The costs of publication of this article were defrayed in part by the payment of page ABCB or TAP, and TAPBP, respectively) that reside in the charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. HLA/H2 complexes. This arrangement makes sense, for one can 1 This work was supported in part by a grant from the Deutsches Humangenomprojekt argue that the genes must either coevolve with the class I genes or (to R.G. and G.-J.R.). their expression must be coordinated with that of these genes (4). 2 Address correspondence requests to Dr. Holger Su¨ltmann, Deutsches Krebsfors- The illogical aspect of this arrangement is that the PSMB, ABCB, chungszentrum, Im Neuenheimer Feld 506, D-69120 Heidelberg, Germany. E-mail address: [email protected] 3 Address reprint requests to Dr. Jan Klein, Max-Planck-Institut fu¨r Biologie, Abtei- 4 Abbreviations used in this paper: ER, endoplasmic reticulum; EST, expressed se- lung Immungenetik, Corrensstrasse 42, D-72076 Tu¨bingen, Germany. E-mail ad- quence tag; PAC, P1-derived artificial chromosome; YAC, yeast artificial dress: [email protected] chromosome. Copyright © 2000 by The American Association of Immunologists 0022-1767/00/$02.00 The Journal of Immunology 6985 and TAPBP genes are found in the class II rather than the class I finding seems to explain one illogical aspect of the HLA/H2 orga- region. nization. The present study has been aimed at shedding light on the More recently, evidence has accumulated that the HLA/H2 par- puzzle of the class III region and so on the other seemingly illog- adigm of Mhc organization has many exceptions, even in mam- ical feature of the Mhc organization. mals. For example, in cattle, a chromosomal segment bearing a part of the class II region has been inverted so that some of the Materials and Methods class II genes are now at a distance of Ͼ17 cM from the main body PCR, subcloning, and sequencing of the Mhc (9–11). In the rabbit, to give another example, the class III region has apparently been transposed to an unidentified loca- PCR amplifications (22) were conducted in 25 or 50 ␮l of reaction mixture using the MJ Research PTC-100 Programmable Thermal Controller (MJ tion, and the class I and class II regions have become directly ϫ Research, Watertown, MA), 1 reaction buffer containing 1.5 mM MgCl2, adjacent (12). Even greater departures from the HLA/H2 norm 100 ␮M of each of the four deoxynucleosidtriphosphates, 0.5–1 ␮Mof have been found when studies of Mhc organization have been ex- each of the sense and antisense primers (Table I),1UofTaq DNA poly- tended to nonmammalian gnathostomes. Thus, in the domestic merase (Amersham Pharmacia Biotech, Freiburg, Germany) or HotStar fowl, the entire Mhc segment has been reduced in length to ϳ100 Taq DNA polymerase (Qiagen, Hilden, Germany), and 20–100 ng of tem- plate DNA.