scholarly journals Developmental Separation of V(D)J Recombinase Expression and Initiation of IgH Recombination in B Lineage Progenitors In Vivo

2004 ◽  
Vol 199 (4) ◽  
pp. 483-489 ◽  
Author(s):  
Lisa Borghesi ◽  
Rachel M. Gerstein
Keyword(s):  
Chromatin Remodeling ◽  
Heavy Chain ◽  
Immunoglobulin Heavy Chain ◽  
Stages Of Development ◽  
Regulated Expression ◽  
B Lineage

In B lineage progenitors, V(D)J recombination occurs only during distinct stages of development and is restricted to immunoglobulin loci. This process is thought to be controlled by both regulated expression of the V(D)J recombinase and by limited accessibility of target loci to the recombinase complex. However, it is unknown whether these two processes occur concomitantly in developing B lineage progenitors or whether these events are temporally distinct and, therefore, potentially independently regulated. To distinguish between these possibilities, we developed a transgenic V(D)J recombination substrate that is not governed by the same chromatin remodeling constraints as endogenous immunoglobulin heavy chain (IgH) loci and examined the requirements for V(D)J recombination to initiate in early B lineage progenitors. We find that single B lineage precursors express an active V(D)J recombinase in vivo before the stage when IgH rearrangements are frequently detectable. Our results indicate that the onset of recombinase activity and the initiation of IgH recombination are developmentally distinct events in the B lineage.

scholarly journals Extreme genomic volatility characterizes the evolution of the immunoglobulin heavy chain locus in cyprinodontiform fishes

2020 ◽  
Vol 287 (1927) ◽  
pp. 20200489 ◽  
Author(s):  
William J. Bradshaw ◽  
Dario Riccardo Valenzano
Keyword(s):  
Immune System ◽  
Heavy Chain ◽  
Genomic Structure ◽  
Adaptive Immune System ◽  
Immunoglobulin Heavy Chain ◽  
Systematic Investigation ◽  
Splice Isoforms ◽  
Diverse Range ◽  
Adaptive Immune

The evolution of the adaptive immune system has provided vertebrates with a uniquely sophisticated immune toolkit, enabling them to mount precise immune responses against a staggeringly diverse range of antigens. Like other vertebrates, teleost fishes possess a complex and functional adaptive immune system; however, our knowledge of the complex antigen-receptor genes underlying its functionality has been restricted to a small number of experimental and agricultural species, preventing systematic investigation into how these crucial gene loci evolve. Here, we analyse the genomic structure of the immunoglobulin heavy chain ( IGH ) gene loci in the cyprinodontiforms, a diverse and important group of teleosts present in many different habitats across the world. We reconstruct the complete IGH loci of the turquoise killifish ( Nothobranchius furzeri ) and the southern platyfish ( Xiphophorus maculatus ) and analyse their in vivo gene expression, revealing the presence of species-specific splice isoforms of transmembrane IGHM . We further characterize the IGH constant regions of 10 additional cyprinodontiform species, including guppy, Amazon molly, mummichog and mangrove killifish. Phylogenetic analysis of these constant regions suggests multiple independent rounds of duplication and deletion of the teleost-specific antibody class IGHZ in the cyprinodontiform lineage, demonstrating the extreme volatility of IGH evolution. Focusing on the cyprinodontiforms as a model taxon for comparative evolutionary immunology, this work provides novel genomic resources for studying adaptive immunity and sheds light on the evolutionary history of the adaptive immune system.

scholarly journals Intracellular dissociation and reassembly of prolyl 4-hydroxylase:the α-subunits associated with the immunoglobulin-heavy-chain binding protein (BiP) allowing reassembly with the β-subunit

1996 ◽  
Vol 317 (3) ◽  
pp. 659-665 ◽  
Author(s):  
David C. A. JOHN ◽  
Neil J. BULLEID
Keyword(s):  
Heavy Chain ◽  
Binding Protein ◽  
Immunoglobulin Heavy Chain ◽  
Β Subunit ◽  
Intact Cells ◽  
Α Subunit ◽  
Free System ◽  
A Cell ◽  
Α Subunits

Prolyl 4-hydroxylase (P4-H) consists of two distinct polypeptides; the catalytically more important α-subunit and the β-subunit, which is identical to the multifunctional enzyme protein disulphide isomerase. The enzyme appears to be assembled in vivo into an α2β2 tetramer from newly synthesized α-subunits associating with an endogenous pool of β-subunits. Using a cell-free system, we have shown previously that enzyme assembly is redox-dependent and that assembled α-subunits are intramolecularly disulphide-bonded [John and Bulleid (1994) Biochemistry 33, 14018–14025]. Here we have studied this assembly process within intact cells by expressing both subunits in COS-1 cells. Newly synthesized α-subunits were shown to assemble with the β-subunit, to form insoluble aggregates, or to remain soluble but not associate with the β-subunit. Treatment of cells with dithiothreitol (DTT) led to dissociation of P4-H into subunits and on removal of DTT the enzyme reassembled. This reassembly was ATP-dependent, suggesting an interaction with an ATP-dependent chaperone. This was confirmed when immunoglobulin-heavy-chain binding protein (BiP) and α-subunits were co-immunoprecipitated with antibodies against the α-subunit and BiP, respectively. These results indicate that unassembled α-subunits are maintained in an assembly-competent form by interacting with the molecular chaperone BiP.

scholarly journals VH gene rearrangement events can modify the immunoglobulin heavy chain during progression of B-lineage acute lymphoblastic leukemia [see comments]

Blood ◽  
1992 ◽  
Vol 79 (1) ◽  
pp. 223-228 ◽  
Author(s):  
R Wasserman ◽  
M Yamada ◽  
Y Ito ◽  
LR Finger ◽  
BA Reichard ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Gene Rearrangement ◽  
Residual Disease ◽  
Lymphoblastic Leukemia ◽  
Immunoglobulin Heavy Chain ◽  
Gene Replacement ◽  
Vh Gene ◽  
Polymerase Chain ◽  
B Lineage ◽  
Complementarity Determining Region

The presence of multiple VHDJH joinings in upwards of 30% of acute lymphoblastic leukemias (ALL) suggests a relative instability of the rearranged immunoglobulin heavy chain (IgH) gene, but the mechanisms involved are not completely understood. An investigation of the structure of the VHDJH joinings using complementarity determining region (CDR)3 polymerase chain reaction (PCR) in 12 leukemias at both diagnosis and relapse indicates that this instability may increase as a function of time. In only one of seven cases in which relapse occurred within 3 years from diagnosis was a new VHDJH joining identified and this coexisted with the original diagnostic joining. Most strikingly, new VHDJH joinings were identified in four of five cases in which relapse occurred more than 5 years from diagnosis. In this latter population, the instability of the joinings was generated from VH----VH gene replacement events in two cases, since the new joinings retained the original DJH sequences and partial N region homology at the VHD junction, and probably in a third case from a VH gene rearrangement to a common DJH precursor. Furthermore, in five of 23 (21.7%) additional cases studied at diagnosis, subclones were identified that had similar modifications of the VH-N region. These data indicate that VH gene replacement events and VH gene rearrangements to a common DJH joining contribute to the instability of the VHDJH joining in ALL. This phenomenon should be taken into consideration in those methodologies that exploit IgH rearrangements for detection of minimal residual disease.

VH gene rearrangement events can modify the immunoglobulin heavy chain during progression of B-lineage acute lymphoblastic leukemia [see comments]

Blood ◽  
1992 ◽  
Vol 79 (1) ◽  
pp. 223-228 ◽  
Author(s):  
R Wasserman ◽  
M Yamada ◽  
Y Ito ◽  
LR Finger ◽  
BA Reichard ◽  
...  
Keyword(s):  
Heavy Chain ◽  
Gene Rearrangement ◽  
Residual Disease ◽  
Lymphoblastic Leukemia ◽  
Immunoglobulin Heavy Chain ◽  
Gene Replacement ◽  
Vh Gene ◽  
Polymerase Chain ◽  
B Lineage ◽  
Complementarity Determining Region

Abstract The presence of multiple VHDJH joinings in upwards of 30% of acute lymphoblastic leukemias (ALL) suggests a relative instability of the rearranged immunoglobulin heavy chain (IgH) gene, but the mechanisms involved are not completely understood. An investigation of the structure of the VHDJH joinings using complementarity determining region (CDR)3 polymerase chain reaction (PCR) in 12 leukemias at both diagnosis and relapse indicates that this instability may increase as a function of time. In only one of seven cases in which relapse occurred within 3 years from diagnosis was a new VHDJH joining identified and this coexisted with the original diagnostic joining. Most strikingly, new VHDJH joinings were identified in four of five cases in which relapse occurred more than 5 years from diagnosis. In this latter population, the instability of the joinings was generated from VH----VH gene replacement events in two cases, since the new joinings retained the original DJH sequences and partial N region homology at the VHD junction, and probably in a third case from a VH gene rearrangement to a common DJH precursor. Furthermore, in five of 23 (21.7%) additional cases studied at diagnosis, subclones were identified that had similar modifications of the VH-N region. These data indicate that VH gene replacement events and VH gene rearrangements to a common DJH joining contribute to the instability of the VHDJH joining in ALL. This phenomenon should be taken into consideration in those methodologies that exploit IgH rearrangements for detection of minimal residual disease.

scholarly journals Interruption of two immunoglobulin heavy-chain switch regions in murine plasmacytoma P3.26Bu4 by insertion of retroviruslike element ETn.

1987 ◽  
Vol 7 (4) ◽  
pp. 1364-1370 ◽  
Author(s):  
B Shell ◽  
P Szurek ◽  
W Dunnick
Keyword(s):  
Heavy Chain ◽  
Immunoglobulin Heavy Chain ◽  
Chain Gene ◽  
Heavy Chain Gene ◽  
Immunoglobulin Heavy Chain Gene ◽  
Genetic Elements ◽  
Somatic Recombination ◽  
Switch Regions ◽  
B Lineage ◽  
B Lineage Cells

A number of moderately reiterated murine genetic elements have been shown to have structures like those of retroviral proviruses. These elements are thought to be transposons, although little evidence of their transposability exists. Two members of one of these families of reiterated elements, the ETn family, have inserted into separate immunoglobulin heavy-chain switch regions in the plasmacytoma P3.26Bu4. Switch regions are those DNA segments associated with each immunoglobulin heavy-chain gene in which the somatic recombinations that accompany the heavy-chain switch occur. This role in somatic recombination may be relevant to the ETn insertions into the switch regions in P3.26Bu4 DNA. P3.26Bu4 and a number of other B-lineage cells contain ETn transcripts.

scholarly journals Extreme genomic volatility characterises the evolution of the immunoglobulin heavy chain locus in teleost fishes

2019 ◽  
Author(s):  
William J. Bradshaw ◽  
Dario Riccardo Valenzano
Keyword(s):  
Immune System ◽  
Heavy Chain ◽  
Genomic Structure ◽  
Adaptive Immune System ◽  
Immunoglobulin Heavy Chain ◽  
Teleost Fishes ◽  
Splice Isoforms ◽  
Diverse Range ◽  
Adaptive Immune

AbstractThe evolution of the adaptive immune system has provided vertebrates with a uniquely sophisticated immune toolkit, enabling them to mount precise immune responses against a staggeringly diverse range of antigens. Like other vertebrates, teleost fishes possess a complex and functional adaptive immune system; however, our knowledge of the complex antigen-receptor genes underlying its functionality has been restricted to a small number of experimental and agricultural species, preventing a systematic investigation of how these crucial gene loci evolve. Here, we analyse the genomic structure of the immunoglobulin heavy chain (IGH) gene loci in the cyprinodontiforms, a diverse and important group of teleosts present in many different habitats across the world. We reconstruct the complete IGH loci of the turquoise killifish (Nothobranchius furzeri) and the southern platyfish (Xiphophorus maculatus) and analyse their in vivo gene expression, revealing the presence of species-specific splice isoforms of transmembrane IGHM. We further characterise the IGH constant regions of ten additional cyprinodontiform species, including guppy, amazon molly, mummichog and mangrove killifish. Phylogenetic analysis of these constant regions reveals multiple independent rounds of duplication and deletion of the teleost-specific antibody class IGHZ in the cyprinodontiform lineage, demonstrating the extreme volatility of IGH evolution. Focusing on the cyprinodontiforms as a model taxon for comparative evolutionary immunology, this work provides novel genomic resources for studying adaptive immunity and sheds light on the evolutionary history of the adaptive immune system.

scholarly journals Immunoglobulin heavy chain and binding protein complexes are dissociated in vivo by light chain addition.

1990 ◽  
Vol 111 (3) ◽  
pp. 829-837 ◽  
Author(s):  
L M Hendershot
Keyword(s):  
Heavy Chain ◽  
Light Chain ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Protein Complexes ◽  
Binding Protein ◽  
Immunoglobulin Heavy Chain ◽  
Light Chains ◽  
Heavy Chains

Immunoglobulin heavy chain binding protein (BiP, GRP78) associates stably with the free, nonsecreted Ig heavy chains synthesized by Abelson virus transformed pre-B cell lines. In cells synthesizing both Ig heavy and light chains, the Ig subunits assemble rapidly and are secreted. Only incompletely assembled Ig molecules can be found bound to BiP in these cells. In addition to Ig heavy chains, a number of mutant and incompletely glycosylated transport-defective proteins are stably complexed with BiP. When normal proteins are examined for combination with BiP, only a small fraction of the intracellular pool of nascent, unfolded, or unassembled proteins can be found associated. It has been difficult to determine whether these BiP-associated molecules represent assembly intermediates which will be displaced from BiP and transported from the cell, or whether these are aberrant proteins that are ultimately degraded. In order for BiP to monitor and aid in normal protein transport, its association with these proteins must be reversible and the released proteins should be transport competent. In the studies described here, transient heterokaryons were formed between a myeloma line producing BiP-associated heavy chains and a myeloma line synthesizing the complementary light chain. Introduction of light chain synthesis resulted in assembly of prelabeled heavy chains with light chains, displacement of BiP from heavy chains, and secretion of Ig into the culture supernatant. These data demonstrate that BiP association can be reversible, with concordant release of transportable proteins. Thus, BiP can be considered a component of the exocytic secretory pathway, regulating the transport of both normal and abnormal proteins.

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