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Sun B, Mallampati S, Gong Y, Wang D, Lefebvre V, Sun X. Sox4 is required for the survival of pro-B cells. THE JOURNAL OF IMMUNOLOGY 2013; 190:2080-9. [PMID: 23345330 DOI: 10.4049/jimmunol.1202736] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The development of mature B cells from hematopoietic stem cells is a strictly orchestrated process involving multiple regulatory genes. The transcription factor Sox4 is required for this process, but its role has not been systematically studied, and the underlying mechanisms remain unknown. To determine when and how Sox4 functions in the stepwise process of B cell development, we used mice harboring conditional null alleles for Sox4 and a Cre transgene. Sox4 deletion in hematopoietic stem cells almost entirely eliminated pro-B cells in both fetal livers and adult bone marrow, resulting in a severe deficiency in later stage B cells, including circulating mature B cells. Sox4-deficient pro-B cells, particularly those expressing the stem cell factor receptor c-Kit, readily underwent apoptosis, and even more so when c-Kit activity was inhibited by imatinib. C-Kit-expressing pro-B cells showed decreased activation of the c-Kit downstream protein Src upon Sox4 deletion. Likewise, the level of the anti-apoptotic Bcl2 protein was decreased in residual pro-B cells, and its restoration using a Bcl2 transgene allowed not only partial rescue of pro-B cell survival but also B cell maturation in the absence of Sox4. Our findings indicate that Sox4 is required for the survival of pro-B cells and may functionally interact with c-Kit and Bcl2.
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Affiliation(s)
- Baohua Sun
- Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Key developmental transitions in human germinal center B cells are revealed by differential CD45RB expression. Blood 2008; 113:3999-4007. [PMID: 19059880 DOI: 10.1182/blood-2008-03-145979] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously reported that RO(+) expression correlated with increased mutation, activation, and selection among human germinal center (GC) B cells. Here, we subdivided human tonsillar B cells, including IgD(-)CD38(+) GC B cells, into different fractions based on RB expression. Although each subset contained RB(+) cells, when used as an intrasubset marker, differential RB expression effectively discriminated between phenotypically distinct cells. For example, RB(+) GC B cells were enriched for activated cells with lower AID expression. RB inversely correlated with mutation frequency, demonstrating a key difference between RB- and RO-expressing GC B cells. Reduced RB expression during the transition from pre-GC (IgM(+)IgD(+)CD38(+)CD27(-)) to GCB cells was followed by a dramatic increase during the GC-to-plasmablast (IgD(-)CD38(++)CD27(+)) and memory (IgD(-)CD38(-)CD27(+)) transition. Interestingly, RB(+) GC B cells showed increased signs of terminal differentiation toward CD27(+) post-GC early plasmablast (increased CD38 and RO) or early memory (decreased CD38 and RO) B cells. We propose that as in T cells, differential RB expression directly correlates with development- and function-based transitions in tonsillar B cells. Application of this RB:RO system should advance our understanding of normal B-cell development and facilitate the isolation of more discrete B-cell populations with potentially different propensities in disease pathogenesis.
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Affiliation(s)
- Stephen M Jackson
- Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA
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Jackson SM, Harp N, Patel D, Henderson M, Roy NM, Courtney MA, Johnson A, Capra JD. CD45RO: A Marker for BCR-mediated Selection. Scand J Immunol 2007; 66:249-60. [PMID: 17635802 DOI: 10.1111/j.1365-3083.2007.01985.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We previously showed that IgH sequence alone minimally influenced germinal centre (GC) B-cell survival fate. As end-stage effector B cells are typically more mutated than founder GC B cells, we worked to develop an assay that would enrich for populations of GC B cells with progressively increasing numbers of somatic mutations, which could potentially be used as an indicator of positive selection. We targeted CD45 as it has been shown to influence activation-induced cytidine deaminase (AID) expression. In this study, anti-CD77 and anti-CD45RO (RO) were used to subdivide CD19(+)IgD(-)CD38(+)CD77(+) centroblasts (CB) and CD19(+)IgD(-)CD38(+)CD77(-) centrocytes (CC) into three contiguous RO fractions (RO(-), RO(+/-) and RO(+)) and assessed whether mutation frequency and characteristics associated with selection varied with respect to increasing RO expression. Here, we show that the average number of mutations per IgV(H)4 transcript increased concordantly with RO for CC, but not for CB. CC also exhibited an RO-associated increase in replacement mutations. Comparative analysis of clonally related sequences revealed that increased mutations were not due to the exclusive persistence of surface RO on highly mutated cells. RO-expressing CC and CB pools showed increased signs of activation (CD69(+)) and were enriched for surface Ig(+) cells. BCR-crosslinking induced a significant increase in surface RO on total tonsillar and GC B cells, which collectively suggests that the RO-associated increase in mutations is attributable, at least in part, to the cycling of cells that may have recently undergone BCR-mediated selection, or are potentially in developmental transition between CC and CB stages.
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Affiliation(s)
- S M Jackson
- Molecular Immunogenetics Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Jackson SM, Harp N, Patel D, Zhang J, Willson S, Kim YJ, Clanton C, Capra JD. CD45RO enriches for activated, highly mutated human germinal center B cells. Blood 2007; 110:3917-25. [PMID: 17644737 PMCID: PMC2190611 DOI: 10.1182/blood-2007-05-087767] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
To date, there is no consensus regarding the influence of different CD45 isoforms during peripheral B-cell development. Examining correlations between surface CD45RO expression and various physiologic processes ongoing during the germinal center (GC) reaction, we hypothesized that GC B cells, like T cells, that up-regulate surface RO should progressively acquire phenotypes commonly associated with activated, differentiating lymphocytes. GC B cells (IgD(-)CD38(+)) were subdivided into 3 surface CD45RO fractions: RO(-), RO(+/-), and RO(+). We show here that the average number of mutations per IgV(H) transcript increased in direct correlation with surface RO levels. Conjunctional use of RO and CD69 further delineated low/moderately and highly mutated fractions. Activation-induced cytidine deaminase (AID) mRNA was slightly reduced among RO(+) GC B cells, suggesting that higher mutation averages are unlikely due to elevated somatic mutation activity. Instead, RO(+) GC B cells were negative for Annexin V, comprised mostly (93%) of CD77(-) centrocytes, and were enriched for CD69(+) cells. Collectively, RO(+) GC B cells occupy what seems to be a specialized niche comprised mostly of centrocytes that may be in transition between activation states. These findings are among the first to sort GC B cells into populations enriched for live mutated cells solely using a single extracellular marker.
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Affiliation(s)
- Stephen M Jackson
- Molecular Immunogenetics Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Shankar M, Nixon JC, Maier S, Workman J, Farris AD, Webb CF. Anti-nuclear antibody production and autoimmunity in transgenic mice that overexpress the transcription factor Bright. THE JOURNAL OF IMMUNOLOGY 2007; 178:2996-3006. [PMID: 17312145 PMCID: PMC2705967 DOI: 10.4049/jimmunol.178.5.2996] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The B cell-restricted transcription factor, B cell regulator of Ig(H) transcription (Bright), up-regulates Ig H chain transcription 3- to 7-fold in activated B cells in vitro. Bright function is dependent upon both active Bruton's tyrosine kinase and its substrate, the transcription factor, TFII-I. In mouse and human B lymphocytes, Bright transcription is down-regulated in mature B cells, and its expression is tightly regulated during B cell differentiation. To determine how Bright expression affects B cell development, transgenic mice were generated that express Bright constitutively in all B lineage cells. These mice exhibited increases in total B220(+) B lymphocyte lineage cells in the bone marrow, but the relative percentages of the individual subpopulations were not altered. Splenic immature transitional B cells were significantly expanded both in total cell numbers and as increased percentages of cells relative to other B cell subpopulations. Serum Ig levels, particularly IgG isotypes, were increased slightly in the Bright-transgenic mice compared with littermate controls. However, immunization studies suggest that responses to all foreign Ags were not increased globally. Moreover, 4-wk-old Bright-transgenic mice produced anti-nuclear Abs. Older animals developed Ab deposits in the kidney glomeruli, but did not succumb to further autoimmune sequelae. These data indicate that enhanced Bright expression results in failure to maintain B cell tolerance and suggest a previously unappreciated role for Bright regulation in immature B cells. Bright is the first B cell-restricted transcription factor demonstrated to induce autoimmunity. Therefore, the Bright transgenics provide a novel model system for future analyses of B cell autoreactivity.
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Affiliation(s)
- Malini Shankar
- Immunobiology and Cancer, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Jamee C. Nixon
- Immunobiology and Cancer, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Shannon Maier
- Arthritis and Immunology Programs, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Jennifer Workman
- Arthritis and Immunology Programs, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - A. Darise Farris
- Arthritis and Immunology Programs, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Oklahoma Medical Research Foundation, Department of Microbiology and Immunobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Carol F. Webb
- Immunobiology and Cancer, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Oklahoma Medical Research Foundation, Department of Microbiology and Immunobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Cell Biology Department, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Zemlin M, Hoersch G, Zemlin C, Pohl-Schickinger A, Hummel M, Berek C, Maier RF, Bauer K. The postnatal maturation of the immunoglobulin heavy chain IgG repertoire in human preterm neonates is slower than in term neonates. THE JOURNAL OF IMMUNOLOGY 2007; 178:1180-8. [PMID: 17202383 DOI: 10.4049/jimmunol.178.2.1180] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
During the perinatal period the development of the IgH chain CDR3 (CDR-H3) repertoire of IgM transcripts is maturity-dependent and not influenced by premature exposure to Ag. To study whether maturity-dependent restrictions also predominate in the perinatal IgG repertoire we compared 1000 IgG transcripts from cord blood and venous blood of extremely preterm neonates (24-28 wk of gestation) and of term neonates from birth until early infancy with those of adults. We found the following. First, premature contact with the extrauterine environment induced the premature development of an IgG repertoire. However after preterm birth the diversification of the IgG repertoire was slower than that after term birth. Second, the IgG repertoire of preterm neonates retained immature characteristics such as short CDR-H3 regions and overrepresentation of D(H)7-27. Third, despite premature exposure to the extrauterine environment, somatic mutation frequency in IgG transcripts of preterm infants remained low until they reached a postconceptional age corresponding to the end of term gestation. Thereafter, somatic mutations accumulated with age at similar rates in preterm and term neonates and reached 30% of the adult level after 6 mo. In conclusion, class switch was inducible already at the beginning of the third trimester of gestation, but the developing IgG repertoire was characterized by similar restrictions as those of the developing IgM repertoire. Those B cells expressing more "mature" H chain sequences were not preferentially selected into the IgG repertoire. Therefore, the postnatal IgG repertoire of preterm infants until the expected date of delivery differs from the postnatal repertoire of term neonates.
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Affiliation(s)
- Michael Zemlin
- Department of Pediatrics, Philipps University Marburg, Baldinger Street, 35033 Marburg, Germany.
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Yang F, Waldbieser GC, Lobb CJ. The nucleotide targets of somatic mutation and the role of selection in immunoglobulin heavy chains of a teleost fish. THE JOURNAL OF IMMUNOLOGY 2006; 176:1655-67. [PMID: 16424195 DOI: 10.4049/jimmunol.176.3.1655] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Sequence analysis of H chain cDNA derived from the spleen of an individual catfish has shown that somatic mutation occurs within both the VH- and JH-encoded regions. Somatic mutation preferentially targets G and C nucleotides with approximately balanced frequencies, resulting in the predominant accumulation of G-to-A and C-to-T substitutions that parallel the activation-induced cytidine deaminase nucleotide exchanges known in mammals. The overall mutation rate of A nucleotides is not significantly different from that expected by sequence-insensitive mutations, and a significant bias exists against mutations occurring in T. Targeting of mutations is dependent upon the sequence of neighboring nucleotides, allowing statistically significant hotspot motifs to be identified. Dinucleotide, trinucleotide, and RGYW analyses showed that mutational targets in catfish are restricted when compared with the spectrum of targets known in mammals. The preferential targets for G and C mutation are the central GC positions in both AGCT and AGCA. The WA motif, recognized as a mammalian hotspot for A mutations, was not a significant target for catfish mutations. The only significant target for A mutations was the terminal position in AGCA. Lastly, comparisons of mutations located in framework region and CDR codons coupled with multinomial distribution studies found no substantial evidence in either independent or clonally related VDJ rearrangements to indicate that somatic mutation coevolved with mechanisms that select B cells based upon nonsynonymous mutations within CDR-encoded regions. These results suggest that the principal role of somatic mutation early in phylogeny was to diversify the repertoire by targeting hotspot motifs preferentially located within CDR-encoded regions.
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Affiliation(s)
- Feixue Yang
- Department of Microbiology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA
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