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c-Myb is required for plasma cell migration to bone marrow after immunization or infection.

Good-Jacobson KL, O'Donnell K, Belz GT, Nutt SL, Tarlinton DM - J. Exp. Med. (2015)

Bottom Line: Here, we detail the critical role of the transcription factor c-Myb in determining plasma cell location.This was correlated with a dramatic reduction of plasma cells in peripheral blood, mislocalization in spleen, and an inability of c-Myb-deficient plasma cells to migrate along a CXCL12 gradient.Therefore, c-Myb plays an essential, novel role in establishing the long-lived plasma cell population in the BM via responsiveness to chemokine migration cues.

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Affiliation: Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia jacobson@wehi.edu.au tarlinton@wehi.edu.au.

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Survival in the BM is not affected by the absence of c-Myb. BM from μMT mice were mixed 4:1 with BM from c-Mybfl/flERT2-Cre/+ or ERT2-Cre/+ controls and used to reconstitute irradiated Ly5.1 recipients (A). Mice were rested for at least 6 wk, and then immunized with NP-KLH. After 4 wk, tamoxifen was administered 6 and 5 d before frequency (B) and affinity (C) of BM ASCs were assessed. n = 5 per genotype; results are representative of four independent experiments at multiple time points after tamoxifen treatment. (D–F) Flow cytometric representative plot (D), frequency (E), and number (F) of B220loCD138hi in the spleen 4 wk after immunization in Cd23Cre/+ (black bars) and c-Mybfl/flCd23Cre/+ (white bars) mice. n = 5 per genotype; results are representative of two independent experiments. (G) Frequency of splenic B220loCD138hi in 1:1 mixed BM chimeras as described in Fig. 2. *, P < 0.05 (Mann-Whitney nonparametric, two-tailed test; mean ± SEM).
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fig3: Survival in the BM is not affected by the absence of c-Myb. BM from μMT mice were mixed 4:1 with BM from c-Mybfl/flERT2-Cre/+ or ERT2-Cre/+ controls and used to reconstitute irradiated Ly5.1 recipients (A). Mice were rested for at least 6 wk, and then immunized with NP-KLH. After 4 wk, tamoxifen was administered 6 and 5 d before frequency (B) and affinity (C) of BM ASCs were assessed. n = 5 per genotype; results are representative of four independent experiments at multiple time points after tamoxifen treatment. (D–F) Flow cytometric representative plot (D), frequency (E), and number (F) of B220loCD138hi in the spleen 4 wk after immunization in Cd23Cre/+ (black bars) and c-Mybfl/flCd23Cre/+ (white bars) mice. n = 5 per genotype; results are representative of two independent experiments. (G) Frequency of splenic B220loCD138hi in 1:1 mixed BM chimeras as described in Fig. 2. *, P < 0.05 (Mann-Whitney nonparametric, two-tailed test; mean ± SEM).

Mentions: It is formally possible that c-Myb could contribute to formation of the BM ASC compartment by regulating retention or survival of ASCs once established. To investigate such a role of c-Myb, we used c-Mybfl/fl mice crossed to the tamoxifen inducible Cre system (Fig. 3). BM from μMT mice was mixed 4:1 with BM from c-Mybfl/flRosa26CreERT2/+ or Rosa26CreERT2/+ controls and used to reconstitute irradiated Ly5.1 recipients. In c-Mybfl/flRosa26CreERT2/+ BM chimeras, all B cells will delete c-Myb upon tamoxifen administration, whereas the majority of non–B cells will continue to express c-Myb. Chimeras were immunized and rested for ∼4 wk to permit the migration and formation of ASCs to the BM. Tamoxifen, delivered by oral gavage, was used to induce deletion of c-Myb in ASCs (deletion efficiency was estimated at over 95%; not depicted) and any impact on their retention was assessed (Fig. 3 A). c-Myb–deficient ASCs were present in the BM (Fig. 3 B) post-tamoxifen treatment at normal frequency and affinity (Fig. 3, B and C), demonstrating that c-Myb does not control the persistence of ASCs already occupying a bone marrow niche. Additionally, expression of the plasma cell survival factor Mcl-1 (Peperzak et al., 2013) in c-Myb–deficient splenic ASCs was comparable to controls (unpublished data). These data indicate that expression of cMyb controls emigration of ASC from secondary lymphoid organs after immunization. Consistent with this, when we assessed ASC in the spleen by flow cytometry 4 wk after primary immunization, we measured a twofold increase in B220loCD138hi cells in the absence of c-Myb at (Fig. 3, D–F), a phenomenon that was B cell intrinsic (Fig. 3 G).


c-Myb is required for plasma cell migration to bone marrow after immunization or infection.

Good-Jacobson KL, O'Donnell K, Belz GT, Nutt SL, Tarlinton DM - J. Exp. Med. (2015)

Survival in the BM is not affected by the absence of c-Myb. BM from μMT mice were mixed 4:1 with BM from c-Mybfl/flERT2-Cre/+ or ERT2-Cre/+ controls and used to reconstitute irradiated Ly5.1 recipients (A). Mice were rested for at least 6 wk, and then immunized with NP-KLH. After 4 wk, tamoxifen was administered 6 and 5 d before frequency (B) and affinity (C) of BM ASCs were assessed. n = 5 per genotype; results are representative of four independent experiments at multiple time points after tamoxifen treatment. (D–F) Flow cytometric representative plot (D), frequency (E), and number (F) of B220loCD138hi in the spleen 4 wk after immunization in Cd23Cre/+ (black bars) and c-Mybfl/flCd23Cre/+ (white bars) mice. n = 5 per genotype; results are representative of two independent experiments. (G) Frequency of splenic B220loCD138hi in 1:1 mixed BM chimeras as described in Fig. 2. *, P < 0.05 (Mann-Whitney nonparametric, two-tailed test; mean ± SEM).
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fig3: Survival in the BM is not affected by the absence of c-Myb. BM from μMT mice were mixed 4:1 with BM from c-Mybfl/flERT2-Cre/+ or ERT2-Cre/+ controls and used to reconstitute irradiated Ly5.1 recipients (A). Mice were rested for at least 6 wk, and then immunized with NP-KLH. After 4 wk, tamoxifen was administered 6 and 5 d before frequency (B) and affinity (C) of BM ASCs were assessed. n = 5 per genotype; results are representative of four independent experiments at multiple time points after tamoxifen treatment. (D–F) Flow cytometric representative plot (D), frequency (E), and number (F) of B220loCD138hi in the spleen 4 wk after immunization in Cd23Cre/+ (black bars) and c-Mybfl/flCd23Cre/+ (white bars) mice. n = 5 per genotype; results are representative of two independent experiments. (G) Frequency of splenic B220loCD138hi in 1:1 mixed BM chimeras as described in Fig. 2. *, P < 0.05 (Mann-Whitney nonparametric, two-tailed test; mean ± SEM).
Mentions: It is formally possible that c-Myb could contribute to formation of the BM ASC compartment by regulating retention or survival of ASCs once established. To investigate such a role of c-Myb, we used c-Mybfl/fl mice crossed to the tamoxifen inducible Cre system (Fig. 3). BM from μMT mice was mixed 4:1 with BM from c-Mybfl/flRosa26CreERT2/+ or Rosa26CreERT2/+ controls and used to reconstitute irradiated Ly5.1 recipients. In c-Mybfl/flRosa26CreERT2/+ BM chimeras, all B cells will delete c-Myb upon tamoxifen administration, whereas the majority of non–B cells will continue to express c-Myb. Chimeras were immunized and rested for ∼4 wk to permit the migration and formation of ASCs to the BM. Tamoxifen, delivered by oral gavage, was used to induce deletion of c-Myb in ASCs (deletion efficiency was estimated at over 95%; not depicted) and any impact on their retention was assessed (Fig. 3 A). c-Myb–deficient ASCs were present in the BM (Fig. 3 B) post-tamoxifen treatment at normal frequency and affinity (Fig. 3, B and C), demonstrating that c-Myb does not control the persistence of ASCs already occupying a bone marrow niche. Additionally, expression of the plasma cell survival factor Mcl-1 (Peperzak et al., 2013) in c-Myb–deficient splenic ASCs was comparable to controls (unpublished data). These data indicate that expression of cMyb controls emigration of ASC from secondary lymphoid organs after immunization. Consistent with this, when we assessed ASC in the spleen by flow cytometry 4 wk after primary immunization, we measured a twofold increase in B220loCD138hi cells in the absence of c-Myb at (Fig. 3, D–F), a phenomenon that was B cell intrinsic (Fig. 3 G).

Bottom Line: Here, we detail the critical role of the transcription factor c-Myb in determining plasma cell location.This was correlated with a dramatic reduction of plasma cells in peripheral blood, mislocalization in spleen, and an inability of c-Myb-deficient plasma cells to migrate along a CXCL12 gradient.Therefore, c-Myb plays an essential, novel role in establishing the long-lived plasma cell population in the BM via responsiveness to chemokine migration cues.

View Article: PubMed Central - HTML - PubMed

Affiliation: Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia jacobson@wehi.edu.au tarlinton@wehi.edu.au.

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Related in: MedlinePlus