c-Myb is required for plasma cell migration to bone marrow after immunization or infection.
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.
Affiliation: Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia firstname.lastname@example.org email@example.com.Show MeSH
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Mentions: We investigated the hypothesis that dysregulated chemokine receptor expression or function may contribute to the lack of Ag-specific ASCs in the blood and BM in the absence of c-Myb. Given that Cxcr4 is regulated by c-Myb in hematopoietic progenitors (Lieu and Reddy, 2009; Quintana et al., 2011), we considered it a candidate to explain the aberrant migration of c-Myb–deficient ASCs. CXCR4 was expressed in similar amounts on c-Myb–deficient plasmablasts and controls (Fig. 5 A), and there was no difference in transcript levels of Cxcr4 (not depicted). Both c-Myb–deficient and wild-type plasmablasts responded to in vitro exposure to CXCL12 by internalization of CXCR4 as detected by equally reduced surface staining (unpublished data), demonstrating that the receptor remains coupled to downstream signaling molecules to some degree. Despite this, the chemotactic response of c-Myb–deficient plasmablasts to CXCL12 was severely impaired (Fig. 5, B and C). Other studies have also demonstrated that surface expression of CXCR4 may not indicate the ability of the cell to migrate to CXCL12 (Wehrli et al., 2001; Hauser et al., 2002; Underhill et al., 2003; Kabashima et al., 2006). c-Myb–deficient plasmablasts did not have a global deficiency in migrating to chemokines, however, as there was no difference in their migration toward CXCL10 (Fig. 5 D). Migration to S1P has been shown to be essential for plasma cells to migrate to the BM (Kabashima et al., 2006). However, the efficiency of the in vitro migration assay to S1P for splenic plasma cells is relatively low (0.5% input; Kabashima et al., 2006), and as such we could not attain a reliable assessment of c-Myb–deficient plasma cells migration to S1P. Therefore, we cannot rule out that migration to this chemokine is also defective. We have, however, assessed transcript levels of S1pr1 in c-Myb–deficient and control plasmablasts and found no significant difference (unpublished data).
Affiliation: Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia firstname.lastname@example.org email@example.com.