J Korean Rheum Assoc.  2006 Mar;13(1):33-45.

Down-regulation of Membrane Bound CD27 Expression Mediated by Protein Kinase C-beta and Protein Kinase C-delta in B Cells

• Lee SY
• Min JK
• Cho ML
• Moon YM
• Kim KW
• Min SY
• Cho YG
• Yoon CH
• Park SH
• Kim HY

Abstract

OBJECTIVE
CD27 is a member of the tumor necrosis factor receptor (TNFR) superfamily and is expressed on T, B, and NK cells. The signaling via CD27 plays pivotal roles in T-T and T-B interaction. CD27 is a useful marker in assessing the number of circulation B cells and B cell subsets because it permits one step identification of the major B cell compartments, CD27- naive and CD27+ memory B cells as well as CD27high plasma cells. We have analyzed the mechanisms underlying the regulation of CD27 expression.
METHODS
Isolation B cells and Raji cells were cultured with PMA. The levels of cell surface CD27 and CD 27 mRNA were analyzed by FACs staining and RT-PCR. Raji cells were cultured with phorbol 12-myristate 13-acetate (PMA), with or without pretreated shedding inhibitor BB3103 and TAPI-1. sCD27 was measured in culture supernatant by ELISA. Cell lysates were analyzed for PKC isotype activation by Western blot. We used PKC inhibitor Ly379196 and rottlen.
RESULTS
Membrane expression of CD27 was down-regulated after PMA stimulation without cytotoxic effect in B cells. Furthermore, PMA treatment could directly reduce CD27 mRNA without intermediate protein synthesis in B cells. In contrast, PMA treatment induced soluble form of CD27 (sCD27), which was shed from the cell surface and was found in PMA treatment B cell culture supernatant. PMA-induced sCD27 proteins were decreased with shedding inhibitor BB3103 and TAPI-1. PMA-induced down regulation of CD27 expressions were quenched with protein kinase C (PKC) inhibitor Staurosporin, PKC-beta inhibitor rottlerin and PKC-delta inhibitor Ly379196.
CONCLUSION
These data suggest that PMA-induced activation of PKC plays a crucial role in down-regulation of the expression of the CD27 and up-regulation of the shedding of the CD27 in human B cells.

Keyword

CD27; B cell; PMA; PKC; Shedding

MeSH Terms

B-Lymphocyte Subsets
B-Lymphocytes*
Blotting, Western
Cell Culture Techniques
Down-Regulation*
Enzyme-Linked Immunosorbent Assay
Humans
Killer Cells, Natural
Membranes*
Memory
Plasma Cells
Protein Kinase C
Protein Kinase C-delta*
Protein Kinases*
Receptors, Tumor Necrosis Factor
RNA, Messenger
Up-Regulation
Protein Kinase C
Protein Kinase C-delta
Protein Kinases
RNA, Messenger
Receptors, Tumor Necrosis Factor