DNA methylation regulates B cell activation via repressing Pax5 expression in teleost

Area of Science:

• Immunology
• Molecular Biology
• Epigenetics

Background:

• Pax5 is a key transcription factor in B cell development, expressed in naive cells and repressed during activation.
• The precise mechanisms of Pax5 repression during B cell activation are not fully understood.

Purpose of the Study:

• To investigate the mechanisms regulating Pax5 repression during B cell activation using a teleost model.
• To explore the role of DNA methylation in controlling Pax5 expression during B cell activation.

Main Methods:

• Treatment of B cells with lipopolysaccharide (LPS) and chitosan oligosaccharide (COS).
• Analysis of gene expression, including Pax5, Bcl6, Blimp1, and sIgM.
• Identification and methylation analysis of CpG islands in the Pax5 promoter region.
• Treatment with DNA methylation inhibitor 5-aza-2'-deoxycytidine (AZA).
• In vitro promoter activity assays.

Main Results:

• LPS and COS treatments enhanced B cell antibody secretion and phagocytosis, with decreased Pax5 and increased activation markers.
• Two CpG islands were identified in the Pax5 promoter; CpG island1 became hypermethylated upon B cell activation.
• AZA treatment prevented CpG island1 hypermethylation, blocked Pax5 downregulation, and impaired B cell activation.
• DNA methylation was shown to inhibit Pax5 promoter activity in vitro.

Conclusions:

• A novel mechanism of Pax5 repression via DNA methylation-induced promoter inhibition during B cell activation has been elucidated.
• This finding advances the understanding of B cell activation regulation and its epigenetic control.