Contribution of Immunoglobulin Enhancers to B Cell Nuclear Organization.

B cells undergo genetic rearrangements at immunoglobulin gene () loci during B cell maturation. First recombination occurs during early B cell stages followed by class switch recombination (CSR) and somatic hypermutation (SHM) which occur during mature B cell stages. Given that RAG1/2 induces DNA double strand breaks (DSBs) during recombination and AID (Activation-Induced Deaminase) leads to DNA modifications (mutations during SHM or DNA DSBs during CSR), it is mandatory that rearrangements be tightly regulated to avoid any mutations or translocations within oncogenes. Ig loci contain various -regulatory elements that are involved in germline transcription, chromatin modifications or RAG/AID recruitment. -regulatory elements are increasingly recognized as being involved in nuclear positioning, heterochromatin addressing and chromosome loop regulation. In this review, we examined multiple data showing the critical interest of studying gene regulation at the whole nucleus scale. In this context, we highlighted the essential function of gene regulatory elements that now have to be considered as nuclear organizers in B lymphocytes.