Project description:The IgH 3â?? regulatory region (3â??RR) controls class switch recombination (CSR) and somatic hypermutation (SHM) in B cells. The mouse 3â??RR contains four enhancer elements with hs1,2 flanked by inverted repeated sequences and the center of a 25-kb palindrome bounded by two hs3 enhancer inverted copies (hs3a and hs3b). hs4 lies downstream of the palindrome. Evolution maintained in mammals this unique palindromic arrangement suggesting that it is functionally significant. We report that deconstructing the palindromic IgH 3â??RR strongly impacts its function even when enhancers are preserved. CSR and IgH transcription appear poorly dependent from the 3â??RR architecture and are more or less preserved provided 3â??RR enhancers are present. By contrast, an â??architectural effectâ?? significantly lowers VH germline transcription, AID recruitment and SHM. In conclusion, this work indicates that the IgH 3â??RR does not simply pile up enhancer units but also optimally expose them into a functional architecture of crucial importance. RNAseq analysis of B-cell splenocytes with (S=stimulated) or without (R=resting) LPS activation from wt, delta2leftPAL, and deltaIRIS mice.
Project description:Expression of stereotyped B cell receptors (BCR), i.e. non-random combinations of immunoglobulin heavy-chain variable (IGHV) genes, complementarity-determining region-3 (HCDR3), and IGV light chains, identifies discrete clusters and represents a peculiar feature of chronic lymphocytic leukemia (CLL). Expression of IGHV3-23 characterized a CLL subset with peculiar molecular and clinical features.
Project description:We describe 9 CLL patients who underwent a spontaneous clinical regression. CD38 and ZAP-70 were negative in all cases. Immunoglobulin heavy chain variable region (IgVH) genes, mutated in all 7 evaluable patients, were restricted to the VH3 family in 6, with the usage of VH3-30 gene in 2. The light chain variable region genes were mutated in 6/8 cases, with the usage of Vκ4-1 gene in 3. Microarray analysis of CLL cells revealed a distinctive genomic profile. The number of activated T lymphocytes expressing IFN-γ, TNF-α and IL-4 was similar between CLL in spontaneous regression and healthy individuals.
Project description:The IgH 3’ regulatory region (3’RR) controls class switch recombination (CSR) and somatic hypermutation (SHM) in B cells. The mouse 3’RR contains four enhancer elements with hs1,2 flanked by inverted repeated sequences and the center of a 25-kb palindrome bounded by two hs3 enhancer inverted copies (hs3a and hs3b). hs4 lies downstream of the palindrome. Evolution maintained in mammals this unique palindromic arrangement suggesting that it is functionally significant. We report that deconstructing the palindromic IgH 3’RR strongly impacts its function even when enhancers are preserved. CSR and IgH transcription appear poorly dependent from the 3’RR architecture and are more or less preserved provided 3’RR enhancers are present. By contrast, an “architectural effect” significantly lowers VH germline transcription, AID recruitment and SHM. In conclusion, this work indicates that the IgH 3’RR does not simply pile up enhancer units but also optimally expose them into a functional architecture of crucial importance.