We analyzed somatic hypermutation (SHM) patterns and secondary rearrangements involving the immunoglobulin (IG) light chain (LC) gene loci in 725 patients with chronic lymphocytic leukemia (CLL). Important differences regarding mutational load and targeting were identified in groups of sequences defined by IGKV/IGLV gene usage and/or K/LCDR3 features. Recurrent amino acid (AA) changes in the IGKV/IGLV sequences were observed in subsets of CLL cases with stereotyped B-cell receptors (BCRs), especially those expressing IGHV3-21/IGLV3-21 and IGHV4-34/IGKV2-30 BCRs. Comparison with CLL LC sequences carrying heterogeneous K/LCDR3s or non-CLL LC sequences revealed that distinct amino acid changes appear to be "CLL-biased." Finally, a significant proportion of CLL cases with monotypic LC expression were found to carry multiple potentially functional LC rearrangements, alluding to active, (auto)antigen-driven receptor editing. In conclusion, SHM targeting in CLL LCs is just as precise and, likely, functionally driven as in heavy chains. Secondary LC gene rearrangements and subset-biased mutations in CLL LC genes are strong indications that LCs are crucial in shaping the specificity of leukemic BCRs, in association with defined heavy chains. Therefore, CLL is characterized not only by stereotyped HCDR3 and heavy chains but, rather, by stereotyped BCRs involving both chains, which generate distinctive antigen-binding grooves.

Transcriptome analysis by RNA-seq technology allows novel insights into gene expression and regulatory networks in health and disease. To better understand the molecular basis of renal fibrosis, we performed RNA-seq analysis in the Unilateral Ureteric Obstruction (UUO) mouse model. We analysed sham operated, 2-and 8-day post-ligation renal tissues. Thousands of genes with statistical significant changes in their expression were identified and classified into cellular processes and molecular pathways. Many novel protein-coding genes were identified, including critical transcription factors with important regulatory roles in other tissues and diseases. Emphasis was placed on long non-coding RNAs (lncRNAs), a class of molecular regulators of multiple and diverse cellular functions. Selected lncRNA genes were further studied and their transcriptional activity was confirmed. For three of them, their transcripts were also examined in other mouse models of nephropathies and their up-or downregulation was found similar to the UUO model. In vitro experiments confirmed that one selected lncRNA is independent of TGFβ or IL1b stimulation but can influence the expression of fibrosis-related proteins and the cellular phenotype. These data provide new information about the involvement of protein-coding and lncRNA genes in nephropathies, which can become novel diagnostic and therapeutic targets in the near future.Chronic kidney disease (CKD) is a frequent condition, causing severe long-term effects with devastating personal and societal consequences 1-3 . There is a need for novel approaches to prevent the decline in renal function during progression of CKD. Considering that the structural basis for this decline is the development of fibrosis, we believe that understanding the molecular basis of renal fibrosis, could offer valuable insights for the improvement of monitoring techniques and therapeutic interventions.To address this question, we combined a systems biology approach in animal models for renal fibrosis, focusing on (but not limited to) the unilateral ureteric obstruction (UUO) model 4,5 . We identified the full transcriptome of renal tissue, using the RNA-seq methodology, during early and late time intervals of kidney fibrosis. This methodology allows the identification of new protein-coding transcripts and novel non-coding RNA transcripts 6 . This is an exciting new direction, since about 75% of the mammalian genome (including human) is transcribed but not translated into proteins, and certain types of non-coding RNAs, especially long non coding RNAs (lncRNAs), play critical regulatory roles in many biological processes 7,8 . However, no data are currently available on the full transcriptome analysis of renal tissue from the UUO model in mice. By performing whole transcriptome sequencing and thorough bioinformatics analysis, we gathered novel information regarding up-regulated and down-regulated genes, pathways and biological processes, and we made lists of differentially expressed genes not suspected so far to be i...

We profiled the expression of genes associated with Toll-like receptor signaling pathways in 192 cases of chronic lymphocytic leukemia and explored potential associations with molecular features of the clonotypic B-cell receptors. ResultsChronic lymphocytic leukemia cells express all Toll-like receptors expressed by normal activated B cells, with high expression of TLR7 and CD180, intermediate expression of TLR1, TLR6, TLR10 and low expression of TLR2 and TLR9. The vast majority of adaptors, effectors and members of the NFKB, JNK/p38, NF/IL6 and IRF pathways are intermediately-to-highly expressed, while inhibitors of Toll-like receptor activity are generally low-to-undetectable, indicating that the Toll-like receptor-signaling framework is competent in chronic lymphocytic leukemia. Significant differences were identified for selected genes between cases carrying mutated or unmutated IGHV genes or assigned to different subsets with stereotyped B-cell receptors. The differentially expressed molecules include receptors, NFkB/MAPK signaling molecules and final targets of the cascade. ConclusionsThe observed variations are suggestive of distinctive activation patterns of the Toll-like receptor signaling pathway in subgroups of cases of chronic lymphocytic leukemia defined by the molecular features of B-cell receptors. Additionally, they indicate that different or concomitant signals acting through receptors other than the B-cell receptor can affect the behavior of the malignant clone.

The chronic lymphocytic leukemia (CLL) immunoglobulin (IG) heavy chain repertoire is known to display biased immunoglobulin variable heavy-chain (IGHV) gene usage, remarkable complementarity determining region 3 (HCDR3) stereotypy as well as distinctive somatic hypermutation (SHM) patterns, at least for subsets of cases. Our aim in the present study was to similarly investigate the IG light chain (LC) genes in terms of mutation frequency and targeting and CDR3 stereotypy to elucidate if the LC may play a significant complementary role in antigen recognition in CLL. We thus examined SHM patterns and secondary rearrangements of the IG LC gene loci in a total of 612 IGKV-J and 279 IGLV-J rearrangements from 725 patients with CLL. Firstly, we observed a highly restricted light chain gene usage in the vast majority of CLL cases with stereotyped HCDR3s. In particular, stereotyped IGHV3-21 CLL cases were characterized by a strikingly biased expression of lambda light chains utilizing the IGLV3-21 gene (36/37 cases of subset#2), whereas all 15 subset #4 cases with stereotyped IGHV4-34 IGs carried an IGKV2-30 rearrangement. In addition, subset-biased light chain CDR3 motifs were identified in groups of sequences utilizing the same IGKV or IGLV gene. For example, all 30 IGKV1-39/1D-39 light chains of subset#1 (using stereotyped IGHV1/5/7 genes) carried notably long KCDR3s (10–11 amino acids) generated by significant N region addition and characterized by the frequent introduction of a junctional proline (26/30 cases). Important differences regarding mutational load were observed in groups of sequences utilizing the same IGKV or IGLV gene and/or belonging to subsets with stereotyped B cell receptors (BCRs). In fact, significant differences were observed with regard to mutational status among groups of sequences utilizing different alleles of certain IGK/LV genes (specifically the IGKV1-5, IGLV1-51 and IGLV3-21 genes). At cohort level, the SHM patterns were typical of a canonical SHM process. A clustering of R mutations in KCDR1 was evident for all IGKV subgroups with the notable exception of the IGKV2 subgroup, which exhibited preferential targeting to the KCDR2, especially in IGKV2-30 rearrangements of cases with stereotyped IGHV4-34/IGKV2-30 BCRs (subset#4). Recurrent amino acid changes at certain positions across the entire IGKV/IGLV sequence were observed at a high frequency (27–67% of cases) in a number of stereotyped subsets, especially those expressing the IGHV3-21/IGLV3-21 BCR (subset #2) and the IGHV4-34/IGKV2-30 BCR (subset #4). Comparison with CLL LC sequences carrying heterogeneous K/LCDR3s or non-CLL LC sequences revealed that these distinct amino acid changes are greatly under-represented in such groups and appear therefore to be “subset-biased”. Finally, a significant proportion of CLL cases (63 cases; 26 kappa- and 37 lambda-expressing) with monotypic LC expression were found to carry multiple potentially functional LC rearrangements. Of note, nineteen of these 63 cases (30%) belonged to subsets with stereotyped BCRs. This finding alludes to the possibility of secondary rearrangements most likely occurring in the context of (auto)antigen-driven receptor editing, particularly in the case of stereotyped subsets. In conclusion, SHM targeting in CLL LCs appears to be just as precise and, most likely, functionally driven as in heavy chains. Secondary LC gene rearrangements and subset-biased mutations in CLL LC genes are strong indications that LCs are crucial in shaping the specificity of leukemic BCRs, in association with defined heavy chains. Therefore, CLL is characterized not only by stereotyped HCDR3 and heavy chains but, rather, by stereotyped BCRs involving both chains, which create distinctive antigen binding grooves.

These data establish for the first time a role for NR5A2 and its SUMOylation on the transcriptional regulation of the calreticulin gene in a rodent model of renal fibrosis and raise the possibility that NR5A2 might be a novel target for future anti-fibrotic interventions.