Mutation of mevalonate kinase （MVK） is thought to account for most cases of hyperimmunoglobulinemia D syndrome （HIDS） with recurrent fever. However, its mechanism and the relationship between elevated serum immunoglobulin D （IgD） and the clinical features of HIDS are unclear. In this study, we generated by fusion PCR a vector to express high levels of chimeric secretory IgD （cslgD） specifically in the liver. We then generated seven founder lines of transgenic mice by co-microinjection, and verified them using genomic PCR and Southern blotting. We detected the expression of csIgD by reverse transcription PCR, quantitative PCR, western blotting, and enzyme-linked immunosorbent assays. We demonstrated that csIgD could be specifically and stably expressed in the liver. We used flow cytometry to show that overexpression of csIgD in the bone marrow and spleen cells had no effect on B cell development. Morphologic and anatomical observation of the transgenic mice revealed skin damage, hepatosplenomegaly, and nephromegaly in some transgenic mice; in these mice, pathological sections showed high levels of cell necrosis and protein-like sediments in the liver, spleen, and kidney. We demonstrated that the genomic insertion sites of the transgeues did not disrupt the MVK gene on mouse chromosome 5. This transgenic mouse will be useful to explore the pathogenesis of HIDS.
WANG PingWEI ZhiGuoYAN BoWenHUANG TanGOU KeMianDAI YunPingZHENG MinWANG MeiLiCHENG XueQianWANG XiFengXU ChenSUN Yi
In the bone marrow and spleen,the developing B cell populations undergo both negative and positive selections to shape their B cell receptor repertoire.To gain insight into the shift of the immunoglobulin heavy(IgH)chain repertoire during B cell development,we undertook large scale Igμchain repertoire analysis of pre-B,immature B and spleen B cell populations.We found that the majority of VH gene segments,VH families,JH and D gene segments,were observed to have significantly different usage frequencies when three B cell populations were compared,but the usage profile of the VH,D,and JH genes between different B cell populations showed high correlations.In both productive and nonproductive rearrangements,the length of CDRH3 shortened significantly on average when B cells entered the periphery.However,the CDRH3 length distribution of nonproductive rearrangements did not follow a Gaussian distribution,but decreased successively in the order 3n–2,3n–1 and 3n,suggesting a direct correlation between mRNA stability and CDRH3 length patterns of nonproductive rearrangements.Further analysis of the individual components comprising CDRH3 of productive rearrangements indicated that the decrease in CDRH3 length was largely due to the reduction of N addition at the 5′and 3′junctions.Moreover,with development,the amino acid content of CDRH3 progressed toward fewer positively charged and nonpolar residues but more polar residues.All these data indicated that the expressed Igμchain repertoire,especially the repertoire of CDRH3,was fine-tuned when B cells passed through several checkpoints of selection during the process of maturation.
In this study,we introduced the bovine immunoglobulinμheavy-chain gene(the orphaned gene on BTA11)into mouse germline cells.Bovine IgM was highly expressed in selected transgenic lines,and it largely inhibited rearrangements of the endogenous immunoglobulin heavy chain(IgH)genes in these lines.The forced expression of bovine IgM resulted in reduced numbers of pro-and pre-B cells but increased the number of immature B cells in the transgenic mice.Bovine IgM-expressing B cells can migrate from the bone marrow to the spleen,but most of the cells are arrested at the T1 transitional B cell stage,leading to a significantly lower number of T2 transitional and mature B cells in the spleen.Although the serum concentrations of endogenous IgM and IgG in the transgenic mice were significantly decreased,the IgA levels were slightly increased compared to the WT mice.The bovine IgM level in the serum was only one-tenth to one-fifth of that of endogenous mouse IgM,suggesting that most of the serum immunoglobulin were contributed by endogenous IgH gene-expressing B cells.These transgenic mice also exhibited a lower frequency of unique complementarity determining region 3(CDR3)sequences in their VH repertoire and Vκrepertoire but exhibited an increased frequency of unique CDR3 in their Vλrepertoire.Compared to the WT mice,the transgenic mice had a significantly higher percentage of mouse IgMexpressing B cells that expressedλchains.Finally,we showed that the transgenic mice were deficient in a specific antibody response to antigen stimulation.
Prof.Liu Feng’s laboratory at the Institute of Zoology,Chinese Academy of Sciences,published their research findings in an article"Inhibition of endothelial ERK signalling by Smadl/5 is essential for haematopoietic stem cell emergence"in Nature Communications(2014,5:3431).The earliest hematopoietic stem cells(HSCs)are derived from hemogenic endothelium(HE)via en-
Prof.Zhu Shunyi and his research team from the Institute of Zoology,Chinese Academy of Sciences,discovered nematode-derived drosomycin-type antifungal peptides(DTAFPs),which provides evidence for horizontal gene transfer(HGT)of a disease resistance gene between plants and ecdysozoans(Nature Communications,2014,5:3154).
With the rapid increase of antibiotic-resistant pathogens and the decline of discovery and development of new antibiotics,there is an urgent need to exploit alternative anti-infective drugs.Fungal defensin-like peptides are emerging as a class of new source of anti-infective drugs due to their potent antibacterial activity,low toxicity,and high serum stability.Fungal genome sequencing projects combined with the development of recombinant expression techniques will accelerate the discovery of fungal defensinlike peptides.
