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author:("He, jinghong")
1.  Critical role of Bcl10 in BAFF-regulated NF-κB activation and survival of anergic B cells 
Anergy is a key physiological mechanism for restraining self-reactive B cells. A marked portion of peripheral B cells are anergic B cells that largely depend on B cell-activating factor (BAFF) for survival. BAFF activates the canonical and noncanonical NF-κB pathways, both of which are required for B cell survival. Here we report that deficiency of the adaptor protein B cell lymphoma 10 (Bcl10) impaired the ability of BAFF to support B cell survival in vitro, and specifically increased apoptosis in anergic B cells in vivo, dramatically reducing anergic B cells in mice. Bcl10-dependent survival of self-reactive anergic B cells was confirmed in the IgHELsHEL double-transgenic mouse model of B cell anergy. Further, we found that BAFF stimulation induced Bcl10 association with IKKβ, a key component of the canonical NF-κB pathway. Consistently, Bcl10-deficient B cells were impaired in BAFF-induced IκBα phosphorylation and formation of nuclear p50:c-Rel complexes. Bcl10-deficient B cells also displayed reduced expression of NF-κB2/p100, severely reducing BAFF-induced nuclear accumulation of noncanonical p52:RelB complexes. Consequently, Bcl10-deficient B cells failed to express Bcl-xL, a BAFF-induced NF-κB target gene. Taken together, these data demonstrate that Bcl10 controls BAFF-induced canonical NF-κB activation directly and noncanonical NF-κB activation indirectly. The BAFF-R/Bcl10/NF-κB signaling axis plays a critical role in peripheral B cell tolerance by regulating the survival of self-reactive anergic B cells.
PMCID: PMC3786778  PMID: 23087406
BAFF; Bcl10; NF-κB; apoptosis; anergic B cells; tolerance
2.  Induction of human fetal hemoglobin expression by adenosine-2’,3’-dialdehyde 
Pharmacologic reactivation of fetal hemoglobin expression is a promising strategy for treatment of sickle cell disease and β-thalassemia. The objective of this study was to investigate the effect of the methyl transferase inhibitor adenosine-2’,3’-dialdehyde (Adox) on induction of human fetal hemoglobin (HbF) in K562 cells and human hematopoietic progenitor cells.
Expression levels of human fetal hemoglobin were assessed by northern blot analysis and Real-time PCR. HbF and adult hemoglobin (HbA) content were analyzed using high-performance liquid chromatography (HPLC). DNA methylation levels on human gamma-globin gene promoters were determined using Bisulfite sequence analysis. Enrichment of histone marks on genes was assessed by chromosome immunoprecipitation (ChIP).
Adox induced γ-globin gene expression in both K562 cells and in human bone marrow erythroid progenitor cells through a mechanism potentially involving inhibition of protein arginine methyltransferase 5 (PRMT5).
The ability of methyl transferase inhibitors such as Adox to efficiently reactivate fetal hemoglobin expression suggests that these agents may provide a means of reactivating fetal globin expression as a therapeutic option for treating sickle cell disease and β-thalassemia.
PMCID: PMC3599103  PMID: 23316703
Adenosine-2’,3’-dialdehyde (Adox); Fetal globin; Histone arginine methylation; DNA methylation
3.  Integrin α3 Mutations with Kidney, Lung, and Skin Disease 
The New England Journal of Medicine  2012;366(16):1508-1514.
Integrin α3 is a transmembrane integrin receptor subunit that mediates signals between the cells and their microenvironment. We identified three patients with homozygous mutations in the integrin α3 gene that were associated with disrupted basement-membrane structures and compromised barrier functions in kidney, lung, and skin. The patients had a multiorgan disorder that included congenital nephrotic syndrome, interstitial lung disease, and epidermolysis bullosa. The renal and respiratory features predominated, and the lung involvement accounted for the lethal course of the disease. Although skin fragility was mild, it provided clues to the diagnosis.
PMCID: PMC3341404  PMID: 22512483
4.  Synergistic Effect of SRY and Its Direct Target, WDR5, on Sox9 Expression 
PLoS ONE  2012;7(4):e34327.
SRY is a sex-determining gene that encodes a transcription factor, which triggers male development in most mammals. The molecular mechanism of SRY action in testis determination is, however, poorly understood. In this study, we demonstrate that WDR5, which encodes a WD-40 repeat protein, is a direct target of SRY. EMSA experiments and ChIP assays showed that SRY could bind to the WDR5 gene promoter directly. Overexpression of SRY in LNCaP cells significantly increased WDR5 expression concurrent with histone H3K4 methylation on the WDR5 promoter. To specifically address whether SRY contributes to WDR5 regulation, we introduced a 4-hydroxy-tamoxifen-inducible SRY allele into LNCaP cells. Conditional SRY expression triggered enrichment of SRY on the WDR5 promoter resulting in induction of WDR5 transcription. We found that WDR5 was self regulating through a positive feedback loop. WDR5 and SRY interacted and were colocalized in cells. In addition, the interaction of WDR5 with SRY resulted in activation of Sox9 while repressing the expression of β-catenin. These results suggest that, in conjunction with SRY, WDR5 plays an important role in sex determination.
PMCID: PMC3327683  PMID: 22523547
5.  Revertant mosaicism in a human skin fragility disorder results from slipped mispairing and mitotic recombination 
The Journal of Clinical Investigation  2012;122(5):1742-1746.
Spontaneous gene repair, also called revertant mosaicism, has been documented in several genetic disorders involving organs that undergo self-regeneration, including the skin. Genetic reversion may occur through different mechanisms, and in a single individual, the mutation can be repaired in various ways. Here we describe a disseminated pattern of revertant mosaicism observed in 6 patients with Kindler syndrome (KS), a genodermatosis caused by loss of kindlin-1 (encoded by FERMT1) and clinically characterized by patchy skin pigmentation and atrophy. All patients presented duplication mutations (c.456dupA and c.676dupC) in FERMT1, and slipped mispairing in direct nucleotide repeats was identified as the reversion mechanism in all investigated revertant skin spots. The sequence around the mutations demonstrated high propensity to mutations, favoring both microinsertions and microdeletions. Additionally, in some revertant patches, mitotic recombination generated areas with homozygous normal keratinocytes. Restoration of kindlin-1 expression led to clinically and structurally normal skin. Since loss of kindlin-1 severely impairs keratinocyte proliferation, we predict that revertant cells have a selective advantage that allows their clonal expansion and, consequently, the improvement of the skin condition.
PMCID: PMC3336993  PMID: 22466645
6.  Phospholipase Cγ1 is essential for T cell development, activation, and tolerance 
Phospholipase Cγ1 (PLCγ1) is an important signaling effector of T cell receptor (TCR). To investigate the role of PLCγ1 in T cell biology, we generated and examined mice with T cell–specific deletion of PLCγ1. We demonstrate that PLCγ1 deficiency affects positive and negative selection, significantly reduces single-positive thymocytes and peripheral T cells, and impairs TCR-induced proliferation and cytokine production, and the activation of ERK, JNK, AP-1, NFAT, and NF-κB. Importantly, PLCγ1 deficiency impairs the development and function of FoxP3+ regulatory T cells, causing inflammatory/autoimmune symptoms. Therefore, PLCγ1 is essential for T cell development, activation, and tolerance.
PMCID: PMC2822604  PMID: 20123962
7.  Phospholipase Cγ2 Contributes to Light-Chain Gene Activation and Receptor Editing▿  
Molecular and Cellular Biology  2007;27(17):5957-5967.
Phospholipase Cγ2 (PLCγ2) is critical for pre-B-cell receptor (pre-BCR) and BCR signaling. Current studies discovered that PLCγ2-deficient mice had reduced immunoglobulin λ (Igλ) light-chain usage throughout B-cell maturation stages, including transitional type 1 (T1), transitional type 2 (T2), and mature follicular B cells. The reduction of Igλ rearrangement by PLCγ2 deficiency was not due to specifically increased apoptosis or decreased proliferation of mutant Igλ+ B cells, as lack of PLCγ2 exerted a similar effect on apoptosis and proliferation of both Igλ+ and Igκ+ B cells. Moreover, PLCγ2-deficient IgHEL transgenic B cells exhibited an impairment of antigen-induced receptor editing among both the endogenous λ and κ loci in vitro and in vivo. Importantly, PLCγ2 deficiency impaired BCR-induced expression of IRF-4 and IRF-8, the two transcription factors critical for λ and κ light-chain rearrangements. Taken together, these data demonstrate that the PLCγ2 signaling pathway plays a role in activation of light-chain loci and contributes to receptor editing.
PMCID: PMC1952164  PMID: 17591700

Results 1-7 (7)