Biomedical subjects
Publications and source records attributed to Ye Zheng.
Regulatory T cells suppress autoimmune responses to self-antigens. Recent studies, including one in this issue of Cell (Wu et al., 2006), suggest that the ability of T cells to choose between launching a productive immune response, functional inactivation, or developing into regulatory T cells depends upon the interplay of the key transcriptional regulators FOXP3 and NFAT.
The relationship between the T cell receptor (TCR) repertoires used by self-reactive transcription factor Foxp3-positive (Foxp3(+)) CD4(+) regulatory T cells (T(reg) cells) and nonregulatory T cells with autoimmune potential is unclear. Here we found that the TCR repertoire of thymic T(reg) cells in TCRbeta-transgenic mice was diverse and was more similar to that of peripheral T(reg) cells than that of nonregulatory T cells, suggesting that thymic T(reg) cells make a substantial contribution to the peripheral T(reg) cell population. Activated T cells in Foxp3-deficient mice, which lack T(reg) cells, 'preferentially' used TCRs found in the TCR repertoire of T(reg) cells in Foxp3-sufficient TCRbeta-transgenic mice, suggesting that these self-reactive TCRs contribute to the pathology of Foxp3-deficient mice. Our analyses suggest that T(reg) cells and potentially pathogenic autoimmune T cells use overlapping pools of self-reactive TCRs.
UNLABELLED: Animal studies showed glucocorticoids could specifically dilate renal vasculature, regulate synthesis and release of atrial natriuretic peptide (ANP), upregulate ANP receptors on vascular endothelial cells, and thus have potent potentiating diuresis and natriuresis effects in animal studies; however, their diuretic efficacy in humans is yet to be known. Therefore, we designed this randomized, double- blind, placebo-controlled, clinical study to determine the diuretic efficacy of prednisone, a glucocorticoid, in patients with congestive heart failure (CHF). METHODS: Twenty clinically stable patients with CHF without overt fluid retention were randomized to a prednisone group or placebo group. Prednisone (1 mg/kg/day with a maximum dose of 60 mg/day) was added to standard care for 7 days, leaving other medications unchanged. Variables included urine volume and electrolytes, serum electrolytes, and change from baseline in serum creatinine. RESULTS: Adding prednisone resulted in striking diuresis and natriuresis with time. As compared with the placebo group, the maximum of mean daily urine volume was 810.5 mL larger than those in the placebo group (95% confidence intervals [CI] 276.25 to 1344.86, P < 0.05). The maximum mean daily sodium excretion was 123.8 mmol higher than those patients given placebo (95% CI 11.4 to 236.2, P < 0.05). The placebo-corrected effect on change from baseline in serum creatinine was -19.5 mumol/L (95% CI -7.4 to -31.6, P < 0.01), favoring prednisone. CONCLUSIONS: This pilot study showed that prednisone had potent potentiating diuretic effects in patients with heart failure and might improve renal function in the same time. Further prospective randomized clinical studies are warranted to determine the preferable dose and its efficacy in decompensated congestive heart failure.
Expression of smooth muscle alpha-actin in growth factor-induced myofibroblasts and in differentiated vascular smooth muscle cells is transcriptionally controlled by multiple positive or negative trans-acting factors interacting with distinct cis-elements in the 5'-flanking region of the gene. Because none of the transcriptional regulators reported to date is smooth muscle cell- or myofibroblast-specific per se, the dynamic interplay among many factors interacting at specific sites along the promoter appears to be a signature feature of smooth muscle alpha-actin gene regulation in these cell types. Herein, the ability of the adenovirus E1A 12 S protein to bind and functionally inactivate specific cell regulatory factors has been exploited to identify several previously unknown coactivators of the mouse smooth muscle alpha-actin promoter in rodent fibroblasts and vascular smooth muscle cells. In transient cotransfection assays, ectopic expression of wild type E1A suppressed promoter activity in a dose- and cis-element-dependent manner. In asynchronous cells, N-terminal E1A mutants defective in CREB-binding protein (CBP) and p300 binding capacity exhibited markedly reduced inhibitory activity toward a smooth muscle alpha-actin promoter driven by a composite TEF-1-, SRF-, and Sp1/3-regulated enhancer. In synchronized cells, however, a more complex mutant E1A inhibitory pattern indicated that collaboration between CBP/p300 and the retinoblastoma family of pocket proteins was required to produce a fully functional enhancer. Cotransfection experiments conducted with Rb(-/-) fibroblasts demonstrated the necessity of pRB in augmenting smooth muscle alpha-actin enhancer/promoter activity. Physical interaction studies with the use of purified wild type and mutant E1A proteins confirmed that CBP, p300, and pRB were targets of E1A binding in nuclear extracts of vascular smooth muscle cells and/or fibroblasts. Collectively, these results suggest that a repertoire of E1A-interacting proteins, namely CBP/p300 and pRB, serve to integrate the activities of multiple trans-acting factors to control smooth muscle alpha-actin gene transcription in a cell type- and cell cycle-dependent manner.
BACKGROUND: To compare the efficacy and safety of hormone replacement therapy (HRT) combined with fluoxetine, with HRT alone, in post-menopausal women suffering from depression. METHODS: A randomized, open-label, parallel trial was applied. HRT was administered to all patients for 2 cycles, with 14 days of estrogen therapy and 14 days of estrogen plus progesterone. Patients who were randomly assigned to the HRT plus fluoxetine group were given fluoxetine in combination with HRT. Hamilton Depression Rating Scale (HAMD), Kupperman Menopausal Index (KMI), and Clinical Global Impressions scale were used to measure the efficacy. RESULTS: One hundred and twenty-three post-menopausal patients with depression were enrolled in the study. Among them, 120 had at least one post-treatment visit and entered into the statistical analysis. The mean total HAMD scores were significantly lower, and the percentages of HAMD score reductions were higher in the HRT plus fluoxetine Group compared with the HRT Group, after at least 3 weeks of treatment, with an average difference of 5 points at the endpoint. The Clinical Global Impression-Severity and Clinical Global Impression-Improvement scores were significantly different in the 2 groups, in favor of the combination therapy. The mean total KMI was significantly lower in the Combination Group compared with the HRT Group, after at least 6 weeks of treatment, with an average 4.5-point difference between the groups. No statistically significant differences were found in most of the adverse events reported in the Combination Group compared with the HRT group, with the exception of 3 symptoms, i.e., dry mouth, loss of appetite, and abdominal distention. They were mild to moderate in severity. Two patients in the HRT group, but none in the combination group, dropped out due to adverse events. CONCLUSION: HRT plus fluoxetine therapy was effective in the treatment of menopausal depression with a satisfactory safety profile.
RNA interference (RNAi) is a post-transcriptional gene silencing process by targeting mRNA for degradation in a sequence-specific manner. This powerful platform has enormous potential in functional genomics and medical research. As a tool to knock out expression of specific genes in a variety of organisms, RNAi was used to investigate gene function in a high throughput fashion. Highly conserved in evolution RNAi appears to have evolved as a cellular defense mechanism in plants and animals to suppress viral infection, transposon jumping and endogenous aberrant genes. Exploiting the natural mechanism, the researchers can shut down disease-causing genes and develop novel therapeutics against infection, tumor and other disease.
Mice deficient in the RelA (p65) subunit of NF-kappaB die during embryonic development. Fetal liver (FL) hemopoietic precursors from these mice were used to generate RelA-deficient lymphocytes by adoptive transfer into lethally irradiated mature lymphocyte-deficient recombination-activating gene-1(-/-) mice. Strikingly, RelA(-/-) lymphocyte generation was greatly diminished compared with that of RelA(+/+) lymphocytes. The most dramatic reduction was noticed in the numbers of developing B cells, which were considerably increased when RelA(-/-) FL cells that were also TNFR1 deficient were used. The role of RelA was further investigated in FL-derived developing B cells in vitro. Our results show that RelA is a major component of constitutive and TNF-alpha-induced kappaB site-binding activity in developing B cells, and provide evidence for a direct role of TNF-alpha in killing RelA(-/-) B cells. The absence of RelA significantly reduced mRNA expression of the antiapoptotic genes cellular FLICE-inhibitory protein and Bcl-2. Retroviral transduction of RelA(-/-) B cells with either cFLIP or Bcl-2 significantly reduced TNF-alpha killing. Together, these results indicate that RelA plays a crucial role in regulating developing B cell survival by inhibiting TNF-alpha cytotoxicity.
Signaling pathways involved in regulating T cell proliferation and survival are not well understood. Here we have investigated a possible role of the nuclear factor (NF)-kappaB pathway in regulating mature T cell function by using CD4+ T cells from p50-/- cRel-/- mice, which exhibit virtually no inducible kappaB site binding activity. Studies with these mice indicate an essential role of T cell receptor (TCR)-induced NF-kappaB in regulating interleukin (IL)-2 expression, cell cycle entry, and survival of T cells. Our results further indicate that NF-kappaB regulates TCR-induced expression of antiapoptotic Bcl-2 family members. Strikingly, retroviral transduction of CD4+ T cells with the NF-kappaB-inducing IkappaB kinase beta showed that NF-kappaB activation is not only necessary but also sufficient for T cell survival. In contrast, our results indicate a lack of involvement of NF-kappaB in both IL-2 and Akt-induced survival pathways. In vivo, p50-/- cRel-/- mice showed impaired superantigen-induced T cell responses as well as decreased numbers of effector/memory and regulatory CD4+ T cells. These findings provide the first demonstration of a role for NF-kappaB proteins in regulating T cell function in vivo and establish a critically important function of NF-kappaB in TCR-induced regulation of survival.
The serine/threonine kinase PAK4 is a target for the Rho GTPase Cdc42 and has been shown to regulate cell morphology and cytoskeletal organization in mammalian cells. To examine the physiological and developmental functions of PAK4, we have disrupted the PAK4 gene in mice. The absence of PAK4 led to lethality by embryonic day 11.5, a result most likely due to a defect in the fetal heart. Striking abnormalities were also evident in the nervous systems of PAK4-deficient embryos. These embryos had dramatic defects in neuronal development and axonal outgrowth. In particular, spinal cord motor neurons and interneurons failed to differentiate and migrate to their proper positions. This is probably related to the role for PAK4 in the regulation of cytoskeletal organization and cell and/or extracellular matrix adhesion. PAK4-null embryos also had defects in proper folding of the caudal portion of the neural tube, suggesting an important role for PAK4 in neural tube development.
The Toll/interleukin-1 receptor (TIR) domains are conserved modules in the intracellular regions of the Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1Rs). The domains are crucial for the signal transduction by these receptors, through homotypic interactions among the receptor and the downstream adapter TIR domains. Previous studies showed that the BB loop in the structure of the TIR domain forms a prominent conserved feature on the surface and is important for receptor signaling. Here we report the crystal structure of the C713S mutant of the TIR domain of human TLR2. An extensively associated dimer is observed in the crystal structure and mutations of several residues in this dimer interface abolished the function of the receptor. Moreover, the structure shows that the BB loop can adopt different conformations, which are required for the formation of this dimer. This asymmetric dimer might represent the TLR2:TLRx heterodimer in the function of this receptor.
Despite the established role of dendritic cells (DCs) in regulating T lymphocyte activation, intracellular mechanisms responsible for controlling DC function are largely undefined. Here, we have studied DCs from mice deficient in the p50, RelA, and cRel subunits of the immunomodulatory NF-kappaB transcription factor. Although DC development and function was normal in mice lacking individual NF-kappaB subunits, development of doubly deficient p50(-/-)RelA(-/-) DCs was significantly impaired. In contrast, DCs from p50(-/-)cRel(-/-) mice developed normally, but CD40L- and TRANCE-induced survival and IL-12 production was abolished. Surprisingly, no significant impairment in MHC and costimulatory molecule expression was seen, despite significantly reduced kappaB site binding activity. These results therefore indicate essential, subunit-specific functions for NF-kappaB proteins in regulating DC development, survival, and cytokine production.