Differential Activation of the Transcription Factor IRF1 Underlies the Distinct Immune Responses Elicited by Type I and Type III Interferons.

Type I and III interferons (IFNs) activate similar downstream signaling cascades, but unlike type I IFNs, type III IFNs (IFNλ) do not elicit strong inflammatory responses in vivo. Here, we examined the molecular mechanisms underlying this disparity. Type I and III IFNs displayed kinetic differences in expression of IFN-stimulated genes and proinflammatory responses, with type I IFNs preferentially stimulating expression of the transcription factor IRF1. Type III IFNs failed to induce IRF1 expression because of low IFNλ receptor abundance and insufficient STAT1 activation on epithelial cells and thus did not activate the IRF1 proinflammatory gene program. Rather, IFNλ stimulation preferentially induced factors implicated in tissue repair. Our findings suggest that IFN receptor compartmentalization and abundance confer a spatiotemporal division of labor where type III IFNs control viral spread at the site of the infection while restricting tissue damage; the transient induction of inflammatory responses by type I IFNs recruits immune effectors to promote protective immunity.

Genetic variation that determines TAPBP expression levels associates with the course of malaria in an HLA allotype-dependent manner.

HLA class I (HLA-I) allotypes vary widely in their dependence on tapasin (TAPBP), an integral component of the peptide-loading complex, to present peptides on the cell surface. We identified two single-nucleotide polymorphisms that regulate TAPBP messenger RNA (mRNA) expression in Africans, rs111686073 (G/C) and rs59097151 (A/G), located in an AP-2α transcription factor binding site and a microRNA (miR)-4486 binding site, respectively. rs111686073G and rs59097151A induced significantly higher TAPBP mRNA expression relative to the alternative alleles due to higher affinity for AP-2α and abrogation of miR-4486 binding, respectively. These variants associated with lower Plasmodium falciparum parasite prevalence and lower incidence of clinical malaria specifically among individuals carrying tapasin-dependent HLA-I allotypes, presumably by augmenting peptide loading, whereas tapasin-independent allotypes associated with relative protection, regardless of imputed TAPBP mRNA expression levels. Thus, an attenuated course of malaria may occur through enhanced breadth and/or magnitude of antigen presentation, an important consideration when evaluating vaccine efficacy.

The KIR2DL1 intermediate upstream element participates in gene activation.

The human KIR genes encode a family of class I MHC receptors that are expressed on subsets of NK cells. The expression of KIR proteins is controlled by a stochastic process, and competition between sense and antisense promoter elements has been suggested to program the variegated expression of these genes. Previous studies have demonstrated distinct roles of distal, intermediate, and proximal sense promoter/enhancer elements in gene activation and expression. Conversely, proximal and intronic antisense promoter transcripts have been associated with gene silencing at different stages of NK cell development. In the current study, we examine the effect of intermediate promoter deletion on KIR2DL1 expression in the YTS cell line. Homozygous deletion of the KIR2DL1 intermediate element did not affect proximal promoter activity but resulted in increased detection of upstream transcripts. No significant changes in alternative mRNA splicing or expression levels of KIR2DL1 protein were observed. However, intermediate element deletion was associated with a reduced frequency of gene activation by 5-azacytidine. Taken together, these results indicate that the intermediate element is not an enhancer required for KIR expression; however, it is required for the efficient activation of the gene.

Biological variation in the serum and urine kidney injury markers of a healthy population measured within 24 hours.

BACKGROUND AND AIMS: To explore the biological variation (BV) of kidney injury markers in serum and urine of healthy subjects within 24 hours to assist with interpretation of future studies using these biomarkers in the context of known BV. MATERIALS AND METHODS: Serum and urine samples were collected every 4 hours (0, 4, 8, 12, 16 and 20 hours) from 31 healthy subjects within 24 hours and serum creatinine (s-Crea), serum ß2-microglobin (s-ß2MG), serum cystatin C (s-CYSC), serum neutrophil gelatinase-associated lipoprotein (s-NGAL), urine creatinine (u-Crea), urine ß2-microglobin (u-ß2MG), urine cystatin C (u-CYSC), urine neutrophil gelatinase-associated lipoprotein (u-NGAL) were measured. Outlier and variance homogeneity analyses were performed, followed by CV-ANOVA analysis on trend-corrected data (if relevant), and analytical (CVA), within-subject (CVI), and between-subject (CVG) biological variation were calculated. RESULTS: The concentration of kidney injury markers in male was higher than that in female, except for u-CYSC and u-NGAL. There were no significant difference in serum and urine kidney injury markers concentration at different time points. Serum CVI was lower than urine CVI, serum CVG was higher than CVI, and urine CVG was lower than CVI. The individual index (II) of serum kidney injury markers was less than 0.6, while the II of urinary kidney injury markers was more than 1.0. CONCLUSIONS: This study provides new short-term BV data for kidney injury markers in healthy subjects within 24 hours, which are of great significance in explaining other AKI / CKD studies.

Identification of an elaborate NK-specific system regulating HLA-C expression.

The HLA-C gene appears to have evolved in higher primates to serve as a dominant source of ligands for the KIR2D family of inhibitory MHC class I receptors. The expression of NK cell-intrinsic MHC class I has been shown to regulate the murine Ly49 family of MHC class I receptors due to the interaction of these receptors with NK cell MHC in cis. However, cis interactions have not been demonstrated for the human KIR and HLA proteins. We report the discovery of an elaborate NK cell-specific system regulating HLA-C expression, indicating an important role for HLA-C in the development and function of NK cells. A large array of alternative transcripts with differences in intron/exon content are generated from an upstream NK-specific HLA-C promoter, and exon content varies between HLA-C alleles due to SNPs in splice donor/acceptor sites. Skipping of the first coding exon of HLA-C generates a subset of untranslatable mRNAs, and the proportion of untranslatable HLA-C mRNA decreases as NK cells mature, correlating with increased protein expression by mature NK cells. Polymorphism in a key Ets-binding site of the NK promoter has generated HLA-C alleles that lack significant promoter activity, resulting in reduced HLA-C expression and increased functional activity. The NK-intrinsic regulation of HLA-C thus represents a novel mechanism controlling the lytic activity of NK cells during development.

HLA-C Level Is Regulated by a Polymorphic Oct1 Binding Site in the HLA-C Promoter Region.

Differential HLA-C levels influence several human diseases, but the mechanisms responsible are incompletely characterized. Using a validated prediction algorithm, we imputed HLA-C cell surface levels in 228 individuals from the 1000 Genomes dataset. We tested 68,726 SNPs within the MHC for association with HLA-C level. The HLA-C promoter region variant, rs2395471, 800 bp upstream of the transcription start site, gave the most significant association with HLA-C levels (p = 4.2 × 10-66). This imputed expression quantitative trait locus, termed impeQTL, was also shown to associate with HLA-C expression in a genome-wide association study of 273 donors in which HLA-C mRNA expression levels were determined by quantitative PCR (qPCR) (p = 1.8 × 10-20) and in two cohorts where HLA-C cell surface levels were determined directly by flow cytometry (n = 369 combined, p < 10-15). rs2395471 is located in an Oct1 transcription factor consensus binding site motif where the A allele is predicted to have higher affinity for Oct1 than the G allele. Mobility shift electrophoresis demonstrated that Oct1 binds to both alleles in vitro, but decreased HLA-C promoter activity was observed in a luciferase reporter assay for rs2395471_G relative to rs2395471_A on a fixed promoter background. The rs2395471 variant accounts for up to 36% of the explained variation of HLA-C level. These data strengthen our understanding of HLA-C transcriptional regulation and provide a basis for understanding the potential consequences of manipulating HLA-C levels therapeutically.

Correction: Activating Receptor Signals Drive Receptor Diversity in Developing Natural Killer Cells.

[This corrects the article DOI: 10.1371/journal.pbio.1002526.].

Activating Receptor Signals Drive Receptor Diversity in Developing Natural Killer Cells.

It has recently been appreciated that NK cells exhibit many features reminiscent of adaptive immune cells. Considerable heterogeneity exists with respect to the ligand specificity of individual NK cells and as such, a subset of NK cells can respond, expand, and differentiate into memory-like cells in a ligand-specific manner. MHC I-binding inhibitory receptors, including those belonging to the Ly49 and KIR families, are expressed in a variegated manner, which creates ligand-specific diversity within the NK cell pool. However, how NK cells determine which inhibitory receptors to express on their cell surface during a narrow window of development is largely unknown. In this manuscript, we demonstrate that signals from activating receptors are critical for induction of Ly49 and KIR receptors during NK cell development; activating receptor-derived signals increased the probability of the Ly49 bidirectional Pro1 promoter to transcribe in the forward versus the reverse direction, leading to stable expression of Ly49 receptors in mature NK cells. Our data support a model where the balance of activating and inhibitory receptor signaling in NK cells selects for the induction of appropriate inhibitory receptors during development, which NK cells use to create a diverse pool of ligand-specific NK cells.

LAB/NTAL facilitates fungal/PAMP-induced IL-12 and IFN-γ production by repressing ß-catenin activation in dendritic cells.

Fungal pathogens elicit cytokine responses downstream of immunoreceptor tyrosine-based activation motif (ITAM)-coupled or hemiITAM-containing receptors and TLRs. The Linker for Activation of B cells/Non-T cell Activating Linker (LAB/NTAL) encoded by Lat2, is a known regulator of ITAM-coupled receptors and TLR-associated cytokine responses. Here we demonstrate that LAB is involved in anti-fungal immunity. We show that Lat2-/- mice are more susceptible to C. albicans infection than wild type (WT) mice. Dendritic cells (DCs) express LAB and we show that it is basally phosphorylated by the growth factor M-CSF or following engagement of Dectin-2, but not Dectin-1. Our data revealed a unique mechanism whereby LAB controls basal and fungal/pathogen-associated molecular patterns (PAMP)-induced nuclear ß-catenin levels. This in turn is important for controlling fungal/PAMP-induced cytokine production in DCs. C. albicans- and LPS-induced IL-12 and IL-23 production was blunted in Lat2-/- DCs. Accordingly, Lat2-/- DCs directed reduced Th1 polarization in vitro and Lat2-/- mice displayed reduced Natural Killer (NK) and T cell-mediated IFN-γ production in vivo/ex vivo. Thus our data define a novel link between LAB and ß-catenin nuclear accumulation in DCs that facilitates IFN-γ responses during anti-fungal immunity. In addition, these findings are likely to be relevant to other infectious diseases that require IL-12 family cytokines and an IFN-γ response for pathogen clearance.

[Clinical outcomes of percutaneous kyphoplasty under local anesthesia for osteoporotic vertebral compression fractures].

OBJECTIVE: To analyze the clinical outcomes of percutaneous kyphoplasty under local anesthesia for osteoporotic vertebral compression fractures. METHODS: In this study, 76 elderly patients with osteoporotic vertebral compression fractures undergoing percutaneous kyphoplasty were followed up for 2-3.1 years. They were divided into 3 groups according to different ages: 60-69 yrs (A group), 70-79 yrs (B group) and 80- 91 yrs (C group). Pre- and post-operative and last follow-up evaluations were conducted. And the parameters of bone mineral density (BMD), kyphotic angle, change of visual analog scale (VAS), Oswestry disability index, average vertebral body height, complications and costs of hospitalization were recorded and analyzed. RESULTS: BMD decreased with advancing age and had statistical significance between three groups (P < 0.05). Three thoracic spine fractures and 6 lumbar spine fractures could not be detected with digital radiography and were observed only on magnetic resonance imaging (MRI). The pre-operative levels of visual analogue scale and Oswestry disability index increased in all groups.No statistical significance existed between A and B groups. But there was statistical significance between A or B and C groups (P < 0.05). Pre- and post-operative assessments showed that statistically significant improvements were found in visual analogue scale and Oswestry disability index in all groups (P < 0.05). And statistically significant improvements were found for the pre- and post-operative kyphotic angles and vertebral body heights in A, C group and B groups (P < 0.05). The sites for symptomatic leakage of cement included paravertebral vein (n = 2), intervertebral disc (n = 1) and paravertebral space (n = 2). Adjacent vertebral fracture occurred in 1 patient at 17 months and underwent percutaneous kyphoplasty. The mean operative duration was 28 minutes per vertebrae and the mean cost of hospitalization at RMB yuan 33 778. CONCLUSION: As a simple and safe procedure for osteoporotic vertebrae compression fractures, percutaneous kyphoplasty may relieve pain quickly, restore vertebral height, prevent further fractures and improve the patient's quality-of-life.

Survival of lateral unicompartmental knee arthroplasty at short-, mid-, and long-term follow-up: a systematic review and meta-analysis.

BACKGROUND: The infrequency of lateral unicompartmental knee arthroplasty (UKA) has led to a lack of understanding of its survival. This study aimed to systematically evaluate the survivorship results of lateral UKA at different follow-ups based on available literature. METHODS: Five databases were searched for eligible studies. Pooled survivorships with 95% confidence intervals (CIs) at 3, 5, 10, 15, and 20 years after lateral UKA were estimated using a random-effect model. Subgroup and sensitivity analyses were performed. RESULTS: A total of 26 studies involving 5470 lateral UKAs were included. Survivorships of lateral UKA at 3-, 5-, 10-, 15-, and 20-year follow-ups were 96% (95% CI: 95-98%, I2 : 77.5%), 94% (95% CI: 93-96%, I2 : 70.8%), 88% (95% CI: 84-91%, I2 : 70.8%), 85% (95% CI: 79-91%, I2 : 70.8%), and 78% (95% CI: 71-85%, I2 : 54.2%), respectively. Subgroup analyses found that bearing type, the number of surgeons, and year of publication might be associated with implant survival outcomes. CONCLUSION: Lateral UKA is an effective procedure with excellent survivorships at short-, mid-, and long-term follow-ups. Results suggest a single-surgeon lateral UKA using fixed-bearing. Additional well-designed studies are needed to elucidate the current findings.

Application of chelate GLDA for remediating Cd-contaminated farmlands using Tagetes patula L.

In the present study, via a 180-day field trial, the indicators of soil total cadmium, DTPA-Cd, organic matter, and plant cadmium extraction were tested after the application of chelate tetrasodium glutamate diacetate (GLDA) to investigate the potential of GLDA combined with Tagetes patula L. to remediate cadmium-contaminated soil. To do so, five GLDA treatments (e.g., 0, 292.5, 585, 1170, and 2340 kg hm-2) were practiced. For each treatment, the total GLDA was divided into two applications with 15-day intervals (0.25, 0.47, and 0.61 mg·kg-1) under T. patula plantation. Compared with the control, our results showed that GLDA application significantly increased the biomass of aerial parts of T. patula by 21.9% (p < 0.05). Likewise, Cd content in aboveground and underground parts of T. patula increased by 94.7% and 60.5%, respectively, compared with the control (p < 0.05). GLDA application caused significant increases in Cd accumulations in cell soluble fraction and cell wall by 290% and 123%, respectively (p < 0.05); soil pH and DTPA-Cd content increased with the increase of total application of GLDA. Co-application of GLDA (2340 kg hm-2) and T. patula reduced the total soil Cd content by 12.87% compared with the soil background. Altogether, our findings conclude on the efficacy of GLDA application for the remediation of Cd-contaminated farmlands under T. patula cultivation.

Role of aspirin in the prevention of heterotopic ossification following total hip replacement: a systematic review and meta-analysis.

BACKGROUND: To systematically investigate if aspirin (ASA), used as venous thromboembolism (VTE) prophylaxis, plays a role in the prevention of heterotopic ossification (HO) following total hip arthroplasty (THA) and if ASA dosage impacted the rate of HO. METHODS: Eligible studies published from January 2000 to July 2022 were identified from the computerized searching of PubMed, Scopus and Web of Science. HO was defined according to Brooker Classification. Pooled risk ratios (OR) and 95% confidence interval (CI) were estimated under a random-effect model. Additionally, combined HO incidences were compared according to ASA dosage (a regular dose of 325 bid vs. a low dose of 81 mg bid/162 mg qd). RESULTS: Thirteen studies were included. ASA administered for VTE prophylaxis was significantly associated with a reduced risk of all-grade HO following THA (univariate, OR: 0.50, 95% CI: 0.34-0.74, P < 0.001; multivariate, OR: 0.60, 95% CI: 0.49-0.73, P < 0.001). Similar results could be observed for high-grade HO (univariate, OR: 0.57, 95% CI: 0.36-0.89, P = 0.015; multivariate, OR: 0.50, 95% CI: 0.27-0.92, P = 0.026). There was a non-significant trend towards a higher incidence of HO formation for low-dose ASA (31%, 95% CI: 29-34%), compared with regular-dose ASA (21%, 95% CI: 11-33%) (P = 0.069 under test of interaction). CONCLUSIONS: ASA can be an effective option for HO prophylaxis. More well-designed trials with long-term follow-ups are encouraged to confirm the current findings and to investigate the effect of ASA dosage on HO reduction.

Intraday Changes and Clinical Applications of Thyroid Function Biomarkers in Healthy Subjects.

OBJECTIVE: We evaluated the intraday changes of thyroid function biomarkers in healthy subjects to help clinicians diagnose thyroid diseases in appropriate timing. METHODS: Blood samples were collected from 31 subjects at 0:00, 4:00, 8:00, 12:00, 16:00 and 20:00 on the sampling day and analyzed for thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free T3 (FT3), and free T4 (FT4). The intraday concentration changes were analyzed using Friedman's 2-way analysis of variance by ranks. RESULTS: The concentrations of TSH, T3, T4, FT3, and FT4 in males were significantly higher than those in females (P < .01). The obvious peak circadian rhythm of TSH was observed at 0:00 AM with gradual decline thereafter, whereas other biomarkers showed no rhythmic changes. CONCLUSION: Sex differences should be considered in interpreting thyroid function tests. It is important to select the sampling time according to the clinician's diagnostic needs, especially at night when TSH secretion peaks.

Abundant binary promoter switches in lineage-determining transcription factors indicate a digital component of cell fate determination.

Previous studies of the murine Ly49 and human KIR gene clusters implicated competing sense and antisense promoters in the control of variegated gene expression. In the current study, an examination of transcription factor genes defines an abundance of convergent and divergent sense/antisense promoter pairs, suggesting that competing promoters may control cell fate determination. Differentiation of CD34+ hematopoietic progenitors in vitro shows that cells with GATA1 antisense transcription have enhanced GATA2 transcription and a mast cell phenotype, whereas cells with GATA2 antisense transcription have increased GATA1 transcripts and an erythroblast phenotype. Detailed analyses of the AHR and RORC genes demonstrate the ability of competing promoters to act as binary switches and the association of antisense transcription with an immature/progenitor cell phenotype. These data indicate that alternative cell fates generated by promoter competition in lineage-determining transcription factors contribute to the programming of cell differentiation.

Promoter variants in the MSMB gene associated with prostate cancer regulate MSMB/NCOA4 fusion transcripts.

Beta-microseminoprotein (MSP)/MSMB is an immunoglobulin superfamily protein synthesized by prostate epithelial cells and secreted into seminal plasma. Variants in the promoter of the MSMB gene have been associated with the risk of prostate cancer (PCa) in several independent genome-wide association studies. Both MSMB and an adjacent gene, NCOA4, are subjected to transcriptional control via androgen response elements. The gene product of NCOA4 interacts directly with the androgen receptor as a co-activator to enhance AR transcriptional activity. Here, we provide evidence for the expression of full-length MSMB-NCOA4 fusion transcripts regulated by the MSMB promoter. The predominant MSMB-NCOA4 transcript arises by fusion of the 5'UTR and exons 1-2 of the MSMB pre-mRNA, with exons 2-10 of the NCOA4 pre-mRNA, producing a stable fusion protein, comprising the essential domains of NCOA4. Analysis of the splice sites of this transcript shows an unusually strong splice acceptor at NCOA4 exon 2 and the presence of Alu repeats flanking the exons potentially involved in the splicing event. Transfection experiments using deletion clones of the promoter coupled with luciferase reporter assays define a core MSMB promoter element located between -27 and -236 of the gene, and a negative regulatory element immediately upstream of the start codon. Computational network analysis reveals that the MSMB gene is functionally connected to NCOA4 and the androgen receptor signaling pathway. The data provide an example of how GWAS-associated variants may have multiple genetic and epigenetic effects.

Fine mapping and functional analysis of a common variant in MSMB on chromosome 10q11.2 associated with prostate cancer susceptibility.

Two recent genome-wide association studies have independently identified a prostate cancer susceptibility locus on chromosome 10q11.2. The most significant single-nucleotide polymorphism (SNP) marker reported, rs10993994, is 57 bp centromeric of the first exon of the MSMB gene, which encodes beta-microseminoprotein (prostatic secretory protein 94). In this study, a fine-mapping analysis using HapMap SNPs was conducted across a approximately 65-kb region (chr10: 51168330-51234020) flanking rs10993994 with 13 tag SNPs in 6,118 prostate cancer cases and 6,105 controls of European origin from the Cancer Genetic Markers of Susceptibility (CGEMS) project. rs10993994 remained the most strongly associated marker with prostate cancer risk [P = 8.8 x 10(-18); heterozygous odds ratio (OR) = 1.20, 95% confidence interval (CI): 1.11-1.30; homozygous OR = 1.64, 95% CI: 1.47-1.86 for the adjusted genotype test with 2 df]. In follow-up functional analyses, the T variant of rs10993994 significantly affected expression of in vitro luciferase reporter constructs. In electrophoretic mobility shift assays, the C allele of rs10993994 preferentially binds to the CREB transcription factor. Analysis of tumor cell lines with a CC or CT genotype revealed a high level of MSMB gene expression compared with cell lines with a TT genotype. These findings were specific to the alleles of rs10993994 and were not observed for other SNPs determined by sequence analysis of the proximal promoter. Together, our mapping study and functional analyses implicate regulation of expression of MSMB as a plausible mechanism accounting for the association identified at this locus. Further investigation is warranted to determine whether rs10993994 alone or in combination with additional variants contributes to prostate cancer susceptibility.

Chemical forms of cadmium in soil and its distribution in French marigold sub-cells in response to chelator GLDA.

The use of degradable chelating agents to facilitate phytoextraction is a promising low-cost method for the remediation of heavy metal-contaminated soils. However, there are few studies on how plants and soils respond to the chelating agents. In this study, the responses of French marigold (Tagetes patula L.) and soil cadmium (Cd) to the chelator tetrasodium glutamate (GLDA) was investigated in a 180 d field trial. Five GLDA treatments (0, 292.5, 585, 1170, and 2340 kg hm-2) were carried out in a Cd-contaminated soil (0.47 mg kg-1) under French marigold plantation. The results showed that the application of GLDA promoted the transformation of other forms of Cd in soil to exchangeable state, and the exchangeable Cd and Fe-Mn oxide bound state increased by 42.13% and 32.97% (p < 0.05), respectively. The cell wall Cd accumulations significantly increased 9.39% (p < 0.05) and the percentages of soluble fractions increased by 460.33% (p < 0.05). Furthermore, increases occurred in soil pH, as well as DOC and DTPA-Cd contents with increasing the total amount of GLDA. The composite application of GLDA (2340 kg hm-2) with French marigold reduced the total soil Cd content by 7.59% compared with the soil background. Altogether, results of this study suggested that the application of GLDA can effectively activate soil Cd and enhance the capability of French marigold for the remediation of Cd-contaminated soils.

HPV16 E7 Nucleotide Variants Found in Cancer-Free Subjects Affect E7 Protein Expression and Transformation.

The human papillomavirus (HPV) type 16 E7 oncogene is critical to carcinogenesis and highly conserved. Previous studies identified a preponderance of non-synonymous E7 variants amongst HPV16-positive cancer-free controls compared to those with cervical cancer. To investigate the function of E7 variants, we constructed full-length HPV16 E7 genes and tested variants at positions H9R, D21N, N29S, E33K, T56I, D62N, S63F, S63P, T64M, E80K, D81N, P92L, and P92S (found only in controls); D14E, N29H cervical intraepithelial neoplasia (CIN2), and P6L, H51N, R77S (CIN3). We determined the steady-state level of cytoplasmic and nuclear HPV16 E7 protein. All variants from controls showed a reduced level of E7 protein, with 7/13 variants having lower protein levels. In contrast, 2/3 variants from the CIN3 precancer group had near-wild type E7 levels. We assayed the activity of representative variants in stably transfected NIH3T3 cells. The H9R, E33K, P92L, and P92S variants found in control subjects had lower transforming activity than D14E and N29H variants (CIN2), and the R77S (CIN3) had activity only slightly reduced from wild-type E7. In addition, R77S and WT E7 caused increased migration of NIH3T3 cells in a wound-healing assay compared with H9R, E33K, P92L, and P92S (controls) and D14E (CIN2). These data provide evidence that the E7 variants found in HPV16-positive cancer-free women are partially defective for transformation and cell migration, further demonstrating the importance of fully active E7 in cancer development.

The transcription factor c-Myc enhances KIR gene transcription through direct binding to an upstream distal promoter element.

The killer cell immunoglobulin-like receptor (KIR) repertoire of natural killer (NK) cells determines their ability to detect infected or transformed target cells. Although epigenetic mechanisms play a role in KIR gene expression, work in the mouse suggests that other regulatory elements may be involved at specific stages of NK-cell development. Here we report the effects of the transcription factor c-Myc on KIR expression. c-Myc directly binds to, and promotes transcription from, a distal element identified upstream of most KIR genes. Binding of endogenous c-Myc to the distal promoter element is significantly enhanced upon interleukin-15 (IL-15) stimulation in peripheral blood NK cells and correlates with an increase in KIR transcription. In addition, the overexpression of c-Myc during NK-cell development promotes transcription from the distal promoter element and contributes to the overall transcription of multiple KIR genes. Our data demonstrate the significance of the 5' promoter element upstream of the conventional KIR promoter region and support a model whereby IL-15 stimulates c-Myc binding at the distal KIR promoter during NK-cell development to promote KIR transcription. This finding provides a direct link between NK-cell activation signals and KIR expression required for acquisition of effector function during NK-cell education.