The transcription factor 7-like 2 (TCF7L2) locus is strongly implicated in the pathogenesis of type 2 diabetes (T2D). We previously mapped the genomic regions bound by TCF7L2 using ChIP (chromatin immunoprecipitation)-seq in the colorectal carcinoma cell line, HCT116, revealing an unexpected highly significant over-representation of genome-wide association studies (GWAS) loci associated primarily with endocrine (in particular T2D) and cardiovascular traits.
In order to further explore if this observed phenomenon occurs in other cell lines, we carried out ChIP-seq in HepG2 cells and leveraged ENCODE data for five additional cell lines. Given that only a minority of the predicted genetic component to most complex traits has been identified to date, plus our GWAS-related observations with respect to TCF7L2 occupancy, we investigated if restricting association analyses to the genes yielded from this approach, in order to reduce the constraints of multiple testing, could reveal novel T2D loci.
We found strong evidence for the continued enrichment of endocrine and cardiovascular GWAS categories, with additional support for cancer. When investigating all the known GWAS loci bound by TCF7L2 in the shortest gene list, derived from HCT116, the coronary artery disease-associated variant, rs46522 at the UBE2Z-GIP-ATP5G1-SNF8 locus, yielded significant association with T2D within DIAGRAM. Furthermore, when we analyzed tag-SNPs (single nucleotide polymorphisms) in genes not previously implicated by GWAS but bound by TCF7L2 within 5 kb, we observed a significant association of rs4780476 within CPPED1 in DIAGRAM.
ChIP-seq data generated with this GWAS-implicated transcription factor provided a biologically plausible method to limit multiple testing in the assessment of genome-wide genotyping data to uncover two novel T2D-associated loci.
Genetic Association; Type 2; Transcription Factor; Gene
Objective: This paper is aimed at to evaluate B7-H1 expression as induced by human cytomegalovirus (HCMV) in extravillous cytotrophoblast cell line HPT-8 and possible underlying mechanism.
Method: Real time PCR and flow cytometry were used to determine B7-H1 mRNA and protein before and after HCMV infection in HPT-8 cells. Western blot analysis was used to determine the level of MAPK phosphorylation in HPT-8 cell lines infected with HCMV.
Results: 100TCID50 was found to be the most effective dose, capable of stimulating B7-H1 mRNA and protein expression in HPT-8 cells. When empty control group was considered to have a B7-H1 mRNA value of 1, B7-H1 mRNA was 4.32 in 100TCID50 group. In flow cytometry study, mean ﬂuorescence intensity (MFI) of 100TCID50 group was 16.14, while empty control group was 1.34. Both mRNA and protein expression were found to be significantly increased (P<0.05) in 100TCID50 group compared to empty control group. The result of Western blot analysis showed increase in B7-H1 expression caused by the extracellular signaling that was related to ERK activation and the ERK inhibitor U0126 was found to reverse this increase.
Conclusion: HCMV upregulates B7-H1 expression in human extravillous cytotrophoblast cell line HPT-8, which is related to MAPK activation. Our result would be helpful in finding better therapies against intrauterine HCMV infection.
Cytomegalovirus; Cytotrophoblast; B7-H1; MAPK
The inflammatory myofibroblastic tumor (IMT) is an uncommon low-risk lesion with only a few cases described in the literature.
Here, we report a unique case of an IMT coexisting with breast cancer. Modified radical mastectomy was performed, followed by TAC chemotherapy (taxotere, adriamycin and cyclophosphamide). At the 2-year follow-up, the patient continues to be disease free.
At the preoperative stage, definitive diagnoses of masses are extremely difficult; surgery is advised only after the diagnosis is confirmed by pathological examination.
Inflammatory myofibroblastic tumor; Breast cancer
Background: In recent years, the spleen has become to be recognized as the “control center” of the immune-metabolic-endocrine network. However, It is controversial that splenomegaly due to portal hypertension is treated by subtotal splenectomy. The aim of this study was to evaluate the distribution of fibrous tissue, morphology of cells as well as splenic size, hemodynamics, hematological and immunological indexes in the residual spleen after subtotal splenectomy. This information may help finding the basis for the operation of subtotal splenectomy. Methods: Ten cases of splenomegaly due to portal hypertension were investigated. Two groups were created: Splenomegaly and Residual spleen. Control group was 10 cases of trauma-induced splenic rupture. Samples were sliced, and morphological changes were observed under light microscopy and electron microscopy. Indexes of splenic size, hemodynamics, hematology and immunology of the spleen were measured. Results: Under light microscopy, the number of collagen fibers and elastic fibers was increased, and the number of reticular fibers was decreased in the residual spleen and splenomegaly groups. Under electron microscopy, the ultrastructure of endothelial cells, lymphocytes, macrophages, and reticular cells in the residual spleen group were noticeably improved more than in the splenomegaly group. Flow volume in the residual spleen and portal vein decreased obviously, with number of platelet rising to normal, and there was no significant difference in the indexes of immunology. Conclusion: After subtotal splenectomy, the residual spleen will not experience a high-pressure environment, and the fibrosis of splenic tissue and remodelling of corpuscular morphology will cease.
Histopathology; cytomorphology; fiber tissues; residual spleen; cirrhosis
The relationship between radial scars and breast cancer is unclear, as the results of different studies are inconsistent. We aim to solve the controversy and assess the breast cancer risk of radial scars.
Case-control or cohort studies about radial scars and breast cancer risk published in PubMed, Web of Science and the Cochrane Library from 2000 to 2013 were searched. Heterogeneity for the eligible data was assessed and a pooled odds ratio (OR) with 95% confidence interval (CI) was calculated.
Five observational studies involving 2521 cases and 20290 controls were included in our study. From pooled analysis, radial scars were found to have a 1.33 fold increased risk of breast cancer, but which was not significant (P = 0.138). Sample size contributed to heterogeneity. In subgroup analysis, the results pooled from studies with sample size >2000 show that presence of radial scars was associated with 1.6 times breast cancer risk compared to absence of radial scars. Radial scars increased the risk of breast cancer among women with proliferative disease without atypia, but no significant association between radial scars and carcinoma was noted among women with atypical hyperplasia.
Radial scars tend to be associated with an increased breast cancer risk. Radial scars should be considered among women with proliferative disease without atypia, while atypical hyperplasia is still the primary concern among women with both radial scars and atypical hyperplasia.
Wound healing is a multi-phased pathophysiological process requiring chemoattractant receptor-dependent accumulation of myeloid cells in the lesion. Two G protein-coupled formylpeptide receptors Fpr1 and Fpr2 mediate rapid neutrophil infiltration in the liver of Listeria-infected mice by sensing pathogen-derived chemotactic ligands. These receptors also recognize host-derived chemotactic peptides in inflammation and injury. Here we report the capacity of Fprs to promote the healing of sterile skin wound in mice by initiating neutrophil infiltration. We found that in normal miceneutrophils rapidly infiltrated the dermis in the wound before the production of neutrophil-specific chemokines by the injured tissue. In contrast, rapid neutrophil infiltration was markedly reduced with delayed wound closure in mice deficient in both Fprs. In addition, we detected Fpr ligand activity that chemoattracted neutrophils into the wound tissue. Our study thus demonstrates that Fprs are critical for normal healing of the sterile skin wound by mediating the first wave of neutrophil infiltration.
Common variation at the loci harboring FTO, MC4R and TMEM18 is consistently reported as being statistically the most strongly associated with obesity. We investigated if these loci also harbor rarer missense variants that confer substantially higher risk of common childhood obesity in African American (AA) children. We sequenced the exons of FTO, MC4R and TMEM18 in an initial subset of our cohort i.e. 200 obese (BMI≥95th percentile) and 200 lean AA children (BMI≤5th percentile). Any missense exonic variants that were uncovered went on to be further genotyped in a further 768 obese and 768 lean (BMI≤50th percentile) children of the same ethnicity. A number of exonic variants were observed from our sequencing effort: seven in FTO, of which four were non-synonymous (A163T, G182A, M400V and A405V), thirteen in MC4R, of which six were non-synonymous (V103I, N123S, S136A, F202L, N240S and I251L) and four in TMEM18, of which two were non-synonymous (P2S and V113L). Follow-up genotyping of these missense variants revealed only one significant difference in allele frequency between cases and controls, namely with N240S in MC4R(Fisher's Exact P = 0.0001). In summary, moderately rare missense variants within the FTO, MC4R and TMEM18 genes observed in our study did not confer risk of common childhood obesity in African Americans except for a degree of evidence for one known loss-of-function variant in MC4R.
Obesity; Pediatrics; Genomics
Birth weight within the normal range is associated with a variety of adult-onset diseases, but the mechanisms behind these associations are poorly understood1. Previous genome-wide association studies identified a variant in the ADCY5 gene associated both with birth weight and type 2 diabetes, and a second variant, near CCNL1, with no obvious link to adult traits2. In an expanded genome-wide association meta-analysis and follow-up study (up to 69,308 individuals of European descent from 43 studies), we have now extended the number of genome-wide significant loci to seven, accounting for a similar proportion of variance to maternal smoking. Five of the loci are known to be associated with other phenotypes: ADCY5 and CDKAL1 with type 2 diabetes; ADRB1 with adult blood pressure; and HMGA2 and LCORL with adult height. Our findings highlight genetic links between fetal growth and postnatal growth and metabolism.
The large individual variability for anticancer drugs in both outcome and toxicity risk makes the identification of pharmacogenetic markers that can be used to screen patients before therapy selection an attractive prospect.
This work aimed to evaluate the importance of genetic polymorphisms involved in drug detoxification to predict clinical outcomes of anthracycline-based neoadjuvant chemotherapy for breast cancer.
GSTP1 313 AA genotype was associated with a poor clinical response relative to G allele carrier (58.4 vs. 80.8%; p = 0.006), and MDR1 3435 TT genotype had a worse response compared with C allele carrier (33.3 vs. 71.2% p = 0.001). Patients with both the adverse genotypes of GSTP1 313AA and MDR 3435TT showed the worst therapy efficacy in all (14.3%; p = 0.000). Kaplan-Meier survival analysis showed that the patients with no adverse genotype were associated with decreased hazard of relapse (p = 0.002), compared with those with 1 or 2 adverse genotypes. Multivariate analysis demonstrated that clinical response and no adverse genotype was independent predictors of disease-free survival (DFS).
Genotyping was performed by allele-specific oligonucleotide ligation reaction (MnSOD, CAT, GSTP1), multiplex PCR (GSTM1, GSTT1) or PCR-RFLP (MDR1). Based on 153 patients received anthracycline-based neoadjuvant chemotherapy, these genotypes or their combinations in relation to treatment-related response, hematologic toxicity and DFS were investigated.
These results suggest that polymorphisms in GSTP1 and MDR1 may help to predict clinical response and DFS of anthracycline-based chemotherapy, and a polygenic pathway approach should provide more useful information. The findings required independent prospective confirmation.
anthracycline; breast cancer; chemotherapy; clinical response; disease-free survival (DFS); individualizing treatment; polymorphism
There is evidence that one of the key type 2 diabetes (T2D) loci identified by GWAS exerts its influence early on in life through its impact on pediatric BMI. This locus on 10q23 harbors three genes, encoding hematopoietically expressed homeobox (HHEX), insulin-degrading enzyme (IDE) and kinesin family member 11 (KIF11), respectively.
We analyzed the impact of adipogeneis on the mRNA and protein expression levels of these genes in the human adipocyte Simpson-Golabi-Behmel syndrome (SGBS) cell line in order to investigate which could be the culprit gene(s) in this region of linkage disequilibrium.
Following activation of differentiation with a PPARγ ligand, we observed ~20% decrease in IDE, ~40% decrease in HHEX and in excess of 80% decrease in KIF11 mRNA levels when comparing the adipocyte and pre-adipocyte states. We also observed decreases in KIF11 and IDE protein levels, but conversely we observed a dramatic increase in HHEX protein levels. Subsequent time course experiments revealed some marked changes in expression as early as three hours after activation of differentiation.
Our data suggest that the expression of all three genes at this locus are impacted during SGBS adipogenesis and provides insights in to the possible mechanisms of how the genes at this 10q23 locus could influence both adipocyte differentiation and susceptibility to T2D through insulin resistance.
Obesity; Pediatrics; Expression; Genomics
To assess the potential efficacy of mechano growth factor (MGF) for bone injury, we firstly investigated the effects of growth factors, including MGF, its E peptide (a short 24-amino acid C-terminal peptide, MGF-Ct24E), and insulin-like growth factor 1(IGF-1) on MC3T3-E1 osteoblast-like cell proliferation. MGF-Ct24E had the highest pro-proliferation activity among three growth factors, which was 1.4 times greater than that of IGF-1. Moreover, MGF-Ct24E promoted cell proliferation by inducing cell cycle arrest in the S and G2/M phase of the cell cycle, but also mainly by the activation of the MAPK-Erk1/2 pathway. In vivo, a 5-mm segmental bone defect in the radius of 27 rabbits was treated with MGF-Ct24E by two doses (28.5 and 57 μg /kg body weight) vs. non-growth factor injection for five consecutive days postoperatively. The cumulative rate of radiographically healed defects and histological scores of bone defect-healing revealed a statistical difference between high-dose treatment and non treatment (p < 0.01), which showed the treatment promoted defect healing. This report is the first to demonstrate that MGF-Ct24E possesses positive effects on osteoblast proliferation and bone-defect healing, suggesting a new strategy in fracture healing.
Multiple genetic variants have been associated with adult obesity and a few with severe obesity in childhood; however, less progress has been made to establish genetic influences on common early-onset obesity. We performed a North American-Australian-European collaborative meta-analysis of fourteen studies consisting of 5,530 cases (≥95th percentile of body mass index (BMI)) and 8,318 controls (<50th percentile of BMI) of European ancestry. Taking forward the eight novel signals yielding association with P < 5×10−6 in to nine independent datasets (n = 2,818 cases and 4,083 controls) we observed two loci that yielded a genome wide significant combined P-value, namely near OLFM4 on 13q14 (rs9568856; P=1.82×10−9; OR=1.22) and within HOXB5 on 17q21 (rs9299; P=3.54×10−9; OR=1.14). Both loci continued to show association when including two extreme childhood obesity cohorts (n = 2,214 cases and 2,674 controls). Finally, these two loci yielded directionally consistent associations in the GIANT meta-analysis of adult BMI1.
Obesity is a major health problem and an immense economic burden on the health care systems both in the United States and the rest of the world. The prevalence of obesity in children and adults in the United States has increased dramatically over the past decade. Besides environmental factors, genetic factors are known to play an important role in the pathogenesis of obesity. Genome-wide association studies (GWAS) have revealed strongly associated genomic variants associated with most common disorders; indeed there is general consensus on these findings from generally positive replication outcomes by independent groups. To date, there have been only a few GWAS-related reports for childhood obesity specifically, with studies primarily uncovering loci in the adult setting instead. It is clear that a number of loci previously reported from GWAS analyses of adult BMI and/or obesity also play a role in childhood obesity.
A number of studies have found that BMI in early life influences the risk of developing type 2 diabetes later in life. Our goal was to investigate if any type 2 diabetes variants uncovered through genome-wide association studies (GWAS) impact BMI in childhood.
RESEARCH DESIGN AND METHODS
Using data from an ongoing GWAS of pediatric BMI in our cohort, we investigated the association of pediatric BMI with 20 single nucleotide polymorphisms at 18 type 2 diabetes loci uncovered through GWAS, consisting of ADAMTS9, CDC123-CAMK1D, CDKAL1, CDKN2A/B, EXT2, FTO, HHEX-IDE, IGF2BP2, the intragenic region on 11p12, JAZF1, KCNQ1, LOC387761, MTNR1B, NOTCH2, SLC30A8, TCF7L2, THADA, and TSPAN8-LGR5. We randomly partitioned our cohort exactly in half in order to have a discovery cohort (n = 3,592) and a replication cohort (n = 3,592).
Our data show that the major type 2 diabetes risk–conferring G allele of rs7923837 at the HHEX-IDE locus was associated with higher pediatric BMI in both the discovery (P = 0.0013 and survived correction for 20 tests) and replication (P = 0.023) sets (combined P = 1.01 × 10−4). Association was not detected with any other known type 2 diabetes loci uncovered to date through GWAS except for the well-established FTO.
Our data show that the same genetic HHEX-IDE variant, which is associated with type 2 diabetes from previous studies, also influences pediatric BMI.
MnAs films are grown on GaAs surfaces by molecular beam epitaxy. Specular and grazing incidence X-ray diffractions are used to study the influence of different strain states of MnAs/GaAs (110) and MnAs/GaAs (001) on the first-order magnetostructural phase transition. It comes out that the first-order magnetostructural phase transition temperature Tt, at which the remnant magnetization becomes zero, is strongly affected by the strain constraint from different oriented GaAs substrates. Our results show an elevated Tt of 350 K for MnAs films grown on GaAs (110) surface, which is attributed to the effect of strain constraint from different directions.
PACS: 68.35.Rh, 61.50.Ks, 81.15.Hi, 07.85.Qe
To identify genetic variants associated with birth weight, we meta-analyzed six genome-wide association (GWA) studies (N=10,623 Europeans from pregnancy/birth cohorts) and followed up two lead signals in thirteen replication studies (N=27,591). Rs900400 near LEKR1 and CCNL1 (P=2×10−35), and rs9883204 in ADCY5 (P=7×10−15) were robustly associated with birth weight. Correlated SNPs in ADCY5 were recently implicated in regulation of glucose levels and type 2 diabetes susceptibility,1 providing evidence that the well described association between lower birth weight and subsequent type 2 diabetes2,3 has a genetic component, distinct from the proposed role of programming by maternal nutrition. Using data from both SNPs, the 9% of Europeans with 4 birth weight-lowering alleles were, on average, 113g (95%CI 89-137g) lighter at birth than the 24% with 0 or 1 allele (Ptrend=7×10−30). The impact on birth weight is similar to that of a mother smoking 4-5 cigarettes per day in the third trimester of pregnancy.4
A number of studies have found that reduced birth weight is associated with type 2 diabetes later in life; however, the underlying mechanism for this correlation remains unresolved. Recently, association has been demonstrated between low birth weight and single nucleotide polymorphisms (SNPs) at the CDKAL1 and HHEX-IDE loci, regions that were previously implicated in the pathogenesis of type 2 diabetes. In order to investigate whether type 2 diabetes risk–conferring alleles associate with low birth weight in our Caucasian childhood cohort, we examined the effects of 20 such loci on this trait.
RESEARCH DESIGN AND METHODS
Using data from an ongoing genome-wide association study in our cohort of 5,465 Caucasian children with recorded birth weights, we investigated the association of the previously reported type 2 diabetes–associated variation at 20 loci including TCF7L2, HHEX-IDE, PPARG, KCNJ11, SLC30A8, IGF2BP2, CDKAL1, CDKN2A/2B, and JAZF1 with birth weight.
Our data show that the minor allele of rs7756992 (P = 8 × 10−5) at the CDKAL1 locus is strongly associated with lower birth weight, whereas a perfect surrogate for variation previously implicated for the trait at the same locus only yielded nominally significant association (P = 0.01; r2 rs7756992 = 0.677). However, association was not detected with any of the other type 2 diabetes loci studied.
We observe association between lower birth weight and type 2 diabetes risk–conferring alleles at the CDKAL1 locus. Our data show that the same genetic locus that has been identified as a marker for type 2 diabetes in previous studies also influences birth weight.
Human height is considered highly heritable and correlated with certain disorders, such as type 2 diabetes and cancer. Despite environmental influences, genetic factors are known to play an important role in stature determination. A number of genetic determinants of adult height have already been established through genome wide association studies.
To examine 51 single nucleotide polymorphisms (SNPs) corresponding to the 46 previously reported genomic loci for height in 8,184 European American children with height measurements. We leveraged genotyping data from our ongoing GWA study of height variation in children in order to query the 51 SNPs in this pediatric cohort.
Sixteen of these SNPs yielded at least nominally significant association to height, representing fifteen different loci including EFEMP1-PNPT1, GPR126, C6orf173, SPAG17, Histone class 1, HLA class III and GDF5-UQCC. Other loci revealed no evidence for association, including HMGA1 and HMGA2. For the 16 associated variants, the genotype score explained 1.64% of the total variation for height z-score.
Among 46 loci that have been reported to associate with adult height to date, at least 15 also contribute to the determination of height in childhood.
The prevalence of obesity in children and adults in the United States has increased dramatically over the past decade. Besides environmental factors, genetic factors are known to play an important role in the pathogenesis of obesity. A number of genetic determinants of adult BMI have already been established through genome wide association studies. In this study, we examined 25 single nucleotide polymorphisms (SNPs) corresponding to thirteen previously reported genomic loci in 6,078 children with measures of BMI. Fifteen of these SNPs yielded at least nominally significant association to BMI, representing nine different loci including INSIG2, FTO, MC4R, TMEM18, GNPDA2, NEGR1, BDNF, KCTD15 and 1q25. Other loci revealed no evidence for association, namely at MTCH2, SH2B1, 12q13 and 3q27. For the 15 associated variants, the genotype score explained 1.12% of the total variation for BMI z-score. We conclude that among thirteen loci that have been reported to associate with adult BMI, at least nine also contribute to the determination of BMI in childhood as demonstrated by their associations in our pediatric cohort.
Beauveria bassiana is an economically important insect-pathogenic fungus which is widely used as a biocontrol agent to control a variety of insect pests. However, its insecticide efficacy in the field is often influenced by adverse environmental factors. Thus, understanding the genetic regulatory processes involved in the response to environmental stress would facilitate engineering and production of a more efficient biocontrol agent. Here, a mitogen-activated protein kinase (MAPK)-encoding gene, Bbhog1, was isolated from B. bassiana and shown to encode a functional homolog of yeast HIGH-OSMOLARITY GLYCEROL 1 (HOG1). A Bbhog1 null mutation was generated in B. bassiana by targeted gene replacement, and the resulting mutants were more sensitive to hyperosmotic stress, high temperature, and oxidative stress than the wild-type controls. These results demonstrate the conserved function of HOG1 MAPKs in the regulation of abiotic stress responses. Interestingly, ΔBbhog1 mutants exhibited greatly reduced pathogenicity, most likely due to a decrease in spore viability, a reduced ability to attach to insect cuticle, and a reduction in appressorium formation. The transcript levels of two hydrophobin-encoding genes, hyd1 and hyd2, were dramatically decreased in a ΔBbhog1 mutant, suggesting that Bbhog1 may regulate the expression of the gene associated with hydrophobicity or adherence.
The diverse biological actions of retinoic acid (RA) are mediated by RA receptors (RARs) and retinoid X receptors (RXRs). While the coregulatory proteins that interact with the ligand-dependent AF-2 in the E region are well studied, the ligand-independent N-terminal AF-1 domain-interacting partners and their influence(s) on the function of RARs are poorly understood. HECT domain and Ankyrin repeat Containing E3 ubiquitin-protein ligase (HACE1) was isolated as a RARβ3 AB region interacting protein. HACE1 interacts with RARβ3 both in in vitro GST pull-down and in cell-based coprecipitation assays. The interaction sites map to the N terminus of RARβ3 and the C terminus of HACE1. HACE1 functionally represses the transcriptional activity of RARα1, RARβ isoforms 1, 2 and 3, but not RARγ1 in luciferase reporter assays. In addition, HACE1 represses the endogenous RAR-regulated genes CRABP II, RIG1 and RARβ2, but not RAI3 in CAOV3 cells. Mutation of the putative catalytic cysteine (C876 of LF HACE1), which is indispensable for its E3 ubiquitin ligase activity, does not alter the repressive effect of HACE1 on the transcriptional activity of RARβ3. On the other hand, HACE1 inhibits the RA dependent degradation of RARβ3. It is possible that the repression of RAR-regulated transcription by HACE1 is due to its ability to inhibit the RA-dependent degradation of RARs.
retinoic acid; RAR; HACE1; transcription; AF-1
The diverse biological actions of retinoic acid (RA) are mediated by RA receptors (RARs) and retinoid X receptors (RXRs). Modulation of transcription by RARs/RXRs is achieved through two activation functions, ligand-independent AF-1 and ligand-dependent AF-2, located in the A/B and E domains, respectively. While the coregulatory proteins that interact with the E domain are well studied, the A/B domain-interacting partners and their influence(s) on the function of RARs are poorly understood. Acinus-S′ is an ubiquitous nuclear protein that has been implicated in inducing apoptotic chromatin condensation and regulating mRNA processing. Our data demonstrate that Acinus-S′ can specifically repress ligand-independent and ligand-dependent expression of a DR5 RA response element(RARE)-dependent reporter gene and several endogenous RAR-regulated genes in a dose-dependent and gene-specific manner. Chromatin immunoprecipitation assays show that Acinus-S′ associates with RAREs within the promoters of endogenous genes independent of RA treatment. Furthermore, the C-terminal end of Acinus-S′ and the B domain of RARβ interact independently of ligand, and the C-terminal end of Acinus-S′ is sufficient for the repression of RAR-regulated gene expression. Finally, histone deacetylase activity only partially accounts for the repressive effect of Acinus-S′ on RAR-dependent gene expression. These findings identify Acinus-S′ as a novel RAR-interacting protein that regulates the expression of a subset of RAR-regulated genes through direct binding to the N-terminal B domains of RARs.