I-mfa domain proteins specifically interact with SERTA domain proteins and repress their transactivating functions

C166 EVs potentiate miR cardiac reprogramming via miR-148a-3p

We have demonstrated that directly reprogramming cardiac fibroblasts into new cardiomyocytes via miR combo improves cardiac function in the infarcted heart. However, major challenges exist with delivery and efficacy. During a screening based approach to improve delivery, we discovered that C166-derived EVs were effective delivery agents for miR combo both in vitro and in vivo. In the latter, EV mediated delivery of miR combo induced significant conversion of cardiac fibroblasts into cardiomyocytes (∼20%), reduced fibrosis and improved cardiac function in a myocardial infarction injury model. When compared to lipid-based transfection, C166 EV mediated delivery of miR combo enhanced reprogramming efficacy. Improved reprogramming efficacy was found to result from a miRNA within the exosome: miR-148a-3p. The target of miR-148a-3p was identified as Mdfic. Over-expression and targeted knockdown studies demonstrated that Mdfic was a repressor of cardiomyocyte specific gene expression. In conclusion, we have demonstrated that C166-derived EVs are an effective method for delivering reprogramming factors to cardiac fibroblasts and we have identified a novel miRNA contained within C166-derived EVs which enhances reprogramming efficacy.

SERTAD3 induces proteasomal degradation of ZIKV capsid protein and represents a therapeutic target

Zika virus (ZIKV) is a mosquito-borne RNA virus that belongs to the Flaviviridae family. While flavivirus replication is known to occur in the cytoplasm, a significant portion of the viral capsid protein localizes to the nucleus during infection. However, the role of the nuclear capsid is less clear. Herein, we demonstrated SERTA domain containing 3 (SERTAD3) as an antiviral interferon stimulatory gene product had an antiviral ability to ZIKV but not JEV. Mechanistically, we found that SERTAD3 interacted with the capsid protein of ZIKV in the nucleolus and reduced capsid protein abundance through proteasomal degradation. Furthermore, an eight amino acid peptide of SERTAD3 was identified as the minimum motif that binds with ZIKV capsid protein. Remarkably, the eight amino acids synthetic peptide from SERTAD3 significantly prevented ZIKV infection in culture and pregnant mouse models. Taken together, these findings not only reveal the function of SERTAD3 in promoting proteasomal degradation of a specific viral protein but also provide a promising host-targeted therapeutic strategy against ZIKV infection.

Type-IInterferon-Inducible SERTAD3 Inhibits Influenza A Virus Replication by Blocking the Assembly of Viral RNA Polymerase Complex

Influenza A virus (IAV) infection stimulates a type I interferon (IFN-I) response in host cells that exerts antiviral effects by inducing the expression of hundreds of IFN-stimulated genes (ISGs). However, most ISGs are poorly studied for their roles in the infection of IAV. Herein, we demonstrate that SERTA domain containing 3 (SERTAD3) has a significant inhibitory effect on IAV replication in vitro. More importantly, Sertad3^-/- mice develop more severe symptoms upon IAV infection. Mechanistically, we find SERTAD3 reduces IAV replication through interacting with viral polymerase basic protein 2 (PB2), polymerase basic protein 1 (PB1), and polymerase acidic protein (PA) to disrupt the formation of the RNA-dependent RNA polymerase (RdRp) complex. We further identify an 8-amino-acid peptide of SERTAD3 as a minimum interacting motif that can disrupt RdRp complex formation and inhibit IAV replication. Thus, our studies not only identify SERTAD3 as an antiviral ISG, but also provide the mechanism of potential application of SERTAD3-derived peptide in suppressing influenza replication.

Multifaceted array-based keloidal gene expression profiling reveals specific MDFI upregulation in keloid lesions

BACKGROUND

Keloid lesions are characterized by mesenchymal cell proliferation and excessive extracellular matrix deposition. Previous microarray analyses have been performed to investigate the mechanism of keloid development. However, the molecular pathology that contributes to keloid development remains obscure.

AIM

To explore the underlying essential molecules of keloids using microarrays.

METHODS

We performed microarray analyses of keloid and nonlesional skin tissues both in vivo and in vitro. Gene expression levels were compared between tissues and cells. Quantitative reverse transcription (qRT)-PCR and immunohistochemical staining were used to determine the expression levels of molecules of interest in keloid tissues.

RESULTS

Several common molecules were upregulated in both keloid tissues and keloid-lesional fibroblasts. PTPRD and NTM were upregulated both in vivo and in vitro. The genes MDFI and ITGA4 were located at the centre of the gene coexpression network analysis using keloid tissues. qRT-PCR revealed significant expression levels of PTPRD and MDFI in keloid tissues. Immunopathological staining revealed that MDFI-positive cells, which have fibroblast characteristics, were located in the keloid-associated lymphoid tissue (KALT) portion of the keloid tissue.

CONCLUSION

Our gene expression profiles of keloids could distinguish the difference between lesional tissue and cultured lesional fibroblasts, and MDFI was found to be commonly expressed in both tissues and cells. Thus, MDFI-positive cells, which were located in the KALT, may play an important role in keloid pathogenesis and thus might be useful for in vitro keloid studies.

Exploring the Role of TRIP-Brs in Human Breast Cancer: An Investigation of Expression, Clinicopathological Significance, and Prognosis

TRIP-Brs, a group of transcription factors (TFs) that modulate several mechanisms in higher organisms. However, the novel paradigm to target TRIP-Brs in specific cancer remains to be deciphered. In particular, comprehensive analysis of TRIP-Brs in clinicopathological and patients’ prognosis, especially in breast cancer (BRCA), is being greatly ignored. Therefore, we explored the key roles of TRIP-Br expression, modulatory effects, mutations, immune infiltration, and prognosis in BRCA using multidimensional approaches. We found elevated levels of TRIP-Brs in numerous cancer tissues than normal. Higher expression of TRIP-Br-2/4/5 was shown to be positively associated with lower survival, tumor grade, and malignancy of patients with BRCA. Additionally, higher TRIP-Br-3/4 were also significantly linked with worse/short survival of BRCA patients. TRIP-Br-1/4/5 were significantly overexpressed and enhanced tumorigenesis in large-scale BRCA datasets. The mRNA levels of TRIP-Brs have been also correlated with tumor immune infiltrate in BRCA patients. In addition, TRIP-Brs synergistically play a pivotal role in central carbon metabolism, cancer-associated pathways, cell cycle, and thyroid hormone signaling, which evoke that TRIP-Brs may be a potential target for the therapy of BRCA. Thus, this investigation may lay a foundation for further research on TRIP-Br-mediated management of BRCA.

Opposite Roles of the JMJD1A Interaction Partners MDFI and MDFIC in Colorectal Cancer

MyoD family inhibitor (MDFI) and MDFI domain-containing (MDFIC) are homologous proteins known to regulate myogenic transcription factors. Hitherto, their role in cancer is unknown. We discovered that MDFI is up- and MDFIC downregulated in colorectal tumors. Mirroring these different expression patterns, MDFI stimulated and MDFIC inhibited growth of HCT116 colorectal cancer cells. Further, MDFI and MDFIC interacted with Jumonji C domain-containing (JMJD) 1 A, a histone demethylase and epigenetic regulator involved in colorectal cancer. JMJD1A influenced transcription of several genes that were also regulated by MDFI or MDFIC. Notably, the HIC1 tumor suppressor gene was stimulated by JMJD1A and MDFIC, but not by MDFI, and HIC1 overexpression phenocopied the growth suppressive effects of MDFIC in HCT116 cells. Similar to colorectal cancer, MDFI was up- and MDFIC downregulated in breast, ovarian and prostate cancer, but both were overexpressed in brain, gastric and pancreatic tumors that implies MDFIC to also promote tumorigenesis in certain tissues. Altogether, our data suggest a tumor modulating function for MDFI and MDFIC in colorectal and other cancers that may involve their interaction with JMJD1A and a MDFIC→HIC1 axis.

Inhibitor of myogenic differentiation family isoform a, a new positive regulator of fibronectin production by glomerular mesangial cells

Overproduction of extracellular matrix proteins, including fibronectin by mesangial cells (MCs), contributes to diabetic nephropathy. Inhibitor of myogenic differentiation family isoform a (I-mfa) is a multifunctional cytosolic protein functioning as a transcriptional modulator or plasma channel protein regulator. However, its renal effects are unknown. The present study was conducted to determine whether I-mfa regulated fibronectin production by glomerular MCs. In human MCs, overexpression of I-mfa significantly increased fibronectin abundance. Silencing I-mfa significantly reduced the level of fibronectin mRNA and blunted transforming growth factor-β1-stimulated production of fibronectin. We further found that high glucose increased I-mfa protein content in a time course (≥48 h) and concentration (≥25 mM)-dependent manner. Although high glucose exposure increased I-mfa at the protein level, it did not significantly alter transcripts of I-mfa in MCs. Furthermore, the abundance of I-mfa protein was significantly increased in the renal cortex of rats with diabetic nephropathy. The I-mfa protein level was also elevated in the glomerulus of mice with diabetic kidney disease. However, there was no significant difference in glomerular I-mfa mRNA levels between mice with and without diabetic nephropathy. Moreover, H2O2 significantly increased I-mfa protein abundance in a dose-dependent manner in cultured human MCs. The antioxidants polyethylene glycol-catalase, ammonium pyrrolidithiocarbamate, and N-acetylcysteine significantly blocked the high glucose-induced increase of I-mfa protein. Taken together, our results suggest that I-mfa, increased by high glucose/diabetes through the production of reactive oxygen species, stimulates fibronectin production by MCs.

Comparative Analysis of MicroRNA and mRNA Profiles of Sperm with Different Freeze Tolerance Capacities in Boar (Sus scrofa) and Giant Panda (Ailuropoda melanoleuca)

Post-thawed sperm quality parameters vary across different species after cryopreservation. To date, the molecular mechanism of sperm cryoinjury, freeze-tolerance and other influential factors are largely unknown. In this study, significantly dysregulated microRNAs (miRNAs) and mRNAs in boar and giant panda sperm with different cryo-resistance capacity were evaluated. From the result of miRNA profile of fresh and frozen-thawed giant panda sperm, a total of 899 mature, novel miRNAs were identified, and 284 miRNAs were found to be significantly dysregulated (195 up-regulated and 89 down-regulated). Combined analysis of miRNA profiling of giant panda sperm and our previously published data on boar sperm, 46, 21 and 4 differentially expressed (DE) mRNAs in boar sperm were believed to be related to apoptosis, glycolysis and oxidative phosphorylation, respectively. Meanwhile, 87, 17 and 7 DE mRNAs in giant panda were associated with apoptosis, glycolysis and oxidative phosphorylation, respectively. Gene ontology (GO) analysis of the targets of DE miRNAs showed that they were mainly distributed on membrane related pathway in giant panda sperm, while cell components and cell processes were tied to the targets of DE miRNAs in boar sperm. Finally, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of DE mRNAs indicated that most of these DE mRNAs were distributed in membrane signal transduction-related pathways in giant panda sperm, while those in boar sperm were mainly distributed in the cytokine-cytokine receptor interaction pathway and inflammatory related pathways. In conclusion, although the different freezing extenders and programs were used, the DE miRNAs and mRNAs involved in apoptosis, energy metabolism, olfactory transduction pathway, inflammatory response and cytokine-cytokine interactions, could be the possible molecular mechanism of sperm cryoinjury and freeze tolerance.

Interaction of phospholipid scramblase 1 with the Epstein-Barr virus protein BZLF1 represses BZLF1-mediated lytic gene transcription

Human phospholipid scramblase 1 (PLSCR1) is strongly expressed in response to interferon (IFN) treatment and viral infection, and PLSCR1 has been suggested to play an important role in IFN-dependent antiviral responses. In this study, we showed that the basal expression of PLSCR1 was significantly elevated in Epstein-Barr virus (EBV)-infected nasopharyngeal carcinoma (NPC). PLSCR1 was observed to directly interact with the EBV immediate-early transactivator BZLF1 in vitro and in vivo, and this interaction repressed the BZLF1-mediated transactivation of an EBV lytic BMRF1 promoter construct. In addition, PLSCR1 expression decreased the BZLF1-mediated up-regulation of lytic BMRF1 mRNA and protein expression in WT and PLSCR1-knockout EBV-infected NPC cells. Furthermore, we showed that PLSCR1 represses the interaction between BZLF1 and CREB-binding protein (CBP), which enhances the BZLF1-mediated transactivation of EBV lytic promoters. These results reveal for the first time that PLSCR1 specifically interacts with BZLF1 and negatively regulates its transcriptional regulatory activity by preventing the formation of the BZLF1-CBP complex. This interaction may contribute to the establishment of latent EBV infection in EBV-infected NPC cells.

Dynamic Chromatin Targeting of BRD4 Stimulates Cardiac Fibroblast Activation

RATIONALE

Small molecule inhibitors of the acetyl-histone binding protein BRD4 have been shown to block cardiac fibrosis in preclinical models of heart failure (HF). However, since the inhibitors target BRD4 ubiquitously, it is unclear whether this chromatin reader protein functions in cell type-specific manner to control pathological myocardial fibrosis. Furthermore, the molecular mechanisms by which BRD4 stimulates the transcriptional program for cardiac fibrosis remain unknown.

OBJECTIVE

We sought to test the hypothesis that BRD4 functions in a cell-autonomous and signal-responsive manner to control activation of cardiac fibroblasts, which are the major extracellular matrix-producing cells of the heart.

METHODS AND RESULTS

RNA-sequencing, mass spectrometry, and cell-based assays employing primary adult rat ventricular fibroblasts demonstrated that BRD4 functions as an effector of TGF-β (transforming growth factor-β) signaling to stimulate conversion of quiescent cardiac fibroblasts into Periostin (Postn)-positive cells that express high levels of extracellular matrix. These findings were confirmed in vivo through whole-transcriptome analysis of cardiac fibroblasts from mice subjected to transverse aortic constriction and treated with the small molecule BRD4 inhibitor, JQ1. Chromatin immunoprecipitation-sequencing revealed that BRD4 undergoes stimulus-dependent, genome-wide redistribution in cardiac fibroblasts, becoming enriched on a subset of enhancers and super-enhancers, and leading to RNA polymerase II activation and expression of downstream target genes. Employing the Sertad4 (SERTA domain-containing protein 4) locus as a prototype, we demonstrate that dynamic chromatin targeting of BRD4 is controlled, in part, by p38 MAPK (mitogen-activated protein kinase) and provide evidence of a critical function for Sertad4 in TGF-β-mediated cardiac fibroblast activation.

CONCLUSIONS

These findings define BRD4 as a central regulator of the pro-fibrotic cardiac fibroblast phenotype, establish a p38-dependent signaling circuit for epigenetic reprogramming in heart failure, and uncover a novel role for Sertad4. The work provides a mechanistic foundation for the development of BRD4 inhibitors as targeted anti-fibrotic therapies for the heart.

Prognostic and Clinicopathological Significance of SERTAD1 in Various Types of Cancer Risk: A Systematic Review and Retrospective Analysis

SERTAD/TRIP-Br genes are considered as a key nuclear transcriptional player in diverse mechanisms of cell including carcinogenesis. The Oncomine™-Online Platform was used for differential expression and biological insights. Kaplan-Meier survival estimated by KM-plotter/cBioPortal/PrognoScan with 95% CI. SERTAD1 was found significantly elevated levels in most of tumor samples. Kaplan-Meier Plotter results distinctly showed the SERTAD1 over-expression significantly reduced median overall-survival (OS) of patients in liver (n = 364/Logrank-test p = 0.0015), ovarian (n = 655/Logrank-test p = 0.00011) and gastric (n = 631/Logrank-test p = 0.1866). Increased level of SERTAD1 has a significantly higher survival rate in the initial time period, but after 100 months slightly reduced OS (n = 26/Logrank-test p = 0.34) and RFS in HER2 positive breast cancer patients. In meta-analysis, cancer patients with higher SERTAD1 mRNA fold resulted worse overall survival than those with lower SERTAD1 levels. Heterogeneity was observed in the fixed effect model analysis DFS [Tau² = 0.0.073, Q (df = 4) = 15.536 (p = 0.004), I² = 74.253], DSS [Tau² = 1.015, Q (df = 2) = 33.214, (p = 0.000), I² = 93.973], RFS [Tau² = 0.492, Q (df = 7) = 71.133 (p = 0.000), I² = 90.159] (Figure 5). OS [Tau² = 0.480, Q (df = 17) = 222.344 (p = 0.000), I² = 92.354]. Lastly, SERTAD1 involved in several signaling cascades through interaction and correlation with many candidate factors as well as miRNAs. This meta-analysis demonstrates a robust evidence of an association between higher or lower SERTAD1, alteration and without alteration of SERTAD1 in cancers in terms of survival and cancer invasiveness.

Hypermethylation of MDFI promoter with NSCLC is specific for females, non-smokers and people younger than 65

Non-small cell lung carcinoma (NSCLC) is a major subtype of lung cancer. Aberrant DNA methylation has been frequently observed in NSCLC. The aim of the present study was to investigate the role of MyoD family inhibitor (MDFI) methylation in NSCLC. Formalin-fixed paraffin-embedded tumor tissues and adjacent non-cancerous tissues were collected from a total of 111 patients with NSCLC. A methylation assay was performed using the quantitative methylation-specific polymerase chain reaction method. The percentage of methylated reference was used to represent the methylation level of the MDFI promoter. Data mining of a dataset from The Cancer Genome Atlas (TCGA) demonstrated that MDFI promoter methylation levels were significantly increased in 830 tumor tissues compared with 75 non-tumor tissues (P=0.012). However, the results on tissues obtained in the present study indicated that the MDFI promoter methylation levels in tumor tissues were not significantly different compared with those in the adjacent non-tumor tissues (P=0.159). Subsequent breakdown analysis identified that higher MDFI promoter methylation levels were significantly associated with NSCLC in females (P=0.031), but not in males (P=0.832). Age-based subgroup analysis demonstrated that higher MDFI promoter methylation levels were significantly associated with NSCLC in younger patients (≤65 years; P=0.003), but not in older patients (P=0.327). In addition, the association of MDFI methylation with NSCLC was significant in non-smokers (P=0.014), but not in smokers (P=0.832). Similar results also have been determined from subgroup analysis of the TCGA datasets. The Gene Expression Omnibus database indicated MDFI expression restoration in partial lung cancer cell lines (H1299 and Hotz) following demethylation treatment. However, it was identified that MDFI promoter hypermethylation was not significantly associated with prognosis of NSCLC (P>0.05). In conclusion, the present study indicated that the association of higher methylation of the MDFI promoter with NSCLC may be specific to females, non-smokers and people aged ≤65.

I-mfa domain proteins specifically interact with HTLV-1 Tax and repress its transactivating functions

The I-mfa domain proteins HIC (also known as MDFIC) and I-mfa (also known as MDFI) are candidate tumor suppressor genes that are involved in cellular and viral transcriptional regulation. Here, we show that HIC and I-mfa directly interact with human T-cell leukemia virus type-1 (HTLV-1) Tax protein in vitro. In addition, HIC and I-mfa repress Tax-dependent transactivation of an HTLV-1 long terminal repeat (LTR) reporter construct in COS-1, Jurkat and high-Tax-producing HTLV-1-infected T cells. HIC also interacts with Tax through its I-mfa domain in vivo and represses Tax-dependent transactivation of HTLV-1 LTR and NF-κB reporter constructs in an interaction-dependent manner. Furthermore, we show that HIC decreases the nuclear distribution and stimulates the proteasomal degradation of Tax. These data reveal that HIC specifically interacts with HTLV-1 Tax and negatively regulates Tax transactivational activity by altering its subcellular distribution and stability.

Interaction of the phospholipid scramblase 1 with HIV-1 Tat results in the repression of Tat-dependent transcription

Human phospholipid scramblase 1 (PLSCR1) is an interferon (IFN)-stimulated gene and possesses an IFN-mediated antiviral function. We show here that PLSCR1 directly interacts with human immunodeficiency virus type-1 (HIV-1) Tat. This interaction occurs both in vitro and in vivo through amino acids 160-250 of PLSCR1. Overexpression of PLSCR1 efficiently represses the Tat-dependent transactivation of the HIV-1 long terminal repeat (LTR) and reduces the nuclear translocation of Tat. In addition, shRNA-mediated suppression of endogenous PLSCR1 expression enhances the levels of gag mRNA in an HIV-1-infected T-cell line. These findings indicate that PLSCR1 negatively regulates the Tat-dependent transactivation of the HIV-1 LTR during HIV-1 infection.

Unveiling clusters of RNA transcript pairs associated with markers of Alzheimer's disease progression

Background

One primary goal of transcriptomic studies is identifying gene expression patterns correlating with disease progression. This is usually achieved by considering transcripts that independently pass an arbitrary threshold (e.g. p<0.05). In diseases involving severe perturbations of multiple molecular systems, such as Alzheimer’s disease (AD), this univariate approach often results in a large list of seemingly unrelated transcripts. We utilised a powerful multivariate clustering approach to identify clusters of RNA biomarkers strongly associated with markers of AD progression. We discuss the value of considering pairs of transcripts which, in contrast to individual transcripts, helps avoid natural human transcriptome variation that can overshadow disease-related changes.

Methodology/Principal Findings

We re-analysed a dataset of hippocampal transcript levels in nine controls and 22 patients with varying degrees of AD. A large-scale clustering approach determined groups of transcript probe sets that correlate strongly with measures of AD progression, including both clinical and neuropathological measures and quantifiers of the characteristic transcriptome shift from control to severe AD. This enabled identification of restricted groups of highly correlated probe sets from an initial list of 1,372 previously published by our group. We repeated this analysis on an expanded dataset that included all pair-wise combinations of the 1,372 probe sets. As clustering of this massive dataset is unfeasible using standard computational tools, we adapted and re-implemented a clustering algorithm that uses external memory algorithmic approach. This identified various pairs that strongly correlated with markers of AD progression and highlighted important biological pathways potentially involved in AD pathogenesis.

Conclusions/Significance

Our analyses demonstrate that, although there exists a relatively large molecular signature of AD progression, only a small number of transcripts recurrently cluster with different markers of AD progression. Furthermore, considering the relationship between two transcripts can highlight important biological relationships that are missed when considering either transcript in isolation.

Genes responsible for the characteristics of primary cultured invasive phenotype hepatocellular carcinoma cells

The common genes responsible for the characteristics of primary cultured invasive phenotype hepatocellular carcinoma (HCC) cells were investigated. Primary cultured HCC cells from three patients were separated by Matrigel invasion into parent and invasive cells. Whole human genome oligo microarray was applied to detect the differentially expressed genes in invasive cells. A purchased HCC cell line (HA 22T/VGH) was studied for comparison. Forty genes were consistently up-regulated and 14 genes were consistently down-regulated among primary cultured invasive cells. Among these genes, only three up-regulated genes (CNN1, PLAT, SPARC) and one down-regulated tumor suppressor gene (MDFI) had same expressions in invasive cells originated from purchased cell line. For primary cultured invasive cells, differential expressions of several groups of common genes are known to have capacities to promote proliferation (CAV1, IL6, PLAT, RRAD, SRPX), remodeling of extracellular matrix (COL1A1, COL1A2, NID2, TNC, RELN, SPARC), migration (ACTG2, CAV1, CCL2, CCL26, CDC42EP3, CNN1, PHLDB2, PLAT, RRAD, SRPX), implantation (IL6), immune escape (CD70) and angiogenesis (CCL2, IL6, IL18, PLAT, SLIT3). Two genes related to signal transduction (AXL, RASL10B) and one related to metabolism (PTGS2) also showed consistent expressions. Differential expressions of these genes are capable for tumor invasiveness. In conclusion, the characteristics of invasive phenotype HCC cells are originated from differential expressions of several groups of genes rather than few target genes. This information may give us a new insight to design new stratagems in HCC treatment. Analysis of the results from a purchased cell line may have bias due to long-term repeated in vitro cultures.

Human phospholipid scramblase 1 interacts with and regulates transactivation of HTLV-1 Tax

Human phospholipid scramblase (PLSCR) 1 expression is strongly activated in response to interferon (IFN) treatment and viral infection, and PLSCR1 is necessary for the IFN-dependent induction of gene expression and antiviral activity. We show here that PLSCR1 directly interacts with human T-cell leukemia virus type-1 (HTLV-1) Tax in vitro and in vivo. This interaction reduced the cytoplasmic distribution of Tax. PLSCR1 efficiently repressed the Tax-mediated transactivation of the HTLV-1 long terminal repeat and the NF-κB binding site reporter constructs in an interaction-dependent manner in COS-1 and Tax-producing HTLV-1-infected T cell lines. Furthermore, we show that PLSCR1 repressed the homodimerization of Tax in vitro. These data reveal for the first time that PLSCR1 specifically interacts with HTLV-1 Tax and negatively regulates its transactivation activity by altering the subcellular distribution and the homodimerization of Tax. PLSCR1 may play an important role in the IFN-mediated repression of Tax-dependent transactivation during HTLV-1 infection.