Dynamic interplay of transcriptional machinery and chromatin regulates "late" expression of the chemokine RANTES in T lymphocytes

Postnatal epigenetic differences in calves following transient fetal infection with bovine viral diarrhea virus

BACKGROUND

Bovine viral diarrhea virus (BVDV) is the most detrimental pestivirus within the cattle industry. Infection with vertically transmissible BVDV prior to 125 days of gestation results in the generation of a persistently infected (PI) calf. These PI calves are unable to clear the virus in utero, due to an incomplete immune response. However, when infection with BVDV occurs after 150 days of gestation, the fetus clears the transient infection (TI) in utero and is born with antibodies specific to the infecting strain of BVDV. Variations in DNA methylation have been identified in white blood cells (WBC) from TI heifers at birth. It was hypothesized that epigenomic alterations persist into the postnatal period and contribute to previously undocumented pathologies. To study these possible effects, DNA was isolated from the WBCs of 5 TI heifers and 5 control heifers at 4 months of age and subjected to reduced representation bisulfite sequencing (RRBS).

RESULTS

Differential analysis of the methylome revealed a total of 3,047 differentially methylated CpG sites (DMSs), 1,349 of which were hypermethylated and the other 1,698 were hypomethylated. Genes containing differential methylation were associated with inflammation, reactive oxygen species (ROS) production, and metabolism. Complete blood count (CBC) data identified a higher lymphocyte percentage in TI heifers. When compared in the context of the CD45+ parent population, spectral flow cytometry revealed increased intermediate monocytes, B cells, and CD25+/CD127- T cells, and decreased CD4+/CD8b+ T cells. Comparative analysis revealed differential methylation of CpG sites contained in 205 genes, 5 promoters, and 10 CpG islands at birth that were also present at 4 months of age. Comparison of differential methylation in TI heifers and PI heifers at 4 months of age showed 465 genes, 18 promoters, and 34 CpG islands in common.

CONCLUSION

Differential methylation of WBC DNA persists to 4 months of age in TI heifers and is associated with dysregulation of inflammation, metabolism, and growth. Analysis of differential methylation in TI heifers contributes to the understanding of how fetal infection with BVDV induces postnatal detriments related to profit loss.

Bioinformatic Evaluation of KLF13 Genetic Variant: Implications for Neurodevelopmental and Psychiatric Symptoms

The Krüppel-like factor (KLF) family represents a group of transcription factors (TFs) performing different biological processes that are crucial for proper neuronal function, including neuronal development, synaptic plasticity, and neuronal survival. As reported, genetic variants within the KLF family have been associated with a wide spectrum of neurodevelopmental and psychiatric symptoms. In a patient exhibiting attention deficit hyperactivity disorder (ADHD) combined with both neurodevelopmental and psychiatric symptoms, whole-exome sequencing (WES) analysis revealed a de novo heterozygous variant within the Krüppel-like factor 13 (KLF13) gene, which belongs to the KLF family and regulates axonal growth, development, and regeneration in mice. Moreover, in silico analyses pertaining to the likely pathogenic significance of the variant and the impact of the mutation on the KLF13 protein structure suggested a potential deleterious effect. In fact, the variant was localized in correspondence to the starting residue of the N-terminal domain of KLF13, essential for protein-protein interactions, DNA binding, and transcriptional activation or repression. This study aims to highlight the potential involvement of the KLF13 gene in neurodevelopmental and psychiatric disorders. Nevertheless, we cannot rule out that excluded variants, those undetectable by WES, or the polygenic risk may have contributed to the patient's phenotype given ADHD's high polygenic risk. However, further functional studies are required to validate its potential contribution to these disorders.

Krüppel-like Factor-9 and Krüppel-like Factor-13: Highly Related, Multi-Functional, Transcriptional Repressors and Activators of Oncogenesis

Specificity Proteins/Krüppel-like Factors (SP/KLF family) are a conserved family of transcriptional regulators. These proteins share three highly conserved, contiguous zinc fingers in their carboxy-terminus, requisite for binding to cis elements in DNA. Each SP/KLF protein has unique primary sequence within its amino-terminal and carboxy-terminal regions, and it is these regions which interact with co-activators, co-repressors, and chromatin-modifying proteins to support the transcriptional activation and repression of target genes. Krüppel-like Factor 9 (KLF9) and Krüppel-like Factor 13 (KLF13) are two of the smallest members of the SP/KLF family, are paralogous, emerged early in metazoan evolution, and are highly conserved. Paradoxically, while most similar in primary sequence, KLF9 and KLF13 display many distinct roles in target cells. In this article, we summarize the work that has identified the roles of KLF9 (and to a lesser degree KLF13) in tumor suppression or promotion via unique effects on differentiation, pro- and anti-inflammatory pathways, oxidative stress, and tumor immune cell infiltration. We also highlight the great diversity of miRNAs, lncRNAs, and circular RNAs which provide mechanisms for the ubiquitous tumor-specific suppression of KLF9 mRNA and protein. Elucidation of KLF9 and KLF13 in cancer biology is likely to provide new inroads to the understanding of oncogenesis and its prevention and treatments.

KLF13 induces apoptotic cell clearance in Penaeus vannamei as an essential part of shrimp innate immune response to pathogens

Although, in mammals, the Krüppel-like transcription factor 13 (KLF13) plays an essential role in cell proliferation, survival, differentiation, apoptosis, tumorigenesis, immune regulation, and inflammation, its role in penaeid shrimp is unclear. In the current study, we characterized a KLF13 homolog in Penaeus vannamei (PvKLF13), with full-length cDNA of 1677 bp and 1068 bp open reading frame (ORF) encoding a putative protein of 355 amino acids, which contains three ZnF_C2H2 domains. Sequence and phylogenetic analysis revealed that PvKLF13 shares a close evolutionary relationship with KLF13 from invertebrates. Transcript levels of PvKLF13 were ubiquitously expressed in shrimp and induced in hemocytes upon challenge with Vibrio parahaemolyticus, Streptococcus iniae, and white spot syndrome virus (WSSV), suggesting the involvement of PvKLF13 in shrimp immune response to pathogens. Besides, knockdown of PvKLF13 decreased hemocytes apoptosis in terms of increased expression of pro-survival PvBcl-2, but decreased expression of pro-apoptotic PvBax and PvCytochrome C, coupled with high PvCaspase3/7 activity, especially upon V. parahaemolyticus challenge. The findings here indicate the involvement of PvKLF13 in apoptotic cell clearance as an essential part of shrimp innate immune response to pathogens.

A Comprehensive Map of the Monocyte-Derived Dendritic Cell Transcriptional Network Engaged upon Innate Sensing of HIV

Transcriptional programming of the innate immune response is pivotal for host protection. However, the transcriptional mechanisms that link pathogen sensing with innate activation remain poorly under-stood. During HIV-1 infection, human dendritic cells (DCs) can detect the virus through an innate sensing pathway, leading to antiviral interferon and DC maturation. Here, we develop an iterative experimental and computational approach to map the HIV-1 innate response circuitry in monocyte-derived DCs (MDDCs). By integrating genome-wide chromatin accessibility with expression kinetics, we infer a gene regulatory network that links 542 transcription factors with 21,862 target genes. We observe that an interferon response is required, yet insufficient, to drive MDDC maturation and identify PRDM1 and RARA as essential regulators of the interferon response and MDDC maturation, respectively. Our work provides a resource for interrogation of regulators of HIV replication and innate immunity, highlighting complexity and cooperativity in the regulatory circuit controlling the response to infection.

Pathogen sensing leads to host transcriptional reprogramming to protect against infection. However, it is unclear how transcription factor activity is coordinated across the genome. Johnson et al. integrate chromatin accessibility and gene expression data to infer and validate a gene regulatory network that directs the innate immune response to HIV.

Chemokine Signatures of Pathogen-Specific T Cells I: Effector T Cells

The choreography of complex immune responses, including the priming, differentiation, and modulation of specific effector T cell populations generated in the immediate wake of an acute pathogen challenge, is in part controlled by chemokines, a large family of mostly secreted molecules involved in chemotaxis and other patho/physiological processes. T cells are both responsive to various chemokine cues and a relevant source for certain chemokines themselves; yet, the actual range, regulation, and role of effector T cell-derived chemokines remains incompletely understood. In this study, using different in vivo mouse models of viral and bacterial infection as well as protective vaccination, we have defined the entire spectrum of chemokines produced by pathogen-specific CD8⁺ and CD4⁺T effector cells and delineated several unique properties pertaining to the temporospatial organization of chemokine expression patterns, synthesis and secretion kinetics, and cooperative regulation. Collectively, our results position the "T cell chemokine response" as a notably prominent, largely invariant, yet distinctive force at the forefront of pathogen-specific effector T cell activities and establish novel practical and conceptual approaches that may serve as a foundation for future investigations into the role of T cell-produced chemokines in infectious and other diseases.

Significant association between high serum CCL5 levels and better disease-free survival of patients with early breast cancer

Analysis of anticancer immunity aids in assessing the prognosis of patients with breast cancer. From 250 operated breast cancers, we focused on serum levels of C‐C motif chemokine ligand 5 (CCL5), which is involved in cancer immune reactions. Serum levels of CCL5 were measured using a cytometric bead‐based immunoassay kit and CCL5 expression in cancer cells was determined using immunohistochemical staining. In addition, mRNA in cancer and stromal cells was analyzed by microdissection and comparison with the public dataset. Disease‐free survival (DFS) of patients with high CCL5 levels (cut‐off, 13.87 ng/mL; n = 192) was significantly better than those with low CCL5 levels (n = 58; hazard ratio, 0.20; 95% confidence interval, 0.10‐0.39; P < .0001). An improved overall survival was observed in patients with high CCL5 levels compared to those with low CCL5 levels (P = .024). On the contrary, high immunohistochemical expression of CCL5 in cancer cells was significantly associated with decreased DFS. As serum CCL5 levels did not correlate with CCL5 expression in cancer cells and the relative expression of mRNA CCL5 was elevated in stromal cells in relation to cancer cells, serum CCL5 might be derived not from cancer cells, but from stromal cells. Expression of CCL5 in serum, but not in cancer cells, might contribute to improved patient prognosis mediating through not only immune reaction, but through other mechanisms. Determination of circulating CCL5 levels could be useful for predicting patient prognosis.

Krüppel-Like Factors in Vascular Inflammation: Mechanistic Insights and Therapeutic Potential

The role of inflammation in vascular disease is well recognized, involving dysregulation of both circulating immune cells as well as the cells of the vessel wall itself. Unrestrained vascular inflammation leads to pathological remodeling that eventually contributes to atherothrombotic disease and its associated sequelae (e.g., myocardial/cerebral infarction, embolism, and critical limb ischemia). Signaling events during vascular inflammation orchestrate widespread transcriptional programs that affect the functions of vascular and circulating inflammatory cells. The Krüppel-like factors (KLFs) are a family of transcription factors central in regulating vascular biology in states of homeostasis and disease. Given their abundance and diversity of function in cells associated with vascular inflammation, understanding the transcriptional networks regulated by KLFs will further our understanding of the pathogenesis underlying several pervasive health concerns (e.g., atherosclerosis, stroke, etc.) and consequently inform the treatment of cardiovascular disease. Within this review, we will discuss the role of KLFs in coordinating protective and deleterious responses during vascular inflammation, while addressing the potential targeting of these critical transcription factors in future therapies.

MKL1 defines the H3K4Me3 landscape for NF-κB dependent inflammatory response

Macrophage-dependent inflammatory response is considered a pivotal biological process that contributes to a host of diseases when aberrantly activated. The underlying epigenetic mechanism is not completely understood. We report here that MKL1 was both sufficient and necessary for p65-dependent pro-inflammatory transcriptional program in immortalized macrophages, in primary human and mouse macrophages, and in an animal model of systemic inflammation (endotoxic shock). Extensive chromatin immunoprecipitation (ChIP) profiling and ChIP-seq analyses revealed that MKL1 deficiency erased key histone modifications synonymous with transactivation on p65 target promoters. Specifically, MKL1 defined histone H3K4 trimethylation landscape for NF-κB dependent transcription. MKL1 recruited an H3K4 trimethyltransferase SET1 to the promoter regions of p65 target genes. There, our work has identified a novel modifier of p65-dependent pro-inflammatory transcription, which may serve as potential therapeutic targets in treating inflammation related diseases.

KLF13 regulates the differentiation-dependent human papillomavirus life cycle in keratinocytes through STAT5 and IL-8

High-risk strains of human papillomavirus (HPV) are the causative agents of cervical and anogenital cancers and are associated with 5% of all human cancers. Although prophylactic vaccines targeting a subset of HPV types are available, they are ineffective in HPV-infected individuals. Elucidation of the mechanisms controlling HPV replication may allow development of novel anti-HPV therapeutics. Infectious HPV virions are produced during terminal differentiation of host cells. The process of viral maturation requires synergistic interactions between viral and cellular proteins that leads to amplification of the viral genome and expression of late viral genes. Here we show that the transcription factor Kruppel-like factor 13 (KLF13) has a critical role in the HPV life cycle. KLF13 is overexpressed in HPV-positive keratinocytes and cervical cancer cell lines. Expression of KLF13 in normal cervical epithelium is low but increases significantly in cervical intraepithelial neoplasia and invasive squamous cervical cancer. After HPV infection, the E7 protein suppresses ubiquitin ligase FBW7 expression leading to an increase in KLF13 expression. Reduction of KLF13 with short hairpin RNA in differentiating HPV-positive cells resulted in diminished levels of viral gene expression and genome amplification. Knockdown of KLF13 also reduced the level of the transcription factor signal transducer and activator of transcription 5, which led to the downregulation of the ataxia-telangiectasia mutated DNA damage pathway and the chemokine interleukin-8 (IL-8). In addition, neutralization of IL-8 diminished viral genome amplification in differentiating HPV-positive cells. Thus, KLF13 is critical for the activation of the HPV productive life cycle and is likely involved in initiation and progression of cervical cancer.

KLF13 promotes porcine adipocyte differentiation through PPARγ activation

Background

Adipogenesis is tightly controlled by a complex network of transcription factors acting at different stages of differentiation. Kruppel-like factors (KLFs) as a family of zinc-finger transcription factors play diverse roles during cell differentiation and development in mammals.

Results

In the present study, we showed that KLF13 acts as a key regulator regulating porcine adipocyte differentiation. The expression of KLF13 was markedly up-regulated during the early stage of porcine adipocyte differentiation, which was followed by expression of PPARγ. Porcine adipocyte differentiation was significantly attenuated by the addition of siRNA against KLF13, whereas overexpression of KLF13 resulted in enhanced porcine adipocyte differentiation. Using promoter deletion and mutation analysis, we identified a KLF13-binding site within −593/-577 region of the porcine PPARγ proximal promoter, indicating that KLF13 directly interacts with porcine PPARγ promoter. However, inhibition of KLF13 by siRNA did not impair mouse adipocyte differentiation. In addition, knockdown and/or overexpression of KLF13 in 3 T3-L1 cells all did not influence expression of PPARγ2.

Conclusions

Collectively, our results suggest that KLF13 exist as a key pro-adipogenic transcription factor through transactivating PPARγ expression in porcine adipocyte differentiation, whereas no such effect was detected in mouse adipocyte differentiation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13578-015-0016-z) contains supplementary material, which is available to authorized users.

Recent Advances in Discovering the Role of CCL5 in Metastatic Breast Cancer

A variety of therapeutic strategies are currently under investigation to inhibit factors that promote tumor invasion, as metastasis is the most common cause of mortality for cancer patients. Notably, considerable emphasis has been placed on studying metastasis as a dynamic process that is highly dependent on the tumor microenvironment. In regards to breast cancer, chemokine C-C motif ligand 5 (CCL5), which is produced by tumor-associated stromal cells, has been established as an important contributor to metastatic disease. This review summarizes recent discoveries uncovering the role of this chemokine in breast cancer metastasis, including conditions that increase the generation of CCL5 and effects induced by this signaling pathway. In particular, CCL-5-mediated cancer cell migration and invasion are discussed in the context of intertwined feedback loops between breast cancer cells and stromal cells. Moreover, the potential use of CCL5 and its receptor chemokine C-C motif receptor 5 (CCR5) as targets for preventing breast cancer metastasis is also reviewed.

KLF13 cooperates with c-Maf to regulate IL-4 expression in CD4+ T cells

Kruppel-like factor (KLF) 13 is a transcription factor that positively regulates expression of the chemokine RANTES 3-5 d after activation of T cells. In this study, we document a key role for KLF13 in the expression of IL-4 in CD4(+) T cells. Gene expression analysis in activated T cells from Klf13(-/-) mice showed that IL-4, along with other Th2 cytokine genes, was downregulated when compared with cells from wild-type mice. The decreased levels of IL-4 were not associated with changes in expression of the Th2-inducing transcription factors GATA3 or c-Maf. Additional analysis revealed that KLF13 directly binds to IL-4 promoter regions and synergizes with c-Maf to positively regulate IL-4 expression. These results indicate that KLF13 is a positive regulator for differentiation of Th2 cells, as part of the transcriptional machinery that regulates IL-4 production in Th2 cells.

Targeting CCL5 in inflammation

INTRODUCTION

Chemokines play important roles in inflammation and in immune responses. This article will discuss the current literature on the C-C chemokine ligand 5 (CCL5), and whether it is a therapeutic target in the context of various allergic, autoimmune or infectious diseases.

AREAS COVERED

Small-molecule inhibitors, chemokine and chemokine receptor-deficient mice, antibodies and modified chemokines are the current tools available for CCL5 research, and there are several ongoing clinical trials targeting the CCL5 receptors, CCR1, CCR3 and CCR5. There are fewer studies specifically targeting the chemokine itself and clinical studies with anti-CCL5 antibodies are still to be carried out.

EXPERT OPINION

Although clinical trials are strongly biased toward HIV treatment and prevention with blockers of CCR5, the therapeutic potential for CCL5 and its receptors in other diseases is relevant. Overall, it is not likely that specific targeting of CCL5 will result in new adjunct strategies for the treatment of infectious diseases with a major inflammatory component. However, targeting CCL5 could result in novel therapies for chronic inflammatory diseases, where it may decrease inflammatory responses and fibrosis, and certain solid tumors, where it may have a role in angiogenesis.

Fbw7γ-mediated degradation of KLF13 prevents RANTES expression in resting human but not murine T lymphocytes

RANTES (CCL5) is a chemokine implicated in many human diseases. We previously showed that the transcription factor Kruppel-like factor 13 (KLF13) controls the late (3-5 days after activation) expression of RANTES in T lymphocytes and that KLF13 itself is translationally regulated through the 5'-untranslated region of its mRNA. Here, we show that KLF13 levels are further regulated by ubiquitination and degradation. KLF13 protein is undetectable in resting human T lymphocytes, but treatment with either proteosomal or lysosomal inhibitors increases KLF13 protein levels. Glycogen synthase kinase 3β (GSK3β)-mediated phosphorylation of KLF13 triggers the ubiquitination of KLF13 by the E3 ligase Fbw7γ, resulting in KLF13 protein degradation. Knockdown of either Fbw7γ or GSK3β by small interfering RNA increases KLF13 expression in resting human T lymphocytes. In contrast, in murine T lymphocytes, KLF13 protein is abundant because of the absence of Fbw7γ. Treatment of unactivated human lymphocytes with lysosomal inhibitors stabilizes KLF13 protein, resulting in an increase of RANTES mRNA and protein. Taken together, these studies found that tightly regulated control of both synthesis and degradation allows rapid changes in the level of KLF13 in human T lymphocytes.

KLF13 sustains thymic memory-like CD8(+) T cells in BALB/c mice by regulating IL-4-generating invariant natural killer T cells

"Memory-like T cells" are a subset of thymic cells that acquire effector function through the maturation process rather than interaction with specific antigen. Disruption of genes encoding T cell signaling proteins or transcription factors have provided insights into the differentiation of such cells. In this study, we show that in BALB/c, but not C57BL/6, mice, a large portion of thymic CD4(-)CD8(+) T cells exhibit a memory-like phenotype. In BALB/c mice, IL-4 secreted by invariant natural killer T (iNKT) cells is both essential and sufficient for the generation of memory-like T cells. In C57BL/6 mice, iNKT cells are less abundant, producing IL-4 that is insufficient to induce thymic memory-like CD8(+) T cells. BALB/c mice deficient in the transcription factor Kruppel-like factor (KLF) 13 have comparable numbers of iNKT cells to C57BL/6 mice and extremely low levels of thymic memory-like CD8(+) T cells. This work documents the impact of a small number of KLF13-dependent iNKT cells on the generation of memory-like CD8(+) T cells.

Regulation of CC ligand 5/RANTES by acid sphingomyelinase and acid ceramidase

Acid sphingomyelinase (aSMase) generates the bioactive lipid ceramide (Cer) from hydrolysis of sphingomyelin (SM). However, its precise roles in regulating specific sphingolipid-mediated biological processes remain ill defined. Interestingly, the aSMase gene gives rise to two distinct enzymes, lysosomal sphingomyelinase (L-SMase) and secretory sphingomyelinase (S-SMase) via alternative trafficking of a shared protein precursor. Previously, our laboratory identified Ser(508) as a crucial residue for the constitutive and regulated secretion of S-SMase in response to inflammatory cytokines, and demonstrated a role for S-SMase in formation of select cellular Cer species (Jenkins, R. W., Canals, D., Idkowiak-Baldys, J., Simbari, F., Roddy, P., Perry, D. M., Kitatani, K., Luberto, C., and Hannun, Y. A. (2010) J. Biol. Chem. 285, 35706-35718). In the present study using a chemokine/cytokine screen, we identified the chemokine CCL5 (formerly known as RANTES) as a candidate-specific downstream target for aSMase. Regulation of CCL5 by aSMase was subsequently validated using both loss-of-function and gain-of-function models indicating that aSMase is both necessary and sufficient for CCL5 production. Interestingly, cells deficient in acid ceramidase (aCDase) also exhibited defects in CCL5 induction, whereas cells deficient in sphingosine kinase-1 and -2 exhibited higher levels of CCL5, suggesting that sphingosine and not sphingosine 1-phosphate (S1P) is responsible for the positive signal to CCL5. Consistent with this, co-expression of aSMase and aCDase was sufficient to strongly induce CCL5. Taken together, these data identify a novel role for aSMase (particularly S-SMase) in chemokine elaboration by pro-inflammatory cytokines and highlight a novel and shared function for aSMase and aCDase.

Mammalian Krüppel-like factors in health and diseases

The Krüppel-like factor (KLF) family of transcription factors regulates diverse biological processes that include proliferation, differentiation, growth, development, survival, and responses to external stress. Seventeen mammalian KLFs have been identified, and numerous studies have been published that describe their basic biology and contribution to human diseases. KLF proteins have received much attention because of their involvement in the development and homeostasis of numerous organ systems. KLFs are critical regulators of physiological systems that include the cardiovascular, digestive, respiratory, hematological, and immune systems and are involved in disorders such as obesity, cardiovascular disease, cancer, and inflammatory conditions. Furthermore, KLFs play an important role in reprogramming somatic cells into induced pluripotent stem (iPS) cells and maintaining the pluripotent state of embryonic stem cells. As research on KLF proteins progresses, additional KLF functions and associations with disease are likely to be discovered. Here, we review the current knowledge of KLF proteins and describe common attributes of their biochemical and physiological functions and their pathophysiological roles.

Role of Kruppel-like factors in leukocyte development, function, and disease

The Krüppel-like transcription factor (KLF) family participates in diverse aspects of cellular growth, development, differentiation, and activation. Recently, several groups have identified new connections between the function of these factors and leukocyte responses in health and disease. Gene targeting of individual KLFs in mice has uncovered novel and unexpected physiologic roles among myeloid and lymphocyte cell lineage maturation, particularly in the bone marrow niche and blood. In addition, several KLF family members are downstream targets of stimuli and signaling pathways critical to T-cell trafficking, T regulatory cell differentiation or suppressor function, monocyte/macrophage activation or renewal, and B memory cell maturation or activation. Indeed, KLFs have been implicated in subtypes of leukemia, lymphoma, autoimmunity, and in acute and chronic inflammatory disease states, such as atherosclerosis, diabetes, and airway inflammation, raising the possibility that KLFs and their upstream signals are of therapeutic interest. This review focuses on the relevant literature of Krüppel-like factors in leukocyte biology and their implications in clinical settings.

Regulation of Kruppel-like factor 4, 9, and 13 genes and the steroidogenic genes LDLR, StAR, and CYP11A in ovarian granulosa cells

Kruppel-like factors (KLFs) are important Sp1-like eukaryotic transcriptional proteins. The LDLR, StAR, and CYP11A genes exhibit GC-rich Sp1-like sites, which have the potential to bind KLFs in multiprotein complexes. We now report that KLF4, KLF9, and KLF13 transcripts are expressed in and regulate ovarian cells. KLF4 and 13, but not KLF9, mRNA expression was induced and then repressed over time (P < 0.001). Combined LH and IGF-I stimulation increased KLF4 mRNA at 2 h (P < 0.01), whereas LH decreased KLF13 mRNA at 6 h (P < 0.05), and IGF-I reduced KLF13 at 24 h (P < 0.01) compared with untreated control. KLF9 was not regulated by either hormone. Transient transfection of KLF4, KLF9, and KLF13 suppressed LDLR/luc, StAR/luc, and CYP11A/luc by 80-90% (P < 0.001). Histone-deacetylase (HDAC) inhibitors stimulated LDLR/luc five- to sixfold and StAR/luc and CYP11A/luc activity twofold (P < 0.001) and partially reversed suppression by all three KLFs (P < 0.001). Deletion of the zinc finger domain of KLF13 abrogated repression of LDLR/luc. Lentiviral overexpression of the KLF13 gene suppressed LDLR mRNA (P < 0.001) and CYP11A mRNA (P = 0.003) but increased StAR mRNA (P = 0.007). Collectively, these data suggest that KLFs may recruit inhibitory complexes containing HDAC corepressors, thereby repressing LDLR and CYP11A transcription. Conversely, KLF13 may recruit unknown coactivators or stabilize StAR mRNA, thereby explaining enhancement of in situ StAR gene expression. These data introduce new potent gonadal transregulators of genes encoding proteins that mediate sterol uptake and steroid biosynthesis.

Relationship between eosinophilia and levels of chemokines (CCL5 and CCL11) and IL-5 in bronchoalveolar lavage fluid of patients with mustard gas-induced pulmonary fibrosis

OBJECTIVE

Therefore, this study was designed to analyze the bronchoalveolar lavage (BAL) fluid concentrations of IL-5, RANTES (CCL5) and eotaxin (CCL11) and also to examine the relationship between the percentage and absolute number of the BAL eosinophils and these measured chemokines in patients with sulfur mustard (SM) gas-induced pulmonary fibrosis (PF).

PATIENTS

Fifteen veterans with mustard gas-induced PF and 14 normal veterans as control group.

INTERVENTION

Pulmonary function tests, tests for D(LCO), computed tomography scans of the chest, analyses of BAL fluids for RANTES (CCL5), eotaxin (CCL11), and IL-5 were performed in all cases.

RESULTS

Eosinophilic alveolitis was the predominant feature (p < 0.0001). There were significant differences in CCL5, CCL11, and IL-5 levels of BAL fluid between patients with PF and controls (p < 0.0001, p < 0.0001, and p = 0.001, respectively). The concentrations of CCL5 and CCL11 showed positive correlations with percentage (r = 0.57 and p = 0.03; r = 0.52 and p = 0.04, respectively) and absolute counts (r = 0.54 and p = 0.04, r = 0.53 and p = 0.04, respectively) of BAL eosinophils. There were significant positive correlations between the concentrations of IL-5 and the proportion and total cell number of eosinophils in BAL (r = 0.67 and p = 0.01; r = 0.59 and p = 0.02, respectively) too.

CONCLUSION

A significant correlation between BAL CCL5, CCL11, and IL-5 levels and eosinophils in patients with pulmonary fibrosis due to SM gas inhalation has been demonstrated, suggesting that these C-C chemokines and IL-5 contribute to the recruitment of eosinophils cells in the lung in these victims.

Kruppel-like Factors (KLFs) in muscle biology

The Kruppel-like Factor (KLF) family of zinc-finger transcription factors are critical regulators of cell differentiation, phenotypic modulation and physiologic function. An emerging body of evidence implicates an important role for these factors in cardiovascular biology, however, the role of KLFs in muscle biology is only beginning to be understood. This article reviews the published data describing the role of KLFs in the heart, smooth muscle, and skeletal muscle and highlights the importance of these factors in cardiovascular development, physiology and disease pathobiology.

Relationship between eosinophilia and levels of chemokines (CCL5 and CCL11) and IL-5 in bronchoalveolar lavage fluid of patients with mustard gas-induced pulmonary fibrosis

OBJECTIVE

Therefore, this study was designed to analyze the bronchoalveolar lavage (BAL) fluid concentrations of interleukin-5 (IL-5), normal T cell expressed and presumably secreted (RANTES; CCL5), and eotaxin (CCL11) and also to examine the relationship between the percentage and absolute number of the BAL eosinophils and these measured chemokines in patients with sulfur mustard (SM) gas-induced pulmonary fibrosis (PF).

PATIENTS

Included in this study were fifteen veterans with mustard gas-induced PF and 14 normal veterans as control group.

INTERVENTION

Pulmonary function tests (PFTs), tests for D (LCO), computed tomography (CT) scans of the chest, analyses of BAL fluids for RANTES (CCL5), eotaxin (CCL11), and IL-5 were performed in all cases.

RESULTS

Eosinophilic alveolitis was the predominant feature (p < 0.0001). There were significant differences in CCL5, CCL11, and IL-5 levels of BAL fluid between patients with PF and controls (p < 0.0001, p < 0.0001, and p = 0.001, respectively). The concentrations of CCL5 and CCL11 showed positive correlations with percentage (r = 0.57 and p = 0.03, r = 0.52 and p = 0.04, respectively) and absolute counts (r = 0.54 and p = 0.04, r = 0.53 and p = 0.04, respectively) of BAL eosinophils. There were significant positive correlations between the concentrations of IL-5 and the proportion and total cell number of eosinophils in BAL (r = 0.67 and p = 0.01; r = 0.59 and p = 0.02, respectively) too.

CONCLUSION

A significant correlation between BAL CCL5, CCL11, and IL-5 levels and eosinophils in patients with pulmonary fibrosis caused by SM gas inhalation has been demonstrated, suggesting that these C-C chemokines and IL-5 contribute to the recruitment of eosinophils cells in the lung in these victims.

Interaction of PRP4 with Kruppel-like factor 13 regulates CCL5 transcription

Activation of resting T lymphocytes initiates differentiation into mature effector cells over 3-7 days. The chemokine CCL5 (RANTES) and its major transcriptional regulator, Krüppel-like factor 13 (KLF13), are expressed late (3-5 days) after activation in T lymphocytes. Using yeast two-hybrid screening of a human thymus cDNA library, PRP4, a serine/threonine protein kinase, was identified as a KLF13-binding protein. Specific interaction of KLF13 and PRP4 was confirmed by reciprocal coimmunoprecipitation. PRP4 is expressed in PHA-stimulated human T lymphocytes from days 1 and 7 with a peak at day 3. Using an in vitro kinase assay, it was found that PRP4 phosphorylates KLF13. Furthermore, although phosphorylation of KLF13 by PRP4 results in lower binding affinity to the A/B site of the CCL5 promoter, coexpression of PRP4 and KLF13 increases nuclear localization of KLF13 and CCL5 transcription. Finally, knock-down of PRP4 by small interfering RNA markedly decreases CCL5 expression in T lymphocytes. Thus, PRP4-mediated phosphorylation of KLF13 plays a role in the regulation of CCL5 expression in T lymphocytes.

Kruppel-like transcription factor 13 regulates T lymphocyte survival in vivo

Krüppel-like transcription factor (KLF)13, previously shown to regulate RANTES expression in vitro, is a member of the Krüppel- like family of transcription factors that controls many growth and developmental processes. To ascertain the function of KLF13 in vivo, Klf13-deficient mice were generated by gene targeting. As expected, activated T lymphocytes from Klf13(-/-) mice show decreased RANTES expression. However, these mice also exhibit enlarged thymi and spleens. TUNEL, as well as spontaneous and activation-induced death assays, demonstrated that prolonged survival of Klf13(-/-) thymocytes was due to decreased apoptosis. Microarray analysis suggests that protection from apoptosis-inducing stimuli in Klf13(-/-) thymocytes is due in part to increased expression of BCL-X(L), a potent antiapoptotic factor. This finding was confirmed in splenocytes and total thymocytes by real-time quantitative PCR and Western blot as well as in CD4+CD8- single-positive thymocytes by real-time quantitative PCR. Furthermore, EMSA and luciferase reporter assays demonstrated that KLF13 binds to multiple sites within the Bcl-X(L) promoter and results in decreased Bcl-X(L) promoter activity, making KLF13 a negative regulator of BCL-X(L).

Mechanisms of disease: regulation of RANTES (CCL5) in renal disease

Chemokines (chemoattractant cytokines) are fundamental regulators of immune cell movement from the bloodstream into tissues. Regulating expression of chemokines might, therefore, alleviate inflammation in autoimmune diseases and transplant rejection, or augment immune responses in cancer and immunodeficiency. RANTES (regulated upon activation, normal T cell expressed and secreted [also known as CCL5]) is a model chemokine of relevance to a myriad of diseases. Regulation of RANTES expression is complex. In fibroblasts and monocytes, rel proteins alone suffice to induce transcription of RANTES. By contrast, expression of RANTES in T lymphocytes 3-5 days after activation requires the development of a molecular complex (enhancesome) including KLF13 (Krueppel-like factor 13), rel proteins p50 and p65, and scaffolding proteins. This complex recruits enzymes involved in acetylation, methylation and phosphorylation of chromatin, and ultimately in the expression of RANTES. In addition, KLF13-the lynchpin for recruitment of this molecular complex-is itself translationally regulated. Such complex regulation of biological systems has major implications for the rational design of drugs aimed at increasing or decreasing inflammatory responses in patients.