Search

Interindividual differences in the expression and activity of drug-metabolizing enzymes, including cytochrome P450, UDP-glucuronosyltransferase, and esterases, cause variability of therapeutic effectiveness and side effects during drug treatment. Conventional research has focused on transcriptional regulation by transcription factors and nuclear receptors such as aryl hydrocarbon receptor, pregnane X receptor (PXR), constitutive androstane receptor, and hepatocyte nuclear factor 4α, as the major mechanisms causing the differences in the expression of drug-metabolizing enzymes. Recently, we have revealed that adenosine-to-inosine RNA editing and methylation of adenosine at the N 6 position on RNA, two major types of posttranscriptional modification, play a pivotal role in the regulation of drug metabolism. In addition, switch/sucrose non-fermentable complex, a chromatin remodeler, is required for PXR-mediated transcriptional regulation of drug-metabolizing enzymes. This review article introduces the significance of these epitranscriptomic and epigenetic regulations as factors in determining drug metabolism potency. Further research on this link is expected to lead to a deeper understanding of interindividual differences in the therapeutic effectiveness and side effects of medicines.

EVI1 is a zinc finger transcription factor encoded by the MECOM locus and is essential for the development and maintenance of hematopoietic stem cells. However, overexpression of EVI1 in various myeloid malignancies is associated with aggressive clinical behavior and poor outcome. The locus encodes multiple isoforms that are differentially acting and independently regulated. EVI1 interacts with a variety of transcription and epigenetic factors via different domains. It also regulates cell survival, differentiation, and proliferation through a variety of mechanisms, including transcriptional activation and repression, regulation of other transcription factors' activity, and chromatin remodeling. While the mechanism by which 3q26 translocation leads to high EVI1 expression through enhancer hijacking of genes active in myeloid development is now better understood, regulation of EVI1 expression in the absence of chromosomal translocations and in normal hematopoiesis remains unclear. Recent studies have provided insight into the regulatory mechanisms of EVI1 expression and action, which may lead to development of targeted therapies in the near future.

Heavy metals, both toxic and essential, have long been an important research focus in life science. To investigate the intracellular actions of heavy metals at the molecular level, I have been exploring protein factors involved in induction of metallothionein (MT) genes by heavy metals that specifically bind to a metal responsive element (MRE) in the region upstream of the human MT-IIA gene. Purification of a zinc-dependent MRE-binding factor, and cloning of its cDNA identified a sequence identical to that of metal-responsive transcription factor-1 (MTF-1). MTF-1, which is characterized by six tandem repeats of the C 2 H 2 type zinc finger motif, is indispensable for induction of MT gene expression by multiple types of heavy metal, but zinc is the only metal that can directly activate MTF-1 binding to the MRE, indicating that other heavy metal signals act through zinc as a second messenger. Functional analysis of various MTF-1 point mutants revealed several cysteine (Cys) residues critical for DNA binding and/or transactivation activity. Interestingly, six finger motifs seem to mediate several MTF-1 functions other than DNA binding. Immunohistochemical analyses of various mouse tissues revealed selective expression of MTF-1 in spermatocytes among the testicular cells, suggesting roles relevant to spermatogenesis. The zinc regulon, under the control of MTF-1, will likely provide good clues to aid in unraveling novel functions of intracellular zinc ions.

Epithelial-mesenchymal transition (EMT) is an important program in epithelial cancer cells to acquire the motility and invasion, which promotes cancer metastasis to remote organs. EMT is induced by various secreted factors, such as transforming growth factor-β (TGF-β) and epidermal growth factor (EGF). TGF-β ligand activates Smad-dependent and -independent pathways by binding to TGF-β receptors. In Smad-dependent pathway, the activated TGF-β receptor phosphorylates Smad2/3 and accelerates its association with Smad4, leading to their nuclear translocation. Smad2/3-4 complex promotes the expression of EMT-inducing transcription factors, such as Snail and Slug. In Smad-independent pathway, mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways are activated and required for TGF-β-induced EMT. Smad-independent pathway is similar to downstream of receptor tyrosine kinases, and therefore EGFR signaling is known to induce EMT synergize with TGF-β signaling. We explored a new mechanism of EGFR-mediated activation of TGF-β signaling and found that c-Abl kinase activates TGF-β signaling. Based on our proteomic analysis, we identified several TGF-β signaling molecules as nuclear c-Abl substrates, including transcriptional intermediary factor 1-γ (TIF1γ/TRIM33/Ectodermin), a suppressor of TGF-β signaling. c-Abl-mediated phosphorylation of TIF1γ inhibits its binding to Smad3, thereby increasing Smad3's transcriptional activity and promoting EMT. TIF1γ phosphorylation is also involved in the EGFR-caused aberrant activation of TGF-β signaling, suggesting that EGFR/c-Abl pathway activates TGF-β signaling through phosphorylation of nuclear substrates and promotes EMT. Our findings provide new insights into the activation machinery of TGF-β signaling, and further studies are required to clarify the clinical significance of the EGFR/c-Abl pathway in cancer metastasis.

Cardiovascular diseases are major increasing causes of death in developed countries. Coordinated transcriptional and post-transcriptional regulation of gene expression is crucial to maintain normal heart physiology. Dysregulation of these processes causes and/or accompanies multiple pathologies, such as cardiomyopathy and myocardial infarction. The exonuclease-mediated shortening of the mRNA poly(A) tail, a process called deadenylation, is a key step in regulated mRNA degradation, and deadenylation is mostly executed by the CCR4-NOT complex. CCR4-NOT complex is a multi-subunit protein complex, which controls gene expression in the levels from transcription through mRNA deadenylation and protein ubiquitination. We had previously identified CNOT3, a scaffold subunit of the CCR4-NOT complex, as a conserved regulator of heart function in Drosophila and mouse. Our recent genetic data of conditional Cnot3 knockout mice revealed unexpected association of poly(A) shortening and transcriptional activation, which is reprersented by Atg7 and p53. In this review, we introduce our recent progress in dissecting the mechanisms how poly(A) shortening contributes to controlling heart functions and overview new aspects of poly(A) regulation in maintaining cardiac homeostasis.

Chondrocytes, which are originated from undifferentiated mesenchymal stem cells, play roles in skeletal development and growth in mammal, and smooth movement of joints. Endochondral ossification is necessary for skeletal development, and the multiple and complex biological events are precisely regulated by several hormones, cytokines, and their downstream signaling and transcriptional regulation. On the other hands, articular chondrocytes physiologically retains their features during a lifetime. Numerous molecules involved in endochondral ossification have been identified and investigation of the molecular mechanisms have amazingly progressed. Although GDF5 and Prg4 were identified as important molecules associated with articular cartilage development and its homeostasis, the molecular mechanisms are very unclear to date.

Autophagy is an evolutionarily conserved process for degradation of long-lived proteins and organelles that govern a number of cardiac pathologies which cause heart failure. Indeed, recent investigations have uncovered pathways that regulate autophagy in the heart and underlying mechanisms by which alterations in this process affect cardiac function and structure. One of the major roles of autophagy in cardiomyocytes is the intracellular protein quality control (PQC). Impairment of autophagy causes aggregation of damaged and/or misfolded proteins in cardiomyocytes, thereby damaging the cells which, in turn leads to pathological cardiac remodeling. We have shown previously that the molecular mechanism of autophagy suppression in response to cardiac stress. Activation of mammalian Ste20-like kinase 1 (Mst1) by stress causes autophagy suppression below physiological levels and inhibits PQC, which in turn contributes to cardiac dysfunction. Specifically, Mst1 inhibits autophagy through phosphorylation of Beclin1, enhancement of Beclin1-Bcl-2 interaction and suppression of Vps34. Here, I show recent advances in understanding the role of autophagy in pathological cardiac remodeling and discuss the therapeutic potential of modulating autophagy in heart disease.

Hematopoietic cell differentiation is regulated by various lineage-specific transcription factors. In the context of erythroid differentiation, the importance of GATA-1 has been unequivocally demonstrated by cell-based ex vivo assays, as well as knockout mouse models and rare patients with anemias. GATA-1 regulates the expression of erythroid-related genes, such as globins and genes involved in heme biosynthesis, by recognizing the DNA binding consensus sequence [(A/T) GATA (A/G)] through dual zinc finger motifs. GATA-1 forms a complex with the basic helix-loop-helix transcription factor SCL/TAL1, another master regulator of hematopoiesis. SCL/TAL1 forms a complex containing LMO2, LDB1, and ETO2, which are all required for GATA-1 activity during the erythroid differentiation. Here we focus on the current understanding of transcriptional regulation of erythropoiesis.

Cell fate and lineage are primarily regulated at the transcriptional level. However, the transcriptional level alone does not appear to control all aspects of cellular functioning, suggesting the presence of other, as-yet-unknown, mechanisms. miR-126 induced B-cell differentiation in MLL-AF4 acute lymphoblastic leukemia (ALL) without upregulation of TCF3/E2A, EBF1, and PAX5. Early B-cell factor 1 (EBF1) which are critical transcription factor involved in B lymphopoiesis. To challenge the conventional wisdom that cell fate is solely governed by transcription factors, we investigated whether microRNAs (miRNAs) could induce complete B-cell lineage commitment in cells lacking EBF1. miR-126 upregulated B220 in EBF1-deficient hematopoietic progenitor cells (HPCs). Moreover, miRNA-195 (miR-195) induced CD19 expression in EBF1-deficient HPCs, suggesting that these cells were committed to the B-cell lineage. The functional target genes of miR-195 involved in this process belonged to the TGF beta family, a potent inhibitor of B-cell differentiation. These results suggest that some miRNAs could function as alternatives to transcription factors.

Elucidating the developmental pathway leading to erythrocytes and being able to isolate their progenitors is crucial to understanding and treating disorders of red cell imbalance such as anemia, myelodysplastic syndrome, and polycythemia vera. Endoglin (CD105) is a key marker for purifying mouse erythroid lineage-committed progenitors (EPs) from bone marrow. Herein, we show that human EPs can also be isolated from adult bone marrow. We identified three subfractions that possessed different expression patterns of CD105 and CD71 within the previously defined human megakaryocyte/erythrocyte progenitor (hMEP; Lineage-CD34(+)CD38(+)IL-3Rα(-)CD45RA(-)) population. Both CD71(-)CD105(-) and CD71(+)CD105(-) MEPs, at least in vitro, retained bipotency for the megakaryocyte (MegK) and erythrocyte (E) lineages, although the latter sub-population had a differentiation potential skewed toward the E-lineage. Notably, the differentiation output of the CD71(+)CD105(+) subset of cells within the MEP population was completely restricted to the E-lineage with the loss of MegK potential; thus, we termed CD71(+)CD105(-) MEPs and CD71(+)CD105(+) cells as E-biased MEPs (E-MEPs) and EPs, respectively. These previously unclassified populations may facilitate understanding of the molecular mechanisms governing human erythroid development and serve as potential therapeutic targets in disorders of the erythroid lineage.

Transcriptional coactivators YAP(yes associated protein)and TAZ(transcriptional coactivator with PDZ-binding motif)regulate gene expression through binding to transcription factors. Recently, some studies showed that YAP/TAZ activity responded to mechanical inputs such as stiffness of the extracellular matrix and the mechanical regulation of YAP/TAZ controlled cell proliferation or differentiation. Additionally, we revealed important roles of YAP in tissue formation and homeostasis through cellular tension and pressure. These reports indicate that YAP/TAZ are major factors in mechanotransduction connecting between the mechanical environment and cell responses.

It is widely known that a variety of immune cells in the liver contribute to the pathogenesis of liver diseases. Recently, roles of chemokines/chemokines receptors axes regarding the migration of immune competent cells to the inflamed liver have been reported as possible therapeutic targets. We here showed that CCR9 + CD11b + macrophages play an important role during the course of Concanavalin A-induced murine acute liver injury as well as human acute hepatitis via the production of inflammatory cytokines and the Th1 induction. Further analysis using liver-shielded radiation and bone marrow (BM) transplantation model mice revealed that these CCR9 + CD11b + macrophages are originated from BM-derived monocytes, but not liver resident macrophages (Kupffer cells). Furthermore, these CD11b + inflammatory macrophages in contact with hepatic stellate cells contribute to the pathogenesis of murine experimental liver fibrosis via CCR9/CCL25 axis. Collectively, these results with further verification in human samples clarify the pathogenic role of CCR9/CCL25 axis as therapeutic target of a variety of liver diseases.

Hematopoietic stem cells give rise to various blood cell types with diverse functions, although these different cell types harbor essentially identical genome sequences. The basis for this cell type diversity is the establishment of specific gene expression patterns through transcription factor regulation. Transcription factors recognize and bind to specific nucleotide sequences in target genes and recruit chromatin modifiers to alter the epigenetic status of these genes, thereby controlling their expression. Dysregulation of these processes can cause diseases such as leukemia. Due to rapid advances in high-throughput experimental techniques including chromatin immunoprecipitation-sequencing (ChIP-seq) and RNA-seq, the study of transcription factors is now entering a new era. In this review, we update the current knowledge of developmental pathways in myeloid cells, particularly mononuclear phagocytes (i.e., monocytes/macrophages and dendritic cells), and the transcription factors known to be required for their development. We subsequently provide an overview of the cooperative and antagonistic mechanisms by which the myeloid transcription factors regulate their target genes, with an emphasis on chromatin biology.

In this section, we describe about key upstream factors to lead to the activation, differentiation of skeletal muscle cells in the mouse and chick models, such as Pax3/Pax7 genes. They are involved in gene regulatory networks at various sites of skeletal muscle formation. And microRNAs intervene with emerging evidences for novel roles to regulate key factors in myogenesis. We discuss new myogenic insights into mechanisms underlying the transcriptional activity of these factors.

Injury to the nervous system results in debilitating chronic pain states (called neuropathic pain) whose mechanisms remain unclear. Emerging lines of evidence indicate the pivotal role of spinal glial cells in neuropathic pain. Spinal microglia rapidly respond to peripheral nerve injury (PNI) and become activated with changing expression of a variety of genes. The best known example is purinergic P2X4 receptors, an ATP-gated cation channel. The expression of P2X4 receptors is upregulated in spinal microglia after PNI, and inhibition of P2X4 activity suppresses neuropathic pain. Furthermore, interferon regulatory factor-8 (IRF8) and IRF5 are identified as microglial transcription factors whose expression is upregulated in spinal microglia after PNI, and the IRF8-IRF5 transcriptional cascade is the core process for shifting spinal microglia toward a state with high expression of P2X4 receptors. Astrocytes in the spinal cord show a delayed onset of activation and play an important role in the maintenance of neuropathic pain via the transcription factor STAT3 and the intracellular kinase JNK. These results obtained from glial cell research will advance our understanding of the development and maintenance of neuropathic pain and provide a new target for treating this pain.

All mammals show daily rhythms in their physiological activity, for example, sleep-wake cycles. This rhythmicity is endogenously generated by a system called the circadian clock, and is composed of reactions occurring in several neural/cellular layers of multicellular organisms. Inter-cellular and inter-organ communication is important for the synchronous action of circadian rhythmicity across the whole body. The heart of the circadian system lies in the rhythmic neuronal activity of the suprachiasmatic nuclei (SCN) in the brain. The oscillation emerges as cell-autonomous rhythmic gene expression observed in individual SCN neurons. Inter-neuronal communication synchronizes the circadian phase of each neuron within the SCN. The integrated rhythmic SCN activity works as a pacemaker for the circadian clocks of non-SCN cells, each of which also rhythmically express clock genes. The -24-h period length of the circadian rhythm is predominantly determined by reactions at the molecular level. Cell-autonomous circadian oscillation is driven by a negative feedback loop of transcription regulation, where CRY/PER heterodimers act as the transcriptional repressors of their own genes. One of the rate limiting steps of circadian cycling is a phosphorylation of CRY and PER proteins followed by proteasome-mediated degradation of those proteins. Pharmacological and genetic perturbation of the phosphorylation or degradation pathways alters the circadian period length. This review provides a hierarchical view of the circadian system, which is important to uncover the different effects of medical or social perturbations on circadian regulation of inter-cellular synchronization, or cell-autonomous oscillation.

Osteoblasts and osteocytes originate from pluripotent mesenchymal stem cells. Mesenchymal stem cells commit to osteogenic lineage and differentiate into mature osteoblasts and osteocytes through osteoprogenitor cells and preosteoblasts in response to multiple stimuli. The osteoblast commitment, differentiation, and functions are governed by several transcription factors. Among these transcription factors, runt-related transcription factor 2 (Runx2) is a crucial factor in osteoblast differentiation and controls bone formation. Differentiation toward these osteogenic lineage is controlled by a multitude of cytokines including WNTs, bone morphogenetic protein (BMP) , transforming growth factor-β (TGF-β) , hedgehog, parathyroid hormone (PTH) /parathyroid hormone related protein (PTHrP) , insulin-like growth factor-1 (IGF-1) , fibroblast growth factor (FGF) , and Notch. Although regulation of Runx2 activity is a point of convergence of many of the signal transduction routes, there is also a high degree of cross-talk between these pathways. Thus, the combined action of the signal transduction pathways induced by some cytokines determines the commitment and differentiation of mesenchymal stem cells toward the osteogenic lineage.

Chondrocytes are derived from mesenchymal stem cells and play an essential role in endochondral ossification. Transcription factors, Sox9, Runx2, Runx3 and Osterix are critical for endochondral ossification, and regulate differentiation of mesenchymal stem cells into chondrocytes, and proliferation, maturation and apoptosis of chondrocytes. Recent advances in gene cloning approaches utilizing microarray and high-throughput sequencing technologies have revealed functional regulatory mechanisms of these transcription factors and contributed to understanding of molecular mechanisms of complex and harmonious chondrocyte differentiation.

Increasing evidence has demonstrated that chronic hypoxia in the tubulointerstitium results in irreversible chronic kidney diseases. Hypoxia inducible factor (HIF) is a transcriptional master regulator which takes control of gene expressions under hypoxia. Recently, HIF1 has been reported to organize a cluster of histone-modifying enzymes by binding to their promoter regions in various kinds of cell line. In order to clarify the epigenetic molecular mechanisms by HIF1, we examined the genome-wide analysis of HIF1-binding sites (ChIP-seq) in endothelial cells and HIF1 downstream target genes using DNA microarrays. ChIP-seq results demonstrated that HIF1 binds to the enhancer regions in addition to the promoter regions. We clarified that one of the HIF1 downstream genes, SLC2A3 (solute-carrier family 2A3, also known as glucose transporter 3: GLUT3), is regulated by changing chromosomal conformations under hypoxia via a cooperative combination of HIF1 and KDM3A(lysine(K) specific demethylase 3A), one of the histone demethylases. KDM3A is recruited to the SLC2A3 loci in an HIF1-dependent manner and demethylates histone repressive mark, H3K9me2, up-regulating its expression. In addition, we confirmed the interactions of HIF1 and KDM3A only under hypoxia using co-immunoprecipitation. These experimental results showed novel HIF1-dependent molecular mechanisms from an epigenetic viewpoint. It is important to elucidate the epigenetic mechanisms of chronic hypoxia in order to identify novel therapeutic approaches against chronic kidney disease.

Studies of tissue-specific gene expression have suggested that tissue-specific transcription factors or tissue-specific combinations of non-cell-type-specific transcription factors regulate tissue-specific gene expression. Although the studies of endothelial cell (EC)-specific gene expression has identified several transcriptional activators such as SP1, ETS family proteins, and GATA proteins, their expression and combinations are not likely to be EC-specific. To investigate the mechanism of EC-specific gene expression, we analyzed the regulation mechanism of an EC-specific gene, Roundabout4 (Robo4). We identified the 3-kb Robo4 promoter and several transcription factors including SP1 and GABP that bind to the Robo4 promoter and promote Robo4 gene expression. However, we could not explain the mechanism for EC-specific Robo4 gene expression with only those factors because their expression and combination are not EC-specific. Therefore, we hypothesized the contribution of other mechanisms, especially epigenetic control, to Robo4 gene regulation and demonstrated the importance of DNA methylation for EC-specific Robo4 expression. In this review, we summarize our recent studies and discuss the novel regulation model of Robo4 gene expression by transcription factors and DNA methylation.

Several epidemiological studies have suggested that the perturbation of circadian rhythm has adverse metabolic consequences (e.g., dyslipidemia) in humans. At the molecular level, circadian rhythms are encoded by an autoregulatory loop composed of a set of transcription activators (BMAL1/CLOCK) that induce expression of repressors (PER/CRY). The mammalian molecular clock is not only expressed within the master suprachiasmatic nucleus pacemaker neurons, but also within nearly all cells. In addition to this core loop, BMAL1/CLOCK also induce expression of the orphan nuclear hormone receptor, which modulates Bmal1 transcription. Disruption of clock genes results in metabolic deregulation in mice. In this article, the roles of clock genes in the regulation of metabolism were summarized based on the phenotypes of the knockout mice.

Both decreased insulin secretion and insulin resistance are two major factors of impaired glucose tolerance (IGT) in the elderly. Up to now, decreased lean body mass and relatively increased fat mass, so-called sarcopenia or sarcopenic obesity, contribute to insulin resistance in the elderly. However, recent reports indicate that muscle mitochondrial function is reduced in aging, and this age-associated decline in mitochondrial function contributes to insulin resistance in the elderly. In addition, exercise intervention to IGT in the elderly is more effective to reduce in the incidence of type 2 diabetes than in younger people. Exercise seems to improve insulin resistance through mitochondrial function by activating AMP-activated protein kinase(AMPK) and PPARgamma coactivator-1alpha (PGC-1alpha). Because cognitive impairment is a most crucial factor plunging into frailty in diabetic elderly, diabetic control would be very important in preventing cognitive decline as well as vascular events. However, comprehensive management of diabetes, including dyslipidemia and hypertension, might contribute to the prevention of declines in cognitive function in older diabetic patients.

Sex differences in the nervous system are prevalent throughout the animal kingdom. In humans, the corpus callosum and anterior commissure are larger in females, whereas some hypothalamic nuclei and associated structures are larger in males. Numerous studies in rodents have demonstrated that when these nuclei are exposed to circulating androgens during the critical period around birth, they develop into male-typical structures. In addition to this organizational effect, androgens exert an activational effect during adulthood. For example, sexually dimorphic gene expression in the hypothalamus and amygdala depends on circulating androgen levels. Cckar encodes a G protein-coupled receptor and its expression is sexually dimorphic. The major of Cckar-expressing neurons in the ventrolateral division of ventromedial hypothalamus (VMHvl) also express progesterone receptor (PR), with a female-biased expansion of arborizations in the anteroventral periventricular hypothalamic nucleus. Selective ablation of these PR-positive neurons in the VMHvl results in a marked reduction in female sexual receptivity and male aggression, demonstrating that these sexually dimorphic neurons contribute to gendered behavior in mammals. Remarkable sex differences in single neurons have been documented in the fruitfly (Drosophila melanogaster). The fruitless (fru) gene in the fruitfly is considered as a major regulator of male courtship circuitry; a male specific fru-expressing neuron cluster, P1, can initiate male courtship when artificially activated even in the absence of courtship target (e.g., a female). The fru gene encodes a set of putative transcription factors that appear to orchestrate the transcription of ~100 genes by recruiting chromatin regulators, histone deacetylase 1 or heterochromatin protein 1a, to the target sites. These studies have unraveled the causal link among genes, brain sexual dimorphisms and gendered behaviors.

Rearrangements of the mixed lineage leukemia MLL gene at chromosome 11q23 are common chromosomal abnormalities in human leukemia. MLL fused with numerous partner genes causes different leukemia phenotypes that depend on the function of partner genes. MLLT3-MLL is generated by translocation t(9;11), which primarily induces acute myeloid leukemia in humans, whereas MLLT3-MLL induces ALL or biphenotypic leukemia in mice. The microenvironment that surrounds leukemia cells plays a central role in this process. We report a patient with mixed phenotype acute leukemia with MLLT3-MLL. This patient, a 44-year-old woman, initially exhibited extramedullary leukemia with multiple tumors and subsequently developed bone marrow disease. The leukemia cells exhibited myeloid (CD13 and MPO) and B cell (CD19 and CD79a) phenotypes. Chromosomal analysis and RT-PCR assay revealed tumor cells with the MLLT3-MLL fusion gene. We treated this patient with a drug regimen for AML (Ara-C plus anthracycline), and complete remission was obtained. This report describes the fourth case of mixed phenotypic leukemia with extramedullary disease. The extramedullary circumstance may underlie the biphenotypic features of these patients.

Many metabolic and physiological processes display daily rhythms oscillated by the internal circadian clock system. This rhythm is generated by interlocked transcription-(post) translation feedback loops of clock genes: the core oscillatory loop, being composed of CLOCK/BMAL1 heterodimer activating the expressions of PER and CRY that directly repress CLOCK/BMAL1, is accompanied by accessory loops consisted with REV-ERB nuclear receptor repressing Bmal1 or with DBP competing with E4BP4 on D-box site. These clock proteins are regulated by phosphorylation and ubiquitination (PER/CRY), and acetylation (CLOCK/BMAL1). Recently, a deacetylating protein SIRT1 mediated metabolic pathway is discovered to be interlocked with core oscillatory loop via Nampt expression, a late-limiting enzyme in NAD+ salvage pathway. Since many key-step enzymes of metabolisms are regulated by the circadian clock, circadian clock system may intimately link to cellular metabolism.

In regenerative medicine, converting one cell type to another type associates with altering epigenome of cells without changing their genome sequences. Since development of iPS cells, it has become possible to convert cell types through altering epigenome by transducing plural kye transcription factors into cells. We found that transduction of two reprogramming factors (c-Myc and Klf4) and one chondrogenic factor (SOX9) into mouse dermal fibroblasts results in direct induction of chondrogeni cells. Directly induced chondrogenic cells showed highly methylated promoter sequences of fibroblastic markers, type I collagen genes. These induced cells, when transplanted into nude mice, produced hyaline cartilage without expressing type I collagen, suggesting that type I collagen genes were silenced in these induced chondrogenic cells in vivo . It is also expected to apply cell reprogramming technique to treatment of osteoarthritis in some aspects including reversion of degenerated fibrocartilage into hyalinecartilage.

In the post-genome era, the analysis of disease-related genes has rapidly advanced, and the medical application of the information obtained from gene analysis is being put into practice. In particular, the development of a novel system to transfect the gene of interest selectively and efficiently into targeted cells is essential for the gene therapy of refractory diseases, in vivo functional analysis of genes, and establishment of animal models for diseases. However, a suitable carrier for selective gene delivery to targeted cells remains to be developed. The sonoporation method using microbubbles and ultrasound (US) exposure is one of the most promising approaches for effective gene transfection. However, it is difficult to transfect the therapeutic gene into the targeted organs/cells selectively by the conventional sonoporation method. Recently, our group has developed mannose-modified and US-responsive carriers/nucleic acid complexes (Man-PEG(2000) bubble lipoplexes), and succeeded in obtaining the enhanced and selective gene expression in mannose receptor-expressing cells by combination with US exposure. In this review, I described our gene transfection methods using Man-PEG(2000) bubble lipoplexes and external US exposure. Additionally, I also reviewed the enhancing mechanism of gene expression focusing on the intracellular transporting processes, in vivo distribution, and the activation of transcriptional factors. I believe that these findings help in the development of an effective gene transfection system using US-exposing system.

MicroRNAs (miRNAs) are endogenous ~22-nucleotide non-coding RNAs that regulate gene expression through the translational repression or degradation of target mRNAs. The human genome contains over 1400 miRNAs and over 60% of human mRNAs are predicted to be targets of miRNAs. The miRNAs have roles in fine-tuning the expression of their target genes forming intricate networks. Research on miRNA is growing exponentially, and it is now clear that miRNAs can potentially regulate every aspect of cellular processes such as differentiation, proliferation and apoptosis as well as a large range of physiological processes such as development, immune response, metabolism, tumor formation, and disease development. The roles of miRNAs in the metabolism of xenobiotics and endobiotics have only recently been revealed. This review describes the current knowledge on the regulation of cytochrome P450s and transcriptional factors by miRNAs, and its physiological and clinical significance, which were disclosed in our studies. The miRNA expression is readily altered by chemicals, carcinogens, drugs, hormones, stress, or diseases, and the dysregulation of specific miRNAs might lead to changes in the drug metabolism potency or pharmacokinetics as well as pathophysiological changes. Utilizing miRNAs opens a new era in the fields of drug metabolism and pharmacokinetics as well as toxicology.

The hedgehog (Hh) signaling pathway was originally found as an organizer in embryonic development. The pathway is now implicated in the development of various tumors. Recently, it has been reported that the pathway activation is resulted from aberrant expression of the ligand, Sonic Hh (Shh), in pancreatic cancer and breast cancer. Here we developed a new strategy to control the activation of the Hh signaling pathway in cancer cells, which have ectopic and ligand dependent activation of the Hh signaling pathway. Our strategy may contribute to the development of a new cancer treatment.