Akiko Hata - Academia.edu (original) (raw)

Papers by Akiko Hata

Research paper thumbnail of down-regulation of Kruppel-like factor-4 (KLF4) by microRNA-143/145 is critical for modulation of vascular smooth muscle cell phenotype by transforming growth factor-beta and bone morphogenetic protein 4

The Journal of biological chemistry, Jan 12, 2011

In the postnatal vasculature, fully differentiated and quiescent vascular smooth muscle cells (VS... more In the postnatal vasculature, fully differentiated and quiescent vascular smooth muscle cells (VSMCs) in a "contractile" phenotype are required for the normal regulation of vascular tone. The transforming growth factor-β (TGF-β) superfamily of growth factors (TGF-βs and bone morphogenetic proteins (BMPs)) are potent inducers of contractile phenotype and mediate (i) induction of contractile genes, and (ii) inhibition of VSMC growth and migration. Transcription of contractile genes is positively regulated by a regulatory DNA element called a CArG box. The CArG box is activated by the binding of serum response factor and its coactivators, myocardin (Myocd) or Myocd-related transcription factors (MRTFs). Krüppel-like factor-4 (KLF4) is known to inhibit activation of the CArG box. However, the potential role of KLF4 in the contractile activities of TGF-β or BMP has not been explored. Here, we demonstrate that TGF-β and BMP4 rapidly down-regulate KLF4 through induction of microR...

Research paper thumbnail of Disruption of miR-29 Leads to Aberrant Differentiation of Smooth Muscle Cells Selectively Associated with Distal Lung Vasculature

PLoS genetics, 2015

Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during developm... more Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during development or in response to challenges in a vessel specific manner. Aberrant vSMCs specifically associated with distal pulmonary arteries have been implicated in the pathogenesis of respiratory diseases, such as pulmonary arterial hypertension (PAH), a progressive and fatal disease, with no effective treatment. Therefore, it is highly relevant to understand the underlying mechanisms of lung vSMC differentiation. miRNAs are known to play critical roles in vSMC maturation and function of systemic vessels; however, little is known regarding the role of miRNAs in lung vSMCs. Here, we report that miR-29 family members are the most abundant miRNAs in adult mouse lungs. Moreover, high levels of miR-29 expression are selectively associated with vSMCs of distal vessels in both mouse and human lungs. Furthermore, we have shown that disruption of miR-29 in vivo leads to immature/synthetic vSMC phenotype ...

Research paper thumbnail of Functions of the bone morphogenetic protein signaling pathway through microRNAs (review)

International journal of molecular medicine, 2015

MicroRNAs (miRNAs or miRs) have emerged as key regulators of gene expression in essential cellula... more MicroRNAs (miRNAs or miRs) have emerged as key regulators of gene expression in essential cellular processes, such as cell growth, differentiation and development. Recent findings have established that the levels of miRNAs are modulated by cell signaling mechanisms, including the bone morphogenetic protein (BMP) signaling pathway. The BMP signaling pathway controls diverse cellular activities by modulating the levels of miRNAs, indicating the complexity of gene regulation by the BMP signaling pathway. The tight regulation of the levels of miRNAs is critical for maintaining normal physiological conditions, and dysregulated miRNA levels contribute to the development of diseases. In the present review, we discuss different insights (provided over the past decade) into the regulation of miRNAs governed by the BMP signaling pathway and the implications of this regulation on the understanding of the cellular differentiation of vascular smooth muscle cells (VSMCs), osteoblasts and neuronal...

Research paper thumbnail of The role of microRNAs in cell fate determination of mesenchymal stem cells: balancing adipogenesis and osteogenesis

BMB reports, Jan 23, 2014

Mesenchymal stem cells (MSCs) are multipotent stem cells capable of differentiating into adipocyt... more Mesenchymal stem cells (MSCs) are multipotent stem cells capable of differentiating into adipocytes, osteoblasts, or chondrocytes. A mutually inhibitory relationship exists between osteogenic and adipogenic lineage commitment and differentiation. Such cell fate decision is regulated by several signaling pathways, including Wnt and bone morphogenetic protein (BMP). Accumulating evidence indicates that microRNAs (miRNAs) act as switches for MSCs to differentiate into either osteogenic or adipogenic lineage. Different miRNAs have been reported to regulate a master transcription factor for osteogenesis, such as Runx2, as well as molecules in the Wnt or BMP signaling pathway, and control the balance between osteoblast and adipocyte differentiation. Here, we discuss recent advancement of the cell fate decision of MSCs by miRNAs and their targets.

Research paper thumbnail of Regulation of pri-miRNA Processing Through Smads

Advances in experimental medicine and biology, 2011

microRNAs (miRNAs) are small (∼22 nucleotides (nt)), noncoding RNAs that play a critical role in ... more microRNAs (miRNAs) are small (∼22 nucleotides (nt)), noncoding RNAs that play a critical role in diverse biological functions by modulating mRNA stability and translational control. Numerous miRNA profiling studies have indicated that the levels of miRNAs are tightly controlled during developmental stages and various pathophysiological and physiological conditions. Following transcription, the long primary miRNA transcript undergoes a series of coordinated maturation steps to generate the mature miRNA. Signaling pathways that control miRNA biogenesis and the mechanisms of regulation, however, are not well understood. In this chapter, we will discuss the finding that signal transducers of the Transforming Growth Factor β (TGFβ) signaling pathway, the Smads, play a critical regulatory role in the nuclear processing of miRNAs by the RNase III-type protein Drosha.

Research paper thumbnail of MicroRNA in Cancer: The Involvement of Aberrant MicroRNA Biogenesis Regulatory Pathways

Genes & cancer, 2010

MicroRNAs (miRNAs) are small, noncoding RNAs that influence diverse biological outcomes through t... more MicroRNAs (miRNAs) are small, noncoding RNAs that influence diverse biological outcomes through the repression of target genes during normal development and pathological responses. In particular, the alteration of miRNA expression has dramatic consequences for the progression of tumorigenesis. miRNAs undergo two processing steps that transform a long primary transcript into the mature miRNA. Although the general miRNA biogenesis pathway is well established, it is clear that not all miRNAs are created equally. Recent studies show that miRNA expression is controlled by diverse mechanisms in response to cellular stimuli. In this review, we discuss the mechanisms that govern the regulation of miRNA biogenesis with particular focus on how these mechanisms are perturbed in cancer.

Research paper thumbnail of MicroRNA miR-425 is a negative regulator of atrial natriuretic peptide

BMC Pharmacology and Toxicology, 2013

Research paper thumbnail of Molecular basis for antagonism between PDGF and the TGFβ family of signalling pathways by control of miR-24 expression

Research paper thumbnail of Smad-mediated miRNA processing: A critical role for a conserved RNA sequence

RNA Biology, 2011

microRNAs (miRNAs) are short, 21-24 nucleotide (nt), non-coding RNAs that post-transcriptionally ... more microRNAs (miRNAs) are short, 21-24 nucleotide (nt), non-coding RNAs that post-transcriptionally regulate the expression of messenger RNAs (mRNAs). Through the regulation of their cognate mRNAs, miRNAs control diverse aspects of biology, including development, cellular differentiation, proliferation, metabolism, and death. Thus, miRNAs play a critical role in the determination of normal cellular physiology and misexpression of miRNAs leads to pathological responses. Understanding the mechanisms that control miRNA expression is an important step forward as novel functions of miRNAs continue to be uncovered. In addition to transcriptional regulation, multiple pathways of post-transcriptional modulation of miRNA expression have been uncovered. In this review we discuss the role of the Smads in the regulation of miRNA processing in response to Transforming Growth Factor-β stimulation.

Research paper thumbnail of SMAD proteins control DROSHA-mediated microRNA maturation

Nature, 2008

MicroRNAs (miRNAs) are small non-coding RNAs that participate in the spatiotemporal regulation of... more MicroRNAs (miRNAs) are small non-coding RNAs that participate in the spatiotemporal regulation of messenger RNA and protein synthesis. Aberrant miRNA expression leads to developmental abnormalities and diseases, such as cardiovascular disorders and cancer; however, the stimuli and processes regulating miRNA biogenesis are largely unknown. The transforming growth factor β (TGF-β) and bone morphogenetic protein (BMP) family of growth factors orchestrates fundamental biological processes in development and in the homeostasis of adult tissues, including the vasculature. Here we show that induction of a contractile phenotype in human vascular smooth muscle cells by TGF-β and BMPs is mediated by miR-21. miR-21 downregulates PDCD4 (programmed cell death 4), which in turn acts as a negative regulator of smooth muscle contractile genes. Surprisingly, TGF-β and BMP signalling promotes a rapid increase in expression of mature miR-21 through a post-transcriptional step, promoting the processing of primary transcripts of miR-21 (pri-miR-21) into precursor miR-21 (pre-miR-21) by the DROSHA (also known as RNASEN) complex. TGF-β-and BMP-specific SMAD signal transducers are recruited to pri-miR-21 in a complex with the RNA helicase p68 (also known as DDX5), a component of the DROSHA microprocessor complex. The shared cofactor SMAD4 is not required for this process. Thus, regulation of miRNA biogenesis by ligand-specific SMAD proteins is critical for control of the vascular smooth muscle cell phenotype and potentially for SMAD4-independent responses mediated by the TGF-β and BMP signalling pathways.

Research paper thumbnail of Smad Proteins Bind a Conserved RNA Sequence to Promote MicroRNA Maturation by Drosha

Research paper thumbnail of Positive and Negative Regulation of the Transforming Growth Factor  /Activin Target Gene goosecoid by the TFII-I Family of Transcription Factors

Molecular and Cellular Biology, 2005

Goosecoid (Gsc) is a homeodomain-containing transcription factor present in a wide variety of ver... more Goosecoid (Gsc) is a homeodomain-containing transcription factor present in a wide variety of vertebrate species and known to regulate formation and patterning of embryos. Here we show that in embryonic carcinoma P19 cells, the transcription factor TFII-I forms a complex with Smad2 upon transforming growth factor ␤ (TGF␤)/activin stimulation, is recruited to the distal element (DE) of the Gsc promoter, and activates Gsc transcription. Downregulation of endogenous TFII-I by small inhibitory RNA in P19 cells abolishes the TGF␤-mediated induction of Gsc. Similarly, Xenopus embryos with endogenous TFII-I expression downregulated by injection of TFII-I-specific antisense oligonucleotides exhibit decreased Gsc expression. Unlike TFII-I, the related factor BEN (binding factor for early enhancer) is constitutively recruited to the distal element in the absence of TGF␤/activin signaling and is replaced by the TFII-I/Smad2 complex upon TGF␤/activin stimulation. Overexpression of BEN in P19 cells represses the TGF␤-mediated transcriptional activation of Gsc. These results suggest a model in which TFII-I family proteins have opposing effects in the regulation of the Gsc gene in response to a TGF␤/activin signal.

Research paper thumbnail of A Novel Regulatory Mechanism of the Bone Morphogenetic Protein (BMP) Signaling Pathway Involving the Carboxyl-Terminal Tail Domain of BMP Type II Receptor

Molecular and Cellular Biology, 2007

Bone morphogenetic protein (BMP) signaling regulates many different biological processes, includi... more Bone morphogenetic protein (BMP) signaling regulates many different biological processes, including cell growth, differentiation, and embryogenesis. BMPs bind to heterogeneous complexes of transmembrane serine/ threonine (Ser/Thr) kinase receptors known as the BMP type I and II receptors (BMPRI and BMPRII). BMPRII phosphorylates and activates the BMPRI kinase, which in turn activates the Smad proteins. The cytoplasmic region of BMPRII contains a "tail" domain (BMPRII-TD) with no enzymatic activity or known regulatory function. The discovery of mutations associated with idiopathic pulmonary artery hypertension mapping to BMPRII-TD underscores its importance.

Research paper thumbnail of Cardiovascular applications of therapeutic ultrasound

Journal of Interventional Cardiac Electrophysiology, 2014

Ultrasound (US) has gained widespread use in diagnostic cardiovascular applications. At amplitude... more Ultrasound (US) has gained widespread use in diagnostic cardiovascular applications. At amplitudes and frequencies typical of diagnostic use, its biomechanical effects on tissue are largely negligible. However, these parameters can be altered to harness US's thermal and non-thermal effects for therapeutic indications. High-intensity focused ultrasound (HIFU) and extracorporeal shock wave therapy (ECWT) are two therapeutic US modalities which have been investigated for treating cardiac arrhythmias and ischemic heart disease, respectively. Here, we review the biomechanical effects of HIFU and ECWT, their potential therapeutic mechanisms, and pre-clinical and clinical studies demonstrating their efficacy and safety limitations. Furthermore, we discuss other potential clinical applications of therapeutic US and areas in which future research is needed.

Research paper thumbnail of Down-Regulation of miR-96 by Bone Morphogenetic Protein Signaling is Critical for Vascular Smooth Muscle Cell Phenotype Modulation

Journal of Cellular Biochemistry, 2014

The bone morphogenetic protein (BMP) signaling pathway is critical for the induction and maintena... more The bone morphogenetic protein (BMP) signaling pathway is critical for the induction and maintenance of contractile phenotype in vascular smooth muscle cells (VSMCs). Inactivation of BMP signaling is common in abnormalities in vascular development and in vascular proliferative conditions, such as pulmonary artery hypertension. Herein, we identify microRNA-96 (miR-96) as a modulator of the VSMC phenotype in response to BMP4 signaling. We show that miR-96 is down-regulated by BMP4 treatment, which results in the derepression of a novel target, Tribbles-like protein 3 (Trb3). miR-96 targets a partially complementary sequence localized in the 3' UTR of Trb3. Trb3 is an essential positive regulator of the BMP signaling pathway and promotes contractile phenotype in VSMCs. In conclusion, our study demonstrates a novel mechanism of regulation of SMC-specific gene expression and induction of a VSMC contractile phenotype by the BMP4 signaling pathway via suppression of the miR-96-Trb3 axis.

Research paper thumbnail of Bone Morphogenetic Protein Signaling in Vascular Disease: ANTI-INFLAMMATORY ACTION THROUGH MYOCARDIN-RELATED TRANSCRIPTION FACTOR A

Journal of Biological Chemistry, 2012

Background: Bone Morphogenetic Proteins (BMP) pathway defects and inflammation are hallmarks of p... more Background: Bone Morphogenetic Proteins (BMP) pathway defects and inflammation are hallmarks of pulmonary arterial hypertension (PAH). Results: BMP signaling inhibits TNF␣-induced activation of NF-B by promoting an MRTF-A/NF-B inhibitory complex in pulmonary smooth muscle cells. Conclusion: BMPs binding to BMPR2 receptor play anti-inflammatory roles by inhibiting TNF␣ signaling via MRTF-A. Significance: Defining how BMP pathway dysfunction promotes vascular pro-inflammatory state is critical to PAH therapy. . 2 The abbreviations used are: PAH, pulmonary arterial hypertension; BMP, bone morphogenetic protein; MRTF, myocardin-related transcription factor; PASMC, pulmonary artery smooth muscle cells; SMC, smooth muscle cells; ICC, inflammatory cytokine and chemokine.

Research paper thumbnail of Induction of MicroRNA-221 by Platelet-derived Growth Factor Signaling Is Critical for Modulation of Vascular Smooth Muscle Phenotype

Journal of Biological Chemistry, 2009

The platelet-derived growth factor (PDGF) signaling pathway is a critical regulator of animal dev... more The platelet-derived growth factor (PDGF) signaling pathway is a critical regulator of animal development and homeostasis. Activation of the PDGF pathway leads to neointimal proliferative responses to artery injury; it promotes a switch of vascular smooth muscle cells (vSMC) to a less contractile phenotype by inhibiting the SMC-specific gene expression and increasing the rate of proliferation and migration. The molecular mechanism for these pleiotropic effects of PDGFs has not been fully described. Here, we identify the microRNA-221 (miR-221), a small noncoding RNA, as a modulator of the phenotypic change of vSMCs in response to PDGF signaling. We demonstrate that miR-221 is transcriptionally induced upon PDGF treatment in primary vSMCs, leading to down-regulation of the targets c-Kit and p27Kip1. Down-regulation of p27Kip1 by miR-221 is critical for PDGF-mediated induction of cell proliferation. Additionally, decreased c-Kit causes inhibition of SMC-specific contractile gene transcription by reducing the expression of Myocardin (Myocd), a potent SMC-specific nuclear coactivator. Our study demonstrates that PDGF signaling, by modulating the expression of miR-221, regulates two critical determinants of the vSMC phenotype; they are SMC gene expression and cell proliferation. . 3 The abbreviations used are: SMC, smooth muscle cell(s); vSMC, vascular SMC; PDGF, platelet-derived growth factor; PDGFR, PDGF receptor; UTR, untranslated region; mi-, micro-; CNN, smooth muscle calponin; IPAH, idiopathic pulmonary artery hypertension; Myocd, myocardin; PASMC, pulmonary artery smooth muscle cells; siRNA, small interference RNA; DAPI, 4Ј-6-Diamidino-2-phenylindole; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; SCF, stem cell factor; qRT, quantitative realtime; GFP, green fluorescent protein; FITC, fluorescein isothiocyanate; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; PCNA, proliferating cell nuclear antigen; BMP, bone morphogenetic protein; SMA, ␣-smooth muscle actin.

Research paper thumbnail of The Four-and-a-half LIM Domain Protein 2 Regulates Vascular Smooth Muscle Phenotype and Vascular Tone

Journal of Biological Chemistry, 2009

In response to vascular injury, differentiated vascular smooth muscle cells (vSMCs) undergo a uni... more In response to vascular injury, differentiated vascular smooth muscle cells (vSMCs) undergo a unique process known as "phenotype modulation," transitioning from a quiescent, "contractile" phenotype to a proliferative, "synthetic" state. We have demonstrated previously that the signaling pathway of bone morphogenetic proteins, members of the transforming growth factor ␤ family, play a role in the induction and maintenance of a contractile phenotype in human primary pulmonary artery smooth muscle cells. In this study, we show that a four-and-ahalf LIM domain protein 2 (FHL2) inhibits transcriptional activation of vSMC-specific genes mediated by the bone morphogenetic protein signaling pathway through the CArG box-binding proteins, such as serum response factor and members of the myocardin (Myocd) family. Interestingly, FHL2 does not affect recruitment of serum response factor or Myocd, however, it inhibits recruitment of a component of the SWI/SNF chromatin remodeling complex, Brg1, and RNA polymerase II, which are essential for the transcriptional activation. This is a novel mechanism of regulation of SMC-specific contractile genes by FHL2. Finally, aortic rings from homozygous FHL2-null mice display abnormalities in both endothelial-dependent and -independent relaxation, suggesting that FHL2 is essential for the regulation of vasomotor tone.

Research paper thumbnail of Control of Phenotypic Plasticity of Smooth Muscle Cells by Bone Morphogenetic Protein Signaling through the Myocardin-related Transcription Factors

Journal of Biological Chemistry, 2007

, unlike other muscle cells, do not terminally differentiate. In response to injury, VSMCs change... more , unlike other muscle cells, do not terminally differentiate. In response to injury, VSMCs change phenotype, proliferate, and migrate as part of the repair process. Dysregulation of this plasticity program contributes to the pathogenesis of several vascular disorders, such as atherosclerosis, restenosis, and hypertension. The discovery of mutations in the gene encoding BMPRII, the type II subunit of the receptor for bone morphogenetic proteins (BMPs), in patients with pulmonary arterial hypertension (PAH) provided an indication that BMP signaling may affect the homeostasis of VSMCs and their phenotype modulation. Here we report that BMP signaling potently induces SMC-specific genes in pluripotent cells and prevents dedifferentiation of arterial SMCs. The BMP-induced phenotype switch requires intact RhoA/ROCK signaling but is not blocked by inhibitors of the TGF␤ and PI3K/ Akt pathways. Furthermore, nuclear localization and recruitment of the myocardin-related transcription factors (MRTF-A and MRTF-B) to a smooth muscle ␣-actin promoter is observed in response to BMP treatment. Thus, BMP signaling modulates VSMC phenotype via cross-talk with the RhoA/MRTFs pathway, and may contribute to the development of the pathological characteristics observed in patients with PAH and other obliterative vascular diseases.

Research paper thumbnail of OAZ Regulates Bone Morphogenetic Protein Signaling through Smad6 Activation

Journal of Biological Chemistry, 2006

The intensity and duration of activation of a signal transduction system are important determinan... more The intensity and duration of activation of a signal transduction system are important determinants of the specificity of the cellular response to the stimulus. It is unclear how different cells can generate a signal of varying intensity and duration in response to the same cytokine. We investigated the role of the transcriptional activator and Smad1/4 cofactor OAZ in regulating bone morphogenetic protein (BMP) signaling. We demonstrate that upon BMP4 stimulation, an OAZ-Smad1/4 complex binds to and activates the gene encoding Smad6, a specific inhibitor of the BMP pathway.

Research paper thumbnail of down-regulation of Kruppel-like factor-4 (KLF4) by microRNA-143/145 is critical for modulation of vascular smooth muscle cell phenotype by transforming growth factor-beta and bone morphogenetic protein 4

The Journal of biological chemistry, Jan 12, 2011

In the postnatal vasculature, fully differentiated and quiescent vascular smooth muscle cells (VS... more In the postnatal vasculature, fully differentiated and quiescent vascular smooth muscle cells (VSMCs) in a "contractile" phenotype are required for the normal regulation of vascular tone. The transforming growth factor-β (TGF-β) superfamily of growth factors (TGF-βs and bone morphogenetic proteins (BMPs)) are potent inducers of contractile phenotype and mediate (i) induction of contractile genes, and (ii) inhibition of VSMC growth and migration. Transcription of contractile genes is positively regulated by a regulatory DNA element called a CArG box. The CArG box is activated by the binding of serum response factor and its coactivators, myocardin (Myocd) or Myocd-related transcription factors (MRTFs). Krüppel-like factor-4 (KLF4) is known to inhibit activation of the CArG box. However, the potential role of KLF4 in the contractile activities of TGF-β or BMP has not been explored. Here, we demonstrate that TGF-β and BMP4 rapidly down-regulate KLF4 through induction of microR...

Research paper thumbnail of Disruption of miR-29 Leads to Aberrant Differentiation of Smooth Muscle Cells Selectively Associated with Distal Lung Vasculature

PLoS genetics, 2015

Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during developm... more Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during development or in response to challenges in a vessel specific manner. Aberrant vSMCs specifically associated with distal pulmonary arteries have been implicated in the pathogenesis of respiratory diseases, such as pulmonary arterial hypertension (PAH), a progressive and fatal disease, with no effective treatment. Therefore, it is highly relevant to understand the underlying mechanisms of lung vSMC differentiation. miRNAs are known to play critical roles in vSMC maturation and function of systemic vessels; however, little is known regarding the role of miRNAs in lung vSMCs. Here, we report that miR-29 family members are the most abundant miRNAs in adult mouse lungs. Moreover, high levels of miR-29 expression are selectively associated with vSMCs of distal vessels in both mouse and human lungs. Furthermore, we have shown that disruption of miR-29 in vivo leads to immature/synthetic vSMC phenotype ...

Research paper thumbnail of Functions of the bone morphogenetic protein signaling pathway through microRNAs (review)

International journal of molecular medicine, 2015

MicroRNAs (miRNAs or miRs) have emerged as key regulators of gene expression in essential cellula... more MicroRNAs (miRNAs or miRs) have emerged as key regulators of gene expression in essential cellular processes, such as cell growth, differentiation and development. Recent findings have established that the levels of miRNAs are modulated by cell signaling mechanisms, including the bone morphogenetic protein (BMP) signaling pathway. The BMP signaling pathway controls diverse cellular activities by modulating the levels of miRNAs, indicating the complexity of gene regulation by the BMP signaling pathway. The tight regulation of the levels of miRNAs is critical for maintaining normal physiological conditions, and dysregulated miRNA levels contribute to the development of diseases. In the present review, we discuss different insights (provided over the past decade) into the regulation of miRNAs governed by the BMP signaling pathway and the implications of this regulation on the understanding of the cellular differentiation of vascular smooth muscle cells (VSMCs), osteoblasts and neuronal...

Research paper thumbnail of The role of microRNAs in cell fate determination of mesenchymal stem cells: balancing adipogenesis and osteogenesis

BMB reports, Jan 23, 2014

Mesenchymal stem cells (MSCs) are multipotent stem cells capable of differentiating into adipocyt... more Mesenchymal stem cells (MSCs) are multipotent stem cells capable of differentiating into adipocytes, osteoblasts, or chondrocytes. A mutually inhibitory relationship exists between osteogenic and adipogenic lineage commitment and differentiation. Such cell fate decision is regulated by several signaling pathways, including Wnt and bone morphogenetic protein (BMP). Accumulating evidence indicates that microRNAs (miRNAs) act as switches for MSCs to differentiate into either osteogenic or adipogenic lineage. Different miRNAs have been reported to regulate a master transcription factor for osteogenesis, such as Runx2, as well as molecules in the Wnt or BMP signaling pathway, and control the balance between osteoblast and adipocyte differentiation. Here, we discuss recent advancement of the cell fate decision of MSCs by miRNAs and their targets.

Research paper thumbnail of Regulation of pri-miRNA Processing Through Smads

Advances in experimental medicine and biology, 2011

microRNAs (miRNAs) are small (∼22 nucleotides (nt)), noncoding RNAs that play a critical role in ... more microRNAs (miRNAs) are small (∼22 nucleotides (nt)), noncoding RNAs that play a critical role in diverse biological functions by modulating mRNA stability and translational control. Numerous miRNA profiling studies have indicated that the levels of miRNAs are tightly controlled during developmental stages and various pathophysiological and physiological conditions. Following transcription, the long primary miRNA transcript undergoes a series of coordinated maturation steps to generate the mature miRNA. Signaling pathways that control miRNA biogenesis and the mechanisms of regulation, however, are not well understood. In this chapter, we will discuss the finding that signal transducers of the Transforming Growth Factor β (TGFβ) signaling pathway, the Smads, play a critical regulatory role in the nuclear processing of miRNAs by the RNase III-type protein Drosha.

Research paper thumbnail of MicroRNA in Cancer: The Involvement of Aberrant MicroRNA Biogenesis Regulatory Pathways

Genes & cancer, 2010

MicroRNAs (miRNAs) are small, noncoding RNAs that influence diverse biological outcomes through t... more MicroRNAs (miRNAs) are small, noncoding RNAs that influence diverse biological outcomes through the repression of target genes during normal development and pathological responses. In particular, the alteration of miRNA expression has dramatic consequences for the progression of tumorigenesis. miRNAs undergo two processing steps that transform a long primary transcript into the mature miRNA. Although the general miRNA biogenesis pathway is well established, it is clear that not all miRNAs are created equally. Recent studies show that miRNA expression is controlled by diverse mechanisms in response to cellular stimuli. In this review, we discuss the mechanisms that govern the regulation of miRNA biogenesis with particular focus on how these mechanisms are perturbed in cancer.

Research paper thumbnail of MicroRNA miR-425 is a negative regulator of atrial natriuretic peptide

BMC Pharmacology and Toxicology, 2013

Research paper thumbnail of Molecular basis for antagonism between PDGF and the TGFβ family of signalling pathways by control of miR-24 expression

Research paper thumbnail of Smad-mediated miRNA processing: A critical role for a conserved RNA sequence

RNA Biology, 2011

microRNAs (miRNAs) are short, 21-24 nucleotide (nt), non-coding RNAs that post-transcriptionally ... more microRNAs (miRNAs) are short, 21-24 nucleotide (nt), non-coding RNAs that post-transcriptionally regulate the expression of messenger RNAs (mRNAs). Through the regulation of their cognate mRNAs, miRNAs control diverse aspects of biology, including development, cellular differentiation, proliferation, metabolism, and death. Thus, miRNAs play a critical role in the determination of normal cellular physiology and misexpression of miRNAs leads to pathological responses. Understanding the mechanisms that control miRNA expression is an important step forward as novel functions of miRNAs continue to be uncovered. In addition to transcriptional regulation, multiple pathways of post-transcriptional modulation of miRNA expression have been uncovered. In this review we discuss the role of the Smads in the regulation of miRNA processing in response to Transforming Growth Factor-β stimulation.

Research paper thumbnail of SMAD proteins control DROSHA-mediated microRNA maturation

Nature, 2008

MicroRNAs (miRNAs) are small non-coding RNAs that participate in the spatiotemporal regulation of... more MicroRNAs (miRNAs) are small non-coding RNAs that participate in the spatiotemporal regulation of messenger RNA and protein synthesis. Aberrant miRNA expression leads to developmental abnormalities and diseases, such as cardiovascular disorders and cancer; however, the stimuli and processes regulating miRNA biogenesis are largely unknown. The transforming growth factor β (TGF-β) and bone morphogenetic protein (BMP) family of growth factors orchestrates fundamental biological processes in development and in the homeostasis of adult tissues, including the vasculature. Here we show that induction of a contractile phenotype in human vascular smooth muscle cells by TGF-β and BMPs is mediated by miR-21. miR-21 downregulates PDCD4 (programmed cell death 4), which in turn acts as a negative regulator of smooth muscle contractile genes. Surprisingly, TGF-β and BMP signalling promotes a rapid increase in expression of mature miR-21 through a post-transcriptional step, promoting the processing of primary transcripts of miR-21 (pri-miR-21) into precursor miR-21 (pre-miR-21) by the DROSHA (also known as RNASEN) complex. TGF-β-and BMP-specific SMAD signal transducers are recruited to pri-miR-21 in a complex with the RNA helicase p68 (also known as DDX5), a component of the DROSHA microprocessor complex. The shared cofactor SMAD4 is not required for this process. Thus, regulation of miRNA biogenesis by ligand-specific SMAD proteins is critical for control of the vascular smooth muscle cell phenotype and potentially for SMAD4-independent responses mediated by the TGF-β and BMP signalling pathways.

Research paper thumbnail of Smad Proteins Bind a Conserved RNA Sequence to Promote MicroRNA Maturation by Drosha

Research paper thumbnail of Positive and Negative Regulation of the Transforming Growth Factor  /Activin Target Gene goosecoid by the TFII-I Family of Transcription Factors

Molecular and Cellular Biology, 2005

Goosecoid (Gsc) is a homeodomain-containing transcription factor present in a wide variety of ver... more Goosecoid (Gsc) is a homeodomain-containing transcription factor present in a wide variety of vertebrate species and known to regulate formation and patterning of embryos. Here we show that in embryonic carcinoma P19 cells, the transcription factor TFII-I forms a complex with Smad2 upon transforming growth factor ␤ (TGF␤)/activin stimulation, is recruited to the distal element (DE) of the Gsc promoter, and activates Gsc transcription. Downregulation of endogenous TFII-I by small inhibitory RNA in P19 cells abolishes the TGF␤-mediated induction of Gsc. Similarly, Xenopus embryos with endogenous TFII-I expression downregulated by injection of TFII-I-specific antisense oligonucleotides exhibit decreased Gsc expression. Unlike TFII-I, the related factor BEN (binding factor for early enhancer) is constitutively recruited to the distal element in the absence of TGF␤/activin signaling and is replaced by the TFII-I/Smad2 complex upon TGF␤/activin stimulation. Overexpression of BEN in P19 cells represses the TGF␤-mediated transcriptional activation of Gsc. These results suggest a model in which TFII-I family proteins have opposing effects in the regulation of the Gsc gene in response to a TGF␤/activin signal.

Research paper thumbnail of A Novel Regulatory Mechanism of the Bone Morphogenetic Protein (BMP) Signaling Pathway Involving the Carboxyl-Terminal Tail Domain of BMP Type II Receptor

Molecular and Cellular Biology, 2007

Bone morphogenetic protein (BMP) signaling regulates many different biological processes, includi... more Bone morphogenetic protein (BMP) signaling regulates many different biological processes, including cell growth, differentiation, and embryogenesis. BMPs bind to heterogeneous complexes of transmembrane serine/ threonine (Ser/Thr) kinase receptors known as the BMP type I and II receptors (BMPRI and BMPRII). BMPRII phosphorylates and activates the BMPRI kinase, which in turn activates the Smad proteins. The cytoplasmic region of BMPRII contains a "tail" domain (BMPRII-TD) with no enzymatic activity or known regulatory function. The discovery of mutations associated with idiopathic pulmonary artery hypertension mapping to BMPRII-TD underscores its importance.

Research paper thumbnail of Cardiovascular applications of therapeutic ultrasound

Journal of Interventional Cardiac Electrophysiology, 2014

Ultrasound (US) has gained widespread use in diagnostic cardiovascular applications. At amplitude... more Ultrasound (US) has gained widespread use in diagnostic cardiovascular applications. At amplitudes and frequencies typical of diagnostic use, its biomechanical effects on tissue are largely negligible. However, these parameters can be altered to harness US's thermal and non-thermal effects for therapeutic indications. High-intensity focused ultrasound (HIFU) and extracorporeal shock wave therapy (ECWT) are two therapeutic US modalities which have been investigated for treating cardiac arrhythmias and ischemic heart disease, respectively. Here, we review the biomechanical effects of HIFU and ECWT, their potential therapeutic mechanisms, and pre-clinical and clinical studies demonstrating their efficacy and safety limitations. Furthermore, we discuss other potential clinical applications of therapeutic US and areas in which future research is needed.

Research paper thumbnail of Down-Regulation of miR-96 by Bone Morphogenetic Protein Signaling is Critical for Vascular Smooth Muscle Cell Phenotype Modulation

Journal of Cellular Biochemistry, 2014

The bone morphogenetic protein (BMP) signaling pathway is critical for the induction and maintena... more The bone morphogenetic protein (BMP) signaling pathway is critical for the induction and maintenance of contractile phenotype in vascular smooth muscle cells (VSMCs). Inactivation of BMP signaling is common in abnormalities in vascular development and in vascular proliferative conditions, such as pulmonary artery hypertension. Herein, we identify microRNA-96 (miR-96) as a modulator of the VSMC phenotype in response to BMP4 signaling. We show that miR-96 is down-regulated by BMP4 treatment, which results in the derepression of a novel target, Tribbles-like protein 3 (Trb3). miR-96 targets a partially complementary sequence localized in the 3' UTR of Trb3. Trb3 is an essential positive regulator of the BMP signaling pathway and promotes contractile phenotype in VSMCs. In conclusion, our study demonstrates a novel mechanism of regulation of SMC-specific gene expression and induction of a VSMC contractile phenotype by the BMP4 signaling pathway via suppression of the miR-96-Trb3 axis.

Research paper thumbnail of Bone Morphogenetic Protein Signaling in Vascular Disease: ANTI-INFLAMMATORY ACTION THROUGH MYOCARDIN-RELATED TRANSCRIPTION FACTOR A

Journal of Biological Chemistry, 2012

Background: Bone Morphogenetic Proteins (BMP) pathway defects and inflammation are hallmarks of p... more Background: Bone Morphogenetic Proteins (BMP) pathway defects and inflammation are hallmarks of pulmonary arterial hypertension (PAH). Results: BMP signaling inhibits TNF␣-induced activation of NF-B by promoting an MRTF-A/NF-B inhibitory complex in pulmonary smooth muscle cells. Conclusion: BMPs binding to BMPR2 receptor play anti-inflammatory roles by inhibiting TNF␣ signaling via MRTF-A. Significance: Defining how BMP pathway dysfunction promotes vascular pro-inflammatory state is critical to PAH therapy. . 2 The abbreviations used are: PAH, pulmonary arterial hypertension; BMP, bone morphogenetic protein; MRTF, myocardin-related transcription factor; PASMC, pulmonary artery smooth muscle cells; SMC, smooth muscle cells; ICC, inflammatory cytokine and chemokine.

Research paper thumbnail of Induction of MicroRNA-221 by Platelet-derived Growth Factor Signaling Is Critical for Modulation of Vascular Smooth Muscle Phenotype

Journal of Biological Chemistry, 2009

The platelet-derived growth factor (PDGF) signaling pathway is a critical regulator of animal dev... more The platelet-derived growth factor (PDGF) signaling pathway is a critical regulator of animal development and homeostasis. Activation of the PDGF pathway leads to neointimal proliferative responses to artery injury; it promotes a switch of vascular smooth muscle cells (vSMC) to a less contractile phenotype by inhibiting the SMC-specific gene expression and increasing the rate of proliferation and migration. The molecular mechanism for these pleiotropic effects of PDGFs has not been fully described. Here, we identify the microRNA-221 (miR-221), a small noncoding RNA, as a modulator of the phenotypic change of vSMCs in response to PDGF signaling. We demonstrate that miR-221 is transcriptionally induced upon PDGF treatment in primary vSMCs, leading to down-regulation of the targets c-Kit and p27Kip1. Down-regulation of p27Kip1 by miR-221 is critical for PDGF-mediated induction of cell proliferation. Additionally, decreased c-Kit causes inhibition of SMC-specific contractile gene transcription by reducing the expression of Myocardin (Myocd), a potent SMC-specific nuclear coactivator. Our study demonstrates that PDGF signaling, by modulating the expression of miR-221, regulates two critical determinants of the vSMC phenotype; they are SMC gene expression and cell proliferation. . 3 The abbreviations used are: SMC, smooth muscle cell(s); vSMC, vascular SMC; PDGF, platelet-derived growth factor; PDGFR, PDGF receptor; UTR, untranslated region; mi-, micro-; CNN, smooth muscle calponin; IPAH, idiopathic pulmonary artery hypertension; Myocd, myocardin; PASMC, pulmonary artery smooth muscle cells; siRNA, small interference RNA; DAPI, 4Ј-6-Diamidino-2-phenylindole; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; SCF, stem cell factor; qRT, quantitative realtime; GFP, green fluorescent protein; FITC, fluorescein isothiocyanate; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; PCNA, proliferating cell nuclear antigen; BMP, bone morphogenetic protein; SMA, ␣-smooth muscle actin.

Research paper thumbnail of The Four-and-a-half LIM Domain Protein 2 Regulates Vascular Smooth Muscle Phenotype and Vascular Tone

Journal of Biological Chemistry, 2009

In response to vascular injury, differentiated vascular smooth muscle cells (vSMCs) undergo a uni... more In response to vascular injury, differentiated vascular smooth muscle cells (vSMCs) undergo a unique process known as "phenotype modulation," transitioning from a quiescent, "contractile" phenotype to a proliferative, "synthetic" state. We have demonstrated previously that the signaling pathway of bone morphogenetic proteins, members of the transforming growth factor ␤ family, play a role in the induction and maintenance of a contractile phenotype in human primary pulmonary artery smooth muscle cells. In this study, we show that a four-and-ahalf LIM domain protein 2 (FHL2) inhibits transcriptional activation of vSMC-specific genes mediated by the bone morphogenetic protein signaling pathway through the CArG box-binding proteins, such as serum response factor and members of the myocardin (Myocd) family. Interestingly, FHL2 does not affect recruitment of serum response factor or Myocd, however, it inhibits recruitment of a component of the SWI/SNF chromatin remodeling complex, Brg1, and RNA polymerase II, which are essential for the transcriptional activation. This is a novel mechanism of regulation of SMC-specific contractile genes by FHL2. Finally, aortic rings from homozygous FHL2-null mice display abnormalities in both endothelial-dependent and -independent relaxation, suggesting that FHL2 is essential for the regulation of vasomotor tone.

Research paper thumbnail of Control of Phenotypic Plasticity of Smooth Muscle Cells by Bone Morphogenetic Protein Signaling through the Myocardin-related Transcription Factors

Journal of Biological Chemistry, 2007

, unlike other muscle cells, do not terminally differentiate. In response to injury, VSMCs change... more , unlike other muscle cells, do not terminally differentiate. In response to injury, VSMCs change phenotype, proliferate, and migrate as part of the repair process. Dysregulation of this plasticity program contributes to the pathogenesis of several vascular disorders, such as atherosclerosis, restenosis, and hypertension. The discovery of mutations in the gene encoding BMPRII, the type II subunit of the receptor for bone morphogenetic proteins (BMPs), in patients with pulmonary arterial hypertension (PAH) provided an indication that BMP signaling may affect the homeostasis of VSMCs and their phenotype modulation. Here we report that BMP signaling potently induces SMC-specific genes in pluripotent cells and prevents dedifferentiation of arterial SMCs. The BMP-induced phenotype switch requires intact RhoA/ROCK signaling but is not blocked by inhibitors of the TGF␤ and PI3K/ Akt pathways. Furthermore, nuclear localization and recruitment of the myocardin-related transcription factors (MRTF-A and MRTF-B) to a smooth muscle ␣-actin promoter is observed in response to BMP treatment. Thus, BMP signaling modulates VSMC phenotype via cross-talk with the RhoA/MRTFs pathway, and may contribute to the development of the pathological characteristics observed in patients with PAH and other obliterative vascular diseases.

Research paper thumbnail of OAZ Regulates Bone Morphogenetic Protein Signaling through Smad6 Activation

Journal of Biological Chemistry, 2006

The intensity and duration of activation of a signal transduction system are important determinan... more The intensity and duration of activation of a signal transduction system are important determinants of the specificity of the cellular response to the stimulus. It is unclear how different cells can generate a signal of varying intensity and duration in response to the same cytokine. We investigated the role of the transcriptional activator and Smad1/4 cofactor OAZ in regulating bone morphogenetic protein (BMP) signaling. We demonstrate that upon BMP4 stimulation, an OAZ-Smad1/4 complex binds to and activates the gene encoding Smad6, a specific inhibitor of the BMP pathway.