Honors & Awards
School of Medicine Dean’s Postdoctoral Fellowship, Stanford University (2019-2020)
Recknagel Symposium Award, Best Academic Record 2011-2012, Dept. of Physiology and Biophysics, Case Western Reserve University School of Medicine (2012)
Young investigator travel award, The American Association for the Study of Liver Diseases (AASLD) (2011)
Japanese Government (Monbukagakusho, MEXT) Scholarship, Kyorin University School of Medicine, Tokyo, Japan (2004 - 2006)
Student Activity Fund, Thammasat University, Bangkok, Thailand (1999 - 2003)
Boards, Advisory Committees, Professional Organizations
Member, American Association for the Advancement of Science (AAAS) (2015 - Present)
Bachelor of Science, Thammasat University (2003)
Doctor of Philosophy, Case Western Reserve University (2017)
Master of Science, Mahidol University (2006)
KLF2 and KLF4 control endothelial identity and vascular integrity.
2017; 2 (4)
Maintenance of vascular integrity in the adult animal is needed for survival, and it is critically dependent on the endothelial lining, which controls barrier function, blood fluidity, and flow dynamics. However, nodal regulators that coordinate endothelial identity and function in the adult animal remain poorly characterized. Here, we show that endothelial KLF2 and KLF4 control a large segment of the endothelial transcriptome, thereby affecting virtually all key endothelial functions. Inducible endothelial-specific deletion of Klf2 and/or Klf4 reveals that a single allele of either gene is sufficient for survival, but absence of both (EC-DKO) results in acute death from myocardial infarction, heart failure, and stroke. EC-DKO animals exhibit profound compromise in vascular integrity and profound dysregulation of the coagulation system. Collectively, these studies establish an absolute requirement for KLF2/4 for maintenance of endothelial and vascular integrity in the adult animal.
View details for DOI 10.1172/jci.insight.91700
View details for PubMedID 28239661
View details for PubMedCentralID PMC5313061
Mitophagy is required for brown adipose tissue mitochondrial homeostasis during cold challenge.
2018; 8 (1): 8251
Brown adipose tissue (BAT) is a specialized thermogenic organ in mammals. The ability of BAT mitochondria to generate heat in response to cold-challenge to maintain core body temperature is essential for organismal survival. While cold activated BAT mitochondrial biogenesis is recognized as critical for thermogenic adaptation, the contribution of mitochondrial quality control to this process remains unclear. Here, we show mitophagy is required for brown adipocyte mitochondrial homeostasis during thermogenic adaptation. Mitophagy is significantly increased in BAT from cold-challenged mice (4 °C) and in β-agonist treated brown adipocytes. Blockade of mitophagy compromises brown adipocytes mitochondrial oxidative phosphorylation (OX-PHOS) capacity, as well as BAT mitochondrial integrity. Mechanistically, cold-challenge induction of BAT mitophagy is UCP1-dependent. Furthermore, our results indicate that mitophagy coordinates with mitochondrial biogenesis, maintaining activated BAT mitochondrial homeostasis. Collectively, our in vivo and in vitro findings identify mitophagy as critical for brown adipocyte mitochondrial homeostasis during cold adaptation.
View details for DOI 10.1038/s41598-018-26394-5
View details for PubMedID 29844467
View details for PubMedCentralID PMC5974273
Uremic Advanced Glycation End Products and Protein‐Bound Solutes Induce Endothelial Dysfunction Through Suppression of Krüppel‐Like Factor 2
Uremic Advanced Glycation End Products and Protein‐Bound Solutes Induce Endothelial Dysfunction Through Suppression of Krüppel‐Like Factor 2
2018; 7 (1)
View details for DOI 10.1161/JAHA.117.007566
miR-483 Targeting of CTGF Suppresses Endothelial-to-Mesenchymal Transition Therapeutic Implications in Kawasaki Disease
2017; 120 (2): 354-?
Endothelial-mesenchymal transition (EndoMT) is implicated in myofibroblast-like cell-mediated damage to the coronary arterial wall in acute Kawasaki disease (KD) patients, as evidenced by positive staining for connective tissue growth factor (CTGF) and EndoMT markers in KD autopsy tissues. However, little is known about the molecular basis of EndoMT involved in KD.We investigated the microRNA (miRNA) regulation of CTGF and the consequent EndoMT in KD pathogenesis. As well, the modulation of this process by statin therapy was studied.Sera from healthy children and KD subjects were incubated with human umbilical vein endothelial cells. Cardiovascular disease-related miRNAs, CTGF, and EndoMT markers were quantified using reverse transcriptase quantitative polymerase chain reaction, ELISA, and Western blotting. Compared with healthy controls, human umbilical vein endothelial cell incubated with sera from acute KD patients had decreased miR-483, increased CTGF, and increased EndoMT markers. Bioinformatics analysis followed by functional validation demonstrated that Krüppel-like factor 4 (KLF4) transactivates miR-483, which in turn targets the 3' untranslated region of CTGF mRNA. Overexpression of KLF4 or pre-miR-483 suppressed, whereas knockdown of KLF4 or anti-miR-483 enhanced, CTGF expression in endothelial cells in vitro and in vivo. Furthermore, atorvastatin, currently being tested in a phase I/IIa clinical trial in KD children, induced KLF4-miR-483, which suppressed CTGF and EndoMT in endothelial cells.KD sera suppress the KLF4-miR-483 axis in endothelial cells, leading to increased expression of CTGF and induction of EndoMT. This detrimental process in the endothelium may contribute to coronary artery abnormalities in KD patients. Statin therapy may benefit acute KD patients, in part, through the restoration of KLF4-miR-483 expression.URL: http://www.clinicaltrials.gov. Unique identifier: NCT01431105.
View details for DOI 10.1161/CIRCRESAHA.116.310233
View details for Web of Science ID 000392226200018
View details for PubMedID 27923814
View details for PubMedCentralID PMC5391835
A conserved KLF-autophagy pathway modulates nematode lifespan and mammalian age-associated vascular dysfunction.
2017; 8 (1): 914
Loss of protein and organelle quality control secondary to reduced autophagy is a hallmark of aging. However, the physiologic and molecular regulation of autophagy in long-lived organisms remains incompletely understood. Here we show that the Kruppel-like family of transcription factors are important regulators of autophagy and healthspan in C. elegans, and also modulate mammalian vascular age-associated phenotypes. Kruppel-like family of transcription factor deficiency attenuates autophagy and lifespan extension across mechanistically distinct longevity nematode models. Conversely, Kruppel-like family of transcription factor overexpression extends nematode lifespan in an autophagy-dependent manner. Furthermore, we show the mammalian vascular factor Kruppel-like family of transcription factor 4 has a conserved role in augmenting autophagy and improving vessel function in aged mice. Kruppel-like family of transcription factor 4 expression also decreases with age in human vascular endothelium. Thus, Kruppel-like family of transcription factors constitute a transcriptional regulatory point for the modulation of autophagy and longevity in C. elegans with conserved effects in the murine vasculature and potential implications for mammalian vascular aging.KLF family transcription factors (KLFs) regulate many cellular processes, including proliferation, survival and stress responses. Here, the authors position KLFs as important regulators of autophagy and lifespan in C. elegans, a role that may extend to the modulation of age-associated vascular phenotypes in mammals.
View details for DOI 10.1038/s41467-017-00899-5
View details for PubMedID 29030550
View details for PubMedCentralID PMC5640649
- Kruppel-like factor 4 regulates neutrophil activation Blood Advances 2017; 1: 662-668
Krüppel-Like Factor 4 Regulation of Cholesterol-25-Hydroxylase and Liver X Receptor Mitigates Atherosclerosis Susceptibility.
2017; 136 (14): 1315–30
Atherosclerosis is a multifaceted inflammatory disease involving cells in the vascular wall (eg, endothelial cells [ECs]), as well as circulating and resident immunogenic cells (eg, monocytes/macrophages). Acting as a ligand for liver X receptor (LXR), but an inhibitor of SREBP2 (sterol regulatory element-binding protein 2), 25-hydroxycholesterol, and its catalyzing enzyme cholesterol-25-hydroxylase (Ch25h) are important in regulating cellular inflammatory status and cholesterol biosynthesis in both ECs and monocytes/macrophages.Bioinformatic analyses were used to investigate RNA-sequencing data to identify cholesterol oxidation and efflux genes regulated by Krüppel-like factor 4 (KLF4). In vitro experiments involving cultured ECs and macrophages and in vivo methods involving mice with Ch25h ablation were then used to explore the atheroprotective role of KLF4-Ch25h/LXR.Vasoprotective stimuli increased the expression of Ch25h and LXR via KLF4. The KLF4-Ch25h/LXR homeostatic axis functions through suppressing inflammation, evidenced by the reduction of inflammasome activity in ECs and the promotion of M1 to M2 phenotypic transition in macrophages. The increased atherosclerosis in apolipoprotein E(-/-)/Ch25h(-/-) mice further demonstrates the beneficial role of the KLF4-Ch25h/LXR axis in vascular function and disease.KLF4 transactivates Ch25h and LXR, thereby promoting the synergistic effects between ECs and macrophages to protect against atherosclerosis susceptibility.
View details for DOI 10.1161/CIRCULATIONAHA.117.027462
View details for PubMedID 28794002
Short-term administration of Nicotinamide Mononucleotide preserves cardiac mitochondrial homeostasis and prevents heart failure.
Journal of molecular and cellular cardiology
2017; 112: 64–73
Heart failure is associated with mitochondrial dysfunction so that restoring or improving mitochondrial health is of therapeutic importance. Recently, reduction in NAD(+) levels and NAD(+)-mediated deacetylase activity has been recognized as negative regulators of mitochondrial function. Using a cardiac specific KLF4 deficient mouse line that is sensitive to stress, we found mitochondrial protein hyperacetylation coupled with reduced Sirt3 and NAD(+) levels in the heart before stress, suggesting that the KLF4-deficient heart is predisposed to NAD(+)-associated defects. Further, we demonstrated that short-term administration of Nicotinamide Mononucleotide (NMN) successfully protected the mutant mice from pressure overload-induced heart failure. Mechanically, we showed that NMN preserved mitochondrial ultrastructure, reduced ROS and prevented cell death in the heart. In cultured cardiomyocytes, NMN treatment significantly increased long-chain fatty acid oxidation despite no direct effect on pyruvate oxidation. Collectively, these results provide cogent evidence that hyperacetylation of mitochondrial proteins is critical in the pathogenesis of cardiac disease and that administration of NMN may serve as a promising therapy.
View details for DOI 10.1016/j.yjmcc.2017.09.001
View details for PubMedID 28882480
Regulation of endothelial hemoglobin alpha expression by Kruppel-like factors.
Vascular medicine (London, England)
2017; 22 (5): 363–69
Hemoglobin subunit alpha (HBA) expression in endothelial cells (ECs) has recently been shown to control vascular tone and function. We sought to elucidate the transcriptional regulation of HBA expression in the EC. Gain of KLF2 or KLF4 function studies led to significant induction of HBA in ECs. An opposite effect was observed in ECs isolated from animals with endothelial-specific ablation of Klf2, Klf4 or both. Promoter reporter assays demonstrated that KLF2/KLF4 transactivated the hemoglobin alpha promoter, an effect that was abrogated following mutation of all four putative KLF-binding sites. Fine promoter mutational studies localized three out of four KLF-binding sites (sites 2, 3, and 4) as critical for the transactivation of the HBA promoter by KLF2/KLF4. Chromatin immunoprecipitation studies showed that KLF4 bound to the HBA promoter in ECs. Thus, KLF2 and KLF4 serve as important regulators that promote HBA expression in the endothelium.
View details for DOI 10.1177/1358863X17722211
View details for PubMedID 28825355
Adipose KLF15 Controls Lipid Handling to Adapt to Nutrient Availability.
2017; 21 (11): 3129-3140
View details for DOI 10.1016/j.celrep.2017.11.032.
Kruppel-like factor 4 is critical for transcriptional control of cardiac mitochondria! homeostasis
JOURNAL OF CLINICAL INVESTIGATION
2015; 125 (9): 3461-3476
Mitochondrial homeostasis is critical for tissue health, and mitochondrial dysfunction contributes to numerous diseases, including heart failure. Here, we have shown that the transcription factor Kruppel-like factor 4 (KLF4) governs mitochondrial biogenesis, metabolic function, dynamics, and autophagic clearance. Adult mice with cardiac-specific Klf4 deficiency developed cardiac dysfunction with aging or in response to pressure overload that was characterized by reduced myocardial ATP levels, elevated ROS, and marked alterations in mitochondrial shape, size, ultrastructure, and alignment. Evaluation of mitochondria isolated from KLF4-deficient hearts revealed a reduced respiration rate that is likely due to defects in electron transport chain complex I. Further, cardiac-specific, embryonic Klf4 deletion resulted in postnatal premature mortality, impaired mitochondrial biogenesis, and altered mitochondrial maturation. We determined that KLF4 binds to, cooperates with, and is requisite for optimal function of the estrogen-related receptor/PPARγ coactivator 1 (ERR/PGC-1) transcriptional regulatory module on metabolic and mitochondrial targets. Finally, we found that KLF4 regulates autophagy flux through transcriptional regulation of a broad array of autophagy genes in cardiomyocytes. Collectively, these findings identify KLF4 as a nodal transcriptional regulator of mitochondrial homeostasis.
View details for DOI 10.1172/JCI79964
View details for Web of Science ID 000362303600023
View details for PubMedID 26241060
View details for PubMedCentralID PMC4588311
Circadian control of bile acid synthesis by a KLF15-Fgf15 axis
Circadian control of nutrient availability is critical to efficiently meet the energetic demands of an organism. Production of bile acids (BAs), which facilitate digestion and absorption of nutrients, is a major regulator of this process. Here we identify a KLF15-Fgf15 signalling axis that regulates circadian BA production. Systemic Klf15 deficiency disrupted circadian expression of key BA synthetic enzymes, tissue BA levels and triglyceride/cholesterol absorption. Studies in liver-specific Klf15-knockout mice suggested a non-hepatic basis for regulation of BA production. Ileal Fgf15 is a potent inhibitor of BA synthesis. Using a combination of biochemical, molecular and functional assays (including ileectomy and bile duct catheterization), we identify KLF15 as the first endogenous negative regulator of circadian Fgf15 expression. Elucidation of this novel pathway controlling circadian BA production has important implications for physiologic control of nutrient availability and metabolic homeostasis.
View details for DOI 10.1038/ncomms8231
View details for Web of Science ID 000357168000005
View details for PubMedID 26040986
View details for PubMedCentralID PMC4457302
Regulation of an Inflammatory Disease Kruppel-Like Factors and Atherosclerosis
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
2014; 34 (3): 499-508
This invited review summarizes work presented in the Russell Ross lecture delivered at the 2012 proceedings of the American Heart Association. We begin with a brief overview of the structural, cellular, and molecular biology of Krüppel-like factors. We then focus on discoveries during the past decade, implicating Krüppel-like factors as key determinants of vascular cell function in atherosclerotic vascular disease.
View details for DOI 10.1161/ATVBAHA.113.301925
View details for Web of Science ID 000332996600006
View details for PubMedID 24526695
View details for PubMedCentralID PMC5539879
Kruppel-like factor 15 is critical for vascular inflammation
JOURNAL OF CLINICAL INVESTIGATION
2013; 123 (10): 4232-4241
Activation of cells intrinsic to the vessel wall is central to the initiation and progression of vascular inflammation. As the dominant cellular constituent of the vessel wall, vascular smooth muscle cells (VSMCs) and their functions are critical determinants of vascular disease. While factors that regulate VSMC proliferation and migration have been identified, the endogenous regulators of VSMC proinflammatory activation remain incompletely defined. The Kruppel-like family of transcription factors (KLFs) are important regulators of inflammation. In this study, we identified Kruppel-like factor 15 (KLF15) as an essential regulator of VSMC proinflammatory activation. KLF15 levels were markedly reduced in human atherosclerotic tissues. Mice with systemic and smooth muscle-specific deficiency of KLF15 exhibited an aggressive inflammatory vasculopathy in two distinct models of vascular disease: orthotopic carotid artery transplantation and diet-induced atherosclerosis. We demonstrated that KLF15 alters the acetylation status and activity of the proinflammatory factor NF-κB through direct interaction with the histone acetyltransferase p300. These studies identify a previously unrecognized KLF15-dependent pathway that regulates VSMC proinflammatory activation.
View details for DOI 10.1172/JCI68552
View details for Web of Science ID 000325443100019
View details for PubMedID 23999430
View details for PubMedCentralID PMC3785338
Antigen-specific, antibody-coated, exosome-like nanovesicles deliver suppressor T-cell microRNA-150 to effector T cells to inhibit contact sensitivity
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
2013; 132 (1): 170-U287
T-cell tolerance of allergic cutaneous contact sensitivity (CS) induced in mice by high doses of reactive hapten is mediated by suppressor cells that release antigen-specific suppressive nanovesicles.We sought to determine the mechanism or mechanisms of immune suppression mediated by the nanovesicles.T-cell tolerance was induced by means of intravenous injection of hapten conjugated to self-antigens of syngeneic erythrocytes and subsequent contact immunization with the same hapten. Lymph node and spleen cells from tolerized or control donors were harvested and cultured to produce a supernatant containing suppressive nanovesicles that were isolated from the tolerized mice for testing in active and adoptive cell-transfer models of CS.Tolerance was shown due to exosome-like nanovesicles in the supernatants of CD8(+) suppressor T cells that were not regulatory T cells. Antigen specificity of the suppressive nanovesicles was conferred by a surface coat of antibody light chains or possibly whole antibody, allowing targeted delivery of selected inhibitory microRNA (miRNA)-150 to CS effector T cells. Nanovesicles also inhibited CS in actively sensitized mice after systemic injection at the peak of the responses. The role of antibody and miRNA-150 was established by tolerizing either panimmunoglobulin-deficient JH(-/-) or miRNA-150(-/-) mice that produced nonsuppressive nanovesicles. These nanovesicles could be made suppressive by adding antigen-specific antibody light chains or miRNA-150, respectively.This is the first example of T-cell regulation through systemic transit of exosome-like nanovesicles delivering a chosen inhibitory miRNA to target effector T cells in an antigen-specific manner by a surface coating of antibody light chains.
View details for DOI 10.1016/j.jaci.2013.04.048
View details for Web of Science ID 000321052300022
View details for PubMedID 23727037
View details for PubMedCentralID PMC4176620
Proteomic Identification of S-Nitrosylated Golgi Proteins: New Insights into Endothelial Cell Regulation by eNOS-Derived NO
2012; 7 (2)
Endothelial nitric oxide synthase (eNOS) is primarily localized on the Golgi apparatus and plasma membrane caveolae in endothelial cells. Previously, we demonstrated that protein S-nitrosylation occurs preferentially where eNOS is localized. Thus, in endothelial cells, Golgi proteins are likely to be targets for S-nitrosylation. The aim of this study was to identify S-nitrosylated Golgi proteins and attribute their S-nitrosylation to eNOS-derived nitric oxide in endothelial cells.Golgi membranes were isolated from rat livers. S-nitrosylated Golgi proteins were determined by a modified biotin-switch assay coupled with mass spectrometry that allows the identification of the S-nitrosylated cysteine residue. The biotin switch assay followed by Western blot or immunoprecipitation using an S-nitrosocysteine antibody was also employed to validate S-nitrosylated proteins in endothelial cell lysates.Seventy-eight potential S-nitrosylated proteins and their target cysteine residues for S-nitrosylation were identified; 9 of them were Golgi-resident or Golgi/endoplasmic reticulum (ER)-associated proteins. Among these 9 proteins, S-nitrosylation of EMMPRIN and Golgi phosphoprotein 3 (GOLPH3) was verified in endothelial cells. Furthermore, S-nitrosylation of these proteins was found at the basal levels and increased in response to eNOS stimulation by the calcium ionophore A23187. Immunofluorescence microscopy and immunoprecipitation showed that EMMPRIN and GOLPH3 are co-localized with eNOS at the Golgi apparatus in endothelial cells. S-nitrosylation of EMMPRIN was notably increased in the aorta of cirrhotic rats.Our data suggest that the selective S-nitrosylation of EMMPRIN and GOLPH3 at the Golgi apparatus in endothelial cells results from the physical proximity to eNOS-derived nitric oxide.
View details for DOI 10.1371/journal.pone.0031564
View details for Web of Science ID 000302873700072
View details for PubMedID 22363674
View details for PubMedCentralID PMC3283662
Reticulon 4B (Nogo-B) Is a Novel Regulator of Hepatic Fibrosis
2011; 53 (4): 1306-1315
Nogo-B, also known as Reticulon 4B, plays important roles in vascular injuries. Its function in the liver is not understood. The aim of this study was to characterize Nogo-B in liver fibrosis and cirrhosis. Nogo-B distribution was assessed in normal and cirrhotic human liver sections. We also determined the levels of liver fibrosis in wild-type (WT) and Nogo-A/B knockout (NGB KO) mice after sham operation or bile duct ligation (BDL). To investigate the mechanisms of Nogo-B's involvement in fibrosis, hepatic stellate cells were isolated from WT and NGB KO mice and transformed into myofibroblasts. Portal pressure was measured to test whether Nogo-B gene deletion could ameliorate portal hypertension. In normal livers, Nogo-B expression was found in nonparenchymal cells, whereas its expression in hepatocytes was minimal. Nogo-B staining was significantly elevated in cirrhotic livers. Fibrosis was significantly increased in WT mice 4 weeks after BDL compared with NGB KO mice. The absence of Nogo-B significantly reduced phosphorylation of Smad2 levels upon transforming growth factor β (TGF-β) stimulation. Reconstitution of the Nogo-B gene into NGB KO fibroblasts restored Smad2 phosphorylation. Four weeks after BDL, portal pressure was significantly increased in WT mice by 47%, compared with sham-operated controls (P = 0.03), whereas such an increase in portal pressure was not observed in NGB KO mice (P = NS).Nogo-B regulates liver fibrosis, at least in part, by facilitating the TGFβ/Smad2 signaling pathway in myofibroblasts. Because absence of Nogo-B ameliorates liver fibrosis and portal hypertension, Nogo-B blockade may be a potential therapeutic target in fibrosis/cirrhosis.
View details for DOI 10.1002/hep.24200
View details for Web of Science ID 000289419600025
View details for PubMedID 21480333
View details for PubMedCentralID PMC3667398
Pyrazolylthiazole as Delta F508-Cystic Fibrosis Transmembrane Conductance Regulator Correctors with Improved Hydrophilicity Compared to Bithiazoles
JOURNAL OF MEDICINAL CHEMISTRY
2010; 53 (9): 3772-3781
Deletion of phenylalanine residue 508 (DeltaF508) in the cystic fibrosis (CF) transmembrane conductance regulator protein (CFTR) is a major cause of CF. Small molecule "correctors" of defective DeltaF508-CFTR cellular processing hold promise for CF therapy. We previously identified and characterized bithiazole CF corrector 1 and s-cis-locked bithiazole 2. Herein, we report the regiodivergent synthesis of Ngamma and Nbeta isomers of thiazole-tethered pyrazoles with improved hydrophilicity compared to bithiazoles. We synthesized a focused library of 54 pyrazolylthiazoles 3, which included examples of both regioisomers 4 and 5. The thiazole-tethered pyrazoles allowed incorporation of property-modulating functionality on the pyrazole ring (ester, acid, and amide) while retaining DeltaF508-CFTR corrector activity (EC(50)) of under 1 microM. The most active pyrazolylthiazole (14h) has an experimentally determined log P of 4.1, which is 1.2 log units lower than bithiazole CF corrector 1.
View details for DOI 10.1021/jm100235h
View details for Web of Science ID 000277352800030
View details for PubMedID 20373765
View details for PubMedCentralID PMC3109609