Comparison of the efficacy of continuous intravenous infusion versus intramuscular injection of epinephrine for initial anaphylaxis treatment.

Aim: Continuous intravenous (CIV) infusion of epinephrine for the treatment of anaphylaxis may be required if symptoms do not improve after intramuscular (IM) injection. As CIV infusion permits precise dose adjustment, we compared treatment course and adverse events following CIV infusion and IM injection of epinephrine for the management of anaphylaxis. Methods: Medical records of patients, who were treated for anaphylaxis with epinephrine, were 18 years or older, and were admitted to our department from April 2005 to March 2016, were retrospectively reviewed. The cases were categorized as CIV infusion or IM injection, and treatment course and outcomes were compared between the two groups. Results: Of the 142 eligible cases, there were 78 in the CIV infusion group and 64 in the IM injection group. The CIV infusion group had lower systolic blood pressure, more respiratory symptoms, and higher Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, but required a lower total dose of epinephrine, had fewer adverse events after epinephrine administration, and showed lower incidence of biphasic reactions. In addition, compared with the IM injection group, time to administration of epinephrine was significantly longer (P < 0.001), but time to resolution of symptoms, both from contact and epinephrine administration, was significantly shorter (P < 0.01 and P = 0.03, respectively). Conclusion: Continuous intravenous infusion of epinephrine for the treatment of anaphylaxis may be safe, has fewer adverse events, improves symptoms, and is relatively easy to administer under ready conditions. CIV infusion of epinephrine may also reduce the incidence of biphasic reactions.

Myeloperoxidase Antineutrophil Cytoplasmic Antibody-Associated Renal-Limited Vasculitis in a Young Adult Woman.

Antineutrophil cytoplasmic antibody (ANCA)-associated renal-limited vasculitis (RLV) is a minor subtype of small vessel vasculitis characterized by the inflammation of blood vessels, tissue damage, and loss of renal function localized in the kidney without systemic involvements. Here, we report a case of myeloperoxidase (MPO) ANCA-associated RLV in a young adult woman in Japan presenting chronic hematuria and newly overt proteinuria. Percutaneous renal biopsy revealed focal fibro-cellular crescent glomerulonephritis and the absence of other small vasculitides, tubular atrophy, and interstitial fibrosis. Therapeutic intravenous methylprednisolone pulse followed by oral prednisolone was administered as a remission induction. The patient's serum MPO-ANCA level gradually decreased, coinciding with dramatic changes in proteinuria and hematuria after therapeutic glucocorticoid administration. Renal function was maintained within the normal range, and disease activity was well-tolerated throughout the follow-up period for more than 14 weeks. While the incidence of RLV is rare among younger patients, it occurs with asymptomatic hematuria and proteinuria, which is important in differentiating RLV from typical glomerulonephritis. The overall prognosis of ANCA-associated RLV potentially depends on the severity of extrarenal involvements. Early diagnosis, appropriate treatment, and regular maintenance are essential for controlling and treating RLV. Due to the nontypical case presented here, further investigation is recommended to improve the diagnosis strategies and treatment options for this disease.

Re-expansion pulmonary edema after thoracentesis for iatrogenic pneumothorax and severe subcutaneous emphysema.

Subclavian central venous catheterization can cause severe complications, including tension pneumothorax, subcutaneous emphysema, and pneumomediastinum. Re-expansion pulmonary edema after thoracentesis is a life-threatening complication.

Accurate and quick predictor of necrotizing soft tissue infection: Usefulness of the LRINEC score and NSTI assessment score.

OBJECTIVE: The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is a diagnostic tool for necrotizing soft tissue infection (NSTI), which is validated and is considered to have high diagnostic value. However, some experts criticize LRINEC score for consisting of laboratory test results only. METHODS: In this single-center retrospective study, we created a new scoring system (NSTI assessment score; NAS), which also incorporated vital signs as another diagnostic tool for NSTI using cases from our hospital and also evaluated diagnostic accuracy of LRINEC score. We identified NSTI predictors by comparing 24 NSTI patients and 80 non NSTI patients using uni- and multivariate logistic regression analysis, and created NAS based on odds ratio of variables which are statistically significant in the multivariate model. RESULTS: We identified mean arterial pressure, C-reactive protein, hemoglobin, serum creatinine, and glucose as a predictor for NSTI. The maximum value of NAS was 11 points with the cut-off value of 6. Sensitivity, specificity, positive predictive value, and negative predictive value of the NAS for diagnosis of NSTI were 87.5%, 91.3%, 75.0%, and 96.1%, respectively. Area under the receiver operating characteristic curve was 0.926 (0.851-1.00) for the NAS and 0.903 (0.833-0.973) for the LRINEC score, and they were not statistically different (p = 0.167). CONCLUSION: The NAS has high diagnostic accuracy in predicting NSTI, and is comparable with the LRINEC score. The NAS needs to be validated in other cohorts in the future.

Adult hypophosphatasia with compound heterozygous p.Phe327Leu missense and c.1559delT frameshift mutations in tissue-nonspecific alkaline phosphatase gene: a case report.

BACKGROUND: Hypophosphatasia is an inherited bone disease characterized by low alkaline phosphatase activity encoded by ALPL. Clinically, hypophosphatasia can be categorized as perinatal, infantile, childhood, and adult forms, as well as odonto-hypophosphatasia, according to the age at first sign or dental manifestations. Adult hypophosphatasia typically presents in middle-aged patients who appear to be in good health in early adulthood and manifests as painful feet caused by recurrent, slow-healing stress fractures of the lower limb. Because the symptoms of adult hypophosphatasia vary and are common, many patients with hypophosphatasia might be not diagnosed accurately and thus may receive inappropriate treatment. CASE PRESENTATION: We report a case of a 35-year-old Japanese woman with low serum alkaline phosphatase detected at a routine medical checkup. She had mild muscle/bone pain but no history of rickets, fractures, or dental problems. Measurement of bone mineral density of the lumbar spine and the femoral neck revealed osteopenia below the expected range for age in a young adult. Abdominal ultrasonography revealed numerous microcalcifications in both kidneys. Analysis of amino acids in urine revealed that phosphoethanolamine was elevated. Low serum alkaline phosphatase activity, elevation of phosphoethanolamine, and low bone mineral density supported the diagnosis of hypophosphatasia. ALPL mutation analysis revealed two mutations: p.Phe327Leu and c.1559delT. These genetic abnormalities were previously reported in perinatal, infantile, and childhood but not adult hypophosphatasia. On the basis of the clinical presentation, laboratory and imaging findings, and genetic analyses, the patient was definitively diagnosed with adult hypophosphatasia. To the best of our knowledge, this is the first case report of adult hypophosphatasia with the compound heterozygous mutations p.Phe327Leu and c.1559delT. CONCLUSIONS: Although the risk of bone fracture was high in this case, treatment approaches differ between osteoporosis and hypophosphatasia. Because adult hypophosphatasia diagnosis is often difficult because of their varied symptoms, hypophosphatasia should be considered in the differential diagnosis of low serum alkaline phosphatase. Early diagnosis is important so that appropriate treatment can be initiated.

Fibroblast growth factor 23 inhibits osteoblastic gene expression and induces osteoprotegerin in vascular smooth muscle cells.

BACKGROUND AND AIMS: Elevated fibroblast growth factor 23 (FGF23) levels are associated with cardiovascular mortality in patients with chronic kidney disease. However, both clinical and basic research have demonstrated conflicting evidence regarding the pathophysiological role of FGF23 in vascular calcification. The aim of this study was to determine the role of FGF23 in the osteoblastic gene expression in vascular smooth muscle cells (SMCs). METHODS AND RESULTS: We transduce human aortic SMCs (HASMCs) expressing klotho and FGF receptors with the adenovirus expressing human FGF23 (Ad-FGF23). We observed significant decreases in the expression of osteoblast-marker genes including BMP2, BMP4, MSX2, RUNX2 and ALP, as well as reduced calcification. Notably, Ad-FGF23 increased mRNA and protein levels of osteoprotegerin (OPG), and human OPG promoter was activated by FGF23. Moreover, in HASMCs overexpressing klotho, FGF23 upregulated OPG expression, whereas depletion of klotho by siRNA attenuated FGF23-induced OPG expression. Furthermore, in 73 consecutive patients with type 2 diabetes mellitus undergoing cardiac computed tomography to determine coronary calcium scores (CCSs), serum FGF23 levels were positively correlated with OPG independent of phosphate and estimated glomerular filtration rate (eGFR, r = 0.65, p < 0.01). Serum FGF23 levels were significantly elevated in patients with high CCSs (≧100) compared to those with low CCSs (<100). CONCLUSIONS: Our in vitro results indicate that FGF23 suppresses osteoblastic gene expression and induces OPG expression in HASMCs. Together with our cross-sectional clinical assessment, the present study lends support to our hypothesis that FGF23 counteracts osteogenic conversion of vascular SMCs as a part of a compensatory mechanism to mitigate vascular calcification.

Azelnidipine inhibits Msx2-dependent osteogenic differentiation and matrix mineralization of vascular smooth muscle cells.

Vascular calcification is an active and regulated process that is similar to bone formation. While calcium channel blockers (CCBs) have been shown to improve outcomes in atherosclerotic vascular disease, it remains unknown whether CCBs have an effect on the process of vascular calcification. Here we investigated whether CCBs inhibit osteogenic differentiation and matrix mineralization of vascular smooth muscle cells induced by Msx2, a key factor of vascular calcification. Human aortic smooth muscle cells (HASMCs) were transduced with adenovirus expressing MSX2 and were treated with 3 distinct CCBs. Azelnidipine, a dihydropyridine subclass of CCBs, significantly decreased alkaline phosphatase (ALP) activity of Msx2-overexpressed HASMCs, whereas verapamil and diltiazem had no effect. Furthermore, azelnidipine, but not verapamil and diltiazem, significantly decreased matrix mineralization of Msx2-overexpressing HASMCs. Azelnidipine significantly attenuated the induction of ALP gene expression by Msx2, a key transcription factor in osteogenesis, while it did not reduce enzymatic activity of ALP. Furthermore, azelnidipine inhibited the ability of Msx2 to activate the ALP gene, but had no effect on Notch-induced Msx2 expression. Given that L-type calcium channels are equally blocked by these CCBs, our results suggest that azelnidipine inhibits the Msx2-dependent process of vascular calcification by mechanisms other than inhibition of calcium channel activity.

Notch induces myofibroblast differentiation of alveolar epithelial cells via transforming growth factor-{beta}-Smad3 pathway.

Notch is an ancient cell-signaling system that regulates the specification of cell fate. This study examined the role of Notch in the epithelial-mesenchymal transition (EMT) and myofibroblast differentiation of cultured RLE-6TN cells (i.e., rat alveolar epithelial cells). The activation of Notch, either by ectopic expression of the Notch intracellular domain or by the co-culture of RLE-6TN cells with L-Jagged1 cells, induces the expression of smooth muscle α-actin (SMA) and other mesenchymal marker genes (collagen I and vimentin), and reduces the expression of epithelial marker genes (E-cadherin, occludin, and zonula occludens-1). The pharmacologic inhibition of the endogenous Notch signal significantly inhibited the transforming growth factor-ß (TGF-ß)-induced expression of SMA. Cell migratory capacity was increased by Notch. Luciferase assays revealed that the CC(A/T)(6)GG (CArG) box and the TGF-ß control element (TCE) are required for Notch-induced SMA gene transcription. DNA microarray analysis revealed that members of the TGF-ß family as well as Jagged1 were induced in RLE-6TN cells by Notch. Western blot analysis showed that Notch induced the phosphorylation of Smad3, and the TGF-ß receptor type I/activin receptor-like kinase 5 (ALK5) kinase inhibitor SB431542 markedly reduced the Notch-induced expression of SMA. Enzyme-linked immunosorbent assays confirmed the production of TGF-ß1 from RLE-6TN cells by Notch. Immunohistochemistry of a bleomycin-induced model of pulmonary fibrosis and lung specimens from patients with idiopathic interstitial pneumonias showed that Notch was strongly expressed in myofibroblasts, identified as SMA-positive cells. These data indicate that Notch induces myofibroblast differentiation through a TGF-ß-Smad3 pathway that activates SMA gene transcription in a CArG-dependent and TCE-dependent manner in alveolar epithelial cells. Our data also imply that Notch induces the EMT phenotype, with increased migratory behavior in pulmonary fibrosis.

Notch signaling pathway enhances bone morphogenetic protein 2 (BMP2) responsiveness of Msx2 gene to induce osteogenic differentiation and mineralization of vascular smooth muscle cells.

Vascular calcification is regulated in a process similar to bone formation. BMP2 (bone morphogenetic protein 2) is essential for osteoblastic differentiation of mesenchymal progenitor cells and thus has been implicated in the development of vascular calcification. Here we examined whether Notch signaling interacts with BMP2 signaling to regulate osteogenic differentiation and mineralization of vascular smooth muscle cells (SMCs). BMP2 alone scarcely induced the expression of alkaline phosphatase (ALP), an ectoenzyme crucially required for active biomineralization, in human aortic SMCs (HASMCs), despite its strong induction in osteoblast precursor MC3T3-E1 cells. Notably, overexpression of the Notch1 intracellular domain (N1-ICD) markedly enhanced BMP2-mediated induction of ALP activity and mineralization of HASMCs. In HASMCs, expression of Msx2 gene, a well documented BMP2 target gene in osteoblasts, was barely induced by BMP2 alone, and N1-ICD clearly enhanced the BMP2-driven Msx2 gene expression. Deletion and site-directed mutation analysis of Msx2 gene promoter revealed that the RBPJk-binding site was necessary for BMP2 responsiveness. Using the RBPJk-deficient cells and siRNA for RBPJk, we showed that RBPJk was required for BMP2 induction of Msx2 gene expression and ALP activity. Moreover, we showed that Smad1, a transcription factor downstream of BMP2 signaling, interacted with N1-ICD to form a complex within the Msx2 promoter. Immunohistochemistry of human calcifying atherosclerotic plaques revealed colocalized expression of Notch1, BMP2, and Msx2. These results indicate that the Notch intracellular domain·RBPJk complex enhances the BMP2-induced Msx2 gene expression by cooperating with Smad1 and suggest that Notch signaling makes vascular SMC responsive to BMP2 and promotes vascular calcification.

Fibroblast growth factor-2 induces osteogenic differentiation through a Runx2 activation in vascular smooth muscle cells.

Expression of bone-associated proteins and osteoblastic transcription factor Runx2 in arterial cells has been implicated in the development of vascular calcification. However, the signaling upstream of the Runx2-mediated activation of osteoblastic program in vascular smooth muscle cells (VSMC) is poorly understood. We examined the effects of fibroblast growth factor-2 (FGF-2), an important regulator of bone formation, on osteoblastic differentiation of VSMC. Stimulation of cultured rat aortic SMC (RASMC) with FGF-2 induced the expression of the osteoblastic markers osteopontin (OPN) and osteocalcin. Luciferase assays showed that FGF-2 induced osteocyte-specific element (OSE)-dependent transcription. Downregulation of Runx2 by siRNA repressed the basal and FGF-2-stimulated expression of the OPN gene in RASMC. FGF-2 produced hydrogen peroxide in RASMC, as evaluated by fluorescent probe. Induction of OPN expression by FGF-2 was inhibited not only by PD98059 (MEK1 inhibitor) and PP1 (c-Src inhibitor), but also by an antioxidant, N-acetyl cysteine. Nuclear extracts from FGF-2-treated RASMC exhibited increased DNA-binding of Runx2 to its target sequence. Immunohistochemistry of human coronary atherectomy specimens and calcified aortic tissues showed that expression of FGF receptor-1 and Runx2 was colocalized. In conclusion, these results suggest that FGF-2 plays a role in inducing osteoblastic differentiation of VSMC by activating Runx2 through mitogen-activated protein kinase (MAPK)-dependent- and oxidative stress-sensitive-signaling pathways.

Notch signaling induces osteogenic differentiation and mineralization of vascular smooth muscle cells: role of Msx2 gene induction via Notch-RBP-Jk signaling.

OBJECTIVE: Vascular calcification is closely correlated with cardiovascular morbidity and mortality. Here, we demonstrate the role of Notch signaling in osteogenic differentiation and mineralization of vascular smooth muscle cells (SMCs). METHODS AND RESULTS: The Msx2 gene, a key regulator of osteogenesis, was highly induced by coculture with Notch ligand-expressing cells or overexpression of Notch intracellular domains (NICDs) in human aortic SMCs (HASMCs). Furthermore, the Notch1 intracellular domain (N1-ICD) overexpression markedly upregulated alkaline phosphatase (ALP) activity and matrix mineralization of HASMCs. A knockdown experiment with a small interfering RNA confirmed that Msx2 mediated N1-ICD-induced osteogenic conversion of HASMCs. Interestingly, Msx2 induction by N1-ICD was independent of bone morphogenetic protein-2 (BMP-2), an osteogenic morphogen upstream of Msx2. The transcriptional activity of the Msx2 promoter was significantly enhanced by N1-ICD overexpression. The RBP-Jk binding element within the Msx2 promoter was critical to Notch-induced Msx2 gene expression. Correspondingly, N1-ICD overexpression did not induce the Msx2 expression in RBP-Jk-deficient fibroblasts. Immunohistochemistry of human carotid artery specimens revealed localization of Notch1, Jagged1 and Msx2 to fibrocalcific atherosclerotic plaques. CONCLUSIONS: These results imply a new mechanism for osteogenic differentiation of vascular SMCs in which Notch/RBP-Jk signaling directly induces Msx2 gene expression and suggest its crucial role in mediating vascular calcification.

PIAS1 mediates TGFbeta-induced SM alpha-actin gene expression through inhibition of KLF4 function-expression by protein sumoylation.

OBJECTIVE: TGFbeta and proliferation/phenotypic switching of smooth muscle cells (SMCs) play a pivotal role in pathogenesis of atherosclerotic and restenotic lesions after angioplasty. We have previously shown that the protein inhibitor of activated STAT (PIAS)1 activates expression of SMC differentiation marker genes including smooth muscle (SM) alpha-actin by interacting with serum response factor (SRF) and class I bHLH proteins. Here, we tested the hypothesis that TGFbeta activates SM alpha-actin through PIAS1. METHODS AND RESULTS: An siRNA specific for PIAS1 and ubc9, an E2-ligase for sumoylation, inhibited TGFbeta-induced expression of SM alpha-actin in cultured SMCs as determined by real-time RT-PCR. Overexpression of PIAS1 increased SM alpha-actin promoter activity in a TGFbeta control element (TCE)-dependent manner. Because the TCE within the SM alpha-actin promoter could mediate repression through interaction with KLF4, we tested whether PIAS1 regulates the function of KLF4 for SMC gene expression. PIAS1 interacted with KLF4 in mammalian two-hybrid and coimmunoprecipitation assays, and overexpression of PIAS1 inhibited KLF4-repression of SM alpha-actin promoter activity. Moreover, PIAS1 promoted degradation of KLF4 through sumoylation. CONCLUSIONS: These results provide evidence that PIAS1 promotes TGFbeta-induced activation of SM alpha-actin gene expression at least in part by promoting sumoylation and degradation of the TCE repressor protein, KLF4.

Runx2 represses myocardin-mediated differentiation and facilitates osteogenic conversion of vascular smooth muscle cells.

Phenotypic plasticity and the switching of vascular smooth muscle cells (SMCs) play a critical role in atherosclerosis. Although Runx2, a key osteogenic transcription factor, is expressed in atherosclerotic plaques, the molecular mechanisms by which Runx2 regulates SMC differentiation remain unclear. Here we demonstrated that Runx2 repressed SMC differentiation induced by myocardin, which acts as a coactivator for serum response factor (SRF). Myocardin-mediated induction of SMC gene expression was enhanced in mouse embryonic fibroblasts derived from Runx2 null mice compared to wild-type mice. Forced expression of Runx2 decreased the expression of SMC genes and promoted osteogenic gene expression, whereas the reduction of Runx2 expression by small interfering RNA enhanced SMC differentiation in human aortic SMCs. Runx2 interacted with SRF and interfered with the formation of the SRF/myocardin ternary complex. Thus, this study provides the first evidence that Runx2 inhibits SRF-dependent transcription, as a corepressor independent of its DNA binding. We propose that Runx2 plays a pivotal role in osteogenic conversion tightly coupled with repression of the SMC phenotype in atherosclerotic lesions.

Multiple repressor pathways contribute to phenotypic switching of vascular smooth muscle cells.

Smooth muscle cell (SMC) differentiation is an essential component of vascular development and these cells perform biosynthetic, proliferative, and contractile roles in the vessel wall. SMCs are not terminally differentiated and possess the ability to modulate their phenotype in response to changing local environmental cues. The focus of this review is to provide an overview of the current state of knowledge of molecular mechanisms involved in controlling phenotypic switching of SMC with particular focus on examination of processes that contribute to the repression of SMC marker genes. We discuss the environmental cues which actively regulate SMC phenotypic switching, such as platelet-derived growth factor-BB, as well as several important regulatory mechanisms required for suppressing expression of SMC-specific/selective marker genes in vivo, including those dependent on conserved G/C-repressive elements, and/or highly conserved degenerate CArG elements found in the promoters of many of these marker genes. Finally, we present evidence indicating that SMC phenotypic switching involves multiple active repressor pathways, including Krüppel-like zinc finger type 4, HERP, and ERK-dependent phosphorylation of Elk-1 that act in a complementary fashion.

PIAS1 activates the expression of smooth muscle cell differentiation marker genes by interacting with serum response factor and class I basic helix-loop-helix proteins.

Although a critical component of vascular disease is modulation of the differentiated state of vascular smooth muscle cells (SMC), the mechanisms governing SMC differentiation are relatively poorly understood. We have previously shown that E-boxes and the ubiquitously expressed class I basic helix-loop-helix (bHLH) proteins, including E2-2 and E12, are important in regulation of the SMC differentiation marker gene, the SM alpha-actin gene. The aim of the present study was to identify proteins that bind to class I bHLH proteins in SMC and modulate transcriptional regulation of SMC differentiation marker genes. Herein we report that members of the protein inhibitor of activated STAT (PIAS) family interact with class I bHLH factors as well as serum response factor (SRF). PIAS1 interacted with E2-2 and E12 based on yeast two-hybrid screens, mammalian two-hybrid assays, and/or coimmunoprecipitation assays. Overexpression of PIAS1 significantly activated the SM alpha-actin promoter and mRNA expression, as well as SM myosin heavy chain and SM22alpha, whereas a small interfering RNA for PIAS1 decreased activity of these promoters, as well as endogenous mRNA expression, and SRF binding to SM alpha-actin promoter within intact chromatin in cultured SMC. Of significance, PIAS1 bound to SRF and activated SM alpha-actin promoter expression in wild-type but not SRF(-/-) embryonic stem cells. These results provide novel evidence that PIAS1 modulates transcriptional activation of SMC marker genes through cooperative interactions with both SRF and class I bHLH proteins.

HERP1 inhibits myocardin-induced vascular smooth muscle cell differentiation by interfering with SRF binding to CArG box.

OBJECTIVE: Myocardin is a coactivator of serum response factor (SRF) required for vascular smooth muscle cell (VSMC) differentiation. HERP1 is a transcriptional repressor, which is abundantly expressed in vascular system and is known to function as a target gene of Notch. However, the role of HERP1 in the pathogenesis of vascular lesions remains unknown. The present study characterizes the expression of HERP1 in normal and diseased vessels, and tests the hypothesis that HERP1 inhibits SRF/myocardin-dependent SMC gene expression. METHODS AND RESULTS: Immunohistochemistry revealed that HERP1 and myocardin expression was localized to SMC in the neointima of balloon-injured rat aorta and in human coronary atherosclerotic lesions. Expression of both HERP1 and myocardin was elevated in cultured VSMCs compared with medial SMC. Overexpressed HERP1 inhibited the myocardin-induced SMC marker gene expression in 10T1/2 cells. HERP1 protein interfered with the SRF/CArG-box interaction in vivo and in vitro. Immunoprecipitation assays showed that HERP1 physically interacts with SRF. CONCLUSIONS: HERP1 expression was associated with the SMC proliferation and dedifferentiation in vitro and in vivo. HERP1 may play a role in promoting the phenotypic modulation of VSMCs during vascular injury and atherosclerotic process by interfering with SRF binding to CArG-box through physical association between HERP1 and SRF.

c-Src and hydrogen peroxide mediate transforming growth factor-beta1-induced smooth muscle cell-gene expression in 10T1/2 cells.

OBJECTIVE: Transforming growth factor-beta1 (TGF-beta1) controls the expression of numerous genes, including smooth muscle cell (SMC)-specific genes and extracellular matrix protein genes. Here we investigated whether c-Src plays a role in TGF-beta1 signaling in mouse embryonic fibroblast C3H10T1/2 cells. METHODS AND RESULTS: TGF-beta1 induction of the SMC contractile protein SM22alpha gene expression was inhibited by PP1 (an inhibitor of Src family kinases) or by C-terminal Src kinase (a negative regulator of c-Src). Induction of SM22alpha by TGF-beta1 was markedly attenuated in SYF cells (c-Src(-), Yes(-), and Fyn(-)) compared with Src(++) cells (c-Src(++), Yes(-), and Fyn(-)). PP1 also inhibited the TGF-beta1-induced expression of serum response factor (SRF), a transcription factor regulating the SMC marker gene expression. Confocal immunofluorescence analysis showed that TGF-beta1 stimulates production of hydrogen peroxide. Antioxidants such as catalase or NAD(P)H oxidase inhibitors such as apocynin inhibited the TGF-beta1-induced expression of SM22alpha. Furthermore, we demonstrate that TGF-beta1 induction of the plasminogen activator inhibitor-1 (PAI-1) gene, which is known to be dependent on Smad but not on SRF, is inhibited by PP1 and apocynin. CONCLUSIONS: Our results suggest that TGF-beta1 activates c-Src and generates hydrogen peroxide through NAD(P)H oxidase, and these signaling pathways lead to the activation of specific sets of genes, including SM22alpha and PAI-1. TGF-beta1 controls the expression of numerous genes, including SM22alpha and PAI-1. We investigated whether c-Src plays a role in TGF-beta1 signaling. TGF-beta1 induction of such genes was significantly reduced in Src family tyrosine kinase-deficient cells, and Csk and pharmacological inhibitors for Src family kinases or antioxidants inhibit the effects of TGF-beta1. These results indicate that c-Src and hydrogen peroxide are required for TGF-beta1 signaling.

Homeobox protein Hex facilitates serum responsive factor-mediated activation of the SM22alpha gene transcription in embryonic fibroblasts.

OBJECTIVE: Hex (hematopoietically expressed homeobox), a member of homeobox family of transcription factors, has been implicated in the vascular development because of its expression in hemangioblast, a hypothetical stem cell that gives rise to both angioblasts and hematopoietic lineages. In the present study, we examined the role of Hex in the differentiation of vascular smooth muscle cells. METHODS AND RESULTS: We constructed adenovirus expressing Hex, to which we refer to as AxCA/Hex, and transduced murine embryonic fibroblasts, 10T1/2 cells. Northern blot analyses showed that Hex increased the mRNA levels of smooth muscle alpha-actin and SM22alpha but not of calponin and smooth muscle myosin heavy chain. Transient transfection assays showed that Hex activates the transcription from the SM22alpha promoter in a CArG box-dependent manner. Electrophoretic mobility shift assays demonstrate that Hex is not able to bind to CArG box, but binding of serum responsive factor (SRF) to CArG box is enhanced in AxCA/Hex-transduced cells. Recombinant Hex protein produced by in vitro translation system augmented the binding activity of SRF to CArG box. Immunoprecipitation experiments revealed the physical association between Hex and SRF. CONCLUSIONS: Hex induces transcription of the SM22alpha gene by facilitating the interaction between SRF and its cognate binding site in pluripotent embryonic fibroblasts. This study demonstrates that Hex, a hematopoietically expressed homeobox protein, induces transcription of the SM22alpha gene by facilitating the interaction between SRF and its cognate binding site in embryonic fibroblasts. These findings will provide the clue for understanding the mechanisms by which bone marrow-derived SMC precursor cells undergo differentiation.

Forced expression of myocardin is not sufficient for induction of smooth muscle differentiation in multipotential embryonic cells.

OBJECTIVE: Myocardin, a coactivator of serum response factor, has been shown to be required for expression of multiple CArG-dependent smooth muscle cell (SMC) marker genes. The aim of the present study was to determine whether myocardin alone is sufficient to induce SMC lineage in multipotential stem cells as evidenced by activation of the entire SMC differentiation program. METHODS AND RESULTS: Overexpression of myocardin induced only a subset of SMC marker genes, including smooth muscle (SM) alpha-actin, SM-myosin heavy chain (MHC), SM22alpha, calponin, and desmin in A404 SMC precursor cells, whereas expression of smoothelin-B, aortic carboxypeptidase-like protein, and focal adhesion kinase-related nonkinase, whose promoters lack efficacious CArG elements, was not induced. Similar results were obtained in cultured SMCs, 10T1/2 cells, and embryonic stem cells. Moreover, myocardin inappropriately induced expression of skeletal and cardiac CArG-dependent genes in cultured SMCs. Stable overexpression of dominant-negative myocardin in A404 cells resulted in impaired induction of SM alpha-actin and SM-MHC by all trans-retinoic acid but had no effect on induction of smoothelin-B and aortic carboxypeptidase-like protein expression. CONCLUSIONS: Taken together with previous studies, results demonstrate that myocardin is required for the induction of CArG-dependent SMC marker genes but is not sufficient to initiate the complete SMC differentiation program. We examined whether myocardin induces the entire smooth muscle cell (SMC) differentiation program. Results of the present study showed that myocardin knockdown or overexpression affected only a subset of SMC marker genes in multipotential cells, indicating that myocardin is required but not sufficient to induce SMC lineage.