Biomedical subjects

Lan Cheng

Publications and source records attributed to Lan Cheng.

At least 19 recordsLinked to original sources

PubMed2006

Impaired notch signaling promotes de novo squamous cell carcinoma formation.

Signaling through Notch receptors in the skin has been implicated in the differentiation, proliferation, and survival of keratinocytes, as well as in the pathogenesis of basal cell carcinoma (BCC). To determine the composite function of Notch receptor-mediated signaling in the skin and overcome potential redundancies between receptors, conditional transgenic mice were generated that express the pan-Notch inhibitor, dominant-negative Mastermind Like 1 (DNMAML1), to repress all canonical [CBF-1/Suppressor of hairless/LAG-1 (CSL)-dependent] Notch signaling exclusively in the epidermis. Here, we report that DNMAML1 mice display hyperplastic epidermis and spontaneously develop cutaneous squamous cell carcinoma (SCC) as well as dysplastic precursor lesions, actinic keratoses. Mice expressing epidermal DNMAML1 display enhanced accumulation of nuclear beta-catenin and cyclin D1 in suprabasilar keratinocytes and in lesional cells from SCCs, which was also observed in human cutaneous SCC. These results suggest a model wherein CSL-dependent Notch signaling confers protection against cutaneous SCC. The demonstration that inhibition of canonical Notch signaling in mice leads to spontaneous formation of SCC and recapitulates the disease in humans yields fundamental insights into the pathogenesis of SCC and provides a unique in vivo animal model to examine the pathobiology of cutaneous SCC and for evaluating novel therapies.

Animals↗

PubMed2006

GATA-6 regulates semaphorin 3C and is required in cardiac neural crest for cardiovascular morphogenesis.

GATA transcription factors play critical roles in restricting cell lineage differentiation during development. Here, we show that conditional inactivation of GATA-6 in VSMCs results in perinatal mortality from a spectrum of cardiovascular defects, including interrupted aortic arch and persistent truncus arteriosus. Inactivation of GATA-6 in neural crest recapitulates these abnormalities, demonstrating a cell-autonomous requirement for GATA-6 in neural crest-derived SMCs. Surprisingly, the observed defects do not result from impaired SMC differentiation but rather are associated with severely attenuated expression of semaphorin 3C, a signaling molecule critical for both neuronal and vascular patterning. Thus, the primary function of GATA-6 during cardiovascular development is to regulate morphogenetic patterning of the cardiac outflow tract and aortic arch. These findings provide new insights into the conserved functions of the GATA-4, -5, and -6 subfamily members and identify GATA-6 and GATA-6-regulated genes as candidates involved in the pathogenesis of congenital heart disease.

Animals↗

PubMed2006

A quantitative, randomized study evaluating three methods of mesenchymal stem cell delivery following myocardial infarction.

AIMS: Mesenchymal stem cells (MSCs), rare bone marrow-derived stem cell precursors of non-haematopoietic tissues, have shown promise in potentially repairing infarcted myocardium. These and similar cell types are being tested clinically, but understanding of delivery and subsequent biodistribution is lacking. This study was designed to quantitatively compare MSC engraftment rates after intravenous (IV), intracoronary (IC), or endocardial (EC) delivery in a porcine myocardial infarction (MI) model. METHODS AND RESULTS: Allogeneic, male MSCs were cultured from porcine bone marrow aspirates. Iridium nanoparticles were added during culturing and internalized by the MSCs. An MI was induced in female swine (27-40 kg in size) by prolonged balloon occlusion of the mid-left anterior descending artery. Animals (n = 6 per group) were randomized to one of three delivery methods. Cellular engraftment was determined 14+/-3 days post-delivery by measuring ex-vivo the iridium nanoparticle concentration in the infarct. Confirmation of cellular engraftment utilized both DiI and fluorescence in situ hybridization (FISH) labelling techniques. During MSC infusion, no adverse events were noted. However, following IC infusion, half of the pigs exhibited decreased blood flow distal to the infusion site. At 14 days, the mean number of engrafted cells within the infarct zone was significantly greater (P< or =0.01) following IC infusion than either EC injection or IV infusion and EC engraftment was greater than IV engraftment (P< or =0.01). There was less systemic delivery to the lungs following [EC vs. IV (P = 0.02), EC vs. IC (P = 0.06)]. Both DiI and FISH labelling demonstrated the presence of engrafted male MSCs within the female infarcted tissue. CONCLUSION: IC and EC injection of MSCs post-MI resulted in increased engraftment within infarcted tissue when compared with IV infusion, and IC was more efficient than EC. However, IC delivery was also associated with a higher incidence of decreased coronary blood flow. EC delivery into acutely infarcted myocardial tissue was safe and well tolerated and was associated with decreased remote organ engraftment with compared with IC and IV deliveries.

Animals↗

PubMed2006

Syk and Slp-76 mutant mice reveal a cell-autonomous hematopoietic cell contribution to vascular development.

Developmental studies support a common origin for blood and endothelial cells, while studies of adult angiogenic responses suggest that the hematopoietic system can be a source of endothelial cells later in life. Whether hematopoietic tissue is a source of endothelial cells during normal vascular development is unknown. Mouse embryos lacking the signaling proteins Syk and Slp-76 develop abnormal blood-lymphatic endothelial connections. Here we demonstrate that expression of GFPSlp-76 in a subset of hematopoietic cells rescues this phenotype, and that deficient cells confer focal vascular phenotypes in chimeric embryos consistent with a cell-autonomous mechanism. Endogenous Syk and Slp-76, as well as transgenic GFPSlp-76, are expressed in circulating cells previously proposed to be endothelial precursors, supporting a causal role for these cells. These studies provide genetic evidence for hematopoietic contribution to vascular development and suggest that hematopoietic tissue can provide a source of vascular endothelial progenitor cells throughout life.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Klf2 is an essential regulator of vascular hemodynamic forces in vivo.

Hemodynamic responses that control blood pressure and the distribution of blood flow to different organs are essential for survival. Shear forces generated by blood flow regulate hemodynamic responses, but the molecular and genetic basis for such regulation is not known. The transcription factor KLF2 is activated by fluid shear stress in cultured endothelial cells, where it regulates a large number of vasoactive endothelial genes. Here, we show that Klf2 expression during development mirrors the rise of fluid shear forces, and that endothelial loss of Klf2 results in lethal embryonic heart failure due to a high-cardiac-output state. Klf2 deficiency does not result in anemia or structural vascular defects, and it can be rescued by administration of phenylephrine, a catecholamine that raises vessel tone. These findings identify Klf2 as an essential hemodynamic regulator in vivo and suggest that hemodynamic regulation in response to fluid shear stress is required for cardiovascular development and function.

Anemia↗

PubMed2006

Evidence for the requirement of ITAM domains but not SLP-76/Gads interaction for integrin signaling in hematopoietic cells.

Syk tyrosine kinase and Src homology 2 (SH2) domain-containing leukocyte-specific phosphoprotein of 76 kDa (SLP-76) are signaling mediators activated downstream of immunoreceptor tyrosine-based activation motif (ITAM)-containing immunoreceptors and integrins. While the signaling cascades descending from integrins are similar to immunoreceptors, the mechanism of Syk activation and SLP-76 recruitment remains unclear. We used an in vivo structure-function approach to study the requirements for the domains of Syk and SLP-76 in immunoreceptor and integrin signaling. We found that both SH2 domains and the kinase domain of Syk are required for immunoreceptor-dependent signaling and cellular response via integrins. While the Gads-binding domain of SLP-76 is needed for immunoreceptor signaling, it appears dispensable for integrin signaling. Syk and SLP-76 also are required for initiating and/or maintaining separation between the blood and lymphatic vasculature. Therefore, we correlated the signaling requirement of the various domains of Syk and SLP-76 to their requirement in regulating vascular separation. Our data suggest ITAMs are required in Syk-dependent integrin signaling, demonstrate the separation of the structural features of SLP-76 to selectively support immunoreceptor versus integrin signaling, and provide evidence that the essential domains of SLP-76 for ITAM signals are those which most efficiently support separation between lymphatic and blood vessels.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Slit/Robo signaling is necessary to confine early neural crest cells to the ventral migratory pathway in the trunk.

Neural crest cells migrate along two discrete pathways within the trunk of developing embryos. In the chick, early migrating crest cells are confined to a ventral pathway medial to the dermamyotome while later cells migrate on a dorsal pathway lateral to the dermamyotome. Here we show that Slits are expressed in the dermamyotome, that early migrating crest cells express the Slit receptors Robo 1 and Robo 2, that Slit2 repels migrating crest cells in an in vitro assay, and that the misexpression of a dominant-negative Robo1 receptor induces a significant fraction of early crest cells to migrate ectopically in the dorso-lateral pathway. These findings suggest that Slits, most likely those expressed in the dermamyotome, help to confine the migration of early crest cells to the ventral pathway.

Animals↗

PubMed2005

Myocardin-related transcription factor B is required in cardiac neural crest for smooth muscle differentiation and cardiovascular development.

Members of the myocardin-related family of transcription factors play critical roles in regulating vascular smooth muscle and cardiac differentiation. To examine the function of myocardin-related transcription factor (MRTF)-B, mice were generated from ES cells harboring a conditional insertional mutation, or gene trap, of the MRTF-B gene. Expression of the MRTF-B mutant allele results in a fusion protein consisting of the N terminus of MRTF-B fused to beta-galactosidase, which is functionally null. Homozygous MRTF-B gene trap mice (MRTF-B-/-) die between embryonic day (E)17.5 and postnatal day 1 from cardiac outflow tract defects. MRTF-B is expressed in the premigratory neural crest, in rhombomeres 3 and 5, and in the neural crest-derived mesenchyme surrounding the aortic arch arteries. Consistent with the pattern of expression, E10.5 and E11.5 MRTF-B-/- mutants exhibit deformation of aortic arch arteries 3, 4, and 6 and severe attenuation of smooth muscle cell differentiation in the arch arteries and the aorticopulmonary septum, despite normal migration and initial patterning of cardiac neural crest cells. Remarkably, the observed pathology was rescued and viable mice generated by intercrossing MRTF-B mutants with mice expressing Cre recombinase under the transcriptional control of the neural crest-restricted Wnt-1 promoter, which results in restoration of normal MRTF-B expression in the neural crest. Taken together, these studies reveal that MRTF-B plays a critical role in regulating differentiation of cardiac neural crest cells into smooth muscle and demonstrate that neural crest-derived smooth muscle differentiation is specifically required for normal cardiovascular morphogenesis.

Animals↗

PubMed2005

High-efficiency somatic mutagenesis in smooth muscle cells and cardiac myocytes in SM22alpha-Cre transgenic mice.

The cytoskeletal protein SM22alpha is expressed in visceral and vascular smooth muscle cells (SMCs), in cardiac myocytes, and in the myotomal components of the somites during murine embryonic development. In this report, we describe the generation and characterization of transgenic mice expressing Cre-recombinase under the transcriptional control of the -2.8-kb SM22alpha promoter. Following interbreeding with the R26R reporter strain, Cre-dependent beta-galactosidase expression was observed as early as embryonic day 9.5 in SMCs of the developing vasculature, in cardiac myocytes, but not in the somites. In adult mice, Cre-mediated recombination was observed in vascular SMCs throughout the venous and arterial systems, in visceral SMCs in multiple organs, and in cardiac, but not skeletal muscle. Importantly, Cre-mediated recombination was present in nearly 100% of arterial SMCs, including in the aorta. These mice are thus an important new tool for performing in vivo loss-of-function studies of genes expressed in vascular SMCs.

Animals↗

PubMed2005

[Analysis of FcgammaRIIIb genotype of periodontal disease in the Han nationality in China].

PURPOSE: The purpose of the present study was to compare FcgammaRIIIb genotype of aggressive periodontitis (AgP) with chronic periodontitis (CP) and control group (Cont) in the Han nationality in China. METHODS: The classification, which was applied in this study, was presented and discussed at the 1999 International Workshop for the Classification of the Periodontal Disease organized by the American Academy of Periodontology (AAP). 23 patients with aggressive periodontitis, including 20 with chronic periodontitis according to the established clinical criteria, and 22 matched healthy controls was included in this study. Peripheral blood samples were taken from all patients and controls, then DNA was isolated from blood using DNA purification kit. And FcgammaRIIIb genotyping was determined by PCR and DNA sequencing. The different results of genotype in all three groups were analysed by chi(2) test. RESULT: FcgammaRIIIb-NA1, -NA2 (old definition) frequencies didn't equal 1.00 in all 3 groups, and also without -SH, -NA(NULL) genotype. At the same time, many new allele of NA1 and NA2 were found in all groups. However, there were no rules of new alleles in each group and between the groups, no statistical significance as well. The -NA1 of FcgammaRIIIb (new definition) frequency was 0.77, and that of -NA2 (new definition) was 0.23 in this study. CONCLUSION: Including FcgammaRIIIb-NA1 and -NA2, five alternate allele of -NA1 (-NA1*01b, -NA1*02a, -NA1*02b, -NA1*03a and-NA1*03b) and three alternate allele of -NA2(-NA2*02, -NA2*03 and -NA2*04) were described. The results suggest that FcgammaRIIIb may not be a risk indicator for the susceptibility of periodontitis in the Han nationality of China.

Aggressive Periodontitis↗

PubMed2004

Inhibitory effects of berberine on ion channels of rat hepatocytes.

AIM: To examine the effects of berberine, an isoquinoline alkaloid with a long history used as a tonic remedy for liver and heart, on ion channels of isolated rat hepatocytes. METHODS: Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of berberine on the delayed outward potassium currents (I(K)), inward rectifier potassium currents (I(K1)) and Ca(2+) release-activated Ca(2+) currents (I(CRAC)) in enzymatically isolated rat hepatocytes. RESULTS: Berberine 1-300 micromol/L reduced I(K) in a concentration-dependent manner with EC(50) of 38.86+/-5.37 micromol/L and n(H) of 0.82+/-0.05 (n = 8). When the bath solution was changed to tetraethylammonium (TEA) 8 mmol/L, I(K) was inhibited. Berberine 30 micromol/L reduced I(K) at all examined membrane potentials, especially at potentials positive to +60 mV (n = 8, P<0.05 or P<0.01 vs control). Berberine had mild inhibitory effects on I(K1) in rat hepatocytes. Berberine 1-300 micromol/L also inhibited I(CRAC) in a concentration-dependent fashion. The fitting parameters were EC(50) = 47.20+/-10.86 micromol/L, n(H) = 0.71+/-0.09 (n = 8). The peak value of I(CRAC) in the I-V relationship was decreased by berberine 30 micromol/L at potential negative to -80 mV (n = 8, P<0.05 vs control). But the reverse potential of I(CRAC) occurred at voltage 0 mV in all cells. CONCLUSION: Berberine has inhibitory effects on potassium and calcium currents in isolated rat hepatocytes, which may be involved in hepatoprotection.

Animals↗

PubMed2004

Effects of berberine on potassium currents in acutely isolated CA1 pyramidal neurons of rat hippocampus.

The effects of berberine, an isoquinoline alkaloid with antiarrhythmic action, on voltage-dependent potassium currents were studied in acutely isolated CA1 pyramidal neurons of rat hippocampus by using the whole-cell patch-clamp techniques. Berberine blocked transient outward potassium current (IA) and delayed rectifier potassium current (IK) in a concentration-dependent manner with EC50 of 22.94+/-4.96 microM and 10.86+/-1.06 microM, Emax of 67.47+/-4.00% and 67.14+/-1.79%, n of 0.77+/-0.08 and 0.96+/-0.07, respectively. Berberine 30 microM shifted the steady-state activation curve and inactivation curve of IA to more negative potentials, but mainly affected the inactivation kinetics. Berberine 30 microM positively shifted the steady-state activation curve of IK. These results suggested that blockades on K+ currents by berberine are preferential for IK, and contribute to its protective action against ischemic brain damage.

Animals↗

PubMed2004

Electrophysiological effects of anthopleurin-Q on rat hepatocytes.

AIM: To study the effects of AP-Q on CCl(4)-induced acute liver injury, delayed outward potassium current (I(K)), inward rectifier potassium current (I(K1)) and calcium release-activated calcium current (I(CRAC)) in isolated rat hepatocytes. METHODS: A single dose of CCl(4) (10 microg/mL, ip) was injected to induce acute liver injury in rats. Serum aminotransferase activities were determined. Whole cell patch-clamp techniques were used to investigate the effects of AP-Q on delayed outward potassium current (I(K)), inward rectifier potassium current (I(K1)) and calcium release-activated calcium current (I(CRAC)). RESULTS: AP-Q (3.5 and 7 microg/kg) pretreatment significantly reduced ALT and AST activities. AP-Q 0.1-100 nM produced a concentration-dependent increase of I(K) with EC(50) value of 5.55+/-1.8 nM (n=6). AP-Q 30 nM shifted the I-V curve of I(K) leftward and upward. CCl(4) 4 mM decreased I(K) current 28.6+/-6.5% at 140 mV. After exposure to CCl(4) for 5 min, AP-Q 30 nM attenuated the decrease of I(K) induced by CCl(4) close to normal amplitude. AP-Q 0.01-100 nM had no significant effect on either inward or outward components of I(K1) at any membrane potential examined. AP-Q 0.1-100 nM had no significant influence on the peak amplitude of I(CRAC), either, and did not affect the shape of its current voltage curve. CONCLUSION: AP-Q has a protective effect on CCl(4)-induced liver injury, probably through selectively increased I(K) in hepatocytes.

Alanine Transaminase↗

PubMed2004

[Cloning of human amelogenin gene encoding mature peptide].

PURPOSE: The purpose of this study was to clone human amelogenin gene encoding mature protein, which provides a basis for expressing the recombinant human amelogenin in Escherichia coli. in the future. METHODS: In this study, total RNA was extracted from the dental germ of a legally aborted embryo by Trizol. Using RT-PCR technique we obtained synthesis of cDNA from the total RNA, and the desired DNA products were conducted with PCR from cDNA. The segment was inserted into expression vector PQE30 and the interesting plasmid was transformed into Escherichia coli. host DH5alpha. The double-stranded DNA of positive clone was analyzed by PCR, restriction endonuclease mapping and DNA sequence analysis. RESULTS: The sequence analysis of recombinant plasmid showed that the human amelogenin encoding mature protein was inserted into vector PQE30 accurately. CONCLUSIONS: We conducted human amelogenin encoding mature protein from dental germ of a legally aborted embryo and got the recombinant plasmid which may express amelogenin gene for further research.

Amelogenin↗

PubMed2004

Effects of amiloride on potassium and calcium currents in guinea pig ventricular myocytes.

AIM: To elucidate the possible mechanisms underlying antiarrhythmia of the non-selective Na+/H+ exchanger inhibitor--amiloride. METHODS: Single ventricular cells were isolated using a double-enzyme method. Effects of amiloride on voltage-dependent potassium and calcium currents in isolated guinea pig ventricular myocyte were recorded by using whole-cell patch clamp techniques. RESULTS: Exposure to amiloride (10 -100 micromol x L(-1)), the L-type and T-type calcium currents were depressed. Amiloride resulted in a concentration-dependent inhibition of peak (Ca,L), But amiloride did not change the shape of their I - V curves. It only decreased the amplitudes of the currents of the two types. When myocytes were incubated with 100 micromol x L(-1) amiloride, I(Kr) was slightly depressed and I(Ks) did not change. Amiloride (1 - 100 micromol x L(-10) depressed I(K1) in a concentration-dependent manner. CONCLUSION: Amiloride depressed potassium and calcium currents, which may give support to its uses in some diseases of the cardiovascular system.

Amiloride↗

PubMed2003

Effects of tetrandrine on calcium and potassium currents in isolated rat hepatocytes.

AIM: To study the effects of tetrandrine (Tet) on calcium release-activated calcium current (I(CRAC)), delayed rectifier potassium current (I(K)), and inward rectifier potassium currents (I(K1)) in isolated rat hepatocytes. METHODS: Hepatocytes of rat were isolated by using perfusion method. Whole cell patch-clamp techniques were used in our experiment. RESULTS: The peak amplitude of I(CRAC) was -508+/-115 pA (n=15), its reversal potential of I(CRAC) was about 0 mV. At the potential of -100 mV, Tet inhibited the peak amplitude of I(CRAC) from -521+/-95 pA to -338+/-85 pA (P<0.01 vs control, n=5), with the inhibitory rate of 35 % at 10 micromol/L and from -504+/-87 pA to -247+/-82 pA (P<0.01 vs control, n=5), with the inhibitory rate of 49 % at 100 micromol/L, without affecting its reversal potential. The amplitude of I(CRAC) was dependent on extracellular Ca(2+) concentration. The peak amplitude of I(CRAC) was -205+/-105 pA (n=3) in tyrode's solution with Ca(2+) 1.8 mmol/L (P<0.01 vs the peak amplitude of I(CRAC) in external solution with Ca(2+) 10 mmol/L). Tet at the concentration of 10 and 100 micromol/L did not markedly change the peak amplitude of delayed rectifier potassium current and inward rectifier potassium current (P>0.05 vs control). CONCLUSION: Tet protects hepatocytes by inhibiting I(CRAC), which is not related to I(K) and I(K1).

Alkaloids↗

PubMed2003

Effects of palmatine on potassium and calcium currents in isolated rat hepatocytes.

AIM: To study the effects of palmatine, a known inhibitor on delayed rectifier potassium current and L-type calcium current (I(Ca,L)) in guinea pig ventricular myocytes, on the potassium and calcium currents in isolated rat hepatocytes. METHODS: Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of palmatine on the delayed outward potassium currents (I(K)), inward rectifier potassium current (I(K1)) and Ca(2+) release-activated Ca(2+) current (I(CRAC)) in enzymatically isolated rat hepatocytes. RESULTS: Palmatine 0.3-100 microM reduced I(K) in a concentration-dependent manner with EC(50) of 41.62+/-10.11 microM and n(H), 0.48+/-0.07 (n=8). The effect of the drug was poorly reversible after washout. When the bath solution was changed to tetraethylammonium (TEA) 8 mM, IK was inhibited. Palmatine 10 microM and 100 microM shifted the I-V curves of I(K) downward, and the block of I(K) was voltage-independent. Palmatine 0.3-100 microM also inhibited I(CRAC) in a concentration-dependent manner. The fitting parameters were as follows: EC(50)=51.19+/-15.18 microM, and n(H)=0.46+/-0.07 (n=8). The peak value of I(CRAC) in the I-V relationship was decreased by palmatine 10 microM and 100 microM. But the reverse potential of I(CRAC) occurred at Voltage=0 mV in all cells. Palmatine 0.3-100 microM failed to have any significant effect on either inward or outward components of I(K1) at any membrane potential examined. CONCLUSION: The inhibitory effects on I(K) and I(CRAC) could be one of the mechanisms that palmatine exerts protective effect on hepatocytes.

Animals↗

PubMed2003

[Effect of ouabain on the aortic rings of guinea pig and its interactions with Ca2+, norepinephrine].

AIM: To observe the effects of ouabain on vascular smooth muscle (VSM) of the guinea pig and its interactions with Ca2+ and norepinephrine (NE). METHODS: Using isolated thoracic aortic ring of the guinea pig, the degrees of contractile activity of drugs were recorded. RESULTS: Ouabain showed a direct contractile effect in a concentration-dependent manner on thoracic aortic ring of guinea pig. Ouabain shifted the NE dose-response curve to the left without changing in the maxium response. Ouabain shifted the CaCl2 dose-response curve to the left and upward, increased the maximum response to Ca2+; In Ca(2+)-free medium, the ouabain induced contraction was abolished, an increase in extracellular Ca2+ restored the response; nifedipine and verapamil abolished the ouabain induced contraction. CONCLUSION: The ouabain induced contraction is mainly dependent on the extracellular Ca2+ concentration, independent on the presence of endothelia of aorta, suggesting that Ca2+ antagonist may treat the hypertension induced by ouabain. Ouabain, NE and CaCl2 have synergetic contractile effects, suggesting that the synergetic contractile effects of ouabain and NE may contribute to the generation and development of hypertension.

Animals↗