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Results for “Phenotypic modulation”

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PubMed1993

Familial hypercholesterolemia in French-Canadians: taking advantage of the presence of a "founder effect".

The frequency of familial hypercholesterolemia (FH) in the Province of Quebec is twice that observed in most population samples. In the French-Canadian population, 5 mutations in the low density lipoprotein (LDL) receptor gene account for 76% of FH cases diagnosed using clinical and biochemical criteria. One of these mutations, a > 10 kilobase (kb) deletion at the 5' end of the gene involving the promoter and exon 1, is present in 60% of FH patients studied in Montréal. This high frequency is attributable to a "founder effect." Contribution to this founder effect included strategies in 17th century France for the settlement of a small number of pioneers, local incentives for early marriages and large families, and geographic and cultural isolation; these factors also favored endogamy. The > 10 kb deletion is present on only one haplotype in all patients studied so far (homozygotes and heterozygotes), a major advantage for studies relating phenotypic variation to haplotype variation in the normal LDL receptor allele of these hemizygous patients. Indeed, the presence of founder effects facilitates screening, genetic counseling, and treatment. It also confers a number of advantages for research: (1) the search for new causes of FH in the 24% unaccounted for to date; (2) the study of the geographic distribution of mutations and population movements; (3) the identification of gene-gene interactions in the etiology of disease; (4) the evaluation of factors modulating phenotypic expression and search for LDL-lowering genes; and (5) the study of genetic determinants of therapeutic response.

Consanguinity↗

PubMed2000

Phenotype-dependent expression of cadherin 6B in vascular and visceral smooth muscle cells.

We used mRNA subtraction of differentiated and dedifferentiated smooth muscle cells (SMCs) to reveal the molecular mechanisms underlying the phenotypic modulation of SMCs. With this approach, we found that a 10 kb mRNA encoding a homotypic cell adhesion molecule, cadherin 6B, was strongly expressed in differentiated vascular and visceral SMCs, but not in the dedifferentiated SMCs derived from them. In vivo, cadherin 6B was expressed in vascular and visceral SMCs, in addition to brain, spinal cord, retina and kidney, at a late stage of chicken embryonic development. These results suggest that cadherin 6B is a novel molecular marker for vascular and visceral SMC phenotypes and is involved in the late differentiation of SMCs.

Animals↗

PubMed2000

Role of endothelial cell denudation and smooth muscle cell dedifferentiation in neointimal formation of human vein grafts after coronary artery bypass grafting: therapeutic implications.

OBJECTIVE: To provide better insights into the genesis of neointimal thickening in human vein grafts early after surgery. DESIGN: Retrospective study. SETTING: Tertiary referral centre. SUBJECTS: 18 distal anastomotic sites of patent grafts, obtained at necropsy from eight patients who died over differing periods (ranging from two days to nine months) after the procedure. MAIN OUTCOME MEASURES: Immunohistochemical evaluation of smooth muscle cell phenotype modulation in relation to proliferative activity. RESULTS: The earliest changes are characterised by loss of surface lining endothelial cells and insudation of blood corpuscular elements admixed with fibrin-platelet thrombus. At sites of injury vimentin positive and actin negative spindle shaped cells appear in the intima, while the related pre-existent media shows focal absence of actin positive smooth muscle cells. Proliferative activity colocalises at these sites. With time distinct neointimal thickening occurs, associated with disappearance of proliferative activity and a phenotypic shift of the smooth muscle cells. CONCLUSIONS: The observation that luminal endothelial cell denudation, with insudation of the intima with blood elements, occurs in the very early stages suggests that these phenomena are responsible for the observed dedifferentiation of pre-existent smooth muscle cells, known to be a prerequisite for cell proliferation and the evolution of intimal thickening. It is likely, therefore, that platelet released growth factors play a pivotal role, which thus may provide a target for preventive pharmacological intervention.

Aged↗

PubMed2002

Constitutive activation of peroxisome proliferator-activated receptor-gamma suppresses pro-inflammatory adhesion molecules in human vascular endothelial cells.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a ligand-activated nuclear receptor that has an essential role in adipogenesis and glucose homeostasis. PPAR-gamma is expressed in vascular tissues including endothelial cells (ECs). PPAR-gamma activity can be regulated by many pathophysiological and pharmacological agonists. However, the role of PPAR-gamma activation in ECs remains unclear. In this study, we examined the effect of the constitutive activation of PPAR-gamma on the phenotypic modulation of ECs. Adenovirus-mediated expression of a constitutively active mutant of PPAR-gamma resulted in significant ligand-independent activation of PPAR-gamma and specific induction of the PPAR-gamma target genes. However, PPAR-gamma activation significantly suppressed the expression of vascular adhesion molecules in ECs and the ensuing leukocyte recruitment. Furthermore, constitutive activation of PPAR-gamma resulted in simultaneous repression of AP-1 and NF-kappaB activity, which suggests that PPAR-gamma may reduce pro-inflammatory phenotypes via, at least in part, suppression of the AP-1 and NF-kappaB pathways. Therefore, using a gain-of-function approach, our study provides novel evidence showing that constitutive activation of PPAR-gamma is sufficient to prevent ECs from converting into a pro-inflammatory phenotype. These results also suggest that, in addition to pharmacological agonists, the genetic modification of the PPAR-gamma activity in ECs may be a potential approach for therapeutic intervention in various inflammatory disorders.

Cells, Cultured↗

PubMed1996

Myocyte enhancer binding factor-2 expression and activity in vascular smooth muscle cells. Association with the activated phenotype.

Proliferation and phenotypic modulation of smooth muscle cells (SMCs) are major components of the vessel's response to injury in experimental models of restenosis. Some of the growth factors involved in restenosis have been identified, but to date little is known about the transcription factors that ultimately regulate this process. We examined the expression of the four members of the myocyte enhancer binding factor-2 (MEF2) family of transcription factors in cultured rat aortic SMCs (RASMCs) and a rat model of restenosis because of their known importance in regulating the differentiated phenotype of skeletal and cardiac muscle. In skeletal and cardiac muscle, the MEF2s are believed to be important for activating the expression of contractile protein and other muscle-specific genes. Therefore, we anticipated that the MEF2s would be expressed at high levels in medial SMCs that are producing contractile proteins and that they would be downregulated along with the contractile protein genes in neointimal SMCs. On the contrary, we observe that MEF2A, MEF2B, and MEF2D mRNAs are upregulated in the neointima, with the highest levels in the layer of cells nearest to the lumen, whereas MEF2C mRNA levels do not appreciably increase. Moreover, few cells in the media are making MEF2 proteins detectable by immunohistochemistry, whereas large numbers of neointimal cells are positive for all four MEF2s. These data suggest that the MEF2s are involved in the activated smooth muscle phenotype and not in the maintenance of contractile protein gene expression.

Animals↗

PubMed1997

Coronary artery smooth muscle in culture: migration of heterogeneous cell populations from vessel wall.

A method for establishing primary cultures of smooth muscle cells (SMCs) from the porcine coronary artery without either microdissection and/or enzymatic dispersion was developed using selective migration of cells from coronary explants in vitro. This culture method relies on the heterogeneity of cell types and differences in their migration and adherence ability to separate SMC from contaminating fibroblasts or endothelial cells. The cell type was determined by immunohistochemical staining with monoclonal antibodies to SM alpha-actin, SM myosin, h-caldesmon and von Willebrand factor. The first wave of migration (1-7 days) consisted of a mixture of fibroblasts and SMCs. Only SMCs were present in the second wave of migration (7-14 days). Endothelial cells, which exhibited a lower capacity for migration and adherence, were restricted to the third wave of migration (14-21 days). Cells obtained from the second wave of migration exhibited the characteristic single-layered, aligned, hill-and-valley pattern of SMCs when confluent. Quiescence was attained 4-5 days after removal of serum, as established by [3H]-thymidine incorporation. Stimulation of the quiescent SMCs with 20% FBS resulted in a synchronous re-entry into the cell-cycle with S phase reached 15-18 h later. The SMCs prepared using this protocol thus exhibit the structural markers and capacity to undergo phenotypic modulation that are characteristic of SMCs in vivo. This approach to establishing primary cultures of SMCs offers the advantage of selecting for the subpopulation of cells capable of migration in response to injury or growth factor stimulation.

Animals↗

PubMed1992

Age-related modification of average volume and anisotropy of vascular smooth muscle cells.

The aim of this study was to determine what changes in the arterial wall are related to age. In two groups of rabbits, one young and one adult, the aorta and carotid were studied using a morphometric approach based on stereological axioms and planimetric morphometry. The problem of anisotropy of smooth muscle cells is discussed in detail. Two forms of anisotropy must be distinguished, that of single cell and that due to the histological pattern of the smooth muscle cells in the arterial wall. Our results show in adult animals, as compared to the young ones, statistically significant decrease in anisotropy of the cell pattern which tends to become more regular. Moreover, in aorta and carotid of young and adult animals there is an increment of 95.39% and 80% of the absolute cell volume, respectively. We suggest that there may be a direct relationship between aging and phenotypical modulation of the smooth muscle cells and that the modification of the architectural cell pattern with age may represent an adaptive event related to the change in forces acting upon the arterial wall.

Aging↗

PubMed1997

Distribution of apolipoprotein E between apo B- and non apo B-containing lipoproteins according to apo E phenotype.

Apolipoprotein E (apo E) is a component of all the classes of lipoproteins and can be distributed among apo B- (LpB) and non apo B-containing lipoproteins (Lp-non-B). Using a new electroimmunoassay kit, plasma apo E, apo E in Lp-non-B (apo E-Lp-non-B) and apo E in LpB (apo E-LpB) levels were measured in healthy control subjects (n=481) from 3 centers participating in the ECTIM study (Etude Cas-Témoins sur l'Infarctus du Myocarde), a population-based study on myocardial infarction. The distribution of apo E among lipoproteins was analyzed according to the apo E phenotype after adjustment for center, body mass index, tobacco use, alcohol consumption and triglycerides. Apo E was higher (average excess: + 0.32; P < 0.0001) and lower (average excess: -0.12; P < 0.0001) in subjects carrying the allele epsilon2 and the allele epsilon4 respectively, than in apo E3/3 subjects. These differences are the consequence of variations in apo E-Lp-non-B which clearly differed between the groups classified according to their apo E phenotype (P < 0.0001). The average excess of apo E Lp non-B compared to apo E3/3 subjects was + 0.43 (P < 0.0001) and -0.22 (P < 0.0001) for the epsilon2 and epsilon4 alleles respectively. Apo E-LpB was lower in subjects carrying the epsilon2 allele (P < 0.02) while the presence of the epsilon4 allele did not modify this parameter. The proportion of apo E within HDL was clearly higher and lower in subjects carrying apo E2 and apo E4 respectively than in apo E3/3 subjects. Although triglyceride levels were dependent on the apo E phenotype, the adjustment of the proportion of apo E in HDL for triglycerides hardly modified the results. For the first time, these results, using direct measurements on a large number of subjects, confirm the greater preference of apo E4 over apo E2 for LpB and vice versa for Lp-non-B. They also show a greater affinity of apo E2 for HDL compared to apo E3. This high affinity of apo E2 for HDL could be due to the formation of the apo E-A-II complex. These results indicate that apo E phenotype modulates the distribution of apo E among lipoproteins and suggest differences in lipoprotein metabolism between apo E2, apo E3 and apo E4.

Adult↗

PubMed1992

The modulation of collagen synthesis in cultured arterial smooth muscle cells by platelet-derived growth factor.

Changes on collagen synthetic activity of cultured arterial smooth muscle cells of rabbits induced with purified platelet-derived growth factor (PDGF) were examined. PDGF treatment (final concentration was 5 units/ml) decreased the total collagen synthesis per cell, while the rate of collagen synthesis against total protein synthesis was raised by PDGF. Type analysis of collagen revealed substantial reduction of type IV collagen and relative increase of type V collagen in the PDGF-treated cells. By immunofluorescence study using anti-type IV collagen antibody, the lacework fluorescence was decreased with PDGF supplement. These findings indicate that PDGF induces the decrease of type IV collagen synthesis with the simultaneous diminution of basement membrane formation probably in association with phenotypic modulation of smooth muscle cells.

Animals↗

PubMed1994

Renal protective effect of TCV-116 in stroke-prone spontaneously hypertensive rats.

We examined the effects of TCV-116, a non-peptide selective AT1 receptor antagonist, on cellular phenotype and on the expression of the transforming growth factor-beta 1 (TGF-beta 1) and extracellular matrix genes in the kidneys of stroke-prone spontaneously hypertensive rats (SHRSP). SHRSP were given vehicle or TCV-116 (10 mg/kg/day) by gastric gavage for 10 weeks (from the age of 22 to 32 weeks). Renal mRNA levels were measured by Northern blot analysis. In vehicle-treated 32-week-old SHRSP, urinary albumin excretion per 24 h was about 26-fold greater than that in age-matched Wistar-Kyoto (WKY) rats, and the mRNA levels of renal TGF-beta 1, fibronectin and collagen types I and III in SHRSP were all several-fold higher than those in WKY. Immunohistochemical studies showed the prominent presence of alpha-smooth muscle actin-expressing glomerular cells in SHRSP, in contrast to their absence in WKY. Treatment of SHRSP with TCV-116 decreased urinary albumin excretion and renal mRNA levels for TGF-beta 1 and for the above-mentioned extracellular matrix components. TCV-116 prevented the phenotypic modulation of glomerular cells in SHRSP. These results suggest that AT1 receptor antagonists may have powerful renal protective effects.

Albuminuria↗

PubMed1998

Molecular genetic basis of hypertrophic cardiomyopathy: genetic markers for sudden cardiac death.

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease caused by mutations in sarcomeric proteins. The disease is characterized by left ventricular hypertrophy in the absence of an increased external load, and myofibrillar disarray. A large number of mutations in genes coding for the beta-myosin heavy chain (beta-MyHC), cardiac troponin T (cTnT), cardiac troponin I, alpha-tropomyosin, myosin binding protein C (MyBP-C), and myosin light chain 1 and 2 in patients with HCM have been identified. Genotype-phenotype correlation studies have shown that mutations carry prognostic significance. The Gly256Glu, Val606Met, and Leu908Val mutations in the beta-MyHC are associated with a benign prognosis. In contrast, Arg403Gln, Arg719Trp, and Arg453Cys mutations are associated with a high incidence of sudden cardiac death (SCD). Mutations in cTnT are associated with a mild degree of hypertrophy, but a high incidence of SCD. Mutations in MyBP-C are associated with mild hypertrophy and a benign prognosis. However, it has become evident that factors other than the underlying mutations, such as genetic background and possibly environmental factors, also modulate phenotypic expression of HCM.

Cardiomegaly↗

PubMed1995

Effect of apolipoprotein E and A-IV phenotypes on the low density lipoprotein response to HMG CoA reductase inhibitor therapy.

Our purpose was to assess the effect of apolipoprotein (apo) E and apo A-IV isoform variation on low density lipoprotein (LDL) cholesterol lowering response to the HMG CoA reductase inhibitor, pravastatin. Plasma samples were obtained from participants (apo E, n = 97; apo A-IV, n = 144) in the PLAC-I (Pravastatin Limitation of Atherosclerosis in Coronary Arteries Study-1). The mean LDL cholesterol reduction in these subjects who were randomized to pravastatin 40 mg/day was 28%. Subjects with the APOE*2 allele (n = 12) had significantly (P = 0.04) greater reductions at 36% than subjects homozygous for the APOE*3 allele (n = 66, 27%) or those with the APOE*4 allele (n = 19, 26%). No significant effect of apo A-IV phenotype on LDL cholesterol lowering in response to pravastatin was noted. A meta-analysis utilizing published data from 4 previously published studies as well as our own data with a total sample size of 625 subjects was carried out. This analysis indicates that the presence of the APOE*2 allele was associated with a significantly greater (P < 0.05) LDL-cholesterol lowering response at 37% than those subjects homozygous for the APOE*3 allele at 35%, while those with the APOE*4 allele had a significantly lower response (P < 0.05), at 33%. These data are consistent with the concept that apo E phenotype modulates the LDL cholesterol lowering response observed with the use of HMG CoA reductase inhibitors.

Alleles↗

PubMed2001

Regulation of Raf by Akt controls growth and differentiation in vascular smooth muscle cells.

The stimulation of platelet-derived growth factor (PDGF) receptors shifts vascular smooth muscle (VSM) cells toward a more proliferative phenotype. Thrombin activates the same signaling cascades in VSM cells, namely the Ras/Raf/MEK/ERK and the phosphatidylinositol 3-kinase (PI 3-kinase)/Akt pathways. Nonetheless, thrombin was not mitogenic, but rather increased the expression of the smooth muscle-specific myosin heavy chain (SM-MHC) indicative of an in vitro re-differentiation of VSM cells. A more detailed analysis of the temporal pattern and relative signal intensities revealed marked differences. The strong and biphasic phosphorylation of ERK1/2 in response to thrombin correlated with its ability to increase the activity of the SM-MHC promoter whereas Akt was only partially and transiently phosphorylated. By contrast, PDGF, a potent mitogen in VSM cells, induced a short-lived ERK1/2 phosphorylation but a complete and sustained phosphorylation of Akt. The phosphorylated form of Akt physically interacted with Raf. Moreover, Akt phosphorylated Raf at Ser(259), resulting in a reduced Raf kinase activity and a termination of MEK and ERK1/2 phosphorylation. Disruption of the PI 3-kinase signaling prevented the PDGF-induced Akt and Raf-Ser(259) phosphorylation. Under these conditions, PDGF elicited a more sustained MEK and ERK phosphorylation and increased SM-MHC promoter activity. Consistently, in cells that express dominant negative Akt, PDGF increased SM-MHC promoter activity. Furthermore, expression of constitutively active Akt blocked the thrombin-stimulated SM-MHC promoter activity. Thus, we present evidence that the balance and cross-regulation between the PI 3-kinase/Akt and Ras/Raf/MEK signaling cascades determine the temporal pattern of ERK1/2 phosphorylation and may thereby guide the phenotypic modulation of vascular smooth muscle cells.

Animals↗

PubMed2005

Myeloperoxidase generates 5-chlorouracil in human atherosclerotic tissue: a potential pathway for somatic mutagenesis by macrophages.

Somatic mutations induced by oxidative damage of DNA might play important roles in atherogenesis. However, the underlying mechanisms remain poorly understood. Myeloperoxidase, a heme protein expressed by select populations of artery wall macrophages, initiates one potentially mutagenic pathway by generating hypochlorous acid. This potent chlorinating agent reacts rapidly with primary amines to yield long-lived, selectively reactive N-chloramines. In the current studies, we demonstrate that myeloperoxidase produced by human macrophages differentiated in the presence of granulocyte macrophage colony-stimulating factor generates 5-chlorouracil, a mutagenic thymine analog. The primary amine taurine fails to block the reaction, suggesting that N-haloamines produced by macrophages might oxidize uracil. Model system studies demonstrated that N-chloramines convert uracil to 5-chlorouracil. Interestingly, the tertiary amine nicotine dramatically enhances uracil chlorination, suggesting that cigarette smoke might promote nucleobase oxidation by N-chloramines. To look for evidence that myeloperoxidase promotes uracil oxidation in vivo, we measured 5-chlorouracil levels in human aortic tissue, using isotope dilution gas chromatography-mass spectrometry. The level of 5-chlorouracil was 10-fold higher in atherosclerotic aortic tissue obtained during vascular surgery than in normal aortic tissue, suggesting that halogenated nucleobases produced by macrophages might contribute to atherogenesis. Because 5-chlorouracil can be incorporated into nuclear DNA, our observations raise the possibility that halogenation reactions initiated by phagocytes provide one pathway for mutagenesis, phenotypic modulation, and cytotoxicity during atherogenesis.

Antioxidants↗

PubMed2007

Induction of original phenotype of human immortalized chondrocytes: a quantitative gene expression analysis.

We previously established a line of immortalized normal human articular chondrocytes, lbpva55, expressing the E6 and E7 transforming genes of the human papilloma virus type 16. With this study we investigated the phenotypic modulation ability of this cell line, cultured in different conditions, with the aim of validating its use for studies on cartilage metabolism and physiology. To this end, we performed a quantitative analysis, using real-time PCR technology, of the expression of the main structural components of the cartilage matrix (collagens I, II and aggrecan), of two transcription factors regulating chondrocyte differentiation (Sox-9 and Egr-1) and of some enzymes involved in matrix turnover (cathepsin B, MMP-1 and MMP-13). Results showed that, under defined conditions, lbpva55 cells were able to re-express the chondrocyte phenotype that was lost in a conventional monolayer condition, as demonstrated by an up-regulation of collagen II, the main marker of hyaline cartilage and Sox-9, a master gene regulator of chondrocytic differentiation. The gene expression profile of our immortalized cells compared with that of normal articular chondrocytes showed that this line could be used as a valid in vitro model for a better understanding of cell molecular mechanisms relevant for the development of new therapeutic approaches in rheumatic diseases and for the cartilage engineering field.

Cell Line↗

PubMed1999

Effects of static or dynamic mechanical stresses on osteoblast phenotype expression in three-dimensional contractile collagen gels.

Studies performed at tissular (three-dimensional, 3-D) or cellular (two-dimensional, 2-D) levels showed that the loading pattern plays a crucial role in the osteoblastic physiology. In this study, we attempted to investigate the response of a 3-D osteoblastic culture submitted to either no external stress or static or dynamic stresses. Rat osteosarcoma cells (ROS 17/2.8) were embedded within collagen type I lattices and studied for 3 weeks. Entrapment and proliferation of cells within the hydrated collagen gel resulted in the generation of contractile forces, which led to contraction of the collagen gel. We used this ability to evaluate the influence of three modes of mechanical stresses on the cell proliferation and differentiation: (1) the freely retracted gels (FRG) were floating in the medium, (2) the tense gels (TG) were stretched statically and isometrically, with contraction prevented in the longitudinal axis, and (3) the dynamic gels (DG) were floating gels submitted to periodic stresses (50 or 25 rpm frequency). Gels showed maximum contraction at day 12 in 50 rpm DG, followed by 25 rpm DG, then FRG (88%, 81%, 70%, respectively) and at day 16 in TG (33%). The proliferation rate was greater in TG than in FRG (+52%) but remained low in both DGs. Gel dimensions were related to the collagen concentration and on a minor extent to cell number. Cells in DG appeared rounder and larger than in other conditions. In TG, cells were elongated and oriented primarily along the tension axis. Scanning electron microscopy (SEM) showed that tension exerted by cells in TG led to reorientation of collagen fibers which, in turn, determined the spatial orientation and morphology of the cells. Transmission electron microscopy (TEM) performed at maximum proliferation showed a vast majority of cells with a distended well-developed RER filled with granular material and numerous mitochondria. Alkaline phosphatase activity peaked close to the proliferation peak in FRG, whereas in TG, a biphasic curve was observed with a small peak at day 4 and the main peak at day 16. In DG, this activity was lower than in the two other conditions. A similar time course was observed for alkaline phosphatase gene expression as assessed by Northern blots. Regardless of the conditions, osteocalcin level showed a triphasic pattern: a first increase at day 2, followed by a decrease from day 4 to 14, and a second increase above initial values at day 18. Microanalysis-x indicated that mineralization occurred after 14 days and TEM showed crystals within the matrix. We showed that static and dynamic mechanical stresses, in concert with 3-D collagen matrices, played a significant role on the phenotypic modulation of osteoblast-like cells. This experimental model provided a tool to investigate the significance and the mechanisms of mechanical activity of the 3-D cultured osteoblast-like cells.

Alkaline Phosphatase↗

PubMed1997

Expression of phenotype- and proliferation-related genes in rat aortic smooth muscle cells in primary culture.

OBJECTIVES: After endothelial injury, smooth muscle cells (SMCs) in the arterial media are modified from a contractile to a sympathetic phenotype. This process includes a prominent structural reorganization and makes the cells able to migrate into the intima, divide, and secrete extracellular matrix components. A similar change occurs in culture and then in vitro system has been established as a useful model in which to study the control of SMC differentiation. The purpose of this study was to analyze the expression of a number of phenotype- and proliferation-related genes in vascular SMCs during the first week in primary culture. METHODS: SMCs were enzymatically isolated from rat aorta and seeded on substrates of fibronectin (an adhesive plasma protein) and laminin-collagen type IV (two major basement membrane proteins) in a serum-free medium or in uncoated dishes in a serum-containing medium. Total RNA was isolated from the cells after different times of culture and analyzed by Northern blotting for expression of specific gene transcripts. In part, expression of the corresponding proteins was also explored by Western blotting and indirect immunofluorescence microscopy. RESULTS: The results indicate that the proto-oncogenes c-fos, c-jun and c-ets-1 were already activated during the isolation of the cells and then continued to be strongly expressed for a few days. Especially in the serum-free groups, there was also early activation of the genes for the matrix metalloproteinases, stromelysin (MMP-3) and type IV collagenase (MMP-2). In parallel, an increased expression of the genes for two extracellular matrix components was observed, with an early rise in osteopontin mRNA and a later rise in collagen type I mRNA. At the end of the test period, the corresponding proteins were deposited around the cells in a fibrillar pattern. Among the matrix receptors investigated, the beta 1 integrin subunit showed a high and persistent expression, whereas the alpha 5 and alpha 1 integrin subunits showed lower and more variable mRNA level. In support of the existence of an autocrine or paracrine platelet-derived growth factor (PDGF) loop, an early rise in expression of the PDGF A-chain gene and a subsequent rise in expression of the PDGF alpha-receptor gene were noted. CONCLUSION: It is proposed that the coordinated shift in gene expression here described to take place in connection with the phenotypic modulation of vascular SMCs in primary culture is part of a predetermined genetic program that normally serves the function to engage the cells in a wound healing response.

Animals↗

PubMed1994

Effect of apolipoprotein E phenotype on diet-induced lowering of plasma low density lipoprotein cholesterol.

The National Cholesterol Education Program (NCEP) has recommended that dietary total fat, saturated fat, and cholesterol intake be reduced to < or = 30% of calories, < 10% of calories, and < 300 mg/day, respectively (Step 1 diet) in the general population to reduce plasma low density lipoprotein (LDL) cholesterol levels and heart disease risk. We examined the LDL cholesterol-lowering response to such a diet (26% fat, 8% saturated fat, and 201 mg/day of cholesterol) as compared to an average American diet (39% fat, 15% saturated fat, and 435 mg/day of cholesterol) in 128 subjects using diet periods of 4-24 weeks for each diet phase. The mean LDL cholesterol reduction was 15% in males (n = 83) and 8% in post-menopausal females (n = 45). The effect of apolipoprotein (apo) E phenotype on responsiveness was examined. LDL cholesterol lowering in males was 14% for 60 apoE3/3 subjects, 23% for 10 apoE3/4 subjects, and 16% for 13 apoE3/2 subjects. Male apoE3/4 subjects had a significantly greater LDL cholesterol reduction (P = 0.006) and a greater decrease in the LDL/HDL ratio (P = 0.047) than apoE3/3 subjects. In females, 7% lowering in LDL cholesterol was observed in 34 apoE3/3 subjects and 11% lowering was observed in 7 apoE3/4 subjects (P = 0.12). A meta-analysis of data from published studies supports this conclusion. These data indicate that apoE phenotype modulates the LDL cholesterol-lowering response to a diet meeting NCEP Step 1 criteria, and that male subjects carrying the apoE4 allele are more responsive than other subjects.

Adult↗