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S L Ferrari

Publications and source records attributed to S L Ferrari.

15 recordsLinked to original sources
PubMed2005

LRP5 gene polymorphisms and idiopathic osteoporosis in men.

Mutations in the low-density lipoprotein receptor-related protein 5 gene (LRP5) have demonstrated the role of LRP5 in bone mass acquisition. LRP5 variants were recently reported to contribute to the population-based variance in vertebral bone mass and size in males. To investigate whether LRP5 variants are implicated in idiopathic male osteoporosis, we studied 78 men with low BMD (<2.5 T score or < -2 Z score) aged less than 70 years (mean +/- SD: 50 +/- 16 years) in whom secondary causes of osteoporosis had been excluded and 86 controls (51 +/- 10 years). Genotypes and haplotypes were based on LRP5 missense substitutions in exons 9 (c.2047G > A, p.V667M) and 18 (c.4037C > T, p.A1330V), and their association with osteoporosis evaluated after adjustment for multiple clinical and environmental variables using logistic regression. The presence of osteoporosis was significantly associated with LRP5 haplotypes (P = 0.0036) independent of age (P = 0.006), weight (P = 0.004), calcium intake (P = 0.002), alcohol (P = 0.005) and tobacco (P = 0.004) consumption. Accordingly, the odds ratio for osteoporosis was 3.78 (95% CI 1.27-11.26, P < 0.001) in male carriers of haplotype 3 (c.2047A-4037T, n = 20 cases and 12 controls) versus homozygous carriers of haplotype 1 (c.2047G-4037C, n = 42 cases and 61 controls). In conclusion, these data indicate beyond a significant role for environmental factors, an association between LRP5 variants and idiopathic osteoporosis in males, pointing to a role of LRP5 in this disease.

Adult↗
PubMed2005

Bone response to intermittent parathyroid hormone is altered in mice null for {beta}-Arrestin2.

Intermittent PTH administration increases bone turnover, resulting in net anabolic effects on bone. These effects are primarily mediated by intracellular cAMP signaling. However, the molecular mechanisms that regulate PTH activity in bone remain incompletely understood. beta-Arrestin2, a G protein-coupled receptor regulatory protein, inhibits PTH-stimulated cAMP accumulation in vitro. Using beta-arrestin2(-/-) (KO) and wild-type (WT) mice, we investigated the response to PTH in primary osteoblasts (POB) and the effects of intermittent PTH administration on bone mass and microarchitecture in vivo. Compared with that in WT mice, PTH-stimulated intracellular cAMP was increased and sustained in KO POB. Intermittent exposure of POB to PTH significantly decreased the ratio of osteoprotegerin (OPG) receptor activator of nuclear factor-kappaB ligand (RANKL) mRNA expression in KO POB, whereas it increased this ratio in WT POB. Total body bone mass and cortical and trabecular bone parameters were 5-10% lower in male KO mice compared with WT, and these differences were magnified upon in vivo administration of intermittent PTH (80 mug/kg.d) for 1 month. Thus, PTH significantly increased total body bone mineral content as well as vertebral trabecular bone volume and thickness in WT, but not KO mice. The anabolic response to PTH in cortical bone was also slightly more pronounced in WT than KO mice. Histomorphometry indicated that PTH prominently stimulated indexes of bone formation in both WT and KO mice, whereas it significantly increased indexes of bone resorption (i.e. osteoclast number and surface) in KO mice only. In conclusion, these results suggest that beta-arrestins may specify the activity of intermittent PTH on the skeleton by limiting PTH-induced osteoclastogenesis.

Animals↗
PubMed2003

Two promoter polymorphisms regulating interleukin-6 gene expression are associated with circulating levels of C-reactive protein and markers of bone resorption in postmenopausal women.

IL-6 is a pleiotropic cytokine that plays a critical role in bone resorption. We describe two allelic variants in the IL-6 promoter, -572 and -174 G-->C, that alone and in combination influence IL-6 activity in vitro and in vivo. The association of IL-6 -572 genotypes and -572/-174 G-->C haplotypes with serum C-reactive protein (CRP), serum and urinary C-terminal cross-linking of type I collagen (a marker of bone resorption), and osteocalcin (a marker of bone formation) was investigated in a cohort of healthy postmenopausal women (n = 495; mean age +/- SD, 72 +/- 5.7 yr). Among IL-6 -572 genotypes, CRP was 37% higher (P = 0.02) and urinary C-terminal cross-linking of type I collagen was 20% higher (P = 0.01) in the presence of the C allele, whereas serum osteocalcin was not different. IL-6 -572/-174 haplotypes (G/C, G/G, and C/G) were significantly associated with all biochemical markers, and additive effects of the two polymorphic loci were found. Thus, there was a significant increase in the level of CRP (up to +79%; P = 0.007) and bone resorption markers (up to +32%; P = 0.017) with a decreasing number (from four to one) of IL-6 protective alleles -572G and -174C. In addition, there was a trend for lower age-adjusted bone mineral density at the lumbar spine in subjects with less IL-6 protective alleles (up to -9.6%; P = 0.037; P = 0.08 after further adjustment for weight). In conclusion, we describe two functional polymorphisms in the IL-6 gene regulatory region associated with IL-6 activity in postmenopausal women, both systemically (CRP) and locally in bone. As such, IL-6 polymorphisms are able to influence the risk of osteoporosis as well as other chronic disorders involving IL-6 activity.

Aged↗
PubMed2001

A functional polymorphic variant in the interleukin-6 gene promoter associated with low bone resorption in postmenopausal women.

OBJECTIVE: To examine functional interleukin-6 (IL-6) -174 G-->C allelic variants in relation to bone turnover and bone mineral density (BMD) in postmenopausal women. METHODS: Four hundred thirty-four healthy women living in the community (mean +/- SD age 71.7 +/- 5.7 years) were genotyped for the IL-6 -174 G-->C polymorphism. Serum levels of C-telopeptide of type I collagen (CTx), a marker of bone resorption, and osteocalcin (OC), a marker of bone formation, were determined. BMD at the hip and forearm was measured by dual-energy x-ray absorptiometry. RESULTS: CTx levels differed significantly (P = 0.006) among IL-6 genotypes (mean +/- SEM 0.275 +/- 0.02 ng/ml, 0.325 +/- 0.01 ng/ml, and 0.356 +/- 0.02 ng/ml in women with the CC genotype [n = 68], the GC genotype [n = 204], and the GG genotype [n = 162], respectively). Compared with the GG group, age-adjusted odds ratios for high bone resorption were 0.65 (95% confidence interval [95% CI] 0.41-1.0, P = 0.06) and 0.37 (95% CI 0.18-0.73, P = 0.0047) in GC and CC subjects, respectively. In contrast, OC levels did not differ by genotype. BMD at the hip and forearm was 1.5-5% higher in CC subjects compared with GG subjects (P not significant). When the cohort was divided according to the median age (70.5 years), BMD was significantly decreased in older compared with younger postmenopausal women with the GG and GC genotypes (-9.6% on average; P < 0.01), but not in those with the CC genotype (-5.1% on average; P not significant). CONCLUSION: Compared with the GC and GG IL-6 -174 G-->C genotypes, the CC genotype is associated with lower bone resorption and lesser decrease in bone mass in older postmenopausal women. These results suggest that IL-6 -174 G-->C alleles may be significant determinants of the risk for osteoporosis in elderly subjects.

Aged↗
PubMed2001

Cellular distribution of constitutively active mutant parathyroid hormone (PTH)/PTH-related protein receptors and regulation of cyclic adenosine 3',5'-monophosphate signaling by beta-arrestin2.

PTH promotes endocytosis of human PTH receptor 1 (PTH1Rc) by activating protein kinase C and recruiting beta-arrestin2. We examined the role of beta-arrestin2 in regulating the cellular distribution and cAMP signaling of two constitutively active PTH1Rc mutants, H223R and T410P. Overexpression of a beta-arrestin2-green fluorescent protein (GFP) conjugate in COS-7 cells inhibited constitutive cAMP accumulation by H223R and T410P in a dose-dependent manner, as well as the response to PTH of both mutant and wild-type PTH1Rcs. The cellular distribution of PTH1Rc-GFP conjugates, fluorescent ligands, and ssarrestin2-GFP was analyzed by fluorescence microscopy in HEK-293T cells. In cells expressing either receptor mutant, a ligand-independent mobilization of beta-arrestin2 to the cell membrane was observed. In the absence of ligand, H223R and wild-type PTH1Rcs were mainly localized on the cell membrane, whereas intracellular trafficking of T410P was also observed. While agonists promoted beta-arrestin2-mediated endocytosis of bot PTH1Rc mutants, antagonists were rapidly internalized only with T410P. The protein kinases inhibitor, staurosporine, significantly decreased internalization of ligand-PTH1Rc mutant complexes, although the recruitment of beta-arrestin2 to the cell membrane was unaffected. Moreover, in cells expressing a truncated wild-type PTH1Rc lacking the C-terminal cytoplasmic domain, agonists stimulated translocation of beta-arrestin2 to the cell membrane followed by ligand-receptor complex internalization without associated beta-arrestin2. In conclusion, cAMP signaling by constitutively active mutant and wild-type PTH1Rcs is inhibited by a receptor interaction with beta-arrestin2 on the cell membrane, possibly leading to uncoupling from G(s)alpha. This phenomenon is independent from protein kinases activity and the receptor C-terminal cytoplasmic domain. In addition, there are differences in the cellular localization and internalization features of constitutively active PTH1Rc mutants H223R and T410P.

Animals↗
PubMed2001

Osteoporosis, genetics and hormones.

Osteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue. At a given age, bone mass results from the amount of bone acquired during growth, i.e. the peak bone mass (Bonjour et al., 1991, Theintz et al. 1992) minus the age-related bone loss which particularly accelerates after menopause. The rate and magnitude of bone mass gain during the pubertal years and of bone loss in later life may markedly differ from one skeletal site to another, as well as from one individual to another. Bone mass gain is mainly related to increases in bone size, that is in bone external dimensions, with minimal changes in bone microarchitecture. In contrast, postmenopausal and age-related decreases in bone mass result from thinning of both cortices and trabeculae, from perforation and eventually disappearance of the latter, leading to significant alterations of the bone microarchitecture (Fig. 1).

Bone Density↗
PubMed2000

A role for N-cadherin in the development of the differentiated osteoblastic phenotype.

Cadherins are a family of cell surface adhesion molecules that play an important role in tissue differentiation. A limited repertoire of cadherins has been identified in osteoblasts, and the role of these molecules in osteoblast function remains to be elucidated. We recently cloned an osteoblast-derived N-cadherin gene from a rat osteoblast complementary DNA library. After in situ hybridization of rat bone and immunohistochemistry of human osteophytes, N-cadherin expression was localized prominently in well-differentiated (lining) osteoblasts. Northern blot hybridization in primary cultures of fetal rat calvaria and in human SaOS-2 and rat ROS osteoblast-like cells showed a relationship between N-cadherin messenger RNA expression and cell-to-cell adhesion, morphological differentiation, and alkaline phosphatase and osteocalcin gene expression. Treatment with a synthetic peptide containing the His-Ala-Val (HAV) adhesion motif of N-cadherin significantly decreased bone nodule formation in primary cultures of fetal rat calvaria and inhibited cell-to-cell contact in rat osteoblastic TRAB-11 cells. HAV peptide also regulated the expression of specific genes such as alkaline phosphatase and the immediate early gene zif268 in SaOS-2 cells. Transient transfection of SaOS-2 cells with a dominant-negative N-cadherin mutant (NCADdeltaC) significantly inhibited their morphological differentiation. In addition, aggregation of NCTC cells derived from mouse connective tissue stably transfected with osteoblast-derived N-cadherin was inhibited by either treatment with HAV or transfection with NCADdeltaC. Together, these results strongly support a role for N-cadherin, in concert with other previously identified osteoblast cadherins, in the late stages of osteoblast differentiation.

Animals↗
PubMed1999

Endocytosis of ligand-human parathyroid hormone receptor 1 complexes is protein kinase C-dependent and involves beta-arrestin2. Real-time monitoring by fluorescence microscopy.

Endocytosis and intracellular trafficking of the human parathyroid hormone receptor subtype 1 (hPTH1-Rc) and its ligands was monitored independently by real-time fluorescence microscopy in stably transfected HEK-293 cells. Complexes of fluorescence-labeled parathyroid hormone (PTH)-(1-34) agonist bound to the hPTH1-Rc internalized rapidly at 37 degrees C via clathrin-coated vesicles, whereas fluorescent PTH-(7-34) antagonist-hPTH1Rc complexes did not. A functional C terminus epitope-tagged receptor (C-Tag-hPTH1-Rc) was immunolocalized to the cell membrane and, to a lesser extent, the cytoplasm. PTH and PTH-related protein agonists stimulated C-Tag-hPTH1-Rc internalization. Relocalization to the cell membrane occurred 1 h after removal of the ligand. Endocytosis of fluorescent PTH agonist-hPTH1-Rc complexes was blocked by the protein kinase C (PKC) inhibitor staurosporine but not by the specific protein kinase A inhibitor N-(2-(methylamino)ethyl)-5-isoquinoline-sulfonamide. Fluorescent PTH antagonist-hPTH1-Rc complexes were rapidly internalized after PKC activation by phorbol 12-myristate 13-acetate or thrombin, but not after stimulation of the cAMP/protein kinase A pathway by forskolin. In cells co-expressing the hPTH1-Rc and a green fluorescent protein-beta-arrestin2 fusion protein (beta-Arr2-GFP), PTH agonists stimulated beta-Arr2-GFP mobilization to the cell membrane. Subsequently, fluorescent PTH-(1-34)-hPTH1Rc complexes and beta-Arr2-GFP co-localized intracellularly. In conclusion, agonist-activated hPTH1-Rc internalization involves beta-arrestin mobilization and targeting to clathrin-coated vesicles. Our results also indicate that receptor occupancy, rather than receptor-mediated signaling, is necessary, although not sufficient, for endocytosis of the hPTH1-Rc. Activation of PKC, however, is absolutely required.

Arrestins↗
PubMed1998

Do dietary calcium and age explain the controversy surrounding the relationship between bone mineral density and vitamin D receptor gene polymorphisms?

Whether vitamin D receptor (VDR) gene polymorphisms are associated with osteoporosis is highly controversial. The relationship between VDR gene polymorphisms and bone mineral density (BMD) might, however, be modified by age-related and/or environmental factors. We studied the potential association between BMD and VDR genotypes in females from prepuberty to premenopause and prospectively investigated the interaction of VDR genotypes with dietary calcium and BMD changes during childhood. Bsm I VDR gene polymorphisms and BMD at the lumbar spine (LS) and femur (neck [FN] and midshaft [FS]) were assessed in 369 healthy Caucasian females, aged 7-56 years (143 prepubertal girls, 54 peri- and postpubertal adolescents, and 172 premenopausal adults). Femoral trochanter (FT) and distal radius BMD (metaphysis and diaphysis) were also measured in 101 of the prepubertal girls who participated in a 1-year, double-blind, randomized study of calcium supplementation (850 mg/day) versus placebo on bone mineral mass accrual. Among all females, 150 (40.7%) had bb, 167 (45.3%) Bb, and 52 (14%) BB VDR genotypes. In prepubertal and adolescent girls altogether, LS BMD (Z scores) was associated with VDR genotypes and was significantly lower in BB than in Bb or bb subjects. Trends for a similar difference were also detected at the FN level as well as on the mean BMD (Z scores) of the three sites measured (LS, FN, and FS). By contrast, no BMD differences were detectable among VDR genotypes in the adults. In 101 prospectively studied prepubertal girls, calcium supplementation significantly increased BMD at most skeletal sites, except LS. After segregation for VDR genotypes (40 bb, 47 Bb, and 14 BB), a significant calcium effect was present in Bb but not bb girls, whereas in BB girls there was a positive but nonsignificant trend for a calcium effect. Moreover, dietary calcium intake was significantly correlated with BMD changes at various independent bone sites in Bb girls but not in bb girls. In contrast, BMD gain in bb girls appeared to be higher than among the other genotypes when the dietary calcium intake was low, i.e., in the absence of calcium supplements. BMD was significantly associated with VDR gene polymorphisms only before puberty, BB girls having significantly lower BMD (Z scores) than the other genotypes. By increasing dietary calcium intake, BMD accrual was increased in Bb and possibly BB prepubertal girls, whereas bb subjects had the highest spontaneous BMD accrual and remained unaffected by calcium supplements. Taking into account complex interactions between VDR gene polymorphisms and environmental factors, including calcium intake, may thus help to understand the discordant relationships between BMD and VDR gene polymorphisms.

Adolescent↗
PubMed1996

Osteoporosis in patients undergoing lung transplantation.

The occurrence of osteoporotic fractures may seriously compromise the quality of life of lung transplant recipients. However, at present, the true risk of osteoporosis in such patients is unknown. We therefore prospectively evaluated bone mass changes in patients undergoing pulmonary transplantation. Bone mineral density (BMD) of lumbar spine (LS), femoral neck (FN) and femoral shaft (FS), as well as whole body bone mineral content (WB-BMC) were measured in 21 consecutive candidates for lung transplantation (9 males and 12 females; mean+/-SD age 47+/-11 yrs). Twelve of the patients had their BMD remeasured within 6 months after surgery, and nine again after 1 year. Before transplantation, BMD at all sites as well as WB-BMC were significantly decreased as compared to the values in young healthy adults, FN being the most affected (FN -25+/-2%; LS, -12+/-4%; FS -9+/-2%, WB-BMC -15+/-4% (mean+/-SEM)). Seven out of 20 adult patients (35%) fulfilled World Health Organization (WHO) criteria for osteoporosis, i.e. BMD more than 2.5 SD below peak bone mass, whereas three had previously been diagnosed as having osteoporotic fractures of the spine or femoral neck. Within 6 months after transplantation, significant bone loss occurred, mostly at the LS level (-4.0+/-1.7%; p=0.04), despite calcium and vitamin D supplementation. Furthermore, two patients had new osteoporotic vertebral fractures. After 1 year, no further bone loss or new osteoporotic fractures were observed. In conclusion, evaluation of bone mass and prevention of bone loss should be considered early before lung transplantation. Further studies are needed to determine the efficacy of antiresorptive drugs on the prevention of accelerated bone loss and vertebral fractures after transplantation.

Adult↗
PubMed1994

Effects of epidermal growth factor on parathyroid hormone-related protein production by mammary epithelial cells.

Parathyroid hormone-related protein (PTHrP) plays a prominent role in the pathogenesis of humoral hypercalcemia of malignancy. However, it is also expressed in various nonmalignant tissues, particularly during fetal organogenesis and tissue differentiation. Thus, PTHrP is synthesized in skin, placenta, and mammary gland during lactation. Little is known, however, about the regulation of PTHrP synthesis and release in nontumoral cells. We investigated the regulation of PTHrP production by epidermal growth factor (EGF), a factor of major importance in the development of lactating breast, in primary cultures of rat mammary epithelial cells. EGF stimulated the production of immunoreactive and bioactive PTHrP in a time- and concentration-dependent manner. A 12 h incubation with 10 ng/ml of EGF increased PTHrP production by 36.0 +/- 7.1% (n = 7 experiments, p < 0.01). This was accompanied by an increase in PTHrP mRNA steady-state levels. The production of PTHrP was stimulated by the protein kinase C (PKC) activator phorbol-12-myristate-13-acetate (PMA) by 82.9 +/- 9.7% (n = 4 experiments, p < 0.01). The effects of PMA and EGF were additive. The EGF-induced stimulation appeared to be independent of extracellular calcium concentration, prostaglandin, or cAMP synthesis, but may have involved tyrosine kinase-mediated mechanisms. These results indicate that EGF was capable of increasing the production of PTHrP by cultured mammary epithelial cells. They also suggest that factors activating the PKC pathway are involved in the upregulation of PTHrP expression in mammary epithelial cells.

Animals↗
PubMed1992

Parathyroid hormone-related protein production by primary cultures of mammary epithelial cells.

Parathyroid hormone-related protein (PTHrP) plays a major role in the pathogenesis of malignant hypercalcemia, but has also been found in fetal and adult non-neoplastic tissues. Among them, lactating mammary gland was shown to produce PTHrP, and high levels of PTHrP were measured in milk. However, the regulation of PTHrP production by breast cells is still unknown. Primary cultures of mammary cells isolated from rat lactating glands were grown on collagen gels in an insulin/epidermal growth factor (EGF)-supplemented medium. Under these conditions, mammary cells displayed an epithelial phenotype and their number increased more than twofold after 1 week in culture. At that time, the cells were capable of producing immunoreactive PTHrP (range: 25 to 150 pg/10(5) cells x 24 h) and PTH-like bioactivity, as indicated by a 60% increase in cyclic adenosine monophosphate (cAMP) production induced by mammary epithelial cell conditioned medium in the PTH-responsive osteoblast-like UMR-106 cell line. When cell proliferation was hindered by lowering plating density, by removing medium supplements, or by adding transforming growth factor (TGF)-beta, a well-known autocrine inhibitor of mammary epithelial cell growth. PTHrP production was increased. In contrast, the omission of EGF or addition of specified anti-EGF antibodies decreased PTHrP production. In conclusion, primary cultures of mammary epithelial cells isolated from lactating rat were shown for the first time to produce PTHrP in vitro. This production was higher in the presence of EGF and could be modulated by cell growth rate.

Animals↗
PubMed1992

Actions of parathyroid hormone and parathyroid hormone-related protein.

By interacting with a structurally identical receptor, parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) display a common spectrum of action on the transport of mineral elements in bone and kidney. In vivo, PTH/PTHrP similarly reduce the renal tubular reabsorption of inorganic phosphate (Pi) and increase that of calcium. The hypercalcemic effect of PTHrP is due to an increase in both bone resorption and renal calcium reabsorption, the latter through a sodium-independent mechanism. The PTHrP-stimulated bone resorption can be totally inhibited by bisphosphonate therapy. Despite that, the fall in calcemia is moderate, indicating that the PTHrP main hypercalcemic action is due to the stimulation of the renal transport of calcium. For identical effects on renal ionic transports, PTHrP appears to less stimulate bone formation than PTH. These experimental findings are similar to clinical observations in patients with primary hyperparathyroidism or with solid malignant tumors. In vitro, the effects of PTH(1-34), PTHrP(1-34) and PTHrP(1-141) on cAMP production and sodium-dependent phosphate transport (NaPiT) are similar in kidney cells, where NaPiT is specifically inhibited by either peptide. This effect is attenuated by the competitive inhibitor [D-Trp12,Tyr34]bPTH(7-34)amide. Transforming growth factor-alpha similarly modulates the cAMP and NaPiT responses to PTH/PTHrP. In cultured mammary cells isolated from lactating rats, PTHrP elicits a 2-fold increase of cAMP production. Various products of bone and stromal cells, and of leukocytes, such as Interleukin-6 or Tumor necrosis factor-alpha, as well as high extracellular calcium concentration enhance PTHrP production by cultured lung squamous cell carcinoma and Leydig tumor cells, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗