Citations

ABSTRACT Initially, it was thought that there was no intracellular signaling mediated by NRP‐1 alone in response to its ligands. However, the emerging data from our group as well as others suggest that the signaling through NRP‐1 actually promotes angiogenesis and is mediated through its C‐terminal domain and downstream molecules such as phosphoinositide 3‐kinase. Hence, understanding the signal transduction pathways mediated by NRP‐1 and identification of its downstream molecules are of importance. By using both in vivo zebrafish model and in vitro tissue culture system, we have shown that the C‐terminal three amino acids of NRP‐1 (SEA‐COOH) are required for NRP‐1‐mediated angiogenesis. Furthermore, knocking down of RGS‐GAIP‐interacting protein C terminus (GIPC) in zebrafish, which is associated with C‐terminal domain of NRP‐1, exhibits similar vasculature phenotypes to those from NRP‐1 null. Specific and effective silencing of GIPC in vascular endothelium results in inhibition of NRP‐1‐mediated migration. In both cases as described, PDZ domain of GIPC is responsible for its function. Taken together, our data suggest a novel role of GIPC in angiogenesis and vessel formation and also support our hypothesis that NRP‐1 can facilitate downstream signaling to promote angiogenesis through GIPC.—Wang, L., Mukhopadhyay, D., Xu, X. C terminus of RGS‐GAIP‐interacting protein conveys neuropilin‐1‐mediated signaling during angiogenesis. FASEB J. 20, E732–E741 (2006)

Abstract Further analyses from the Women's Health Initiative estrogen trial shows that CEE reduced fracture risk. The fracture reduction at the hip did not differ appreciably among risk strata. These data do not support overall benefit over risk, even in women at highest risk for fracture. Introduction: The Women's Health Initiative provided evidence that conjugated equine estrogen (CEE) can significantly reduce fracture risk in postmenopausal women. Additional analysis of the effects of CEE on BMD and fracture are presented. Materials and Methods: Postmenopausal women 50–79 years of age with hysterectomy were randomized to CEE 0.625 mg daily (n = 5310) or placebo (n = 5429) and followed for an average 7.1 years. Fracture incidence was assessed by semiannual questionnaire and verified by adjudication of radiology reports. BMD was measured in a subset of women (N = 938) at baseline and years 1, 3, and 6. A global index was used to examine whether the balance of risks and benefits differed by baseline fracture risk. Results: CEE reduced the risk of hip (hazard ratio [HR], 0.65; 95% CI, 0.45–0.94), clinical vertebral (HR, 0.64; 95% CI, 0.44–0.93), wrist/lower arm (HR, 0.58; 95% CI, 0.47–0.72), and total fracture (HR, 0.71; 95% CI, 0.64–0.80). This effect did not differ among strata according to age, oophorectomy status, past hormone use, race/ethnicity, fall frequency, physical activity, or fracture history. Total fracture reduction was less in women at the lowest predicted fracture risk in both absolute and relative terms (HR, 0.86; 95% CI, 0.68–1.08). CEE also provided modest but consistent positive effects on BMD. The HRs of the global index for CEE were relatively balanced across tertiles of summary fracture risk (lowest risk: HR, 0.81; 95% CI, 0.62–1.05; mid risk: HR, 1.09; 95% CI, 0.92–1.30; highest risk: HR, 1.04; 95% CI, 0.88–1.23; interaction, p = 0.42). Conclusions: CEE reduces the risk of fracture and increases BMD in hysterectomized postmenopausal women. Even among the women with the highest risk for fractures, when considering the effects of estrogen on other important health outcomes, a summary of the burden of monitored effects does not indicate a significant net benefit.

Abstract We report here the first association between vitamin D–resistant rickets, alopecia, and type 1 diabetes in a child with compound heterozygous mutations in the VDR gene. Transfection studies suggest dissociated effects of VDR gene mutations on the regulation of genes involved in vitamin D metabolism and dendritic cell maturation. Introduction: Whereas vitamin D may play a role in the immune tolerance process, no patient has been reported to associate hereditary vitamin D–resistant rickets (HVDRR) and an autoimmune disease, and no attempt has been made to delineate the outcome of mutations of the vitamin D receptor (VDR) on the transcription of genes controlling immune tolerance. Materials and Methods: The VDR gene was analyzed in a child with vitamin D–resistant rickets, total alopecia, and early childhood–onset type 1 diabetes. Patient's fibroblasts and COS-7 cells transfected with wildtype or mutant VDRs were studied for ligand-binding capacity, transactivation activity using two gene promoters [CYP-24, a classical 1,25(OH)2D3-responsive gene, and relB, a critical NF-κB component for regulation of dendritic cell differentiation], VDR-RXR heterodimers association to CYP 24 VDREs by gel mobility shift assays, and co-activator binding by Glutathione-S-transferase pull-down assays. Results: Two novel compound heterozygous mutations (L263R and R391S) were identified in the VDR ligand-binding domain in this child. Both mutations significantly impaired VDR ligand-binding capacity but had dissociated effects on CYP-24 and RelB promoter responses to vitamin D. CYP 24 response binding to SRC-1 and RXR-heterodimer binding to CYP24 VDREs were abolished in L263R mutants but normal or partially altered in R391S mutants. In the opposite, RelB responses to vitamin D were close to normal in L263R mutants but abolished in R391S mutants. Conclusions: We report the first clinical association between HVDRR, total alopecia, and early childhood–onset type 1 diabetes. Mutations in the VDR ligand-binding domain may hamper the 1,25(OH)2D3–mediated relB responses, an effect that depends on the site of the VDR mutation and cannot be anticipated from VDR ligand-binding ability or CYP-24 response. Based on these results, we propose to survey the immune function in patients with HVDRR, including those with moderate features of rickets.

Background and Purpose— Genetic factors that influence interindividual variation in levels of plasma homocysteine, a risk factor for vascular disease, are not fully understood. We performed linkage analyses to identify genomic regions that influence homocysteine levels in blacks and non-Hispanic whites. Methods— Subjects (n=2283) belonged to hypertensive sibships and included 1319 blacks (63±10 years, 70% women) and 964 non-Hispanic whites (61±7 years, 57% women). Fasting plasma homocysteine was measured by high-pressure liquid chromatography. Genotypes were measured at 366 microsatellite marker loci distributed across the 22 autosomes. Plasma homocysteine adjusted for age, sex, body mass index, serum creatinine, and estrogen use (in women) was used in the genetic analyses. Heritability and linkage analyses were performed using a variance components approach. Results— Mean (±SD) homocysteine levels were 10.4±5.27 μmol/L in blacks and 10.0±2.84 μmol/L in non-Hispanic whites ( P =0.58 for difference). Homocysteine levels were significantly ( P <0.0001) heritable in blacks ( h 2 =0.70) and in non-Hispanic whites ( h 2 =0.49). Linkage analyses demonstrated significant evidence of linkage (multipoint logarithm of odds≥3.0) for homocysteine on chromosomes 1q42, 14q32, and 19p13 in blacks and on chromosomes 9q34 and 12q24 in non-Hispanic whites. Tentative evidence of linkage (logarithm of odds 1.3 to 2.0) was present on chromosomes 2q32, 7p15, 8q24, 18q21, and 20p12 in blacks and chromosomes 6q26 and 18q21 in non-Hispanic whites. Four genes in the homocysteine metabolism pathway ( MTR , DNMT1 , GAMT , and CARM1 ) were present under 2 of the significant linkage signals in blacks (chromosomes 1q42 and 19p13). Conclusions— Plasma homocysteine is a significantly heritable trait. Linkage analyses reveal several unique genomic loci that may influence circulating levels of homocysteine and therefore susceptibility to vascular diseases including stroke.

For fusion to occur the repulsive forces between two interacting phospholipid bilayers must be reduced. In model systems, this can be achieved by increasing the surface tension of at least one of the membranes. However, there has so far been no evidence that the secretory granule membrane is under tension. We have been studying exocytosis by using the patch-clamp technique to measure the surface area of the plasma membrane of degranulating mast cells. When a secretory granule fuses with the plasma membrane there is a step increase in the cell surface area. Some fusion events are reversible, in which case we have found that the backstep is larger than the initial step, indicating that there is a net decrease in the area of the plasma membrane. The decrease has the following properties: (i) the magnitude is strongly dependent on the lifetime of the fusion event and can be extensive, representing as much as 40% of the initial granule surface area; (ii) the rate of decrease is independent of granule size; and (iii) the decrease is not dependent on swelling of the secretory granule matrix. We conclude that the granule membrane is under tension and that this tension causes a net transfer of membrane from the plasma membrane to the secretory granule, while they are connected by the fusion pore. The high membrane tension in the secretory granule may be the critical stress necessary for bringing about exocytotic fusion.

Abstract An abnormal serum immunoglobulin free light chain (FLC) ratio at diagnosis may identify risk of progression to myeloma in patients with solitary bone plasmacytoma (SBP). In the cohort of 116 patients, 43 have progressed to myeloma, with a median time to progression of 1.8 years. The FLC ratio was determined in all 116 patients on serum collected at time of diagnosis and was abnormal in 54 patients (47%). An abnormal FLC ratio was associated with a higher risk of progression to myeloma (P = .039). The risk of progression at 5 years was 44% in patients with an abnormal serum FLC ratio at diagnosis compared with 26% in those with a normal FLC ratio. One to 2 years following diagnosis, a persistent serum M protein level of 5 g/L (0.5 g/dL) or higher was an additional risk factor for progression. A risk stratification model was constructed using the 2 variables of FLC ratio and M protein level: patients with a normal FLC ratio at baseline and M protein level less than 5 g/L (0.5 g/dL) at 1 to 2 years following diagnosis (low risk, n = 31); with either risk factor abnormal (intermediate risk, n = 26); and with both an abnormal FLC ratio and M protein level of 5 g/L (0.5 g/dL) or higher (high risk, n = 18). The corresponding progression rates at 5 years were significantly different in the low, intermediate, and high groups: 13%, 26%, and 62%, respectively (P < .001).