Biomedical subjects

Caroline Marty

Publications and source records attributed to Caroline Marty.

4 recordsLinked to original sources

PubMed2006

Activation state-dependent interaction between Galphai and p67phox.

The phagocyte NADPH oxidase consists of multiple protein subunits that interact with each other to form a functional superoxide-generating complex. Although the essential components for superoxide production have been well characterized, other proteins potentially involved in the regulation of NADPH oxidase activation remain to be identified. We report here that the Galphai subunit of heterotrimeric G proteins is a novel binding partner for p67phox in transfected HEK293T cells and peripheral blood polymorphonuclear leukocytes. p67phox preferably interacted with inactive Galphai. Expression of p67phox caused a dose-dependent decrease in intracellular cyclic AMP concentration, suggesting altered function of Galphai. We identified a fragment of p67phox, consisting of the PB1 domain and the C-terminal SH3 domain, to be critical for the interaction with Galphai. Because these domains are involved in the interaction with p47phox and p40phox, the relationship between the respective binding events was investigated. Wild-type Galphai, but not its QL mutant, could promote the interaction between p67phox and p47phox. However, the interaction between p67phox and p40phox was not affected by either Galphai form. These results provide the first evidence for an interaction between p67phox and an alpha subunit of heterotrimeric G proteins, suggesting a potential role for Galphai in the regulation or activation of NADPH oxidase.

Animals↗

PubMed2004

Severe osteopenia in CFTR-null mice.

Osteoporosis is a common complication in cystic fibrosis (CF) patients. In this study, we performed a histomorphometric analysis of the bones of a mouse genetic model of human CF in which both copies of the cystic fibrosis transmembrane conductance regulator (CFTR) gene are inactivated. We find that, even in the absence of obvious nutritional and therapeutic differences, the CFTR mutation is associated with severe osteopenia. Bone mineral density (BMD) of total body and of individual bones is significantly diminished. CFTR mutants display a striking significant (50%) reduction of cortical bone width and thinner trabeculae. Analysis of dynamic parameters indicates a significant reduction of bone formation and a concomitant strong increase in bone resorption. Active osteoclasts where found mostly associated with cortical bone. Our data support the concept that CF-associated osteoporosis is part of the syndromic symptoms associated with the CFTR mutation.

Animals↗

PubMed2004

Arterial calcifications and bone histomorphometry in end-stage renal disease.

Arterial calcification (AC) is a common complication of end-stage renal disease (ESRD). The mechanisms responsible are complex, including disturbances of mineral metabolism and active expression of various mineral-regulating proteins. An inverse relationship between AC and bone density has been documented in uremic patients. In the study presented here, which included 58 patients with ESRD on hemodialysis (HD), bone-histomorphometry characteristics were compared with the AC scores (0 to 4) determined according to the number of arterial sites with calcifications. Patients with AC scores of 0 (no calcifications), or 1 or 2 (mild calcifications) had similar serum parathyroid hormone levels and bone histomorphometry, with larger osteoclast resorption, higher osteoclast numbers, and larger osteoblastic and double tertracycline-labeled surfaces. In contrast, patients with high AC scores (3 and 4) were characterized by lower serum parathyroid hormone, low osteoclast numbers and osteoblastic surfaces, smaller or absent double tetracycline-labeled surfaces, and high percentages of aluminum-stained surfaces. According to multivariate analysis, AC score was positively associated with age (P < 0.0001), daily dose of calcium-containing phosphate binders (P = 0.009), and bone aluminum-stained surfaces (P = 0.037), and an inverse correlation was observed with osteoblastic surfaces (P = 0.001). A high AC score is associated with bone histomorphometry suggestive of low bone activity and adynamic bone disease. These findings suggest that therapeutic interventions associated with excessive lowering of parathyroid activity (parathyroidectomy, excessive calcium or aluminum load) favor lower bone turnover and adynamic bone disease, which could influence the development and progression of AC.

Aluminum↗

PubMed2003

Identification of tetratricopeptide repeat 1 as an adaptor protein that interacts with heterotrimeric G proteins and the small GTPase Ras.

The biological functions of heterotrimeric G proteins and small GTPases are modulated by both extracellular stimuli and intracellular regulatory proteins. Using Saccharomyces cerevisiae two-hybrid screening, we identified tetratricopeptide repeat 1 (TPR1), a 292-amino-acid protein with three TPR motifs, as a Galpha16-binding protein. The interaction was confirmed both in vitro and in transfected mammalian cells, where TPR1 also binds to several other Galpha proteins. TPR1 was found to interact with Ha-Ras preferentially in its active form. Overexpression of TPR1 promotes accumulation of active Ras. TPR1 was found to compete with the Ras-binding domain (RBD) of Raf-1 for binding to the active Ras, suggesting that it may also compete with Ras GTPase-activating protein, thus contributing to the accumulation of GTP-bound Ras. Expression of Galpha16 strongly enhances the interaction between TPR1 and Ras. Removal of the TPR1 N-terminal 112 residues abolishes potentiation by Galpha16 while maintaining the interaction with Galpha16 and the ability to discriminate active Ras from wild-type Ras. We have also observed that LGN, a Galphai-interacting protein with seven TPR motifs, binds Ha-Ras. Thus, TPR1 is a novel adaptor protein for Ras and selected Galpha proteins that may be involved in protein-protein interaction relating to G-protein signaling.

Adaptor Proteins, Vesicular Transport↗