Thrombomodulin (TM) is an endothelial anticoagulant cofactor that promotes thrombin-mediated formation of activated protein C (APC). We have found that the N-terminal lectin-like domain (D1) of TM has unique antiinflammatory properties. TM, via D1, binds high-mobility group-B1 DNA-binding protein (HMGB1), a factor closely associated with necrotic cell damage following its release from the nucleus, thereby preventing in vitro leukocyte activation, in vivo UV irradiation-induced cutaneous inflammation, and in vivo lipopolysaccharide-induced lethality. Our data also demonstrate antiinflammatory properties of a peptide spanning D1 of TM and suggest its therapeutic potential. These findings highlight a novel mechanism, i.e., sequestration of mediators, through which an endothelial cofactor, TM, suppresses inflammation quite distinctly from its anticoagulant cofactor activity, thereby preventing the interaction of these mediators with cell surface receptors on effector cells in the vasculature.

The Rho family of GTPases are involved in actin cytoskeleton organization and associated with carcinogenesis and progression of human cancers. We investigated the roles of Rho family GTPases, prototypes RhoA, Rac1, and Cdc42, and the major downstream targets of RhoA, ROCK-I, and ROCK-II in testicular cancer. We quantified protein expression in paired tumor and nontumor samples from surgical specimens from 57 consecutive patients with testicular germ cell tumors using Western blotting. Protein expression of RhoA, ROCK-I, ROCK-II, Rac1, and Cdc42 was significantly higher in tumor tissue than in nontumor tissue (P < 0.0001). Expression of protein for RhoA, ROCK-I, ROCK-II, Rac1, and Cdc42 was greater in tumors of higher stages than lower stages (P < 0.0001, P < 0.001, P < 0.001, P < 0.0001, P < 0.0001, respectively). Within stage II nonseminoma (31 patients), protein levels of RhoA, ROCK-I, ROCK-II, Rac1, and Cdc42 in the primary tumor were lower in the group of 24 patients with no evidence of disease after therapy compared with 7 patients with disease that was refractory/recurrent (P < 0.05). Rho family GTPases may be involved in the progression of testicular germ cell tumors.

The modeling and remodeling of bone requires activation and polarization of osteoclasts, achieved by reorganization of the cytoskeleton. Members of the Rho subfamily of small GTPases, including Cdc42, are known regulators of cytoskeletal components, but the role of these proteins in bone physiology and pathophysiology remains unclear. Here, we examined loss-of-function mice in which Cdc42 was selectively ablated in differentiated osteoclasts and gain-of-function animals wherein Cdc42Gap, a protein that inactivates the small GTPase, was deleted globally. Cdc42 loss-of-function mice were osteopetrotic and resistant to ovariectomy-induced bone loss, while gain-of-function animals were osteoporotic. Isolated Cdc42-deficient osteoclasts displayed suppressed bone resorption, while osteoclasts with increased Cdc42 activity had enhanced resorptive capacity. We further demonstrated that Cdc42 modulated M-CSF-stimulated cyclin D expression and phosphorylation of Rb and induced caspase 3 and Bim, thus contributing to osteoclast proliferation and apoptosis rates. Furthermore, Cdc42 was required for multiple M-CSF-and RANKL-induced osteoclastogenic signals including activation and expression of the differentiation factors MITF and NFATc1 and was a component of the Par3/Par6/atypical PKC polarization complex in osteoclasts. These data suggest that Cdc42 regulates osteoclast formation and function and may represent a promising therapeutic target for prevention of pathological bone loss.

Maintenance of bone mass and integrity requires a tight balance between resorption by osteoclasts and formation by osteoblasts. Exocytosis of functional proteins is a prerequisite for the activity of both cells. In the present study, we show that synaptotagmin VII, a calcium sensor protein that regulates exocytosis, is associated with lysosomes in osteoclasts and bone matrix protein-containing vesicles in osteoblasts. Absence of synaptotagmin VII inhibits cathepsin K secretion and formation of the ruffled border in osteoclasts and bone matrix protein deposition in osteoblasts, without affecting the differentiation of either cell. Reflecting these in vitro findings, synaptotagmin VII-deficient mice are osteopenic due to impaired bone resorption and formation. Therefore, synaptotagmin VII plays an important role in bone remodeling and homeostasis by modulating secretory pathways functionally important in osteoclasts and osteoblasts.

ypertrophic cardiomyopathy (HCM) is characterized by disproportionate left ventricular (LV) hypertrophy and LV diastolic dysfunction. However, some patients with HCM develop LV wall thinning associated with LV dilatation and systolic dysfunction. [1][2][3][4][5][6][7] The pathological features reveal that such patients have myocardium with marked fibrosis and abnormal collagen matrices. 8 Evidence suggests that LV myocardial collagen matrix disorganization and changes in the fibrillar collagen network contribute to the progression of LV dilatation and dysfunction. 9,10 Matrix disorganization in LV dilatation has, in turn, been attributed to enhanced collagen degradation Circulation Journal Vol.68, April 2004 through changes in the concentrations of matrix metalloproteinases (MMPs) or their tissue inhibitors (TIMPs). [11][12][13] It has been suspected that the MMPs play an important role in tissue remodeling in both normal and pathological conditions. 14-22 Enhanced activity of MMPs could lead to increased collagen turnover and has been reported in idiopathic dilated cardiomyopathy (DCM), 19 tachycardiainduced heart failure 12,20 and pressure-overload hypertrophy. 13 Elevated concentrations of the serum markers of collagen turnover have also been reported in patients with idiopathic DCM. 21 Soejima et al showed a significant negative correlation between the concentration of serum MMP-1 and LV ejection fraction (LVEF). 22 Collectively, these findings suggest that changes in collagen metabolism may be associated with LV remodeling and the progression of LV systolic dysfunction in patients with HCM. However, the exact details and sequence of clinicopathological events remain uncertain.The present study was conducted in order to test the hypothesis that circulating MMPs and TIMPs may be altered in patients with HCM with systolic dysfunction and may be associated with LV remodeling in HCM. Methods and ResultsEnzyme-linked immunoassays were used to measure the plasma concentrations of MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 in 11 patients with HCM accompanied by systolic dysfunction (fractional shortening (FS) <25%, group A), 17 patients with HCM who had preserved systolic function (FS ≥25%, group B), and 50 age-matched clinically healthy control subjects (mean age: 57 years). The concentration of MMP-2 in group A was significantly higher than in group B and the control subjects (1,124±84, 792±49, 809±26 ng/ml, respectively), whereas there was no significant difference between group B and the control subjects. MMP-2 concentrations significantly increased as the New York Heart Association functional class increased in patients with HCM. TIMP-2 was also significantly higher in group A patients than in group B and the control subjects (45.3±4.7, 34.6±2.2, 33.7±1.8 ng/ml, respectively), but there was no difference between group B and control subjects. TIMP-1 was significantly higher in HCM patients than in control subjects. MMP-3 and MMP-9 concentrations did not differ among the 3 groups. Both MMP-2 and TIMP-2 correlat...