The heparan sulfate proteoglycan syndecan-1 (Sdc1) modulates cell proliferation, adhesion, migration and angiogenesis. Proteinase-mediated shedding converts Sdc1 from a membrane-bound coreceptor into a soluble effector capable of binding the same ligands. In breast carcinomas, Sdc1 overexpression correlates with poor prognosis and an aggressive phenotype. To distinguish between the roles of membrane-bound and shed forms of Sdc1 in breast cancer progression, human MCF-7 breast cancer cells were stably transfected with plasmids overexpressing wild-type (WT), constitutively shed and uncleavable forms of Sdc1. Overexpression of WT Sdc1 increased cell proliferation, whereas overexpression of constitutively shed Sdc1 decreased proliferation. Fibroblast growth factor-2-mediated mitogen-activated protein kinase signaling was reduced following small-interfering RNA (siRNA)-mediated knockdown of Sdc1 expression. Constitutively, membrane-bound Sdc1 inhibited invasiveness, whereas soluble Sdc1 promoted invasion of MCF-7 cells into matrigel matrices. The latter effect was reversed by the matrix metalloproteinase inhibitors N-isobutyl-N-(4-methoxyphenylsufonyl) glycyl hydroxamic acid and tissue inhibitor of metalloproteinase (TIMP)-1. Affymetrix microarray analysis identified TIMP-1, Furin and urokinase-type plasminogen activator receptor as genes differentially regulated in soluble Sdc1-overexpressing cells. Endogenous TIMP-1 expression was reduced in cells overexpressing soluble Sdc1 and increased in those overexpressing the constitutively membrane-bound Sdc1. Moreover, E-cadherin protein expression was downregulated in cells overexpressing soluble Sdc1. Our results suggest that the soluble and membrane-bound forms of Sdc1 play different roles at different stages of breast cancer progression. Proteolytic conversion of Sdc1 from a membrane-bound into a soluble molecule marks a switch from a proliferative to an invasive phenotype, with implications for breast cancer diagnostics and potential glycosaminoglycan-based therapies.

No abstract

The Escherichia coli protein YjeQ represents a protein family whose members are broadly conserved in bacteria and have been shown to be indispensable to the growth of E. coli and Bacillus subtilis [Arigoni, F., et al. (1998) Nat. Biotechnol. 16, 851]. Proteins of the YjeQ family contain all sequence motifs typical of the vast class of P-loop-containing GTPases, but show a circular permutation, with a G4-G1-G3 pattern of motifs as opposed to the regular G1-G3-G4 pattern seen in most GTPases. All YjeQ family proteins display a unique domain architecture, which includes a predicted N-terminal OB-fold RNA-binding domain, the central permuted GTPase module, and a zinc knuckle-like C-terminal cysteine cluster. This domain architecture suggests a possible role for YjeQ as a regulator of translation. YjeQ was overexpressed, purified to homogeneity, and shown to contain 0.6 equiv of GDP. Steady state kinetic analyses indicated slow GTP hydrolysis, with a k(cat) of 9.4 h(-)(1) and a K(m) for GTP of 120 microM (k(cat)/K(m) = 21.7 M(-)(1) s(-)(1)). YjeQ also hydrolyzed other nucleoside triphosphates and deoxynucleotide triphosphates such as ATP, ITP, and CTP with specificity constants (k(cat)/K(m)) ranging from 0.2 to 1.0 M(-)(1) s(-)(1). Pre-steady state kinetic analysis of YjeQ revealed a burst of nucleotide hydrolysis for GTP described by a first-order rate constant of 100 s(-)(1) as compared to a burst rate of 0.2 s(-)(1) for ATP. In addition, a variant in the G1 motif of YjeQ (S221A) was substantially impaired for GTP hydrolysis (0.3 s(-)(1)) with a less significant impact on the steady state rate (1.8 h(-)(1)). In summary, E. coli YjeQ is an unusual, circularly permuted P-loop-containing GTPase, which catalyzes GTP hydrolysis at a rate 45 000 times greater than that of turnover.

The purpose of this prospective study was to examine the incidence, nature, causes, and severity of injuries in female floorball. Three hundred and seventy‐four licensed female floorball players from Finnish top leagues were observed prospectively for one season (6 months). The practice and game hours of floorball were recorded on an exercise diary. All injuries were registered with a structured questionnaire and verified by a physician. During the study period, 133 out of the 374 (35%) players sustained 172 injuries. The injury incidence was 1.8 per 1000 practice hours and 40.3 per 1000 game hours. Of all injuries, 70% were traumatic and 30% were from overuse. The most common injury type was joint sprain (27%). The most commonly injured sites were the knee (27%) and ankle (22%). Twenty‐one of the knee injuries (46%) were serious including 10 anterior cruciate ligament (ACL) ruptures. Eight of ACL ruptures occurred during floorball games, giving an ACL rupture incidence of 3.6 per 1000 game hours. Eleven injuries (6%) needed hospital admission. The study attested that injury rate in floorball game is very high. Injury prevention strategies in female floorball should be targeted at injuries occurring at the knee and ankle.

No abstract

Low-molecular-weight heparin in the treatment of patients with venous thromboembolism Büller, H.R.; Gent, M.; Gallus, A.S.; Ginsberg, J.; Prins, M.H.; Baildon, R.; ten Cate, J.W.

No abstract

Autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED) is a monogenic autoimmune disease that is caused by mutations in the AIRE gene. Murine studies have linked AIRE to thymocyte selection and peripheral deletional tolerance, but the pathogenesis of the human disease remains unclear. In this study, we show that APECED patients have elevated IL-7 levels and a drastically decreased expression of IL-7R on CD8+ T cells. This is associated with increased proliferation and a decreased expression of the negative TCR regulator CD5 in the CD45RO− subset. The CD45RO− cells also display oligoclonal expansions, decreased expression of the lymph node homing factors CCR7 and CD62L, and increased expression of perforin, consistent with the accumulation of highly differentiated effector cells. The CD45RO−CCR7+CD8+ population of cells with markers characteristic of naive phenotype is also skewed, as shown by decreased expression of CD5 and increased expression of perforin. The putative CD31+ recent thymic emigrant population is likewise affected. These data are consistent with IL-7 dysregulation inducing a decreased threshold of TCR signaling and self-antigen–driven proliferation, probably in synergy with the failed thymic selection. The resultant loss of CD8+ T cell homeostasis is likely to play a significant role in the pathogenesis of APECED. Our findings may also hold lessons for other diseases in which the IL-7–IL-7R pathway has emerged as a risk factor.