The type II transmembrane multidomain serine proteinase MT-SP1/matriptase is highly expressed in many human cancer-derived cell lines and has been implicated in extracellular matrix re-modeling, tumor growth, and metastasis. We have expressed the catalytic domain of MT-SP1 and solved the crystal structures of complexes with benzamidine at 1.3 Å and bovine pancreatic trypsin inhibitor at 2.9 Å. MT-SP1 exhibits a trypsinlike serine proteinase fold, featuring a unique nine-residue 60-insertion loop that influences interactions with protein substrates. The structure discloses a trypsinlike S1 pocket, a small hydrophobic S2 subsite, and an open negatively charged S4 cavity that favors the binding of basic P3/P4 residues. A complementary charge pattern on the surface opposite the active site cleft suggests a distinct docking of the preceding low density lipoprotein receptor class A domain. The benzamidine crystals possess a freely accessible active site and are hence well suited for soaking small molecules, facilitating the improvement of inhibitors. The crystal structure of the MT-SP1 complex with bovine pancreatic trypsin inhibitor serves as a model for hepatocyte growth factor activator inhibitor 1, the physiological inhibitor of MT-SP1, and suggests determinants for the substrate specificity.The activity of proteolytic enzymes is required at multiple stages during the growth, invasion, and progression of human tumors (for a review, see Ref. 1). For example, these complex processes entail extensive re-modeling of the extracellular matrix as well as the activation of latent growth factors and pro-angiogenic proteins. Consequently, the high level expression of particular proteinases often correlates with poor patient survival for several different cancers (see, for instance, Ref. The enzyme was initially assigned as a gelatinase, because of its gelatinolytic properties and gelatinase-like molecular weight. However, isolation and sequencing of the cDNA revealed a 683-residue multidomain proteinase with a C-terminal serine proteinase domain. The enzyme was then named matriptase to emphasize its matrix degrading properties and trypsin-like specificity (5). Independently, Takeuchi and coworkers (6) cloned and characterized a type-II membranebound trypsin-like serine proteinase from a human prostatic cancer cell line, which they called membrane-type serine proteinase 1, MT-SP1. This 855-residue proteinase contained two tandem repeats of the complement component C1r/s domain (CUB, derived from complement factor/1R-urchin embryonic growth factor/bone morphogenetic protein) and four tandem repeats of the low density lipoprotein receptor (LDLR) class A domain between the N-terminal transmembrane signal anchor and the C-terminal catalytic domain (5, 6). Because the matriptase sequence reported by Lin turned out to be part of the translated MT-SP1 cDNA sequence, matriptase is likely to be a form of MT-SP1 produced by ectodomain shedding (7). Alternatively, the two cDNAs may result from alternative splicing. MT-SP1 is highly exp...

Hermansky-Pudlak syndrome (HPS) is a rare heterogeneously inherited autosomal recessive group of disorders presenting with oculocutaneous albinism, bleeding diathesis and pulmonary disease. HPS is thought to occur as a consequence of disturbed formation or trafficking of intracellular vesicles, most importantly, melanosomes, platelet dense granules and lysosomes. The latter finding, in particular, contributes much to the morbidity associated with the disease, as ceroid lipofuscin deposits in lysosomes affect many organ systems. This is especially problematic in the lungs where it is often associated with pulmonary fibrosis and premature death. Currently, there are 7 known HPS genes in humans. In the mouse, at least 16 known HPS genes produce HPS-mutant phenotypes. The HPS gene mutation is considered to be one of the most prevalent single-gene disorders in northwest Puerto Rico, home to the largest cohort of known patients. In HPS, interventions addressing the bleeding diathesis and pulmonary fibrosis are often disappointingly ineffectual. Pirfenidone, a novel compound with documented anti-inflammatory, antioxidant and antifibrotic effects, appears to hold promise in delaying or preventing fibrosis. To date, there has been one successful lung transplant performed on a patient with HPS. We present a patient with HPS and review the current literature on our understanding of this rare disorder.

Previous studies have shown that docosahexaenoic acid (DHA) has an antihypertensive effect in spontaneously hypertensive rats (SHR). To investigate possible mechanisms for this effect, vascular pathology and reactivity were determined in SHR treated with dietary DHA. SHR (7 weeks) were fed a purified diet with either a combination of corn/soybean oils or a DHA-enriched oil for 6 weeks. Histological evaluation of heart tissue, aorta, coronary, and renal arteries was performed. Vascular responses were determined in isolated aortic rings. Contractile responses to agonists, including norepinephrine (10(-9) to 10(-4) M), potassium chloride (5-55 mM), and angiotensin II (5 x 10(-7) M) were assessed. Vasorelaxant responses to acetylcholine (10(-9) to 10 (-4) M), sodium nitroprusside (10(-9) to 10(-6) M), papaverine (10(-5) to 10(-4) M), and methoxyverapamil (D600, 1-100 microM) were determined. DHA-fed SHR had significantly reduced blood pressure (P < 0.001) and vascular wall thicknesses in the coronary, thoracic, and abdominal aorta compared with controls (P < 0.05) Contractile responses to agonists mediated by receptor stimulation and potassium depolarization were not altered in DHA-fed SHR. Endothelial-dependent relaxations to acetylcholine were not altered which suggests endothelial-derived nitric oxide production/release is not affected by dietary DHA. Other mechanisms of vascular relaxation, including intracellular cyclic nucleotides, cGMP, and cAMP were not altered by dietary DHA because aortic relaxant responses to sodium nitroprusside and papaverine were similar in control and DHA-fed SHR. No significant differences were seen in relaxant responses to the calcium channel blocker, D600, or contractile responses to norepinephrine in the absence of extracellular calcium. These results suggest that dietary DHA does not affect mechanisms related to extracellular calcium channels or intracellular calcium mobilization. Moreover, the contractile and vasorelaxant responses are not differentially altered with dietary DHA in this in vivo SHR model. The findings demonstrate that dietary DHA reduces systolic blood pressure and vascular wall thickness in SHR. This may contribute to decrease arterial stiffness and pulse pressure, in addition to the antihypertensive properties of DHA. The antihypertensive properties of DHA are not related to alterations in vascular responses.

Background: CD26 is expressed by most CD41 T cells in normal peripheral blood specimens. Neoplastic T cells are frequently CD262 in mycosis fungoides/Sezary syndrome involving the peripheral blood. However, CD26 expression by reactive and neoplastic T cells in solid tissues and body fluids has not been fully characterized by flow cytometry (FC).Methods: Solid tissue and body fluid specimens were assayed for CD26 expression using four-color FC immunophenotyping, by qualitative assessment of population clusters, and by quantitation with comparison with isotype controls. Benign T cells were studied in reactive tissues and in the background of other malignancies.Results: Many T-cell lymphomas were dim or negative for CD26, whereas a few were brightly positive. In the majority of T-cell lymphomas, CD26 expression could potentially help identify aberrant population clusters. T cells in reactive tissue specimens and tumor-infiltrating T cells were commonly dim to negative for CD26.Conclusions: Both T-cell lymphomas and reactive T cells in tissue and body fluid specimens often show low levels of CD26 expression. Therefore, quantitative methods may not reliably distinguish benign from neoplastic T cells in these specimens. However, CD26, in combination with other T-cell markers, can be helpful for identifying aberrant population clusters in T-cell lymphomas. q 2008 Clinical Cytometry

We report a newborn female with craniofacial malformations, bilateral anophthalmia, large abnormally shaped ears, short neck, small distal phalanges and nails, left diaphragmatic hernia, hypoplastic optic nerves, severe pulmonary hypoplasia, and an accessory spleen, and describe the autopsy findings. The infant expired at 18 h of life. The features were most consistent with Fryns syndrome although other conditions were considered including Matthew Wood syndrome. Anophthalmia, to our knowledge, has not been reported previously in Fryns syndrome; however, eye findings are common, particularly microphthalmia and cloudy cornea.