C3 glomerulopathy is a recently introduced pathological entity whose original definition was glomerular pathology characterized by C3 accumulation with absent or scanty immunoglobulin deposition. In August 2012, an invited group of experts (comprising the authors of this document) in renal pathology, nephrology, complement biology, and complement therapeutics met to discuss C3 glomerulopathy in the first C3 Glomerulopathy Meeting. The objectives were to reach a consensus on: the definition of C3 glomerulopathy, appropriate complement investigations that should be performed in these patients, and how complement therapeutics should be explored in the condition. This meeting report represents the current consensus view of the group.

The functional capacity of C5 variants with mutations at Arg885, together with their failure to undergo blockade by eculizumab, account for the poor response to this agent in patients who carry these mutations. (Funded by Alexion Pharmaceuticals and the Ministry of Health, Labor, and Welfare of Japan.).

Eculizumab, a monoclonal antibody (mAb) directed against complement protein C5, is considered to be the current standard of care for patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome. This study describes the generation and preclinical attributes of ALXN1210, a new long-acting anti-C5 mAb, obtained through select modifications to eculizumab to both largely abolish target-mediated drug disposition (TMDD) and increase recycling efficiency via the neonatal Fc receptor (FcRn). To attenuate the effect of TMDD on plasma terminal half-life (t1/2), histidine substitutions were engineered into the complementarity-determining regions of eculizumab to enhance the dissociation rate of the mAb:C5 complex in the acidic early endosome relative to the slightly basic pH of blood. Antibody variants with optimal pH-dependent binding to C5 exhibited little to no TMDD in mice in the presence of human C5. To further enhance the efficiency of FcRn-mediated recycling of the antibody, two additional substitutions were introduced to increase affinity for human FcRn. These substitutions yielded an additional doubling of the t½ of surrogate anti-mouse C5 antibodies with reduced TMDD in transgenic mice expressing the human FcRn. In conclusion, ALXN1210 is a promising new therapeutic candidate currently in clinical development for treatment of patients with PNH and atypical hemolytic uremic syndrome.

We have characterized comprehensive transcript and proteomic profiles of cell lines corresponding to normal breast (MCF10A), noninvasive breast cancer (MCF7) and invasive breast cancer (MDA-MB-231). The transcript profiles were first analysed by a modified protocol for representational difference analysis (RDA) of cDNAs between MCF7 and MDA-MB-231 cells. The majority of genes identified by RDA showed nearly complete concordance with microarray results, and also led to the identification of some differentially expressed genes such as lysyl oxidase, copper transporter ATP7A, EphB6, RUNX2 and a variant of RUNX2. The altered transcripts identified by microarray analysis were involved in cell-cell or cell-matrix interaction, Rho signaling, calcium homeostasis and copper-binding/sensitive activities. A set of nine genes that included GPCR11, cadherin 11, annexin A1, vimentin, lactate dehydrogenase B (upregulated in MDA-MB-231) and GREB1, S100A8, amyloid b precursor protein, claudin 3 and cadherin 1 (downregulated in MDA-MB-231) were sufficient to distinguish MDA-MB-231 from MCF7 cells. The downregulation of a set of transcripts for proteins involved in cell-cell interaction indicated these transcripts as potential markers for invasiveness that can be detected by methylation-specific PCR. The proteomic profiles indicated altered abundance of fewer proteins as compared to transcript profiles. Antisense knockdown of selected transcripts led to inhibition of cell proliferation that was accompanied by altered proteomic profiles. The proteomic profiles of antisense transfectants suggest the involvement of peptidyl-prolyl isomerase, Raf kinase inhibitor and 80 kDa protein kinase C substrate in mediating the inhibition of cell proliferation.

We reported previously the cloning of a novel human serine protease inhibitor containing two Kunitz-like domains, designated as placental bikunin, and the subsequent purification of a natural counterpart from human placental tissue (Marlor, C. W., Delaria, K. A., Davis, G., Muller, D. K., Greve, J. M., and Tamburini, P. P. (1997) J. Biol. Chem. 272, 12202-12208). In this report, the 170 residue extracellular domain of placental bikunin (placental bikunin (1-170) ) was expressed in baculovirus-infected Sf9 cells using its putative signal peptide. The resulting 21.3-kDa protein accumulated in the medium with the signal peptide removed and could be highly purified by sequential kallikrein-Sepharose and C 18 reverse-phase chromatography. To provide insights as to the potential in vivo functions of this protein, we performed an extensive investigation of the inhibitory properties of recombinant placental bikunin (1-170) and both of its synthetically prepared Kunitz domains. All three proteins inhibited a number of serine proteases involved in the intrinsic pathway of blood coagulation and fibrinolysis. Placental bikunin (1-170) formed inhibitor-protease complexes with a 1:2 stoichiometry and strongly inhibited human plasmin (K i ‫؍‬ 0.1 nM), human tissue kallikrein (K i ‫؍‬ 0.1 nM), human plasma kallikrein (K i ‫؍‬ 0.3 nM) and human factor XIa (K i ‫؍‬ 6 nM). Conversely, this protein was a weaker inhibitor of factor VIIa-tissue factor (K i ‫؍‬ 1.6 M), factor IXa (K i ‫؍‬ 206 nM), factor Xa (K i ‫؍‬ 364 nM), and factor XIIa (K i ‫؍‬ 430 nM). This specificity profile was to a large extent mimicked, albeit with reduced potency, by the individual Kunitz domains. As predicted from this in vitro specificity profile, recombinant placental bikunin (1-170) prolonged the clotting time in an activated partial thromboplastin time assay.Blood clotting, resulting either from the extrinsic pathway following tissue injury or the intrinsic pathway following contact activation, involves tightly regulated proteolytic cascades (1). The intrinsic pathway is initiated by activation of factor XII either through proteolysis or contact with negatively charged surfaces. Activated factor XIIa, in turn, converts plasma prekallikrein to kallikrein, which can then activate additional factor XII. Factor XIIa activates factor XI, which, in turn, activates factor IX. Activated factor IX forms a complex with factor VIIIa, phospholipid, and calcium, which converts factor X to factor Xa. Factor X is also activated by the factor VIIatissue factor complex operating within the extrinsic pathway. Thrombin generation by factor Xa in complex with factor Va leads ultimately to the formation of the fibrin clot. Thrombus formation is also regulated by the fibrinolytic system whereby plasmin, formed from plasminogen by the action of kallikrein, tissue plasminogen activator (tPA), 1 or urokinase, breaks down both fibrinogen and fibrin (2).Protease inhibitors play critical roles in the regulation of the coagulation and fibrinolytic systems. Tissue factor pathway i...

Interrogation of the public expressed sequence tag (EST) data base with the sequence of preproaprotinin identified ESTs encoding two potential new members of the Kunitz family of serine protease inhibitors. Through reiterative interrogation, an EST contig was obtained, the consensus sequence from which encoded both of the novel Kunitz domains in a single open reading frame. This consensus sequence was used to direct the isolation of a full-length cDNA clone from a placental library. The resulting cDNA sequence predicted a 252-residue protein containing a putative NH 2 -terminal signal peptide followed sequentially by each of the two Kunitz domains within a 170-residue ectodomain, a putative transmembrane domain, and a 31-residue hydrophilic COOH terminus. The gene for this putative novel protein was mapped by use of a radiation hybrid panel to chromosome 19q13, and Northern analysis showed that the corresponding mRNA was expressed at high levels in human placenta and pancreas and at lower levels in brain, lung, and kidney. An endogenous soluble form of this protein, which was designated as placental bikunin, was highly purified from human placenta by sequential kallikrein-Sepharose affinity, gel filtration, and C 18 reverse-phase chromatography. The natural protein exhibited the same NH 2 terminus as predicted from the cloned cDNA and inhibited trypsin, plasma kallikrein, and plasmin with IC 50 values in the nanomolar range.The Kunitz (1, 2), Kazal (2), Serpin (3), and mucus (4) families of biological serine protease inhibitors play a vital role in the spatial and temporal regulation of in vivo proteolysis. The prototypical Kunitz inhibitor, bovine aprotinin (2), is a 58-amino acid protein containing three intrachain disulfide bonds in a spacing that is conserved in all family members (1, 2). Although the physiologic function of aprotinin is uncertain, it is a potent inhibitor of several serine proteases, and its potency against kallikrein and plasmin (5) may be relevant to its clinical mode of action (5, 6), particularly in the reduction of perioperative blood loss. A human functional homolog of aprotinin has not been identified, although several larger human proteins containing one or more Kunitz domains are known. These include: tissue factor pathway inhibitor (TFPI), 1 which contains three Kunitz domains (7) and inhibits both factor Xa and the factor VIIa-tissue factor complex (8); TFPI-2 (9), which contains two Kunitz domains (a bikunin) and is a potent inhibitor of the factor VIIa-tissue factor complex, factor XIa, and plasmin (10); and inter-␣-trypsin inhibitor, a plasma-associated bikunin (11). In addition, the following proteins are known to contain a single Kunitz domain: COL␣3/VI, the ␣(3) chain of type VI collagen (12); HKI-B9, a human Kunitz inhibitor (13); the membrane-associated amyloid precursor proteins APP 751 (14) and APP 770 (15); the amyloid precursor-like proteins (APLP) such as APLP2 (16). To identify novel human homologs of aprotinin we employed a bioinformatic approach that exploited the...

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A covalent complex between rabbit hepatic microsomal cytochromes P-450 isozyme 2 (LM2) and b5 was created and purified to >95% homogeneity. The purified complex was largely comprised of the two cytochromes covalently attached at the interface of the functional electron transfer-effector complex as shown by the following evidence.(i) The spin state of the LM2 within the complex was greater than the spin state of free LM2, and the addition of free cytochrome b5 (cyt b5) did not further increase the spin state of the LM2 within the complex. (il) The spectral binding parameters (Kd and AAI.,.X) for the association of benzphetamine with LM2 in the complex were identical to those observed with free LM2 in the presence of saturating concentrations of free cyt b5 and much different from those observed for LM2 in the absence of cyt b5. (Wi) Reconstituted monooxygenase activity of the covalent LM2-cyt b5 complex (LM2-cyt b5) in the presence of NADPH-cytochrome P-450 reductase was much higher than the activity of free LM2 and approached the activity of free LM2 in the presence of optimal concentrations of free cyt b5. Furthermore, the Km for the flavoprotein in supporting either free LM2 or LM2-cyt b5-dependent p-nitroanisole demethylation were similar. (iv) Less than 20-25% of the cyt b5 within the complex could be reduced by free NADH-cytochrome b5 reductase (NADH-cyt b5 reductase) albeit at a slow rate. The implications of this data to the current understanding of the mechanism and stoichiometry of protein interactions in the hepatic mixed function oxidase system are discussed.Selective chemical modification of amino and carboxyl groups on several redox proteins has established that many of the protein-protein interactions within electron transport chains are mediated by complementary clusters of amino and carboxyl groups situated in the proximity of the respective redox centers (1-6). Data available for the most extensively investigated systems, in particular those involving cytochrome c and/or b5 (cyt b5), have generally supported hypothetical models derived from the computer-graphicassisted manipulation of available x-ray crystal data (7-9).Water-soluble carbodiimides such as 1-(3-dimethylaminopropyl)-3-ethyl-carbodiimide hydrochloride (EDC) have been used as zero-distance cross-linking reagents to promote selective amide bond formation between complementary amino and carboxyl groups located on the respective redox proteins at the interface of the electron transfer complex. Using this technique covalent binary complexes between NADH-cyt b5 reductase and cyt b5 (10), between cytochrome c peroxidase and cytochrome c (11), between adrenodoxin and cytochrome P-40ScC (12), and between NADPH-cytochrome P-450 reductase and cyt b5 (13) have been generated.In some cases the covalent complexes have been separated from the unreacted monomers whereupon catalytic (10,11) studies have often shown the complexes to retain functionality.Cyt b5 is well known to effect a stimulation of the activity of reconstituted cytochrome P...