Secukinumab improves psoriasis symptoms in patients with inadequate response to cyclosporine A: A prospective study to evaluate direct switch

There are limited data on the safety and efficacy of switching to secukinumab from cyclosporine A (CyA) in patients with psoriasis. The purpose of the present study was to assess the efficacy and safety of secukinumab for 16 weeks after direct switching from CyA in patients with moderate-to-severe psoriasis. In this multicenter, open-label, phase IV study, 34 patients with moderate-to-severe psoriasis and inadequate response to CyA received secukinumab 300 mg s.c. at baseline and weeks 1, 2, 3, 4, 8 and 12. The primary end-point was ≥75% improvement from baseline in Psoriasis Area and Severity Index score (PASI 75) at week 16. The efficacy of secukinumab treatment was evaluated up to week 16, and adverse events (AE) were monitored during the study. The primary end-point of the PASI 75 response at week 16 was achieved by 82.4% (n = 28) of patients receiving secukinumab. Early improvements were observed with secukinumab, with PASI 50 response of 41.2% at week 2 and PASI 75 response of 44.1% at week 4. AE were observed in 70.6% (n = 24) of patients, and there were no serious AE or deaths reported in the entire study period. Secukinumab showed a favorable safety profile consistent with previous data with no new or unexpected safety signals. The results of the present study show that secukinumab is effective in patients with psoriasis enabling a smooth and safe direct switch from CyA to biological therapy.

Altered mechanical properties in smooth muscle of mice with a mutated calponin locus

The mechanical properties of smooth muscles in aorta and vas deferens were studied in mice with a mutated basic calponin locus to learn the physiological function of calponin. The intact smooth muscles were stimulated with high KCl and the force development was compared between calponin deficient (knockout, KO) mice and wild type (WT) ones. The isometric force induced by various concentrations of high KCl was lower in KO than in WT both in aorta and in vas deferens. The length-force relations were compared between KO and WT. The active isometric force in KO was significantly lower at most muscle lengths examined than in WT without the change in resting force both in aorta and in vas deferens. In vas deferens, the rate of force development after quick release in length at the peak force was significantly faster in KO than in WT. The above results show that the force development is lower and the rate of cross-bridge cycle is faster in KO mice than in WT ones, suggesting that calponin plays basic roles in the control of the contraction of smooth muscle.

Regulation of shortening velocity by calponin in intact contracting smooth muscles

To elucidate the function of calponin in intact contracting smooth muscle cells in vivo, we generated mice with a mutated basic calponin (h1) locus (Yoshikawa et al., Genes Cells 3, 685-695, 1998). Crossbridge cycling rates were estimated in aortic smooth muscle by the force redevelopment following an isometric step shortening as a function of time after K(+) depolarization. Evidence is presented that calponin is involved in the inhibition of shortening velocity in the tonic phase of contraction. The phosphorylation levels of myosin regulatory light chain and cytosolic calcium concentrations were not significantly different in paired comparisons between calponin-deficient (-/-) and wild-type (+/+) muscles at any time point after stimulation. The force-velocity relationships in vas deferens smooth muscle showed that the maximum shortening velocity of -/- muscle was significantly faster than that of +/+ muscle. There was no change in the length-force relationships in both -/- and +/+ muscles of aorta and vas deferens. The results suggest that calponin plays a role in regulation of the crossbridge cycling and that it may be responsible for reduced shortening velocity during a maintained contraction of mammalian smooth muscle.

Control of melanosome movement in intact and cultured melanophores in the bitterling, Acheilognathus lanceolatus

The melanophores in the dermis on scales in the bitterling, Acheilognathus lanceolatus were studies to obtain information about the control mechanism of aggregation and dispersion using intact, membrane-permeabilized and cultured cells. The cultured melanophores showed supersensitivity, namely, they responded to norepinephrine with much higher sensitivity than intact cells. The cultured melanophores failed to respond to high KCl. Melatonin aggregated and adenosine dispersed melanosomes within a cell. Digitonin permeabilized cells showed aggregation with Ca ions and dispersion by cyclic adenosine 3',5'-monophosphate (cAMP) in the presence of ATP. Movement of melanosomes was observed under the high magnification of light microscope and the tracks of each pigment granule were followed. The granules moved fast and linearly during aggregation, whereas they showed to-and-fro movement during dispersion.

Correct folding of alpha-lytic protease is required for its extracellular secretion from Escherichia coli

alpha-Lytic protease is a bacterial serine protease of the trypsin family that is synthesized as a 39-kD preproenzyme (Silen, J. L., C. N. McGrath, K. R. Smith, and D. A. Agard. 1988. Gene (Amst.). 69: 237-244). The 198-amino acid mature protease is secreted into the culture medium by the native host, Lysobacter enzymogenes (Whitaker, D. R. 1970. Methods Enzymol. 19:599-613). Expression experiments in Escherichia coli revealed that the 166-amino acid pro region is transiently required either in cis (Silen, J. L., D. Frank, A. Fujishige, R. Bone, and D. A. Agard. 1989. J. Bacteriol. 171:1320-1325) or in trans (Silen, J. L., and D. A. Agard. 1989. Nature (Lond.). 341:462-464) for the proper folding and extracellular accumulation of the enzyme. The maturation process is temperature sensitive in E. coli; unprocessed precursor accumulates in the cells at temperatures above 30 degrees C (Silen, J. L., D. Frank, A. Fujishige, R. Bone, and D. A. Agard. 1989. J. Bacteriol. 171:1320-1325). Here we show that full-length precursor produced at nonpermissive temperatures is tightly associated with the E. coli outer membrane. The active site mutant Ser 195----Ala (SA195), which is incapable of self-processing, also accumulates as a precursor in the outer membrane, even when expressed at permissive temperatures. When the protease domain is expressed in the absence of the pro region, the misfolded, inactive protease also cofractionates with the outer membrane. However, when the folding requirement for either wild-type or mutant protease domains is provided by expressing the pro region in trans, both are efficiently secreted into the extracellular medium. Attempts to separate folding and secretion functions by extensive deletion mutagenesis within the pro region were unsuccessful. Taken together, these results suggest that only properly folded and processed forms of alpha-lytic protease are efficiently transported to the medium.

Structural basis for broad specificity in alpha-lytic protease mutants

Binding pocket mutants of alpha-lytic protease (Met 192----Ala and Met 213----Ala) have been constructed recently in an effort to create a protease specific for Met just prior to the scissile bond. Instead, mutation resulted in proteases with extraordinarily broad specificity profiles and high activity [Bone, R., Silen, J. L., & Agard, D. A. (1989) Nature 339, 191-195]. To understand the structural basis for the unexpected specificity profiles of these mutants, high-resolution X-ray crystal structures have been determined for complexes of each mutant with a series of systematically varying peptidylboronic acids. These inhibitory analogues of high-energy reaction intermediates provide models for how substrates with different side chains interact with the enzyme during the transition state. Fifteen structures have been analyzed qualitatively and quantitatively with respect to enzyme-inhibitor hydrogen-bond lengths, buried hydrophobic surface area, unfilled cavity volume, and the magnitude of inhibitor accommodating conformational adjustments (particularly in the region of another binding pocket residue, Val 217A). Comparison of these four parameters with the Ki of each inhibitor and the kcat and Km of the analogous substrates indicates that while no single structural parameter consistently correlates with activity or inhibition, the observed data can be understood as a combination of effects. Furthermore, the relative contribution of each term differs for the three enzymes, reflecting the altered conformational energetics of each mutant. From the extensive structural analysis, it is clear that enzyme flexibility, especially in the region of Val 217A, is primarily responsible for the exceptionally broad specificity observed in either mutant. Taken together, the observed patterns of substrate specificity can be understood to arise directly from interactions between the substrate and the residues lining the specificity pocket and indirectly from interactions between peripheral regions of the protein and the active-site region that serve to modulate active-site flexibility.

Analysis of prepro-alpha-lytic protease expression in Escherichia coli reveals that the pro region is required for activity

The alpha-lytic protease of Lysobacter enzymogenes was successfully expressed in Escherichia coli by fusing the promoter and signal sequence of the E. coli phoA gene to the proenzyme portion of the alpha-lytic protease gene. Following induction, active enzyme was found both within cells and in the extracellular medium, where it slowly accumulated to high levels. Use of a similar gene fusion to express the protease domain alone produced inactive enzyme, indicating that the large amino-terminal pro region is necessary for activity. The implications for protein folding are discussed. Furthermore, inactivation of the protease by mutation of the catalytic serine residue resulted in the production of a higher-molecular-weight form of the alpha-lytic protease, suggesting that the enzyme is self-processing in E. coli.

Non-histone chromosomal protein HMG1 modulates the histone H1-induced condensation of DNA

Circular dichroic spectra revealed that the previously known regular, asymmetric condensation of DNA by H1 histone was modulated by HMG1, a nonhistone chromosomal protein. Under approximately physiological salt and pH conditions (150 mM NaCl, pH 7), ellipticities at 270 nm were observed as follows: DNA, 9 X 10(3) degree, cm2/dmol nucleotide; DNA X H1 histone complex (1:0.4, w/w), -37 X 10(3) degree, cm2/dmol nucleotide, and DNA X H1 X HMG1 complex (1:0.4:0.4 w/w/w), -52 X 10(3) degree, cm2/dmol. HMG1 by itself did not distort the spectrum of DNA, showing that the effect of HMG1 on the DNA X H1 complex was not simply the summation of individual effects of HMG1 and H1 on the DNA spectrum. The effect of added HMG1 on the spectrum of the preformed DNA X H1 complex depended on the amount of HMG1 added and developed slowly (a day) as if a structure required annealing. The ternary complex, DNA X HMG1 X 1, seemed to represent a specific structure, since its formation depeNded on the reduced sulfhydryl state of HMG1; the disulfide form of HMG1, which was shown by circular dichroism to contain more random coil than did the reduced form, had no effect on the circular dichroic spectrum of the DNA X H1 complex.