| 1. |
- Brännström, Kristoffer, et al.
(författare)
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The Schistosoma mansoni protein Sm16/SmSLP/SmSPO-1 assembles into a nine-subunit oligomer with potential To inhibit Toll-like receptor signaling
- 2009
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 77:3, s. 1144-1154
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Tidskriftsartikel (refereegranskat)abstract
- The Sm16/SmSLP/SmSPO-1 (Sm16) protein is secreted by the parasite Schistosoma mansoni during skin penetration and has been ascribed immunosuppressive activities. Here we describe the strategy behind the design of a modified Sm16 protein with a decreased aggregation propensity, thus facilitating the expression and purification of an Sm16 protein that is soluble in physiological buffers. The Stokes radii and sedimentation coefficients of recombinant and native proteins indicate that Sm16 is an approximately nine-subunit oligomer. Analysis of truncated Sm16 derivatives showed that both oligomerization and binding to the plasma membrane of human cells depend on multiple C-terminal regions. For analysis of immunomodulatory activities, Sm16 was expressed in Pichia pastoris to facilitate the preparation of a pyrogen/endotoxin-free purified protein. Recombinant Sm16 was found to have no effect on T-lymphocyte activation, cell proliferation, or the basal level of cytokine production by whole human blood or monocytic cells. However, Sm16 exerts potent inhibition of the cytokine response to the Toll-like receptor (TLR) ligands lipopolysaccharide (LPS) and poly(I:C) while being less efficient at inhibiting the response to the TLR ligand peptidoglycan or a synthetic lipopeptide. Since Sm16 specifically inhibits the degradation of the IRAK1 signaling protein in LPS-stimulated monocytes, our findings indicate that inhibition is exerted proximal to the TLR complex.
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| 2. |
- Holmfeldt, Per, 1973-, et al.
(författare)
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Predominant regulators of tubulin monomer-polymer partitioning and their implication for cell polarization.
- 2009
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Ingår i: Cellular and Molecular Life Sciences (CMLS). - : Springer Science and Business Media LLC. - 1420-682X .- 1420-9071. ; 66:20, s. 3263-3276
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Tidskriftsartikel (refereegranskat)abstract
- The microtubule-system organizes the cytoplasm during interphase and segregates condensed chromosomes during mitosis. Four unrelated conserved proteins, XMAP215/Dis1/TOGp, MCAK, MAP4 and Op18/stathmin, have all been implicated as predominant regulators of tubulin monomer-polymer partitioning in animal cells. However, while studies employing the Xenopus egg extract model system indicate that the partitioning is largely governed by the counteractive activities of XMAP215 and MCAK, studies of human cell lines indicate that MAP4 and Op18 are the predominant regulators of the interphase microtubule-array. Here, we review functional interplay of these proteins during interphase and mitosis in various cell model systems. We also review the evidence that MAP4 and Op18 have interphase-specific, counteractive and phosphorylation-inactivated activities that govern tubulin subunit partitioning in many mammalian cell types. Finally, we discuss evidence indicating that partitioning regulation by MAP4 and Op18 may be of significance to establish cell polarity.
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