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CD22 is a negative regulator of B-cell receptor signaling, an activity mediated by recruitment of SH2 domain–containing phosphatase 1 through a phosphorylated immunoreceptor tyrosine inhibitory motif in its cytoplasmic domain. As in other members of the sialic acid–binding immunoglobulin-like lectin, or siglec, family, the extracellular N-terminal immunoglobulin domain of CD22 binds to glycan ligands containing sialic acid, which are highly expressed on B-cell glycoproteins. B-cell glycoproteins bind to CD22 in cis and 'mask' the ligand-binding domain, modulating its activity as a regulator of B-cell signaling. To assess cell-surface cis ligand interactions, we developed a new method for in situ photoaffinity cross-linking of glycan ligands to CD22. Notably, CD45, surfaceIgM (sIgM) and other glycoproteins that bind to CD22 in vitro do not appear to be important cis ligands of CD22 in situ. Instead, CD22 seems to recognize glycans of neighboring CD22 molecules as cis ligands, forming homomultimeric complexes. [ABSTRACT FROM AUTHOR]

Two new hybrid nonlinear optical (NLO) polymeric films have been fabricated from the corresponding monomers, α, ω-bis(trimethoxysilyl)-1,4-dipropoxybenzenes bearing one or two moieties of pendant groups of N-(4)-nitrophenol-(L)-prolinol (NPP) on the spacer respectively by molecular design and “in-situ poling and sol-gel” process. These films are of enhanced thermal stability, extended temporal stability and higher second harmonic generation (SHG) susceptibilities. Their d33 values are 2.0 × 10−8 esu and 3.2 × 10−8 esu., respectively. These properties can be ascribed to the molecule-level embedment of NPP moieties in size-matched pore of the polysilsesquioxanes and fixation of the orientation of the poled chromophore given by the pore formed after the alignment of NPP moieties. The structures and morphologies of the two polymeric films investigated by XRD, FT-IR, DSC, TGA, AFM, etc. show a close correlation with the SHG properties. [ABSTRACT FROM AUTHOR]

Sialic acid (Sia) residues on cell surface are critical for myriad cellular events such as immunity and inflammation. We herein reported the use of abiotic Sia to raise the thresholds of inflammatory cell responses. Identified from a panel of structurally diversified Sia analogs via a cell inflammation assay, Sia-2, with N-butyryl moiety at C-5, markedly lowered LPS-stimulated NF-κB activity in macrophages. Further analysis shows that Sia-2 attenuates phosphorylation of IκB and Erk1/2/p38/JNK, critical for NF-κB signaling and MAPK signaling, and lowers gene transcription of proinflammatory interleukin-6. These results support the use of abiotic Sia as promising agents to modulate cell surface Sia-pertinent cell signaling. [ABSTRACT FROM AUTHOR]