Carbohydrates and glycoconjugates

Expression of pancreatitis-associated protein after traumatic brain injury: a mechanism potentially contributing to neuroprotection in human brain

Neuronal cell death after severe traumatic brain injury (TBI) is caused by a complex interplay of pathological mechanisms including excitotoxicity, oxidative stress, mitochondrial dysfunction, extensive neuroinflammation, and ischemia-reperfusion injury. Pancreatitis-associated protein I (PAP I/reg2) was reported to be a survival factor for peripheral neurons, particularly sensory and motor neurons. In rat brains, by experimental TBI as well as by kainic acid induced brain seizure, PAP I and PAP III were found to be up-regulated in central neurons. In this study, we performed immunohistochemical staining in postmortem human brain from patients who died after severe TBI to demonstrate PAP expression on protein level in cerebellar Purkinje cells, pyramidal and granular neurons in cerebral cortex, and cortical neurons in the fore- and mid-brain. In primary cultures of rat brain cortical, hippocampal, and cerebellar neurons, we found neuroprotective effects for PAP I on H(2)O(2)-induced oxidative stress. Moreover, serum K(+)-deprivation induces apoptotic cell death in 55% of cerebellar granule neurons (CGN), whereas upon treatment with PAP I only 32% of CGN are apoptotic. Using Western blot analyses, we compared protein phosphorylation in neuronal signaling pathways activated by PAP I versus Interleukin-6 (IL-6). We found a rapid activation of Akt-kinase phosphorylation by PAP I with a peak at 15 min, whereas IL-6 induces Akt-phosphorylation lasting longer than 30 min. Phosphorylation of MAP-42/44 kinases is stimulated in a comparable fashion. Both, IL-6 and PAP I increase phosphorylation of NFκB for activation of gene transcription, whereas only IL-6 recruits STAT3 phosphorylation, indicating that STAT3 is not a target of PAP I transcription activation in brain neurons. Application of the Akt-inhibitor Wortmanin reveals only a partial inhibition of PAP I-dependent protection of CGN from H(2)O(2)-induced oxidative stress. Based on our findings, we suggest that PAP I is a long lasting neurotrophic signal for central neurons. The neuroprotective effects parallel those that have been described for effects of PAP I in ciliary neurotrophic factor (CNTF)-mediated survival of sensory and motor neurons. PAP I may act in autocrine and/or paracrine fashion and thus may contribute to endogenous protective mechanisms relevant under harmful conditions like oxidative stress, brain injury, or neurodegeneration.

2,5-Anhydro sugar diacid and 2,5-anhydro sugar diamine based C 2 symmetric peptidomimetics as potential HIV-1 protease inhibitors

Conformationally constrained molecular frameworks of the 2,5-anhydro sugar diacid (9) and 2,5-anhydro sugar diamines (10, 11) were used to construct architecturally beautiful novel C ₂ symmetric peptidomimetics 1-8. Although none of these compounds showed any significant HIV-1 protease inhibitory activity, further refinements in design may lead to protease inhibitors based on these rigid carbohydrate-derived scaffolds.

CD69 and regulation of the immune function

CD69, also known as activation inducer molecule, very early activation antigen, MLR-3 and Leu-23, is a member of the natural killer (NK) cell gene complex family of signal transducing receptors. CD69 is as a type II transmembrane glycoprotein with a C-type lectin binding domain in the extracellular portion of the molecule. CD69 expression is induced in vitro on cells of most hematopoietic lineages, including T and B lymphocytes, NK cells, murine macrophages, neutrophils and eosinophils, while it is constitutively expressed on human monocytes, platelets and epidermal Langerhans cells. Although a specific ligand for CD69 has not been identified, its wide cellular distribution and the induction of intracellular signals upon CD69 crosslinking suggest a role for the receptor in the biology of hematopoietic cells. Moreover, certain results indicate that CD69 may be involved in the pathogenesis of such diseases as rheumatoid arthritis, chronic inflammatory liver diseases, mild asthma, and acquired immunodeficiency syndrome.

Two-dimensional mapping of 8-amine-1,3,6-naphthalene trisulfonic acid derivatives of N-linked neutral and sialyloligosaccharides

We describe a simple and sensitive two-dimensional sugar-mapping technique of 8-amine-1,3,6-naphthalene trisulfonic acid derivatives (ANTS derivatives) of neutral and sialyloligosaccharides for structure analysis and characterization of N-linked oligosaccharides using picomoles of samples. The method includes: (1) reductive amination with ANTS of enzymatically released oligosaccharides, (2) simultaneous separation of oligosaccharide derivatives in a fluorophore-assisted carbohydrate electrophoresis and NH2-HPLC column under ion suppression conditions, (3) plotting of the relative migration indexes (X axis) and relative retention times (Y axis), and (4) when necessary, additional exoglycosidase digestion. As illustrated by the glycosylation profiling and structural analysis of alpha 1 anti-trypsin and murine IgG 2a, this methodology fulfills most of the requirements for a complete characterization of neutral and charged oligosaccharides released from N-glycosylated glycoprotein.