Proteolytic regulation of the urokinase receptor/CD87 on monocytic cells by neutrophil elastase and cathepsin G

The urokinase receptor (CD87) participates to the pericellular proteolytic potential of migrating cells and to the recruitment of leukocytes during inflammation. It consists of three structurally homologous domains, with the C-terminal domain D3 attached to cell membranes through a GPI anchor. CD87 is susceptible to an endoproteolytic processing removing the N-terminal domain D1 and generating truncated D2D3 membrane species, thus modulating CD87-associated functions. Full-length or truncated CD87 can be also released from cells via juxtamembrane cleavage by phospholipases and/or by yet unidentified proteinases. Using a recombinant CD87 and the CD87-positive monocytic U937 cell line and isolated blood monocytes, we show by protein immunoblotting and flow immunocytometry that the human neutrophil serine-proteinases elastase and cathepsin G cleave CD87 within the D1-D2 linker sequence, while in addition cathepsin G is highly efficient in cleaving the C terminus of D3. The combination of cathepsin G and elastase provided by degranulated neutrophils results in enzymatic cooperation leading to the release from monocytic cells of a truncated D2D3 species resembling that previously described in pathological body fluids. Using mass spectrometry analysis, the proteolytic fragmentation of synthetic peptides mapping the D1-D2 linker and D3 C-terminal domains identifies potential cleavage sites for each enzyme and suggests the existence of a mechanism regulating the CD87(D1-D2)-associated chemotactic activity. Finally, isolated or combined elastase and cathepsin G drastically reduce the capacity of cells to bind urokinase. Secretable leukocyte serine-proteinases are thus endowed with high potential for the regulation of CD87 expression and function on inflammatory cells.     

Aspirin Recapitulates Features of Caloric Restriction

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Co-ordination between membrane oriC sequestration factors and a chromosome partitioning protein, TolC (MukA)

oriC DNA in the hemimethylated (but not in the fully methylated) state reacts with an Escherichia coli K-12 outer membrane preparation. This reaction is drastically reduced when the membrane preparation of a seqA null mutant is used. An in vitro reconstitution of the activity was undertaken by adding a partially purified SeqA protein to a seqA mutant membrane without success. A possible reason for this failure might be a profound modification of the outer membrane of the seqA mutant (as revealed by the fact that membrane from the mutant sediments more slowly than that from the wild type during ultracentrifugation). There is also a reduction in the content of OmpF protein. Moreover, one of the minor outer membrane proteins involved in partitioning of newly synthesized chromosomes, the TolC (MukA) protein, was also found to be downregulated in the seqA mutant. This is also true of the hobH mutant grown in a high-osmolarity medium. Mutants of both seqA and hobH stop dividing after hyperosmotic shock, forming filaments (as observed in dam mutants).     

Liraglutide ameliorated peripheral neuropathy in diabetic rats: Involvement of oxidative stress,inflammation and extracellular matrix remodeling

Diabetic peripheral neuropathy is one of the most common microvascular complications that occurs with both type 1 and type 2 diabetes mellitus. It has a significant negative impact on patients’ quality of life; as it starts with loss of limbs’ sensation and may lead to lower limb amputation. This study aimed at investigating the effect of liraglutide on peripheral neuropathy in diabetic rats. Experimental diabetes was induced by single intraperitoneal injections of nicotinamide (50 mg/kg) and streptozotocin (52.5 mg/kg). Rats were allocated into five groups. Two groups were given saline or liraglutide (0.8 mg/kg, s.c.). Three diabetic groups were either untreated or treated with liraglutide (0.8 mg/kg, s.c.) or pregabalin (10 mg/kg, i.p.). After 2 weeks of treatment, behavioral, biochemical, histopathological, and immunohistochemical investigations were performed. Treatment with liraglutide‐restored animals’ body weight, normalized blood glucose, decreased glycated hemoglobin, and increased insulin levels. In parallel, it normalized motor coordination and the latency withdrawal time of both tail flick and hind paw cold allodynia tests and reversed histopathological alterations. Treatment with liraglutide also normalized malondialdehyde, matrix metalloproteinase‐2 and ‐9 contents in sciatic nerve. Likewise, it decreased sciatic nerve nitric oxide and interleukin‐6 contents, DNA fragmentation and expression of cyclooxygenase‐2. Meanwhile, it increased superoxide dismutase and interleukin‐10 contents in sciatic nerve. These findings indicate the neuroprotective effect of liraglutide against diabetic peripheral neuropathy probably via modulating oxidative stress, inflammation, and extracellular matrix remodeling.