Metalloprotease-mediated cleavage of CD95 ligand

CD95 is a member of the TNF receptor superfamily that is ubiquitously expressed in healthy and pathological tissues. Stimulation of CD95 by its physiological ligand CD95L induces its oligomerization leading in turn to the transduction of either apoptotic or nonapoptotic signals. CD95L can exist as both membrane-anchored and soluble forms (sCD95L), the latter resulting from the proteolytic cleavage of the former. Candidate proteases able to achieve CD95L cleavage were identified as matrix metalloproteases (MMP) due to their demonstrated ability to cleave other TNF superfamily ligands. The main goal of this study was to systematically identify the MMP family members capable of cleaving CD95L and subsequently determine the corresponding cleavage sites. By using different orthogonal biochemical approaches and combining them with molecular modelling, we confirmed data from the literature regarding CD95L cleavage by MMP-3 and MMP-7. Moreover, we found that MMP-2 and MMP-12 can cleave CD95L and characterized their resulting cleavage sites. This study provides a systematic approach to analyse the cleavage of CD95L, which until now had only been poorly described.

Therapeutic approaches targeting CD95L/CD95 signaling in cancer and autoimmune diseases

Cell death plays a pivotal role in the maintenance of tissue homeostasis. Key players in the controlled induction of cell death are the Death Receptors (DR). CD95 is a prototypic DR activated by its cognate ligand CD95L triggering programmed cell death. As a consequence, alterations in the CD95/CD95L pathway have been involved in several disease conditions ranging from autoimmune diseases to inflammation and cancer. CD95L-induced cell death has multiple roles in the immune response since it constitutes one of the mechanisms by which cytotoxic lymphocytes kill their targets, but it is also involved in the process of turning off the immune response. Furthermore, beyond the canonical pro-death signals, CD95L, which can be membrane-bound or soluble, also induces non-apoptotic signaling that contributes to its tumor-promoting and pro-inflammatory roles. The intent of this review is to describe the role of CD95/CD95L in the pathophysiology of cancers, autoimmune diseases and chronic inflammation and to discuss recently patented and emerging therapeutic strategies that exploit/block the CD95/CD95L system in these diseases.

Atropisomerism in a 10-Membered Ring with Multiple Chirality Axes: (3 Z,9 Z)-1,2,5,8-Dithiadiazecine-6,7(5 H,8 H)-dione Series

For the first time, chirality in (3 Z,9 Z)-1,2,5,8-dithiadiazecine-6,7(5 H,8 H)-dione series was recognized. Enantiomers of the 4,9-dimethyl-5,8-diphenyl analogue were isolated at room temperature, and their thermal stability was determined. X-ray crystallography confirmed the occurrence of a pair of enantiomers in the crystal. Absolute configurations were assigned by comparing experimental and calculated vibrational/electronic circular dichroism spectra of isolated enantiomers. A distorted tesseract (four-dimensional hypercube) was used to visualize the calculated enantiomerization process, which requires the rotation around four chirality axes. Conformers of higher energy as well as several concurrent pathways of similar energies were revealed.

A forgotten chiral spiro compound revisited: 3,3'-dimethyl-3H,3'H-2,2'-spirobi[[1,3]benzothiazole]

The title compound was obtained as a side product during dimerization-oxidation steps of the carbene generated from N-methylbenzothiazolium iodide. Chromatography on (S,S)-Whelk O1 column showed on cooling a typical plateau shape chromatogram indicating an exchange between two enantiomers on the column. The thermal barrier to racemization was determined (85 kJ.mol(-1) at 10 °C) by dynamic high-performance liquid chromatography (DHPLC).The absolute configuration of the first (M) and second eluted (P) enantiomers on the (S, S)-Whelk O1 column was established by comparing the reconstructed circular dichroism (CD) spectra from the CD detector signal and the calculated CD spectrum of the (P) enantiomer. Mass spectrometry revealed that 3,3'-dimethyl-3H,3'H-2,2'-spirobi[[1,3]benzothiazole] can be viewed as a masked thiophenate attached to a benzothiazolium framework.