A fluorescent polarization-based assay for the identification of disruptors of the RCAN1-calcineurin A protein complex.

Calcineurin is a Ca(2+)/calmodulin-dependent serine/threonine protein phosphatase involved in many biological processes and developmental programs, including immune response. One of the most studied substrates of calcineurin is the transcription factor NFAT (nuclear factor of activated T cells) responsible for T-cell activation. Different anticalcineurin drugs, such as cyclosporine A and FK506, are the most commonly used immunosuppressants in transplantation therapies. Unfortunately, their mechanism of action, completely blocking the calcineurin phosphatase activity while also requiring continuous administration, bears severe side effects. During recent years, the family of regulators of calcineurin (RCAN) has been described and studied extensively as modulators of calcineurin signaling pathways. The RCAN1 region, spanning amino acids 198 to 218 and responsible for inhibiting the calcineurin-NFAT signaling pathway in vivo, has been identified. An RCAN1-derived peptide spanning this sequence interferes with the calcineurin-NFAT interaction without affecting the general calcineurin phosphatase activity. Here we report the development of an optimized in vitro high-throughput fluorescence polarization assay based on the disruption of the RCAN1(198-218)-CnA interaction for identifying molecules with immunosuppressant potential. This approach led us to identify dipyridamole as a disruptor of such interaction. Moreover, three small molecules with a potential immunosuppressive effect were also identified.

Synthesis of a positional scanning library of pentamers of N-alkylglycines assisted by microwave activation and validation via the identification of trypsin inhibitors.

A positional scanning library of 625 N-alkylglycine pentamers has been synthesized on solid-phase, employing a set of 10 commercially available primary amines as a source of chemical diversity. The iterative synthetic steps were carried out in tea bags and accelerated by using microwave assisted organic synthesis (MAOS). The reactivity study of the primary amines used as diversity sources led to determine their relative reactivity values and equireactivity factors, which were applied to the library synthesis to ensure comparable concentrations of all final oligomers in the mixtures. This library was validated by the screening, deconvolution, and identification of trypsin inhibitors. These compounds are of potential interest for controlling the intracellular transport of TRPV1 channel.

Manufacturing of Plasma-Derived Medicinal Products: Qualification Process of Plasma Suppliers.

Manufacturers of human plasma-derived products ensure, through their qualification departments, the quality and safety of human plasma-the biological starting material of the industrial fractionation process. The qualification department has established written procedures to approve the plasma supplier (i.e., initial qualification) according to current regulations and to the manufacturer's plasma specifications. Once the plasma supplier is approved, a periodical assessment is necessary (i.e., continuous qualification) to guarantee the level of compliance. In addition, a signed quality agreement between the plasma supplier and the manufacturer defines the duties and the responsibilities of both parties. The qualification department implements the following requirements to ensure the quality of plasma from suppliers: (i) a regular audit program to confirm the satisfactory initiation of the quality arrangements and (ii) monitoring of the quality and safety of plasma including critical quality parameters. For several years, the Grifols Qualification Department has worked with several plasma suppliers of the European Union (EU) and has performed a detailed, continuous assessment of the audits, deviations, operational incidences, epidemiological data, and quality controls. In this article, we will report data from this Grifols assessment from 2010 through 2013 on plasma suppliers from four EU countries. In the future, additional data will be collected and studied to confirm and verify the conclusions and trends observed in this study.

A semaphorin 3A inhibitor blocks axonal chemorepulsion and enhances axon regeneration.

Secreted semaphorins are a large group of extracellular proteins involved in a variety of processes during development, including neuronal migration and axon guidance. We screened a peptoid combinatorial library to search for semaphorin 3A inhibitors, and identified a peptoid (SICHI: semaphorin Induced chemorepulsion inhibitor) that blocks semaphorin 3A-chemorepulsion and growth-cone collapse in axons at millimolar concentrations. SICHI inhibits the binding of semaphorin 3A to its receptor complex (neuropilin 1/plexin A1) and semaphorin 3A-induced phosphorylation of GSK3. Chemorepulsion induced by semaphorin 3F or netrin 1 is not blocked by SICHI. We also show that SICHI promotes neural regeneration of damaged axons. We suggest that SICHI, a selective inhibitor of semaphorin 3A, is of therapeutic interest for approaches aimed at promoting axonal regeneration and brain repair.

Inhibiting the calcineurin-NFAT (nuclear factor of activated T cells) signaling pathway with a regulator of calcineurin-derived peptide without affecting general calcineurin phosphatase activity.

Calcineurin phosphatase plays a crucial role in T cell activation. Dephosphorylation of the nuclear factors of activated T cells (NFATs) by calcineurin is essential for activating cytokine gene expression and, consequently, the immune response. Current immunosuppressive protocols are based mainly on calcineurin inhibitors, cyclosporine A and FK506. Unfortunately, these drugs are associated with severe side effects. Therefore, immunosuppressive agents with higher selectivity and lower toxicity must be identified. The immunosuppressive role of the family of proteins regulators of calcineurin (RCAN, formerly known as DSCR1) which regulate the calcineurin-NFAT signaling pathway, has been described recently. Here, we identify and characterize the minimal RCAN sequence responsible for the inhibition of calcineurin-NFAT signaling in vivo. The RCAN-derived peptide spanning this sequence binds to calcineurin with high affinity. This interaction is competed by a peptide spanning the NFAT PXIXIT sequence, which binds to calcineurin and facilitates NFAT dephosphorylation and activation. Interestingly, the RCAN-derived peptide does not inhibit general calcineurin phosphatase activity, which suggests that it may have a specific immunosuppressive effect on the calcineurin-NFAT signaling pathway. As such, the RCAN-derived peptide could either be considered a highly selective immunosuppressive compound by itself or be used as a new tool for identifying innovative immunosuppressive agents. We developed a low throughput assay, based on the RCAN1-calcineurin interaction, which identifies dipyridamole as an efficient in vivo inhibitor of the calcineurin-NFAT pathway that does not affect calcineurin phosphatase activity.