Poly-ADP-ribose-polymerases (PARPs) 1 and 2 are nuclear enzymes that catalyze the poly-ADP-ribosylation of nuclear proteins transferring poly-ADP-ribose (PAR) polymers to specific residues. PARPs and PAR intervene in diverse functions, including DNA repair in the nucleus and stress granule assembly in the cytoplasm. Stress granules contribute to the regulation of translation by clustering and stabilizing mRNAs as well as several cytosolic PARPs and signaling proteins to modulate cell metabolism and survival. Our study is focused on one of these PARPs, PARP12, a Golgi-localized mono-ADP-ribosyltransferase that under stress challenge reversibly translocates from the Golgi complex to stress granules. PARP1 activation and release of nuclear PAR drive this translocation by direct PAR binding to the PARP12-WWE domain. Thus, PAR formation functionally links the activity of the nuclear and cytosolic PARPs during stress response, determining the release of PARP12 from the Golgi complex and the disassembly of the Golgi membranes, followed by a block in anterograde-membrane traffic. Notably, these functions can be rescued by reverting the stress condition (by drug wash-out). Altogether these data point at a novel, reversible nuclear signaling that senses stress to then act on cytosolic PARP12, which in turn converts the stress response into a reversible block in intracellular-membrane traffic.

Highlights d ER exit sites are endowed with an auto-regulatory signaling complex called AREX d The COPII subunit Sec24 senses folded cargo and activates the AREX signaling network d AREX responds to folded cargo fluxes by regulating cargo export and protein synthesis d AREX maintains potentially harmful folded cargo in the ER at steady low levels

Transient receptor potential melastatin 8 (TRPM8), a nonselective cation channel, is the predominant mammalian cold temperature thermosensor and it is activated by cold temperatures and cooling compounds, such as menthol and icilin. Because of its role in cold allodynia, cold hyperalgesia and painful syndromes TRPM8 antagonists are currently being pursued as potential therapeutic agents for the treatment of pain hypersensitivity. Recently TRPM8 has been found in subsets of bladder sensory nerve fibres, providing an opportunity to understand and treat chronic hypersensitivity. However, most of the known TRPM8 inhibitors lack selectivity, and only three selective compounds have reached clinical trials to date. Here, we applied two virtual screening strategies to find new, clinics suitable, TRPM8 inhibitors. This strategy enabled us to identify naphthyl derivatives as a novel class of potent and selective TRPM8 inhibitors. Further characterization of the pharmacologic properties of the most potent compound identified, compound 1, confirmed that it is a selective, competitive antagonist inhibitor of TRPM8. Compound 1 also proved itself active in a overreactive bladder model in vivo. Thus, the novel naphthyl derivative compound identified here could be optimized for clinical treatment of pain hypersensitivity in bladder disorders but also in different other pathologies.

Adenosine diphosphate (ADP)-ribosylation is a posttranslational modification involved in key regulatory events catalyzed by ADP-ribosyltransferases (ARTs). Substrate identification and localization of the mono-ADP-ribosyltransferase PARP12 at the trans-Golgi network (TGN) hinted at the involvement of ARTs in intracellular traffic. We find that Golgin-97, a TGN protein required for the formation and transport of a specific class of basolateral cargoes (e.g., E-cadherin and vesicular stomatitis virus G protein [VSVG]), is a PARP12 substrate. PARP12 targets an acidic cluster in the Golgin-97 coiled-coil domain essential for function. Its mutation or PARP12 depletion, delays E-cadherin and VSVG export and leads to a defect in carrier fission, hence in transport, with consequent accumulation of cargoes in a trans-Golgi/Rab11–positive intermediate compartment. In contrast, PARP12 does not control the Golgin-245–dependent traffic of cargoes such as tumor necrosis factor alpha (TNFα). Thus, the transport of different basolateral proteins to the plasma membrane is differentially regulated by Golgin-97 mono-ADP-ribosylation by PARP12. This identifies a selective regulatory mechanism acting on the transport of Golgin-97– vs. Golgin-245–dependent cargoes. Of note, PARP12 enzymatic activity, and consequently Golgin-97 mono-ADP-ribosylation, depends on the activation of protein kinase D (PKD) at the TGN during traffic. PARP12 is directly phosphorylated by PKD, and this is essential to stimulate PARP12 catalytic activity. PARP12 is therefore a component of the PKD-driven regulatory cascade that selectively controls a major branch of the basolateral transport pathway. We propose that through this mechanism, PARP12 contributes to the maintenance of E-cadherin–mediated cell polarity and cell–cell junctions.

This work aims to elucidate the mechanism by which N-methylpyrrolidone (NMP) enhances the skin permeation of a compound by combining experimental data with molecular dynamic (MD) simulations. The addition of 10% NMP significantly increased the propranolol (PR) permeation through the human epidermis (∼ 15 μg/cm(2) vs ∼ 30 μg/cm(2)) while resulting inefficacious on hydrocortisone (HC) diffusion. No significant alterations in the stratum corneum structure were found after the in vitro treatment of human epidermis with NMP dispersed in mineral oil or water by attenuated total reflectance Fourier transform infrared (ATR-FTIR) analyses. MD simulations revealed the formation of a complex by H-bonds and the π-π stacking interactions between the NMP's amido group and the drug's aromatic systems. The size of the depicted NMP/PR clusters was in line with the hydrodynamic radius derived by dynamic light scattering analyses (∼ 2.00 nm). Conversely, no interaction, and consequently cluster formation, between NMP and HC occurred. These results suggest that NMP is effective in enhancing the drug permeation through human epidermis by a cotransport mechanism when NMP/drug interaction occurs.

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Background Shp1, a tyrosine-phosphatase-1 containing the Src-homology 2 (SH2) domain, is involved in inflammatory and immune reactions, where it regulates diverse signalling pathways, usually by limiting cell responses through dephosphorylation of target molecules. Moreover, Shp1 regulates actin dynamics. One Shp1 target is Src, which controls many cellular functions including actin dynamics. Src has been previously shown to be activated by a signalling cascade initiated by the cytosolic-phospholipase A 2 (cPLA 2 ) metabolite glycerophosphoinositol 4-phosphate (GroPIns4 P ), which enhances actin polymerisation and motility. While the signalling cascade downstream Src has been fully defined, the mechanism by which GroPIns4 P activates Src remains unknown. Methods Affinity chromatography, mass spectrometry and co-immunoprecipitation studies were employed to identify the GroPIns4 P- interactors; among these Shp1 was selected for further analysis. The specific Shp1 residues interacting with GroPIns4 P were revealed by NMR and validated by site-directed mutagenesis and biophysical methods such as circular dichroism, isothermal calorimetry, fluorescence spectroscopy, surface plasmon resonance and computational modelling. Morphological and motility assays were performed in NIH3T3 fibroblasts. Results We find that Shp1 is the direct cellular target of GroPIns4 P . GroPIns4 P directly binds to the Shp1-SH2 domain region (with the crucial residues being Ser 118, Arg 138 and Ser 140) and thereby promotes the association between Shp1 and Src, and the dephosphorylation of the Src-inhibitory phosphotyrosine in position 530, resulting in Src activation. As a consequence, fibroblast cells exposed to GroPIns4 P show significantly enhanced wound healing capability, indicating that GroPIns4 P has a stimulatory role to activate fibroblast migration. GroPIns4 P is produced by cPLA 2 upon stimulation by diverse receptors, including the EGF receptor. Indeed, endogenously-produced GroPIns4 P was shown to mediate the EGF-induced cell motility. Conclusions This study identifies a so-far undescribed mechanism of Shp1/Src modulation that promotes cell motility and that is dependent on the cPLA 2 metabolite GroPIns4 P . We show that GroPIns4 P is required for EGF-induced fibroblast migration and that it is part of a cPLA 2 /GroPIns4 P/ Shp1/Src cascade that might have broad implications for studies of immune-inflammatory response and cancer. El...

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