Rosario González-Muñiz

SUMMARY: The phospholipase C-β (PLCβ) signaling pathway plays a pivotal role in peripheral nociception, particularly during inflammation and pain transduction. Despite their validation as important therapeutic targets, PLCβ isoforms are yet undruggable due to the difficulties to identify potent and selective modulators. Here, we addressed this question and used the autoinhibitory XY linker present in these enzymes as a source of peptide inhibitors of PLCβ activity. We report that peptides patterned after this motif inhibited PIP ₂ hydrolysis and the consequent calcium release from endoplasmic reticulum. In primary nociceptor cultures, active peptides notably attenuated bradykinin-induced electrogenesis and TRPV1 sensitization, thus reducing nociceptor hyperexcitability. Noteworthy, intraplantar administration of a lead peptide prevented inflammation and hypersensitivity in a mouse model of inflammatory pain. Collectively, our findings indicate that peptides patterned after the autoinhibitory XY linker act as selective PLCβ inhibitors with in vivo anti-inflammatory and antinociceptive activity, providing pharmacological tools for this enzyme family. SIGNIFICANCE: Phospholipases C (PLC) are intracellular signaling proteins, with PLCβ isoforms crucial in somatosensory neuron signaling. These enzymes interact with G-protein coupled receptors for pro-inflammatory and algesic agents, sensitizing nociceptors by increasing their excitability. Despite their importance, selective PLCβ modulators remain limited; U73122 is widely used, though it lacks specificity and has off-target effects. Here, we introduce peptide inhibitors based on the XY autoinhibitory motif that selectively block PLCβ activity, reduce bradykinin-induced neuronal responses and TRPV1 sensitization, and do not affect other PLC isoforms. In a murine inflammatory pain model, local administration of our lead peptide showed both anti-inflammatory and antinociceptive effects, highlighting its therapeutic potential. This approach expands the toolkit of PLC-isoform selective modulators for drug development.

Aim: To expand the understanding of the structure-activity relationship within a family of amino acid-derived β-lactam TRPM8 (transient receptor potential melastatin channel, subtype 8) antagonists, this work investigated both the configuration-dependence of potency and selectivity, and explored strategies for increasing total polar surface area (TPSA). Methods: Diastereoisomeric compounds derived from H-Phe-OtBu, and analogues incorporating differently substituted benzoyl groups, were synthesized by stereoselective solution pathways. Ca2+ microfluorometry assays were used for TRPM8 antagonist activity assessment, and then confirmed through electrophysiology (patch-clamp assay). The pharmacological activity in vivo was studied on a mice model of oxaliplatin-induced peripheral neuropathy. Results: For OtBu derivatives, a 3S,4S-configuration was preferred, while compounds with 2'R chiral centers show higher selectivity for TRPM8 versus transient receptor potential vanilloid, subtype 1 (TRPV1) than their 2'S-counterparts. N-terminal benzoyl derivatives, which increased TPSA values, resulted in equipotent compounds as previous prototypes, but also showed activity in other pain-related targets [TRPV1 and cannabinoid receptor, subtype 2 (CB2R)]. A selected N-benzoyl derivative displays antinociceptive activity in vivo. Conclusions: The potency and selectivity of these β-lactam TRPM8 antagonists developed from amino acid derivatives depend not only on the configuration but also on the substituents at the 4-carboxy and at the N-benzoyl groups. Dual and multitarget compounds were discovered within this family of TRPM8 antagonists.

The protein transient receptor potential melastatin type 8 (TRPM8), a non-selective, calcium (Ca²⁺)-permeable ion channel is implicated in several pathological conditions, including neuropathic pain states. In our previous research endeavors, we have identified β-lactam derivatives with high hydrophobic character that exhibit potent and selective TRPM8 antagonist activity. This work describes the synthesis of novel derivatives featuring C-terminal amides and diversely substituted N′-terminal monobenzyl groups in an attempt to increase the total polar surface area (TPSA) in this family of compounds. The primary goal was to assess the influence of these substituents on the inhibition of menthol-induced cellular Ca²⁺ entry, thereby establishing critical structure–activity relationships. While the substitution of the tert-butyl ester by isobutyl amide moieties improved the antagonist activity, none of the N′-monobencyl derivatives, regardless of the substituent on the phenyl ring, achieved the activity of the model dibenzyl compound. The antagonist potency of the most effective compounds was subsequently verified using Patch-Clamp electrophysiology experiments. Furthermore, we evaluated the selectivity of one of these compounds against other members of the transient receptor potential (TRP) ion channel family and some receptors connected to peripheral pain pathways. This compound demonstrated specificity for TRPM8 channels. To better comprehend the potential mode of interaction, we conducted docking experiments to uncover plausible binding sites on the functionally active tetrameric protein. While the four main populated poses are located by the pore zone, a similar location to that described for the N-(3-aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)-benzamide (AMTB) antagonist cannot be discarded. Finally, in vivo experiments, involving a couple of selected compounds, revealed significant antinociceptive activity within a mice model of cold allodynia induced by oxaliplatin (OXA).

β-Turns are one of the most common secondary structures found in proteins. In the interest of developing novel β-turn inducers, a diastereopure azepane-derived quaternary amino acid has been incorporated into a library of simplified tetrapeptide models in order to assess the effect of the azepane position and peptide sequence on the stabilization of β-turns. The conformational analysis of these peptides by molecular modeling, NMR spectroscopy, and X-ray crystallography showed that this azepane amino acid is an effective β-turn inducer when incorporated at the i + 1 position. Moreover, the analysis of the supramolecular self-assembly of one of the β-turn-containing peptide models in the solid state reveals that it forms a supramolecular helical arrangement while maintaining the β-turn structure. The results here presented provide the basis for the use of this azepane quaternary amino acid as a strong β-turn inducer in the search for novel peptide-based bioactive molecules, catalysts, and biomaterials.

The protein TRPM8, a non-selective, calcium (Ca2+) permeable ion channel is implicated in several pathological conditions, including neuropathic pain states. In our previous research endeavors, we have identified β–lactam derivatives with high hydrophobic character that exhibit potent and selective TRPM8 antagonist activity. This work describes the synthesis of novel derivatives featuring C-terminal amides and diversely substituted N’-terminal monobenzyl groups, in an attempt to increase the total polar surface area (TPSA) in this family of compounds. The primary goal was to assess the influence of these substituents on the inhibition of menthol-induced cellular Ca2+ entry, thereby establishing critical structure-activity relationships. While the substitution of the tert-butyl ester by isobutyl amide moieties improved the antagonist activity, none of the N’-monobencyl derivatives, regardless of the substituent on the phenyl ring, achieved the activity of the model dibenzyl compound. The antagonist potency of the most effective compounds was subsequently verified using Patch-Clamp electrophysiology experiments. Furthermore, we evaluated the selectivity of one of these compounds against other members of the TRP ion channel family and some receptors connected to peripheral pain pathways. This compound demonstrated specificity for TRPM8 channels. To better comprehend the potential mode of interaction, we conducted docking experiments to uncover plausible binding sites on the functionally active tetrameric protein, which come upon four main poses by the pore zone, differents from those described for other known antagonists. Finally, in vivo experiments, involving a couple of selected compounds, revealed significant antinociceptive activity within a mice model of cold allodynia induced by oxaliplatin.

The transient melastatin receptor potential (TRPM) ion channel subfamily functions as cellular sensors and transducers of critical biological signal pathways by regulating ion homeostasis. Some members of TRPM have been cloned from cancerous tissues, and their abnormal expressions in various solid malignancies have been correlated with cancer cell growth, survival, or death. Recent evidence also highlights the mechanisms underlying the role of TRPMs in tumor epithelial-mesenchymal transition (EMT), autophagy, and cancer metabolic reprogramming. These implications support TRPM channels as potential molecular targets and their modulation as an innovative therapeutic approach against cancer. Here, we discuss the general characteristics of the different TRPMs, focusing on current knowledge about the connection between TRPM channels and critical features of cancer. We also cover TRPM modulators used as pharmaceutical tools in biological trials and an indication of the only clinical trial with a TRPM modulator about cancer. To conclude, the authors describe the prospects for TRPM channels in oncology.

The mineralocorticoid receptor (MR) belongs to the steroid receptor subfamily of nuclear receptors. MR is a transcription factor key in regulating blood pressure and mineral homeostasis. In addition, it plays an important role in a broad range of biological and pathological conditions, greatly expanding its interest as a pharmacological target. Non-steroidal MR antagonists (MRAs) are of particular interest to avoid side effects and achieve tissue-specific modulation of the receptor. The 1,4-dihydropyridine (1,4-DHP) ring has been identified as an appropriate scaffold to develop non-steroidal MRAs. We report the identification of a novel series of 1,4-DHP that has been guided by structure-based drug design, focusing on the less explored DHP position 2. Interestingly, substituents at this position might interfere with MR helix H12 disposition, which is essential for the recruitment of co-regulators. Several of the newly synthesized 1,4-DHPs show interesting properties as MRAs and have a good selectivity profile. These 1,4-DHPs promote MR nuclear translocation with less efficiency than the natural agonist aldosterone, which explains, at least in part, its antagonist character. Molecular dynamic studies are suggestive of several derivatives interfering with the disposition of H12 in the agonist-associated conformation, and thus, they might stabilize an MR conformation unable to recruit co-activators.

The COVID‐19 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), is still affecting people worldwide. Despite the good degree of immunological protection achieved through vaccination, there are still severe cases that require effective antivirals. In this sense, two specific pharmaceutical preparations have been marketed already, the RdRp polymerase inhibitor molnupiravir and the main viral protease inhibitor nirmatrelvir (commercialized as Paxlovid, a combination with ritonavir). Nirmatrelvir is a peptidomimetic acting as orally available, covalent, and reversible inhibitor of SARS‐CoV‐2 main viral protease. The success of this compound has revitalized the search for new peptide and peptidomimetic protease inhibitors. This highlight collects some selected examples among those recently published in the field of SARS‐CoV‐2.

Transient receptor potential melastatin subtype 8 (TRPM8) is a cation channel extensively expressed in sensory neurons and implicated in different painful states. However, the effectiveness of TRPM8 modulators for pain relief is still a matter of discussion, since structurally diverse modulators lead to different results, depending on the animal pain model. In this work, we described the antinociceptive activity of a β–lactam derivative, RGM8-51, showing good TRPM8 antagonist activity, and selectivity against related thermoTRP channels and other pain-mediating receptors. In primary cultures of rat dorsal root ganglion (DRG) neurons, RGM8-51 potently reduced menthol-evoked neuronal firing without affecting the major ion conductances responsible for action potential generation. This compound has in vivo antinociceptive activity in response to cold, in a mouse model of oxaliplatin-induced peripheral neuropathy. In addition, it reduces cold, mechanical and heat hypersensitivity in a rat model of neuropathic pain arising after chronic constriction of the sciatic nerve. Furthermore, RGM8-51 exhibits mechanical hypersensitivity-relieving activity, in a mouse model of NTG-induced hyperesthesia. Taken together, these preclinical results substantiate that this TRPM8 antagonist is a promising pharmacological tool to study TRPM8-related diseases.