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The history of discovery by Rosetta Reusch of oligo‐ and poly‐β‐hydroxybutyrates (OHBs and PHBs) consisting of less than ca. 150 HB units is described. These 'short‐chain' biopolymers can be detected in all living organisms and have numerous physiological activities of fundamental importance for the chemistry of life. The largest are components of ion channels such as Ca2+‐polyphosphate‐PHB (Ca‐PPi‐PHB) in genetically competent E. coli and in mammalian mitochondria. Sequences with chain lengths < ca. 30 occur covalently attached to proteins (post‐translational PHBylation), and methyl esters of the dimer and trimer are used by certain bacteria as highly efficient antioxidants. With synthetic monodisperse OHBs (up to 128mer) our group has contributed structural investigations, and we have shown that OHBs≥16 alone make phospholipid bilayer vesicles permeable to Ca ions. An extensive biochemical analysis of the TRPM8 protein channel, responsible for the sense of heat in our skin, proved to be fully active only when PHBylated. Reasons for the difficulty of detecting OHBs and PHBs are discussed: the polyester chain is highly flexible, and there is ester cleavage by base, acid, nucleophiles, Lewis acids, and heat – in stark contrast to peptides. PHBs may be called a ubiquitous but fleeting species in the chemistry of life – worth being appreciated and studied much more intensively in the future! A speculation about PHB's possible role in prebiotic compartmentalization is presented, and recent uses of compartmentalization in organic synthesis are briefly mentioned. Portions of the figures used herein were presented in a lecture at the International Symposium on Biopolymers on September 13, 2022, in Sion (Switzerland). [ABSTRACT FROM AUTHOR]

Various families of ion channels have been characterized in mesenchymal stem cells (MSCs), including some members of transient receptor potential (TRP) channels family. TRP channels are involved in critical cellular processes as differentiation and cell proliferation. Here, we analyzed the expression of TRPM8 channel in human bone marrow MSCs (hBM-MSCs), and its relation with osteogenic differentiation. Patch-clamp recordings showed that hBM-MSCs expressed outwardly rectifying currents which were increased by exposure to 500 μM menthol and were partially inhibited by 10 μM of BCTC, a TRPM8 channels antagonist. Additionally, we have found the expression of TRPM8 by RT-PCR and western blot. We also explored the TRPM8 localization in hBM-MSCs by immunofluorescence using confocal microscopy. Remarkably, hBM-MSCs treatment with 100 μM of menthol or 10 μM of icilin, TRPM8 agonists, increases osteogenic differentiation. Conversely, 20 μM of BCTC, induced a decrease of osteogenic differentiation. These results suggest that TRPM8 channels are functionally active in hBM-MSCs and have a role in cell differentiation.

Abstract Transient receptor potential (TRP) channels are a family of non-selective cation channels that are functionally expressed in various organs and cells. Among them, transient receptor potential vanilloid (TRPV) 1 and TRPV4 channels are expressed in T cells, where they serve as Ca2+ channels for T-cell receptor signaling [Bertin et al., 2014, Majhi et al., 2015]. Here, we show that not only TRPV1 and TRPV4 channel inhibitors, but also a transient receptor potential melastatin (TRPM) 8 channel inhibitor can suppress murine T-cell activation. Mouse splenic lymphocytes pretreated with N-(3-aminopropyl)-2-[(3-methylphenyl)methoxy]-N-(2-thienylmethyl)benzamide hydrochloride (AMTB), a TRPM8 channel-selective inhibitor, showed significantly reduced IL-2 and IL-6 release from T cells after stimulation with anti-CD3ε/anti-CD28 antibodies or concanavalin A. AMTB also suppressed IL-2 mRNA expression and activation of extracellular signal-regulated kinase 1/2, which is involved in IL-2 production. Further, the increase of CD25 (IL-2 receptor alpha chain) expression after T-cell activation was suppressed by AMTB. TRPM8 channel was expressed in CD4+ T cells isolated from splenocytes, and we confirmed that the release of IL-2 from isolated CD4+ T cells was significantly suppressed by AMTB. In vitro re-stimulation of splenocytes from external antigen-immunized mice with the same antigen induced IL-2 and IL-6 production, which was significantly suppressed by AMTB. Thus, the TRPM8 channel inhibitor AMTB suppresses T-cell activation induced by various stimulants. Highlights • We examined the effect of TRPM8 channel inhibitor on T cell activation. • TRPM8 inhibitor AMTB suppressed cytokine production in activated CD4 T cells. • AMTB suppressed increase of CD25 expression and ERK1/2 activation. • AMTB suppressed cytokine production in antigen-restimulated lymphocytes. • TRPM8 channel may be a novel therapeutic target for immune diseases. [ABSTRACT FROM AUTHOR]

Transient receptor potential (TRP) channels are known to regulate energy metabolism, and TRPM8 has become an interesting player in this context. Here we demonstrate the role of the cold sensor TRPM8 in the regulation of clock gene and clock controlled genes in brown adipose tissue (BAT). We investigated TrpM8 temporal profile in the eyes, suprachiasmatic nucleus and BAT; only BAT showed temporal variation of TrpM8 transcripts. Eyes from mice lacking TRPM8 lost the temporal profile of Per1 in LD cycle. This alteration in the ocular circadian physiology may explain the delay in the onset of locomotor activity in response to light pulse, as compared to wild type animals (WT). Brown adipocytes from TrpM8 KO mice exhibited a larger multilocularity in comparison to WT or TrpV1 KO mice. In addition, Ucp1 and UCP1 expression was significantly reduced in TrpM8 KO mice in comparison to WT mice. Regarding circadian components, the expression of Per1, Per2, Bmal1, Pparα, and Pparβ oscillated in WT mice kept in LD, whereas in the absence of TRPM8 the expression of clock genes was reduced in amplitude and lack temporal oscillation. Thus, our results reveal new roles for TRPM8 channel: it participates in the regulation of clock and clock-controlled genes in the eyes and BAT, and in BAT thermogenesis. Since disruption of the clock machinery has been associated with many metabolic disorders, the pharmacological modulation of TRPM8 channel may become a promising therapeutic target to counterbalance weight gain, through increased thermogenesis, energy expenditure, and clock gene activation. [ABSTRACT FROM AUTHOR]

Objective To evaluate the role of the transient receptor potential melastatin 8 ( TRPM8) channel on bladder mechanosensory function by using L-menthol, a TRPM8 agonist, and RQ-00203078 ( RQ), a selective TRPM8 antagonist. Materials and methods Female Sprague-Dawley rats were used. In conscious cystometry ( CMG), the effects of intravesical instillation of L-menthol (3 m m) were recorded after intravenous (i.v.) pretreatment with RQ (3 mg/kg) or vehicle. The direct effects of RQ on conscious CMG and deep body temperature were evaluated with cumulative i.v. administrations of RQ at 0.3, 1, and 3 mg/kg. Single-unit mechanosensitive bladder afferent activities ( SAAs) were monitored in a newly established ex vivo rat bladder model to avoid systemic influences of the drugs. Recordings were performed after cumulative intra-aortic administration of RQ (0.3 and 3 mg/kg) with or without intra-vesical L-menthol instillation (3 m m). Results Intravesical L-menthol decreased bladder capacity and voided volume, which was counteracted by RQ-pretreatment. RQ itself increased bladder capacity and voided volume, and lowered deep body temperature in a dose-dependent manner. RQ decreased mechanosensitive SAAs of C-fibres, and inhibited the activation of SAAs induced by intravesical L-menthol. Conclusion Our results suggest that TRPM8 channels have a role in activation of bladder afferent pathways during filling of the bladder in the normal rat. This effect seems, at least partly, to be mediated via mechanosensitive C-fibres. [ABSTRACT FROM AUTHOR]

Abstract: Aims: Transient receptor potential (TRP) vanilloid-1 (TRPV1) and melastatin-8 (TRPM8) channels play a role in transmitting sensory information in primary-afferent neurons. TRPV1 agonists at high concentrations inhibit action potential conduction in the neurons and thus have a local anesthetic effect. The purpose of the present study was to know whether TRPM8 agonist menthol at high concentrations has a similar action and if so whether there is a structure–activity relationship among menthol-related chemicals. Main methods: Compound action potentials (CAPs) were recorded from the frog sciatic nerve by using the air-gap method. Key findings: (−)-Menthol and (+)-menthol concentration-dependently reduced CAP peak amplitude with the IC50 values of 1.1 and 0.93mM, respectively. This (−)-menthol activity was resistant to non-selective TRP antagonist ruthenium red; TRPM8 agonist icilin did not affect CAPs, indicating no involvements of TRPM8 channels. p-Menthane, (+)-limonene and menthyl chloride at 7–10mM minimally affected CAPs. On the other hand, (−)-menthone, (+)-menthone, (−)-carvone, (+)-carvone and (−)-carveol (in each of which chemicals :glyph name="dbnd" />O group was added to p-menthane and limonene) and (+)-pulegone inhibited CAPs with extents similar to that of menthol. 1,8-Cineole and 1,4-cineole were less effective while thymol and carvacrol were more effective than menthol in inhibiting CAPs. Significance: Menthol-related chemicals inhibited CAPs and were thus suggested to exhibit local anesthetic effects comparable to those of lidocaine and cocaine as reported previously for frog CAPs. This result may provide information to develop local anesthetics on the basis of the chemical structure of menthol. [Copyright &y& Elsevier]

Abstract: The TRPM8 cation channel belongs to the superfamily of transient receptor potential (TRP) channels. It is involved in non-painful cool sensation and triggered by diverse chemical and physical stimuli whose precise activation mechanism is still unknown. The study presents a set of targeted molecular dynamics (MD) simulations involving selected complexes of the TRPM8 channel whose homology model was recently generated by some of us. More in detail, the MD simulations concerned the TRPM8 alone and in complex with agonists and antagonists. These simulations were focused on voltage sensor module and designed to validate the ligand induced activation mechanism as hypothesized in our previous study. The obtained results are in encouraging agreement with the proposed mechanism and allow a clear discrimination between agonists and antagonists. In addition, the MD runs confirm that the agonist binding triggers a set of concatenate conformational shifts which induce the approaching of the S3 segment toward the S4 segment and culminate in an extension of the latter. By introducing suitable constraints, the reported MD simulations were rendered as fast as possible in order to achieve a truly productive compromise between reliability and computational costs. The obtained results emphasize that suitably targeted MD runs can be fast enough to be systematically applied to predict the bioactivity of large datasets providing it as an useful tool in rational ligand design process. [Copyright &y& Elsevier]

Accumulating evidences have indicated that disturbances in intracellular free calcium ([Ca2+]i) concentration play an important role in the pathophysiology of prostate cancers. Ca2+ passes cell membrane via different channels such as chemical and voltage gated channels. Apart from the well-known cation channels, there is recently discovered channels namely transient receptor potential (TRP) family. One member of the TRP superfamily is TRP melastatin 8 (TRPM8). The Na+ and Ca2+-permeable TRPM8 channels can be gated by different stimuli including cold and menthol. In etiology of prostate cancer, excessive Ca2+ entry and oxidative stress have important role (Grolez and Gkika, 206). Considering that TRPM8 is activated by menthol, mediated cell death and proliferation, and is highly expressed in the plasmalemma of epithelial cells, androgen-dependent extracapsular prostate cancers and androgen-dependent metastasis (Bidaux et al. 2016). Recently, we found that oxidative stress and ADPRibose (ADPR) treatments could induce the TRPM8 activations resulting in the overload Ca2+ entry, apoptosis, and mitochondrial oxidative stress. More importantly, we found that GSH could protect the Du 145 prostate cancer cells from oxidative stress-induced apoptosis via maintaining the intracellular Ca2+ hemostasis as well as down-regulating mitochondrial oxidative stress pathway (Unpublished data) I concluded that the oxidative dysfunction of TRPM8 causes changes through activation of second messengers, which may lead to the pathology of prostate cancer. It seems to that the exact relationship between TRPM8 channels activation and prostate cancers still remain to be determined. [ABSTRACT FROM AUTHOR]