Search

Dopamine is a key catecholamine in the brain and kidney, where it is involved in a number of physiological functions such as locomotion, cognition, emotion, endocrine regulation, and renal function. As a membrane-impermeant hormone and neurotransmitter, dopamine is thought to signal by binding and activating dopamine receptors, members of the G protein coupled receptor (GPCR) family, only on the plasma membrane. Here, using novel nanobody-based biosensors, we demonstrate for the first time that the dopamine D1 receptor (D1DR), the primary mediator of dopaminergic signaling in the brain and kidney, not only functions on the plasma membrane but becomes activated at the Golgi apparatus in the presence of its ligand. We present evidence that activation of the Golgi pool of D1DR is dependent on organic cation transporter 2 (OCT2), a dopamine transporter, providing an explanation for how the membrane-impermeant dopamine accesses subcellular pools of D1DR. We further demonstrate that dopamine activates Golgi-D1DR in murine striatal medium spiny neurons, and this activity depends on OCT2 function. We also introduce a new approach to selectively interrogate compartmentalized D1DR signaling by inhibiting Gαs coupling using a nanobody-based chemical recruitment system. Using this strategy, we show that Golgi-localized D1DRs regulate cAMP production and mediate local protein kinase A activation. Together, our data suggest that spatially compartmentalized signaling hubs are previously unappreciated regulatory aspects of D1DR signaling. Our data provide further evidence for the role of transporters in regulating subcellular GPCR activity.

Microalgae are currently considered an attractive source of highly valuable metabolites potentially exploitable as anticancer agents, nutraceuticals and cosmeceuticals and for bioenergy purposes. Their ease of culturing and their high growth rates further promote their use as raw material for the production of specialty products. In the present paper, we focused our attention on specific glycerol-based lipid compounds, monoacylglycerols (MAGs), which displayed in our previous studies a selective cytotoxic activity against the haematological U-937 and the colon HCT-116 cancer cell lines. Here, we performed a quali/quantitative analysis of MAGs and total fatty acids (FAs) along with a profiling of the main lipid classes in a panel of 12 microalgal species, including diatoms and dinoflagellates. Our results highlight an inter- and intraspecific variability of MAG profile in the selected strains. Among them, Skeletonema marinoi (strain FE7) has emerged as the most promising source for possible biotechnological production of MAGs. [ABSTRACT FROM AUTHOR]

Serotonin receptors play central roles in neuromodulation and are critical drug targets for psychiatric disorders. Optical control of serotonin receptor subtypes has the potential to greatly enhance our understanding of the spatiotemporal dynamics of receptor function. While other neuromodulatory receptors have been successfully rendered photoswitchable, reversible photocontrol of serotonin receptors has not been achieved, representing a major gap in GPCR photopharmacology. Herein, we develop the first tools that allow for such control. Azo5HT‐2 shows light‐dependent 5‐HT2AR agonism, with greater activity in the cis‐form. Based on docking and test compound analysis, we also develop photoswitchable orthogonal, remotely‐tethered ligands (PORTLs). These BG‐Azo5HTs provide rapid, reversible, and repeatable optical control following conjugation to SNAP‐tagged 5‐HT2AR. Overall, this study provides a foundation for the broad extension of photopharmacology to the serotonin receptor family. [ABSTRACT FROM AUTHOR]

Summary: Because of their importance as chemical mediators, the presence of a rich and varied family of lipoxygenase (LOX) products, collectively named oxylipins, has been investigated thoroughly in diatoms, and the involvement of these products in important processes such as bloom regulation has been postulated. Nevertheless, little information is available on the enzymes and pathways operating in these protists.Exploiting transcriptome data, we identified and characterized a LOX gene, PaLOX, in Pseudo‐nitzschia arenysensis, a marine diatom known to produce different species of oxylipins by stereo‐ and regio‐selective oxidation of eicosapentaenoic acid (EPA) at C12 and C15.PaLOX RNA interference correlated with a decrease of the lipid‐peroxidizing activity and oxylipin synthesis, as well as with a reduction of growth of P. arenysensis. In addition, sequence analysis and structure models of the C‐terminal part of the predicted protein closely fitted with the data for established LOXs from other organisms.The presence in the genome of a single LOX gene, whose downregulation impairs both 12‐ and 15‐oxylipins synthesis, together with the in silico 3D protein modelling suggest that PaLOX encodes for a 12/15S‐LOX with a dual specificity, and provides additional support to the correlation between cell growth and oxylipin biosynthesis in diatoms. [ABSTRACT FROM AUTHOR]

The mu-opioid receptor (MOR) is a major target for the treatment of pain. However, opioids are prone to side effects which limit their effectiveness as analgesics and can lead to opioid use disorders or, even, lethal overdose. The systemic administration of opioid agonists makes it both very difficult to decipher their underlying circuit mechanisms of action and to limit drug action to specific receptor subpopulations to isolate therapeutic effects from adverse side effects. Here we design, synthesize, and characterize a reversibly photoswitchable morphinan agonist termed "azo-morphine-3" ( AM-3 ) which interconverts from low to high efficacy in response to different wavelengths of light to enable optical control of MOR signaling. Cryo-EM structures of the low efficacy " trans " and high efficacy " cis " states of AM-3 bound to the MOR reveal distinct binding modes of the photoswitchable azobenzene moiety, each inducing unique structural dynamics, providing insight into the molecular basis of agonist efficacy. In mice, AM-3 drives reversible and repeatable optical control of anti-nociception with a reduced side effect profile owing to its restriction to the periphery and its ability to be locally activated at the site of pain.