Activation of Multiple G Protein Pathways to Characterize the Five Dopamine Receptor Subtypes Using Bioluminescence Technology

The dual role of dopamine and serotonin in cancer progression and inflammation: Mechanisms and therapeutic potential

This review examines the critical functions of dopamine and serotonin in the regulation of inflammation and cancer, emphasizing their potential as therapeutic targets. Traditionally recognized for their roles in neural communication, these neurotransmitters are now understood to play substantial roles in immune modulation and tumor progression. We conducted a systematic review of studies published between 2013 and 2024, using databases such as PubMed, Google Scholar, and Scopus, to assess dopamine and serotonin synthesis, receptor activity, and involvement in disease pathways. Findings indicate that dopamine, through its D1 and D2 receptors, exerts both pro- and anti-inflammatory effects, influencing tumor growth and immune responses in cancers such as breast and pancreatic. Similarly, serotonin, particularly through receptors HTR2A and HTR2B, has demonstrated dual roles in cancer progression, impacting the growth and metastasis of cancers such as gastric and colorectal. This review also addresses the interaction between dopamine and serotonin signaling pathways, which may collectively alter immune cell function and tumor microenvironment dynamics, suggesting a promising direction for combined therapeutic approaches. By synthesizing current data on dopamine and serotonin pathways, this review aims to inform the development of targeted therapies that modulate immune responses in inflammation-driven cancers. Our findings underscore the potential of neurotransmitter-based interventions as a novel strategy for managing cancer and inflammatory diseases.

LYCHOS is a human hybrid of a plant-like PIN transporter and a GPCR

Lysosomes have crucial roles in regulating eukaryotic metabolism and cell growth by acting as signalling platforms to sense and respond to changes in nutrient and energy availability1. LYCHOS (GPR155) is a lysosomal transmembrane protein that functions as a cholesterol sensor, facilitating the cholesterol-dependent activation of the master protein kinase mechanistic target of rapamycin complex 1 (mTORC1)2. However, the structural basis of LYCHOS assembly and activity remains unclear. Here we determine several high-resolution cryo-electron microscopy structures of human LYCHOS, revealing a homodimeric transmembrane assembly of a transporter-like domain fused to a G-protein-coupled receptor (GPCR) domain. The class B2-like GPCR domain is captured in the apo state and packs against the surface of the transporter-like domain, providing an unusual example of a GPCR as a domain in a larger transmembrane assembly. Cholesterol sensing is mediated by a conserved cholesterol-binding motif, positioned between the GPCR and transporter domains. We reveal that the LYCHOS transporter-like domain is an orthologue of the plant PIN-FORMED (PIN) auxin transporter family, and has greater structural similarity to plant auxin transporters than to known human transporters. Activity assays support a model in which the LYCHOS transporter and GPCR domains coordinate to sense cholesterol and regulate mTORC1 activation.

Dopamine Dysregulation in Reward and Autism Spectrum Disorder

Autism spectrum disorder (ASD) is primarily characterized by core deficits in social skills, communication, and cognition and by repetitive stereotyped behaviors. These manifestations are variable between individuals, and ASD pathogenesis is complex, with over a thousand implicated genes, many epigenetic factors, and multiple environmental influences. The mesolimbic dopamine (DA) mediated brain reward system is held to play a key role, but the rapidly expanding literature reveals intricate, nuanced signaling involving a wide array of mesolimbic loci, neurotransmitters and receptor subtypes, and neuronal variants. How altered DA signaling may constitute a downstream convergence of the manifold causal origins of ASD is not well understood. A clear working framework of ASD pathogenesis may help delineate common stages and potential diagnostic and interventional opportunities. Hence, we summarize the known natural history of ASD in the context of emerging data and perspectives to update ASD reward signaling. Then, against this backdrop, we proffer a provisional framework that organizes ASD pathogenesis into successive levels, including (1) genetic and epigenetic changes, (2) disrupted mesolimbic reward signaling pathways, (3) dysregulated neurotransmitter/DA signaling, and finally, (4) altered neurocognitive and social behavior and possible antagonist/agonist based ASD interventions. This subdivision of ASD into a logical progression of potentially addressable parts may help facilitate the rational formulation of diagnostics and targeted treatments.