Intracellular dynamics of the Sigma-1 receptor observed with super-resolution imaging microscopy

From Synaptic Plasticity to Neurodegeneration: BDNF as a Transformative Target in Medicine

The brain-derived neurotrophic factor (BDNF) has become one of the cornerstones of neuropathology, influencing synaptic plasticity, cognitive resilience, and neuronal survival. Apart from its molecular biology, BDNF is a powerful target for transformative benefit in precision medicine, leading to innovative therapeutic approaches for neurodegenerative and psychiatric diseases like Alzheimer's disease (AD), Parkinson's disease (PD), major depressive disorder (MDD), and post-traumatic stress disorder (PTSD). Nevertheless, clinical applicability is obstructed by hurdles in delivery, patient-specific diversity, and pleiotropic signaling. Here, we summarize findings in BDNF research, including its regulatory pathways and diagnostic/prognostic biomarkers and integrative therapeutic approaches. We describe innovative delivery systems, such as lipid nanoparticle-based mRNA therapies and CRISPR-dCas9-based epigenetic editing that bypass obstacles such as BBB (blood-brain barrier) and enzymatic degradation. The recent implementation of multiplex panels combining BDNF biodynamic indicators with tau and amyloid-β signaling markers showcases novel levels of specificity for both early detection and potential therapeutic monitoring. Humanized preclinical models like iPSC-derived neurons and organoids point to the key role of BDNF in neurodeveloping and neurodegenerative processes, paralleling advances in bridging preclinical observation and clinical environments. Moreover, novel therapeutic tools delivering TrkB activators or the implementation of AI-based dynamic care platforms enable tailored and scalable treatments. This review also aims to extend a framework used in the understanding of BDNF's relevance to traditional neurodegenerative models by situating more recent work detailing BDNF's actions in ischemic tissues and the gut-brain axis in the context of systemic health. Finally, we outline a roadmap for the incorporation of BDNF-centered therapies into worldwide healthcare, highlighting ethical issues, equity, and interdisciplinary decomposition. The therapeutic potential of BDNF heralds a new era in neuroscience and medicine, revolutionizing brain health and paving the way for the advancement of precision medicine.

Sigma-1 Receptor Specific Biological Functions, Protective Role, and Therapeutic Potential in Cardiovascular Diseases

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide, and there is an urgent need for efficient and cost-effective treatments to decrease the risk of CVD. The sigma-1 receptor (S1R) plays a role in the development of cardiac hypertrophy, heart failure, ventricular remodeling, and various other cardiac diseases. Preclinical studies have shown that S1R activation has considerable beneficial effects on the cardiovascular system, and this knowledge might contribute to informing clinical trials associated with the prevention and treatment of CVDs. Therefore, the objective of this review was to investigate the mechanisms of S1R in CVD and how modulation of pathways contributes to cardiovascular protection to facilitate the development of new therapeutic agents targeting the cardiovascular system.

Phthalate monoesters affect membrane fluidity and cell-cell contacts in endometrial stromal adherent cell lines and spheroids

Phthalate monoesters have been identified as endocrine disruptors in a variety of models, yet understanding of their exact mechanisms of action and molecular targets in cells remains incomplete. Here, we set to determine whether epidemiologically relevant mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) can affect biological processes by altering cell plasma membrane fluidity or formation of cell-cell contacts. As a model system, we chose endometrial stromal cell lines, one of which was previously used in a transcriptomic study with MEHHP or MEHHP-containing mixtures. A short-term exposure (1 h) of membrane preparations to endocrine disruptors was sufficient to induce changes in membrane fluidity/rigidity, whereas different mixtures showed different effects at various depths of the bilayer. A longer exposure (96 h) affected the ability of cells to form spheroids and highlighted issues with membrane integrity in loosely assembled spheroids. Finally, in spheroids assembled from T-HESC cells, MEHHP interfered with the formation of cell-cell contacts as indicated by the immunostaining of zonula occludens 1 protein. Overall, this study emphasized the need to consider plasma membrane, membrane-bound organelles, and secretory vesicles as possible biological targets of endocrine disruptors and offered an explanation for a multitude of endocrine disruptor roles documented earlier.

Structural determinants of M2R involved in inhibition by Sigma-1R

Sigma-1 receptor (S1R) is a multimodal chaperone protein that is implicated in various pathophysiological conditions including drug addiction, Alzheimer's disease, and amyotrophic lateral sclerosis (ALS). S1R interacts with various ion channels and receptors on the endoplasmic reticulum or plasma membrane (PM). It has been reported that S1R colocalizes with the M2-muscarinic acetylcholine receptor (M2R) on the soma of motoneurons, although a functional interaction between these two proteins has not been established. Here, we investigated the regulation of M2R signaling by S1R using electrophysiological recordings of GIRK currents in HEK293T cells. We observed that S1R strongly inhibited M2R-mediated activation of GIRK1/2, but the disease mutant linked to ALS, S1R E102Q, did not. The inhibitory effect of S1R was selective for M2R and wasn't seen when S1R was co-expressed with other Gi/o coupled receptors including M4R. Chimeric and mutant receptors of M2R and M4R were generated and analyzed, and this highlighted Ala401 in the transmembrane 6 domain (TM6) of M2R and Glu172 as well as Glu175 in the extracellular loop 2 regions of M2R, as essential for the inhibition by S1R. Co-immunoprecipitation confirmed the physical interaction between M2R and S1R. Immunocytochemical labeling of M2R and S1R expressed in HeLa cells, HEK293T cells, and cultured hippocampal neurons, showed clear PM expression of M2R throughout the cell which was decreased by coexpression with S1R but was still apparent. Taken together, our results show that S1R interacts with M2R to reduce both its PM expression and function, and this involves TM6 and the extracellular loop 2.

Enhanced osteointegration and osteogenesis of osteoblast cells by laser-induced surface modification of Ti implants

Dental and orthopedic implants have become routine medical technologies for tooth replacement and bone fixation. Despite significant progress in implantology, achieving sufficient osseointegration remains a challenge, often leading to implant failure over the long term. Nanotechnology offers the potential to mimic the natural patterns of living tissues, providing a promising platform for tissue engineering and implant surface design. Among the various methods for developing nanostructures, High-Regular Laser-Induced Periodic Surface Structures (HR-LIPSS) techniques stand out for their ability to fabricate highly ordered nanostructures with excellent long-range repeatability and production efficiency. In this study, we utilized an innovative technical approach to generate traditional laser-induced superficial LIPSS nanostructures, followed by detailed surface analysis using classical microscopy and physicochemical methods. Our findings demonstrate for the first time that nanostructured LIPSS surfaces can significantly enhance cell adhesion and proliferation while providing an optimal environment for cell metabolism. Given the high reproducibility, low cost, and potential of HR-LIPSS techniques to support cell growth and differentiation, this novel technology has the potential to impact both the industrial development of new implants and clinical outcomes after implantation.

Illuminating Neuropeptide Y Y4 Receptor Binding: Fluorescent Cyclic Peptides with Subnanomolar Binding Affinity as Novel Molecular Tools

The neuropeptide Y (NPY) Y4 receptor (Y4R), a member of the family of NPY receptors, is physiologically activated by the linear 36-amino acid peptide pancreatic polypeptide (PP). The Y4R is involved in the regulation of various biological processes, most importantly pancreatic secretion, gastrointestinal motility, and regulation of food intake. So far, Y4R binding affinities have been mostly studied in radiochemical binding assays. Except for a few fluorescently labeled PP derivatives, fluorescence-tagged Y4R ligands with high affinity have not been reported. Here, we introduce differently fluorescence-labeled (Sulfo-Cy5, Cy3B, Py-1, Py-5) Y4R ligands derived from recently reported cyclic hexapeptides showing picomolar Y4R binding affinity. With pKi values of 9.22-9.71 (radioligand competition binding assay), all fluorescent ligands (16-19) showed excellent Y4R affinity. Y4R saturation binding, binding kinetics, and competition binding with reference ligands were studied using different fluorescence-based methods: flow cytometry (Sulfo-Cy5, Cy3B, and Py-1 label), fluorescence anisotropy (Cy3B label), and NanoBRET (Cy3B label) binding assays. These experiments confirmed the high binding affinity to Y4R (equilibrium pKd: 9.02-9.9) and proved the applicability of the probes for fluorescence-based Y4R competition binding studies and imaging techniques such as single-receptor molecule tracking.

Pharmacological Analysis of GABAA Receptor and Sigma1R Chaperone Interaction: Research Report I-Investigation of the Anxiolytic, Anticonvulsant and Hypnotic Effects of Allosteric GABAA Receptors' Ligands

Two groups of facts have been established in previous drug development studies of the non-benzodiazepine anxiolytic fabomotizole. First, fabomotizole prevents stress-induced decrease in binding ability of the GABAA receptor's benzodiazepine site. Second, fabomotizole is a Sigma1R chaperone agonist, and exposure to Sigma1R antagonists blocks its anxiolytic effect. To prove our main hypothesis of Sigma1R involvement in GABAA receptor-dependent pharmacological effects, we performed a series of experiments on BALB/c and ICR mice using Sigma1R ligands to study anxiolytic effects of benzodiazepine tranquilizers diazepam (1 mg/kg i.p.) and phenazepam (0.1 mg/kg i.p.) in the elevated plus maze test, the anticonvulsant effects of diazepam (1 mg/kg i.p.) in the pentylenetetrazole-induced seizure model, and the hypnotic effects of pentobarbital (50 mg/kg i.p.). Sigma1R antagonists BD-1047 (1, 10, and 20 mg/kg i.p.), NE-100 (1 and 3 mg/kg i.p.), and Sigma1R agonist PRE-084 (1, 5, and 20 mg/kg i.p.) were used in the experiments. Sigma1R antagonists have been found to attenuate while Sigma1R agonists can enhance GABAARs-dependent pharmacological effects.

Sigma-1 Receptor Signaling: In Search of New Therapeutic Alternatives for Cardiovascular and Renal Diseases

Cardiovascular and renal diseases are among the leading causes of death worldwide, and regardless of current efforts, there is a demanding need for therapeutic alternatives to reduce their progression to advanced stages. The stress caused by diseases leads to the activation of protective mechanisms in the cell, including chaperone proteins. The Sigma-1 receptor (Sig-1R) is a ligand-operated chaperone protein that modulates signal transduction during cellular stress processes. Sig-1R interacts with various ligands and proteins to elicit distinct cellular responses, thus, making it a potential target for pharmacological modulation. Furthermore, Sig-1R ligands activate signaling pathways that promote cardioprotection, ameliorate ischemic injury, and drive myofibroblast activation and fibrosis. The role of Sig-1R in diseases has also made it a point of interest in developing clinical trials for pain, neurodegeneration, ischemic stroke, depression in patients with heart failure, and COVID-19. Sig-1R ligands in preclinical models have significantly beneficial effects associated with improved cardiac function, ventricular remodeling, hypertrophy reduction, and, in the kidney, reduced ischemic damage. These basic discoveries could inform clinical trials for heart failure (HF), myocardial hypertrophy, acute kidney injury (AKI), and chronic kidney disease (CKD). Here, we review Sig-1R signaling pathways and the evidence of Sig-1R modulation in preclinical cardiac and renal injury models to support the potential therapeutic use of Sig-1R agonists and antagonists in these diseases.

Specific detection and deletion of the sigma-1 receptor widely expressed in neurons and glial cells in vivo

The chaperon protein sigma-1 receptor (S1R) has been discovered over forty years ago. Recent pharmacological studies using S1R exogenous ligands demonstrated a promising therapeutical potential of targeting the S1R for several neurological disorders. Although intensive in vitro studies have revealed S1Rs are mainly residing at the membrane of the endoplasmic reticulum (ER), the cell-specific in vivo expression pattern of S1Rs is still unclear, mainly due to the lack of a reliable detection method which also prevented a comprehensive functional analysis. Here, first, we identified a highly specific antibody using S1R knockout (KO) mice and established an immunohistochemical protocol involving a 1% SDS antigen retrieval step. Second, we characterized the S1R expression in the mouse brain and can demonstrate that the S1R is widely expressed: in principal neurons, interneurons, and all glial cell types. In addition, unlike reported in previous studies, we showed that the S1R expression in astrocytes is not colocalized with the astrocytic cytoskeleton protein GFAP. Thus, our results raise concerns over previously reported S1R properties. Finally, we generated a Cre-dependent S1R conditional KO mouse (S1R flox) to study cell type-specific functions of the S1R. As a proof of concept, we successfully ablated S1R expressions in neurons or microglia employing neuronal and microglial Cre-expressing mice, respectively. In summary, we provide powerful tools to cell-specifically detect, delete and functionally characterize S1R in vivo.