Biology subjects

Flowers, M.

Publications and source records attributed to Flowers, M..

3 recordsLinked to original sources

bioRxiv2025

Molecular Dynamics in the Ventral Tegmental Area during Chronic Pain-Induced Negative Affect

Chronic pain frequently coexists with negative affect, with about 60% of patients suffering from both. This dual condition complicates treatment and exacerbates both disorders, highlighting the urgent need for innovative therapeutic strategies. Chronic pain negative affect (CPNA) involves complex neurobiological changes, including increased hyperexcitability of the ventral tegmental area (VTA), a critical region involved in reward, mood, and pain processing. To elucidate CPNAs underlying mechanisms, we employed a multidisciplinary approach using immunohistochemistry, lipidomic analysis, and proteomic screening to investigate VTA molecular alterations in mice subjected to partial sciatic nerve ligation (pSNL) at one and four weeks post-injury. Our results revealed a significant, sex-dependent increase in Kv7.2 channel expression in dopamine neurons, alongside a notable reduction in endocannabinoid 2-arachidonoylglycerol (2-AG) levels, which plays a vital role in mood regulation. This neurochemical shift associated with an increase in negative affect-like behaviors, as determined by the forced swim test. Furthermore, pharmacological intervention utilizing either exogenous 2-AG or retigabine, a Kv7 channel opener, effectively alleviated pain-related negative affect symptoms. Proteomic profiling further uncovered alterations within the CaMKK2 pathway, involving crucial proteins such as PLC{gamma}2, AMPK{gamma}2, and AMPK{beta}1, and CaMK1, with changes in abundance and phosphorylation activity that could be reversed with the next-generation CaMK1 antagonist CS640. This research provides the first comprehensive analyses of VTA adaptations linked to CPNA, yielding significant insights into molecular changes impacting VTA neuronal integrity and signaling throughout CPNA progression.

neuroscience↗

bioRxiv2025

Mapping affinity and allostery in human IgG antibody Fc region-Fc γ receptor interactions

IgG antibodies, required for a functional immune system, recognize antigens and neutralize pathogens using their Fab regions, while signaling to the immune system by binding to host Fc {gamma} receptors (Fc{gamma}Rs) through their Fc regions. These Fc{gamma}R interactions initiate and modulate antibody-mediated effector functions that are essential for host immunity, therapeutic monoclonal antibody effectiveness and IgG-mediated pathologies. Fc{gamma}Rs include both activating and inhibitory receptors and the relative binding affinities of the IgG Fc region to Fc{gamma}Rs that generate opposing signals is a key determinant of the immune response. Substantial research effort has been devoted to understanding and manipulating Fc{gamma}R interactions to decipher their fundamental biological activities and to develop therapeutic monoclonal antibodies with tailored effector functions. However, a common Fc-Fc{gamma}R binding interface, the high sequence identity of Fc{gamma}Rs, and the inherent conformational dynamics of the IgG Fc region, have prohibited a full understanding of these interactions, even when employing state-of-the-art biophysical and biological methods. Here, we used site-saturation libraries of the human IgG1 Fc region to determine the effective affinities of more than 98% of all possible single-site amino acid substitutions in the Fc to all human Fc{gamma}Rs, as well as the most common Fc{gamma}R polymorphisms. We provide a comprehensive analysis of Fc amino acid variations that determine Fc stability, orthosteric control of Fc{gamma}R binding, and short- and long-range allosteric control of Fc{gamma}R binding. We also predict the relative activating versus inhibitory effector function capacity of nearly every possible single-site Fc mutation.

biochemistry↗

bioRxiv2024

Expert Panel Curation of 31 Genes in Relation to Limb Girdle Muscular Dystrophy

IntroductionLimb girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous autosomal conditions with some degree of phenotypic homogeneity. LGMD is defined as having onset >2 years of age with progressive proximal weakness, elevated serum creatine kinase levels and dystrophic features on muscle biopsy. Advances in massively parallel sequencing have led to a surge in genes linked to LGMD. MethodsThe ClinGen Muscular Dystrophies and Myopathies gene curation expert panel (MDM GCEP, formerly Limb Girdle Muscular Dystrophy GCEP) convened to evaluate the strength of evidence supporting gene-disease relationships (GDR) using the ClinGen gene-disease clinical validity framework to evaluate 31 genes implicated in LGMD. ResultsThe GDR was exclusively LGMD for 17 genes, whereas an additional 14 genes were related to a broader phenotype encompassing congenital weakness. Four genes (CAPN3, COL6A1, COL6A2, COL6A3) were split into two separate disease entities, based on each displaying both dominant and recessive inheritance patterns, resulting in curation of 35 GDRs. Of these, 30 (86%) were classified as Definitive, 4 (11%) as Moderate and 1 (3%) as Limited. Two genes, POMGNT1 and DAG1, though definitively related to myopathy, currently have insufficient evidence to support a relationship specifically with LGMD. ConclusionsThe expert-reviewed assertions on the clinical validity of genes implicated in LGMDs form an invaluable resource for clinicians and molecular geneticists. We encourage the global neuromuscular community to publish case-level data that help clarify disputed or novel LGMD associations.

genetics↗