Biology subjects

Glennon, J.

Publications and source records attributed to Glennon, J..

3 recordsLinked to original sources

bioRxiv2026

Whole-Mount Optical Clearing of Rabbit Tenuissimus Muscle for Assessment of Muscle Spindle Morphology

Proprioception and reflexive control of muscle tone depend on the activity of muscle spindles, specialized sensory receptors embedded deep within skeletal muscle that detect changes in muscle length. Their location and complex three-dimensional architecture have historically limited morphological analysis to techniques such as silver-impregnation, muscle teasing, or serial sectioning followed by volumetric reconstruction. Here, we describe a workflow for three-dimensional, in situ visualization of muscle spindles in the rabbit tenuissimus muscle, a preparation uniquely enriched in spindles and well suited for whole-mount imaging. The protocol combines fluorescent labeling of spindle sensory and motor innervation, including intrafusal {gamma} neuromuscular junctions labeled with -bungarotoxin, with immunolabeling and solvent-based optical clearing. Optically cleared tenuissimus muscles were compatible with both whole-mount confocal and light-sheet microscopy, enabling volumetric imaging of complete spindle structures and detailed visualization of Ia annulospiral endings at the spindle equator. This approach provides access to spindle morphology and connectivity at multiple spatial scales while avoiding physical sectioning and reconstruction. By enabling reproducible three-dimensional imaging of intact muscle spindles, this workflow offers a practical platform for studying spindle structure and plasticity in health and disease.

neuroscience↗

bioRxiv2025

KCNQ1 regulates human neuronal development through mitochondrial and insulin signalling pathways

KCNQ1 encodes a voltage-gated potassium channel implicated in various peripheral and neurological disorders, yet its role during human neuronal development remains unclear. To investigate this, we generated KCNQ1 knockouts (KO) in human induced pluripotent stem cell lines and differentiated them into neural stem cells (NSCs) and cortical neurons. KCNQ1-deficient NSCs showed impaired neurite outgrowth, linked to reduced cell adhesion and disrupted neural cell adhesion molecule (NCAM) signalling. This phenotype was reproduced in wild-type and heterozygous lines by pharmacological KCNQ1 inhibition. Whole transcriptome, proteome, and follow-up analyses revealed mitochondrial dysfunction in KO NSCs, including reduced mitochondrial copy number and ATP synthase expression. Additionally, evidence was obtained for an impairment of insulin signalling in NSCs and neurons, with diminished insulin receptor gene expression and perturbation of key downstream signalling pathways (RAS-MAPK, PI3K-AKT). In neurons, KCNQ1 loss resulted in decreased synaptic activity and a more immature gene expression profile. Overall, our work reveals a novel role for KCNQ1 in human neurodevelopment by regulating cell adhesion, mitochondrial function, and insulin signalling. This work increases our understanding of KCNQ1 function in neurons and its contribution to neurological phenotypes observed in patients with KCNQ1-related diseases.

molecular biology↗

bioRxiv2020

GADL1 is a multifunctional decarboxylase with tissue specific roles in β-alanine and carnosine production

Carnosine and related {beta}-alanine-containing peptides are believed to be important antioxidants, pH-buffers and neuromodulators. However, their biosynthetic routes and therapeutic potential are still being debated. This study describes the first animal model lacking the enzyme glutamic acid decarboxylase-like 1 (GADL1). We show that Gadl1-/-mice are deficient in {beta}-alanine, carnosine and anserine, particularly in the olfactory bulb, cerebral cortex, and skeletal muscle. Gadl1-/-mice also exhibited decreased anxiety, increased levels of oxidative stress markers, alterations in energy and lipid metabolism, and age-related changes. Examination of the GADL1 active site indicated that the enzyme may have multiple physiological substrates, including aspartate and cysteine sulfinic acid, compatible with organ-specific functions. Human genetic studies show strong associations of the GADL1 locus with plasma levels of carnosine, subjective well-being, and muscle strength, also indicating a role for {beta}-alanine and its peptide derivatives in these traits. Together, this shows the multifaceted and organ specific roles of carnosine peptides and establishes Gadl1 knockout mice as a versatile model to explore carnosine biology and its therapeutic potential.

neuroscience↗