Biology subjects

Al-Shanti, N.

Publications and source records attributed to Al-Shanti, N..

3 recordsLinked to original sources

bioRxiv2026

Detrimental effects of advanced glycation end-products (AGEs) on a human neuromuscular junction co-culture model

The neuromuscular junction (NMJ) is a specialised synapse between motor neurons and skeletal muscle, and its progressive deterioration contributes to age-related and metabolic disease-associated declines in muscle function. Advanced glycation end-products (AGEs) accumulate in tissues during ageing, diabetes, and chronic metabolic dysfunction and have been implicated in neuromuscular degeneration, yet their effects on the intact NMJ have not previously been examined in a human model system. This study employed a fully human, serum-free, and neural growth factor-free NMJ co-culture system, combining neural progenitor cells with immortalised human myoblasts derived from an 83-year-old donor, to investigate the effects of AGE exposure on neuromuscular integrity across structural, metabolic, functional, and secretory outcomes. AGE exposure induced significant reductions in motor neuron axonal length, myotube remodelling with centralised nuclear positioning, mitochondrial membrane depolarisation, elevated mitochondrial superoxide production, mitochondrial uncoupling, and reductions in spontaneous contraction intensity and frequency. Neurotrophic and myogenic growth factor signalling was significantly downregulated in AGE-treated co-cultures. These findings identify the NMJ as a sensitive target of glycation stress and establish this fully human co-culture platform as a physiologically relevant model for investigating glycation-related neuromuscular pathology and evaluating candidate therapeutic interventions.

cell biology↗

bioRxiv2024

A combination of major histocompatibility complex (MHC) I overexpression and type I interferon induce mitochondrial dysfunction in human skeletal myoblasts.

The overexpression of major histocompatibility complex (MHC) I on the surface of muscle fibres is a characteristic hallmark of the idiopathic inflammatory myopathies (IIMs), collectively termed myositis. Alongside MHC-I overexpression, sub-types of myositis, display a distinct type I interferon (IFN) signature. This study examined the combinational effects of elevated MHC-I and type I IFNs (IFN/{beta}) on mitochondrial function, as mitochondrial dysfunction is often seen in IIMs. Human skeletal muscle myoblasts were transfected with an MHC-I isoform using the mammalian HLA-A2/Kb vector. Mitochondrial respiration, mitochondrial membrane potential, and reactive oxygen/nitrogen species generation were assessed with or without IFN and IFN{beta}. We show that MHC-I overexpression in human skeletal muscle myoblasts led to decreased basal glycolysis and mitochondrial respiration, cellular spare respiratory capacity, ATP-linked respiration, and an increased proton leak, which were all exaggerated by type I IFNs. Mitochondrial membrane depolarisation was induced by MHC-I overexpression both in absence and presence of type I IFNs. Human myoblasts overexpressing MHC-I showed elevated nitric oxide generation that was abolished when combined with IFN. MHC-I on its own did not result in an increased ROS production, but IFN on their own, or combined with MHC-I overexpression did induce elevated ROS generation. We present new evidence that MHC-I overexpression and type I IFNs aggravate the effects each has on mitochondrial function in human skeletal muscle cells, providing novel insights into their mechanisms of action and suggesting important implications in the further study of myositis pathogenesis.

cell biology↗

bioRxiv2020

Eukarion-134 attenuates endoplasmic reticulum stress-induced mitochondrial dysfunction in human skeletal muscle cells

ABSTRACTMaladaptive endoplasmic reticulum (ER) stress is associated with modified reactive oxygen species (ROS) generation, altered mitochondrial bioenergetics, and oxidative damage; and is postulated as a potential mechanism involved in the underlying muscle weakness experienced by patients with myositis, an acquired autoimmune neuromuscular disease. In this study, we investigate the impact of ROS generation in an in vitro model of ER stress in skeletal muscle, using the ER stress inducer tunicamycin (24 hours) in presence or absence of a superoxide dismutase/catalase mimetic Eukarion (EUK)-134. ER stress activation, ROS generation, mitochondrial function, biogenesis, morphology and dynamics (fusion/fission) were examined. Tunicamycin induced maladaptive ER stress, validated by stimulation of GRP94, GRP78, CHOP, XBP-1, ERDJ4, and GADD34, which were mostly mitigated by EUK-134 at transcriptional level. ER stress triggered mitochondrial unfolded protein response and promoted mitochondrial dysfunction, described by substantial loss of mitochondrial membrane potential, as well as reduction of respiratory control ratio, reserve capacity, phosphorylating respiration, and coupling efficiency, which was ameliorated by EUK-134. ROS-mediated biogenesis and fusion of mitochondria was evident in presence of tunicamycin, which however, had high propensity of fragmentation, accompanied by upregulated mRNA levels of fission-related markers. Increased cellular ROS generation oxidative stress was observed in response to ER stress that was ameliorated in the presence of EUK-134, even though no changes in mitochondrial superoxide were noticeable. These findings suggest that targeting ROS generation using the superoxide dismutase/catalase mimetic EUK-134 can amend aspects of ER stress-induced changes in mitochondrial dynamics and function. Overall, this study suggests that in instances of chronic ER stress, such as in myositis, quenching ROS generation may be a promising therapy for muscle weakness and dysfunction.Competing Interest StatementThe authors have declared no competing interest.View Full Text

physiology↗