Biology subjects

Milosevic, M.

Publications and source records attributed to Milosevic, M..

7 recordsLinked to original sources

bioRxiv2026

TRANSSULFURATION LINKS ASPARTATE-ASPARAGINE METABOLISM AND REDOX HOMEOSTASIS TO DRIVE TUMOR GROWTH

Cytosolic redox balance is tightly coupled to aspartate synthesis through the malate-aspartate shuttle, and limiting the malate-aspartate shuttle has been proposed to constrain tumor growth by restricting aspartate availability. Here we show that tumors derived from cancer cells lacking GOT1 and GOT2, the cytosolic and mitochondrial aspartate aminotransferases essential for as-partate production and malate-aspartate shuttle function, grow despite impaired canonical as-partate synthesis. This is because cytosolic redox state, not aspartate supply, is the primary metabolic bottleneck in GOT1/GOT2 knockout cells. Using single-cell transcriptomics, metabo-lite tracing, and a loss-of-function CRISPR screen, we find that these tumors engage an adaptive bypass in which availability of asparagine, a product of aspartate, enables serine- and methio-nine-dependent transsulfuration to generate -ketobutyrate, whose reduction regenerates cy-tosolic NAD and restores redox homeostasis. Pharmacological inhibition or genetic ablation of transsulfuration abrogates this asparagine-driven rescue. These findings define asparagine as a regulator of cytosolic NAD/NADH balance and reveal a link between amino acid metabolism and redox control that suggests transsulfuration as a targetable vulnerability in tumor redox maintenance. Significance statementAspartate synthesis and cytosolic redox balance are both coupled through the malate-aspartate shuttle. We show that the cytosolic NAD/NADH ratio, not aspartate supply, is a critical output of the malate-aspartate shuttle for tumor growth. Availability of asparagine, a product of aspar-tate, enables serine- and methionine-dependent transsulfuration to restore cytosolic NAD/NADH balance, proliferation and tumor growth independently of canonical aspartate pro-duction by the malate-aspartate shuttle. This defines asparagine as a regulator of cytosolic re-dox and identifies transsulfuration as a targetable vulnerability in tumor redox maintenance.

cancer biology↗

bioRxiv2026

Cortical and spinal contributions to remote interlimb facilitation in humans

Voluntary contraction in one limb can facilitate motor output in a distant limb, a phenomenon commonly referred to as the remote effect. However, the neural mechanisms underlying this remote interlimb facilitation remain unclear. This study investigated cortical and spinal contributions to the remote effect in able-bodied participants. Transcranial magnetic stimulation (TMS) was applied over the hand area of the primary motor cortex using posterior-anterior (PA) and anterior-posterior (AP) current directions, which are sensitive to different cortical inputs. Cortical excitability was assessed using single- and paired-pulse paradigms to measure short-interval intracortical inhibition (SICI), short-interval intracortical facilitation (SICF), and short-latency afferent inhibition (SAI). Spinal motoneuron excitability was assessed from F-waves elicited by peripheral nerve stimulation. During voluntary lower-limb contractions, single-pulse TMS elicited larger motor evoked potentials in hand muscles across current directions, indicating a broad increase in net corticospinal output. However, only AP-sensitive paired-pulse measures showed reduced SICI and enhanced SICF during contraction, whereas PA-sensitive SICI and SICF were not significantly altered, suggesting that cortical modulation during the remote effect is expressed more clearly in AP-sensitive measures. SAI with PA stimulation was less consistently expressed during contraction, suggesting that afferent-related inhibitory modulation may also be influenced during the remote effect. In parallel, F-wave amplitude and persistence increased, consistent with enhanced spinal motoneuron excitability. Together, these results provide converging evidence that the remote effect in humans involves broad corticospinal and spinal facilitation, accompanied by current direction-dependent modulation of cortical excitability measures. KEY POINTS SUMMARYO_LIVoluntary contraction in one limb can facilitate motor output in a distant limb, but the mechanisms underlying this remote interlimb facilitation remain unclear. C_LIO_LIWe tested whether remote lower-limb contraction modulates corticospinal output, intracortical excitability, and spinal motoneuron excitability in a resting hand muscle. C_LIO_LISingle-pulse transcranial magnetic stimulation showed that motor evoked potentials in the hand were facilitated during remote lower-limb contraction across multiple current directions, indicating a broad increase in net corticospinal output. C_LIO_LIPaired-pulse measures were modulated preferentially with anterior-posterior stimulation, with reduced short-interval intracortical inhibition and increased short-interval intracortical facilitation, suggesting current direction-dependent modulation of cortical excitability measures. C_LIO_LIF-wave amplitude and persistence were also enhanced during remote lower-limb contraction, indicating increased spinal motoneuron excitability. These findings provide converging evidence that the remote effect involves both cortical and spinal contributions. C_LI

neuroscience↗

bioRxiv2026

Virtual prototyping of non-invasive spinal cord electrical stimulation targeting upper limb motor function

Transcutaneous spinal cord stimulation (tSCS) applied over the cervical or lumbar spinal cord facilitates motor function after paralysis. However, emerging electrophysiological evidence indicates mechanistic differences between cervical and lumbar tSCS and across different cervical tSCS paradigms. To clarify these discrepancies, we developed and validated a multi-scale, whole-body computational model of tSCS-induced volume conduction, axonal recruitment, and synaptic transmission. Across 24 cervical and four lumbar tSCS paradigms, simulations showed that somatosensory afferents consistently exhibit lower stimulation thresholds than motor efferents. In turn, region-specific synaptic transmission differences may explain electrophysiological discrepancies between cervical and lumbar tSCS. Across cervical tSCS paradigms, substantial volume conduction and axonal recruitment differences were observed that explain electrophysiological discrepancies. Specifically, clinically-prevalent paradigms, including those with anodes placed over the clavicles or iliac crests, engaged peripheral nerves in addition to spinal roots. This effect was amplified by multiphasic waveforms, which introduced recruitment sites near the anodes. By integrating simulations with electrophysiological recordings in 14 able-bodied individuals, we investigated previously unexplored cervical tSCS paradigms on their capacity to recruit somatosensory afferents relative to motor threshold.

neuroscience↗

bioRxiv2025

HSCs and Tregs cooperate to preserve extramedullary hematopoiesis under chronic inflammation

Hematopoietic stem cells (HSCs) are localized within specialized niches of the bone marrow (BM). However, during hematological disorders or infections, the functionality of HSCs in the BM is compromised, leading to extramedullary hematopoiesis (EMH). Chronic inflammation drives EMH, yet its impact on HSCs outside the BM is poorly understood. Using a mouse model of chronic autoinflammatory disease, we demonstrated the presence of extramedullary HSCs in blood, spleen, and inflamed tails and paws. Single-cell transcriptomics revealed a unique expression profile in extramedullary HSCs, with significant upregulation of Cd53, MHCII-associated, and immunosuppressive genes. We further demonstrated that extramedullary CD53+ HSCs act as antigen-presenting cells, promoting the development of regulatory T cells (Tregs) to control chronic inflammation at extramedullary sites. Conversely, Tregs exert a protective role on extramedullary HSCs. Altogether, our findings revealed a mutually supportive relationship between a unique subset of HSCs and T cells in inflamed tissues during chronic inflammation.

immunology↗

bioRxiv2022

Preferential activation of proprioceptive and cutaneous sensory fibers compared to motor fibers during cervical transcutaneous spinal cord stimulation: A computational study

ObjectiveCervical transcutaneous spinal cord stimulation (tSCS) is a promising technology that can support motor function recovery of upper-limbs after spinal cord injury. Its efficacy may depend on the ability to recruit sensory afferents and convey excitatory inputs onto motoneurons. Therefore, understanding its physiological mechanisms is critical to accelerate its development towards clinical applications. In this study, we used an anatomically realistic computational model of the cervical spine to compare -motor, A-sensory, and A{beta}-sensory fiber activation thresholds and activation sites. ApproachWe developed a tridimensional geometry of the cervical body and tSCS electrodes with a cathode centred at the C7 spinous process and an anode placed over the anterior neck. The geometrical model was used to estimate the electric potential distributions along motor and sensory fiber trajectories at the C7 spinal level using a finite element method. We implemented dedicated motor and sensory fiber models to simulate the -motor and A-sensory fibers using 12, 16, and 20 m diameter fibers, and A{beta}-sensory fibers using 6, 9, and 12 m diameter fibers. We estimated nerve fiber activation thresholds and sites for a 2 ms monophasic stimulating pulse and compared them across the fiber groups. Main resultsOur results showed lower activation thresholds of A- and A{beta}-sensory fibers compared with -motor fibers, suggesting preferential sensory fiber activation. We also found no differences between activation thresholds of A-sensory and large A{beta}-sensory fibers, implying they were co-activated. The activation sites were located at the dorsal and ventral root levels. SignificanceUsing a realistic computational model, we demonstrated preferential activation of dorsal root A- and A{beta}-sensory fibers compared with ventral root -motor fibers during cervical tSCS. These findings suggest high proprioceptive and cutaneous contributions to neural activations during cervical tSCS, which inform the underlying mechanisms of upper-limb functional motor recovery.

neuroscience↗

bioRxiv2020

Long-lasting event-related beta synchronization and theta desynchronization of electroencephalographic activity in response to support-surface perturbations during upright stance: Novel findings from experimental and model-based results

Movement related beta band cortical oscillations, including beta rebound after execution and/or suppression of movement, have drawn attention in upper extremity motor control literature. However, fewer study focused on beta band oscillations during postural control in upright stance. Here, we examined beta rebound and other components of electroencephalogram (EEG) activity during perturbed upright stance to investigate supraspinal contributions to postural stabilization. Particularly, we aimed to clarify the timing and duration of beta rebound within a non-sustained, but long-lasting, postural recovery process that occurs more slowly compared to upper extremities. To this end, EEG signals were acquired from nine healthy young adults in response to a support-surface perturbation, together with the center of pressure (CoP) and mass (CoM) and electromyogram (EMG) activities of ankle muscles. Event-related potentials (ERPs) and event-related spectral perturbations were computed from EEG data using the perturbation-onset as a triggering event. After short-latency (< 0.3 s) ERPs, our results showed high-beta band power decrease (event-related desynchronization), which was followed by an event-related synchronization at high-beta band and theta band desynchronization. Specifically, beta synchronization (beta rebound) was sustained for as long as three seconds. EMGs of the ankle muscles and the ankle and hip joint torques remained activated in the first half period of the beta rebound. They returned to the steady-state in the remaining phase, where the CoP/CoM were in their final approach to the equilibrium. We propose possible mechanistic causes of the long-lasting beta rebound, which may be related to underlying intermittent control strategy in upright stance. New & NoteworthyBeta rebound cortical activity was identified during postural recovery from a perturbed upright stance. Contrary to upper extremities, it was initiated before the recovery of motion was completed, and sustained for as long as three seconds. Those novel characteristics of the beta rebound might be caused by slow dynamics of the upright posture and by selections of on/off switching in an intermittent feedback controller, which was shown to stabilize upright posture.

neuroscience↗

bioRxiv2019

The Innate Immune Toll-Like Receptor-2 modulates the Depressogenic and Anorexiolytic Neuroinflammatory Response in Obstructive Sleep Apnoea

BackgroundThe neurological mechanisms of the disease process of obstructive sleep apnea, the second most frequent sleep disorder, remain unclear whilst its links with several major neuropsychiatric disorders, such as depression, anxiety and even Alzheimers disorder, are increasingly recognised. A radical theory, that inflammation in the brain may underlie certain phenotypes of many of these disorders, has been proposed, and the microglial TLR2 system may serve as an important crossroad at the borderlands of several pathogenesis. This study undertook to investigate whether a neuroinflammatory response occurs under conditions of OSA, and whether it might be related to a modulated response due to TLR2 functionality in an established rodent model of OSA. MethodsThe effects of three weeks exposure to chronic intermittent hypoxia were monitored in mice with or without functional TLR2 (C57BL/6-Tyrc-Brd-Tg(Tlr2-luc/gfp)Kri/Gaj; TLR2-/-, C57BL/6-Tlr2tm1Kir), that were investigated by multimodal in vivo and ex vivo imaging, combining magnetic resonance and bioluminescence imaging and a variety of functional tests. ResultsAn acute neuroinflammatory response was demonstrated following the three days in the basal forebrain of mice, and more chronically in other parts of the frontal cortex. Adaptive changes in specific neurocircuitry were demonstrated, with significant links to agitated (mal)adaptive behaviour under episodes of stress, and an increased ability to gain weight. ConclusionsOur results suggest that microglial activation and an innate immune response might be the missing link underlying the pathogenesis of well known structural, psychologic and metabolic changes experienced by some patients with OSA.

neuroscience↗