Biology subjects

Zhu, M. M.

Publications and source records attributed to Zhu, M. M..

4 recordsLinked to original sources

bioRxiv2026

Device-embedded accelerometry complements neural signals for tracking parkinsonian motor states

Adaptive deep brain stimulation (aDBS) relies on physiological biomarkers to infer motor state and guide therapeutic stimulation in Parkinsons disease. However, neural biomarkers may themselves be altered by stimulation, potentially limiting their utility for closed-loop control. We address this limitation by testing whether DBS device-embedded accelerometers can accurately track Parkinsonian motor state across stimulation conditions. We analysed over 1,900 hours of chronic recordings of subthalamic nucleus (STN), sensorimotor cortical and device-embedded accelerometry signals acquired before and during continuous STN stimulation, alongside continuous wearable assessments of bradykinesia and dyskinesia. Across stimulation conditions, accelerometry-derived features robustly tracked motor symptom severity and outperformed neural features for symptom decoding. Mechanistically, total STN beta power - a widely used biomarker for aDBS - proved less informative because it conflates periodic and aperiodic neural processes with opposing relationships to motor state. Under active stimulation, periodic beta activity showed reduced coupling to symptom severity, whereas STN aperiodic activity, cortical periodic activity and cortico-subthalamic coherence remained comparatively stable. Together, these findings demonstrate that neural and behavioural biomarkers exhibit differential robustness during deep brain stimulation and identify device-embedded accelerometry as a robust behavioural biomarker of motor state, motivating its use in next-generation adaptive DBS systems.

bioengineering↗

bioRxiv2023

The Unexpected Role of GCN2 Kinase Activation in Mediating Pulmonary Vascular Remodeling and Pulmonary Arterial Hypertension

BackgroundPulmonary arterial hypertension (PAH) is characterized by progressive increase of pulmonary vascular resistance and remodeling that result in right heart hypertrophy and failure. Published studies show that recessive mutations of EIF2AK4 gene (encoding GCN2, General control nonderepressibe 2 kinase) are linked to heritable pulmonary veno-occlusive disease (PVOD) in patients and EIF2AK4 mutations were also found in PAH patients although very rare. However, the role of GCN2 kinase in the pathogenesis of PAH remains unclear. MethodsEif2ak4-/- mice with genetic disruption of the kinase domain and GCN2 kinase inhibitor A-92 were employed in animal models of PH including chronic hypoxia-exposed mice and monocrotaline-challenged rats. Human lung endothelial cells (HLMVECs) were used for mechanistic studies. Endothelium-targeted nanoparticles were employed to deliver plasmid DNA to adult mice to knockout Eif2ak4 or overexpress Endothelin-1 (Edn1) selectively in ECs. ResultsHere we show that loss of GCN2 induced neither spontaneous PVOD nor PH in Eif2ak4-/- mice but inhibited hypoxia-induced PH evident by reduced right ventricular systolic pressure, right ventricle hypertrophy and pulmonary vascular remodeling. RNA sequencing analysis suggested Edn1 as the downstream target of GCN2. In cultured HLMVECs, GCN2 was phosphorylated and activated in response to hypoxia, mediating hypoxia-induced Edn1 expression via HIF-2. Restored Edn1 expression in ECs in Gcn2-deficient mice reversed the reduced phenotype of hypoxia-induced PH. Furthermore, loss of endothelial Eif2ak4 in mice attenuated hypoxia-induced PH. Monocrotaline-induced PH and pulmonary vascular remodeling in rats were inhibited by GCN2 inhibitor A-92 treatment. The clinical relevance of the observation was validated by GCN2 hyperphosphorylation indicative of activation in ECs of pulmonary vascular lesions of PAH patients. ConclusionThese studies demonstrate that GCN2 activation by hypoxia mediates pulmonary vascular remodeling and PAH through Edn1. Thus, targeting GCN2 signaling is a promising therapeutic strategy for treatment of PAH in patients without EIF2AK4 loss of function mutations.

physiology↗

bioRxiv2021

Endothelial PHD2 Deficiency Induces Nitrative Stress via Suppression of Caveolin-1 in Pulmonary Arterial Hypertension

Nitrative stress is a characteristic feature of the pathology of human pulmonary arterial hypertension (PAH). However, the role of nitrative stress in the pathogenesis of obliterative vascular remolding and severe PAH remains largely unclear. Our recent studies identified a novel mouse model (Egln1Tie2Cre, Egln1 encoding prolyl hydroxylase 2 [PHD2]) with obliterative vascular remodeling and right heart failure, which provides us an excellent model to study the role of nitrative stress in obliterative vascular remodeling. Here we show that nitrative stress was markedly elevated whereas endothelial Caveolin-1 (Cav1) expression was suppressed in the lungs of Egln1Tie2Cre mice. Treatment with a superoxide dismutase mimetic, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTmPyP, also known as a peroxynitrite scavenger) treatment inhibited obliterative pulmonary vascular remodeling and attenuated severe PAH in Egln1Tie2Cre mice. Genetic restoration of endothelial Cav1 expression in Egln1Tie2Cre mice normalized nitrative stress, reduced PAH and improved right heart function. These data suggest that suppression of endothelial Cav1 expression secondary to PHD2 deficiency augments nitrative stress, which contributes to obliterative vascular remodeling and severe PAH. Thus, reactive oxygen/nitrogen species scavenger might have great therapeutic potential for the inhibition of obliterative vascular remodeling and severe PAH.

physiology↗

bioRxiv2021

Loss of Endothelial HIF-Prolyl hydroxylase 2 (PHD2) Induces Cardiac Hypertrophy and Fibrosis

BackgroundCardiac hypertrophy and fibrosis are common adaptive responses to injury and stress, eventually leading to heart failure. Hypoxia signaling is important to the (patho)physiological process of cardiac remodeling. However, the role of endothelial Prolyl-4 hydroxylase 2 (PHD2)/hypoxia inducible factors (HIFs) signaling in the pathogenesis of heart failure remains elusive. Methods and ResultsMice with Tie2-Cre-mediated deletion of Egln1 (encoding PHD2) (Egln1Tie2Cre) exhibited left ventricular (LV) hypertrophy evident by increased thickness of anterior and posterior wall and LV mass, as well as cardiac fibrosis. Tamoxifen-induced endothelial Egln1 deletion in adult mice also induced LV hypertrophy and fibrosis. Additionally, we observed a marked decrease of PHD2 expression in heart tissues and cardiovascular endothelial cells from patients with cardiomyopathy. Moreover, genetic ablation of Hif2a but not Hif1a in Egln1Tie2Cre mice normalized cardiac size and function. RNA sequencing analysis also demonstrated HIF-2 as a critical mediator of signaling related to cardiac hypertrophy and fibrosis. Pharmacological inhibition of HIF-2 attenuated cardiac hypertrophy and fibrosis in Egln1Tie2Cre mice. ConclusionsThe present studies define for the first time an unexpected role of endothelial PHD2 deficiency in inducing cardiac hypertrophy and fibrosis in a HIF-2 dependent manner. PHD2 was markedly decreased in cardiovascular endothelial cells in patients with cardiomyopathy. Thus, targeting PHD2/HIF-2 signaling may represent a novel therapeutic approach for the treatment of pathological cardiac hypertrophy and failure.

physiology↗