Hai-Ying Shen

DNA methylation is implicated in epileptogenesis. Sarcosine, a glycine transporter 1 (GlyT1) inhibitor and methyl donor, attenuates behavioral progression during rapid hippocampal kindling and alters hippocampal DNA methylation, but its locus-specific epigenetic effects remain poorly understood. Here, reduced representation bisulfite sequencing (RRBS) was combined with targeted gene expression analysis in the hippocampi of sarcosine-treated kindled rats. RRBS identified 563, 533, and 390 differentially methylated regions (DMRs), corresponding to 521, 499, and 374 DMR-associated genes, in vehicle-kindled versus sham (vKD vs. vSH), sarcosine-kindled versus sham (sKD vs. vSH), and sarcosine-kindled versus vehicle-kindled (sKD vs. vKD) comparisons, respectively. Pathway enrichment analysis identified 217 significantly affected pathways, including glutamatergic signaling, extracellular matrix (ECM) organization, chromatin regulation, axon guidance, and apoptotic processes. Eleven candidate genes involved in epigenetic regulation, excitatory neurotransmission, and ECM remodeling were selected for transcriptional validation. All 11 genes were significantly upregulated in kindled hippocampi, whereas sarcosine was associated with reduced expression relative to vehicle-kindled rats for eight genes (Hdac9, Fos, Smad7, Unc5a, Grik2, Gpr37l1, Cacna2d2, and Yy1). Collectively, these findings indicate that sarcosine remodels DNA methylation-associated transcriptional networks during rapid hippocampal kindling and support GlyT1 inhibition as a potential disease-modifying approach in experimental epileptogenesis.

DNA methylation is a key regulator of epileptogenesis. Sarcosine, a glycine transporter 1 (GlyT1) inhibitor and methyl donor, suppresses kindling-induced epileptogenesis and alters hippocampal DNA methylation, but its locus-specific epigenetic effects remain poorly understood. Here, reduced representation bisulfite sequencing (RRBS) was combined with targeted gene expression analysis in the hippocampus of sarcosine-treated kindled rats. RRBS identified 563, 533, and 390 differentially methylated regions (DMRs), corresponding to 521, 499, and 374 DMR-associated genes, in vehicle-kindled versus sham (vKD vs vSH), sarcosine-kindled versus sham (sKD vs vSH), and sarcosine-kindled versus vehicle-kindled (sKD vs vKD) comparisons, respectively. Pathway enrichment analysis identified 217 significantly affected pathways, including glutamatergic signaling, extracellular matrix (ECM) organization, chromatin regulation, axon guidance, and apoptotic processes. Eleven candidate genes involved in epigenetic regulation, excitatory neurotransmission, and ECM remodeling were selected for transcriptional validation. All 11 genes were significantly upregulated in kindled hippocampi, whereas sarcosine normalized expression of eight genes (Hdac9, Fos, Smad7, Unc5a, Grik2, Gpr37l1, Cacna2d2, and Yy1) toward control levels. Collectively, these findings indicate that sarcosine remodels DNA methylation-associated transcriptional networks during epileptogenesis and support GlyT1 inhibition as a potential disease-modifying strategy for epilepsy.

As we celebrate the 15th anniversary of Frontiers in Cellular Neuroscience, it is an opportune moment to reflect on the pivotal research contributions that have shaped our understanding of glial cells in schizophrenia and related disorders. Over the past decade and a half, this journal has been at the forefront of unveiling the complex roles that glial cells, particularly microglia and astrocytes, play in the pathophysiology of mental illnesses.The Intricate Dance of Microglia and Neurons in SchizophreniaHartmann et al. delve into the interactions between microglia and neurons in schizophrenia. Their comprehensive review highlights how microglia, the brain's resident immune cells, engage in a delicate balance of neuroprotection and neuroinflammation, which can be disrupted in schizophrenia. The study underscores the dual role of microglia in either exacerbating or mitigating neuronal damage, depending on their states (1). The authors argue that therapeutic strategies targeting specific microglial reaction states could offer new avenues for treating schizophrenia.Astrocytes: The Unsung Heroes of Brain HealthAstrocytes, another type of glial cell, have also been spotlighted for their crucial role in maintaining brain homeostasis and their involvement in mental disorders. While review articles provide a detailed account of how astrocytes contribute to the pathophysiology of schizophrenia (2), and discuss the astrocytic regulation of neurotransmitter systems, blood-brain barrier integrity, and synaptic function, all of which are often disrupted in schizophrenia (3, 4), Ling Yan et al. have further elucidated the heterogeneity of astrocytes and their distinct roles in various central nervous system (CNS) regions and pathological states, emphasizing the importance of these cells in both health and disease contexts.The Impact of Environmental Stressors: High Altitude and NeuroinflammationIn addition to genetic and molecular factors, environmental stressors such as high altitude have been shown to exacerbate microglial and astrocyte reactions, a common feature in many neurological disorders, including schizophrenia. Liu et al.'s study on the effects of high altitude on traumatic brain injury (TBI) reveals that hypoxic conditions can significantly worsen neuroinflammatory responses. The research demonstrates that L-serine, an endogenous amino acid, can mitigate these effects by modulating microglial activation through the NFAT1 pathway. This finding not only sheds light on the potential for L-serine as a neuroprotective agent but also underscores the broader implications of environmental factors on brain health.Innovative Approaches to Schizophrenia TreatmentSinger et al. explored the inhibition of astrocytic glycine transporter-1 (GlyT1) as a potential therapeutic approach for ameliorating NMDA receptor hypofunction in schizophrenia. The authors discuss the dual nature of GlyT1 inhibition, considering both its potential benefits and drawbacks. Their research suggests that while inhibiting GlyT1 may enhance N-methyl-D-aspartate (NMDA) receptor function and improve cognitive deficits in schizophrenia, careful consideration of the associated risks is essential. This study highlights the complexity of targeting astrocytic functions for therapeutic purposes and underscores the need for nuanced approaches in developing effective treatments.The insights gained from these studies highlight the multifaceted roles of glial cells in brain health and disease. As we look forward to the next decade of Frontiers in Cellular Neuroscience, several promising research directions emerge. (i) Microglial Modulation: Developing therapies that can precisely modulate microglial activation states to promote neuroprotection while minimizing neuroinflammation. (ii) Targeting Astrocyte Functions: Exploring astrocyte-targeted therapies to restore neurotransmitter balance and synaptic function in schizophrenia. (iii) Environmental Considerations: Investigating the impact of environmental stressors on glial cell function and developing strategies to mitigate their adverse effects. (iv) GlyT1 Inhibition: Further examining the therapeutic potential and risks of inhibiting astrocytic glycine transporter-1 to enhance NMDA receptor function in schizophrenia. In conclusion, the past 15 years have seen remarkable advancements in our understanding of glial cells and their roles in schizophrenia and related disorders. The continued exploration of these cellular players holds great promise for developing more effective treatments and improving the lives of those affected by these debilitating conditions.

A series of 1,3-oxazolo[4,5-d]pyrimidine and 1,3-oxazolo[5,4-d]pyrimidine derivatives were synthesized and functionalized in this study. The obtained compounds were tested against breast cancer cell lines of the NCI subpanel, followed by further analysis using the COMPARE algorithm from the Therapeutics Development Program, NCI. All synthesized derivatives displayed activity against most cell lines in the range of micromolar concentrations in terms of all parameters studied. Oxazolopyrimidine 5 exhibited the highest antitumor activity. A standard COMPARE analysis of the compounds showed that the vectors of the cytotoxic activity of derivatives 10 and 11 displayed a close to very high correlation with tamoxifen, and oxazolopyrimidine 13 displayed a very high correlation with the same drug. Five derivatives (2, 4, 6, 11 and 13) showed a high correlation with aclacinomycin A in the TGI vector. At the same time, compound 1 effectively suppressed ADK in cultured MDA-MB 231 cell lines, indicating that ADK is one of its targets through which it exerts anticancer properties. Based on molecular docking results, the possible binding mode of oxazolopyrimidine 1 to ADK has been suggested.

Original Article Comprehensive analysis of the correlation between GSTM1 and tumor immunity in colon cancer Hao-Yun Luo, Wen-Lian Tang, Ling Xiang, Ling-Long Peng, Da-Bin Wu, Zhi-Yong Zhu, Hai-Tao Gu, Yun-Hao Tang, R. Serene Perkins, Hai-Ying Shen, Ya-Xu Wang

Adenosinergic activities are suggested to participate in SUDEP pathophysiology; this study aimed to evaluate the adenosine hypothesis of SUDEP and specifically the role of adenosine A_2A receptor (A_2AR) in the development of a SUDEP mouse model with relevant clinical features. Using a combined paradigm of intrahippocampal and intraperitoneal administration of kainic acid (KA), we developed a boosted-KA model of SUDEP in genetically modified adenosine kinase (ADK) knockdown (Adk^+/-) mice, which has reduced ADK in the brain. Seizure activity was monitored using video-EEG methods, and in vivo recording of local field potential (LFP) was used to evaluate neuronal activity within the nucleus tractus solitarius (NTS). Our boosted-KA model of SUDEP was characterized by a delayed, postictal sudden death in epileptic mice. We demonstrated a higher incidence of SUDEP in Adk^+/- mice (34.8%) vs. WTs (8.0%), and the ADK inhibitor, 5-Iodotubercidin, further increased SUDEP in Adk^+/- mice (46.7%). We revealed that the NTS level of ADK was significantly increased in epileptic WTs, but not in epileptic Adk^+/- mutants, while the A_2AR level in NTS was increased in epileptic (WT and Adk^+/-) mice vs. non-epileptic controls. The A_2AR antagonist, SCH58261, significantly reduced SUDEP events in Adk^+/- mice. LFP data showed that SCH58261 partially restored KA injection-induced suppression of gamma oscillation in the NTS of epileptic WT mice, whereas SCH58261 increased theta and beta oscillations in Adk^+/- mutants after KA injection, albeit with no change in gamma oscillations. These LFP findings suggest that SCH58261 and KA induced changes in local neuronal activities in the NTS of epileptic mice. We revealed a crucial role for NTS A_2AR in SUDEP pathophysiology suggesting A_2AR as a potential therapeutic target for SUDEP risk prevention.

Methylation is an important mechanism contributing to cancer pathology. Methylation of tumor suppressor genes and oncogenes has been closely associated with tumor occurrence and development. New insights regarding the potential role of the adenosine receptor-independent pathway in the epigenetic modulation of DNA methylation offer the possibility of new interventional strategies for cancer therapy. Targeting DNA methylation of cancer-related genes is a promising therapeutic strategy; drugs like 5-Aza-2′-deoxycytidine (5-AZA-CdR, decitabine) effectively reverse DNA methylation and cancer cell growth. However, current anti-methylation (or methylation modifiers) are associated with severe side effects; thus, there is an urgent need for safer and more specific inhibitors of DNA methylation (or DNA methylation modifiers). The adenosine signaling pathway is reported to be involved in cancer pathology and participates in the development of tumors by altering DNA methylation. Most recently, an adenosine metabolic clearance enzyme, adenosine kinase (ADK), has been shown to influence methylation on tumor suppressor genes and tumor development and progression. This review article focuses on recent updates on ADK and its two isoforms, and its actions in adenosine receptor-independent pathways, including methylation modification and epigenetic changes in cancer pathology.

Purpose: Glia and their communication via connexin 43 (Cx43) gap junctions are known to mediate neurovascular coupling, a process driven by metabolic demand. However, it is unclear whether Cx43 mediated glial communication intermediates classical autoregulation. Here we used viral transfection and a glial fibrillary acidic protein (GFAP) promoter to downregulate glial Cx43 to evaluate its role in retinal vascular autoregulation to ocular perfusion pressure (OPP) reduction. Methods: Adult rats were intravitreally injected with the viral active construct or a control. Three weeks after the injection, eyes were imaged using confocal scanning laser ophthalmoscopy before and during a period of OPP decrease induced by blood draw to lower blood pressure or by manometric IOP elevation. Vessel diameter responses to the OPP decrease were compared between Cx43-downregulated and control-injected eyes. The extent of Cx43 downregulation was evaluated by Western blot and immunohistochemistry. Results: In control eyes, the OPP decrease induced dilatation of arterioles, but not venules. In Cx43-downregulated eyes, Cx43 expression in whole retina was decreased by approximately 40%. In these eyes, the resting diameter of the venules increased significantly, but there was no effect on arterioles. In Cx43-downregulated eyes, vasoreactivity evoked by blood pressure lowering was significantly compromised in both arterioles (P = 0.005) and venules (P = 0.001). Cx43 downregulation did not affect the arteriole responses to IOP elevation, whereas the responses of the venules showed a significantly greater decrease in diameter (P < 0.001). Conclusions: The downregulation of retinal Cx43 in GFAP–expressing cells compromises vasoreactivity of both arterioles and venules in response to an OPP decrease achieved via blood pressure lowering or IOP elevation. The results also suggest that Cx43-mediated glial communication actively regulates resting venular diameter.

Epileptogenesis is a common consequence of brain insults, however, the prevention or delay of the epileptogenic process remains an important unmet medical challenge. Overexpression of glycine transporter 1 (GlyT1) is proposed as a pathological hallmark in the hippocampus of patients with temporal lobe epilepsy (TLE), and we previously demonstrated in rodent epilepsy models that augmentation of glycine suppressed chronic seizures and altered acute seizure thresholds. In the present study we evaluated the effect of the GlyT1 inhibitor, sarcosine (aka N-methylglycine), on epileptogenesis and also investigated possible mechanisms. We developed a modified rapid kindling model of epileptogenesis in rats combined with seizure score monitoring to evaluate the antiepileptogenic effect of sarcosine. We used immunohistochemistry and Western blot analysis for the evaluation of GlyT1 expression and epigenetic changes of 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in the epileptogenic hippocampi of rats, and further evaluated expression changes in enzymes involved in the regulation of DNA methylation, ten-eleven translocation methylcytosine dioxygenase 1 (TET1), DNA-methyltransferase 1 (DNMT1), and DNMT3a. Our results demonstrated: (i) experimental evidence that sarcosine (3 g/kg, i.p. daily) suppressed kindling epileptogenesis in rats; (ii) the sarcosine-induced antiepileptogenic effect was accompanied by a suppressed hippocampal GlyT1 expression as well as a reduction of hippocampal 5mC levels and a corresponding increase in 5hmC; and (iii) sarcosine treatment caused differential expression changes of TET1 and DNMTs. Together, these findings suggest that sarcosine has unprecedented disease-modifying properties in a kindling model of epileptogenesis in rats, which was associated with altered hippocampal DNA methylation. Thus, manipulation of the glycine system is a potential therapeutic approach to attenuate the development of epilepsy.