Project description:NG2 glia, also known as oligodendrocyte precursor cells (OPCs), play an important role in proliferation and give rise to myelinating oligodendrocytes during early brain development. In contrast to other glial cell types, the most intriguing aspect of NG2 glia is their ability to directly sense synaptic inputs from neurons. However, whether this synaptic interaction is bidirectional or unidirectional, or its physiological relevance has not yet been clarified. Here, we report that NG2 glia form synaptic complexes with hippocampal interneurons and that selective photostimulation of NG2 glia (expressing channelrhodopsin-2) functionally drives GABA release and enhances inhibitory synaptic transmission onto proximal interneurons in a microcircuit. The mechanism involves GAD67 biosynthesis and VAMP-2 containing vesicular exocytosis. Further, behavioral assays demonstrate that NG2 glia photoactivation triggers an anxiety-like behavior in vivo and induces anxiety-like behavior in a mouse model of chronic social defeat stress.
Project description:NG2 glia, also known as oligodendrocyte precursor cells (OPCs), play an important role in proliferation and give rise to myelinating oligodendrocytes during early brain development. In contrast to other glial cell types, the most intriguing aspect of NG2 glia is their ability to directly sense synaptic inputs from neurons. However, whether this synaptic interaction is bidirectional or unidirectional, or its physiological relevance has not yet been clarified. Here, we report that NG2 glia form synaptic complexes with hippocampal interneurons and that selective photostimulation of NG2 glia (expressing channelrhodopsin-2) functionally drives GABA release and enhances inhibitory synaptic transmission onto proximal interneurons in a microcircuit. The mechanism involves GAD67 biosynthesis and VAMP-2 containing vesicular exocytosis. Further, behavioral assays demonstrate that NG2 glia photoactivation triggers anxiety-like behavior in vivo and contributes to chronic social defeat stress.
Project description:Microglia, the resident immune cells of the brain, have emerged as crucial regulators of synaptic refinement and therefore wiring precision. However, whether the remodeling of distinct synapses during development is mediated by specialized microglia is unknown. Here, using in vivo two-photon imaging, we show that GABA-receptive microglia selectively interact with inhibitory synapses during a critical window of mouse postnatal development. GABA initiates a transcriptional synapse remodeling program within these specialized microglia, which in turn sculpt inhibitory connectivity without impacting excitatory synapses. Ablation of GABAB receptors within microglia impairs this process and leads to stereotyped repetitive behavior and hyperactivity. These findings demonstrate that distinct microglia differentially engage with specific synapse types during development.
Project description:This study aimed to investigate the anxiolytic effects of GABA administration and its underlying molecular mechanisms in a chronic restraint stress (CRS)-induced anxiety model in C57BL/6J mice. CRS mice were established by placing the animals in well-ventilated 50 ml centrifuge tubes for 2 hours daily over 14 consecutive days, while control mice were housed under standard conditions. Behavioral assessments, including the elevated plus maze (EPM) test and open field test (OFT), were performed on days 15 and 16, respectively. GABA was administered intragastrically at various doses throughout the experiment, and prefrontal cortex (PFC) and hippocampal tissues were harvested on day 17 for further proteomic and biochemical analyses. Behavioral results demonstrated that GABA treatment exerted dose-dependent anxiolytic effects, as evidenced by increased time and entries in the open arms in the EPM and increased time and distance spent in the center area in the OFT. Furthermore, GABA treatment significantly elevated reduced GABA levels in the PFC. To elucidate the molecular mechanisms of GABA’s anxiolytic effects, a 4D-label-free quantitative proteomics approach was employed. Principal component analysis (PCA) and differential protein analyses revealed that CRS induced substantial proteomic alterations in the hippocampus, while GABA treatment partially reversed these changes. Functional clustering (Mfuzz) and gene ontology (GO) enrichment analysis identified critical pathways involved in the “humoral immune response,” “complement activation,” and “acute inflammatory response.” Key proteins such as C3, Cfh, C4b, and Cfi were found to overlap across these pathways, highlighting their involvement in CRS-induced neuroimmune dysfunction and GABA-mediated rescue effects. This integrated analysis provides valuable insights into the behavioral and neuroimmune mechanisms through which GABA alleviates anxiety-like behaviors, shedding light on its potential as a therapeutic agent for stress-related disorders.
Project description:NG2/CSPG4 is expressed in soft tissue sarcomas, however, its function in this tumor type, and its capacity to serve as a therapeutic target are unknown. Here, we used genetically engineered mice and cells from human tumors to determine the function of Ng2/Cspg4 in soft tissue sarcoma initiation and growth. We also investigated the potential for NG2/CSPG4 mAb immunotherapy to target human sarcomas established as xenografts in mice. Inhibiting Ng2/Cspg4 expression in established soft tissue sarcomas is associated with a smaller tumor volume and a reduction in cell proliferation. Intriguingly, deleting Ng2/Cspg4 at the time of tumor initiation has the opposite effect. Gene profiling found that Igfbp3/5 are substantially downregulated when Ng2/Cspg4 is depleted at the time of tumor initiation, but upregulated or only minimally downregulated when Ng2/Cspg4 is depleted after tumor initiation. Furthermore, the normal regulation of Igfbp is blunted when Ng2/Cspg4 is deleted at the time of tumor initiation. Our data show a difference in NG2/CSPG4 function in tumor initiation and maintenance, and provides pre-clinical evidence supporting NG2/CSPG4 as a therapeutic approach in soft tissue sarcoma.
Project description:Changes in the mechanical homeostasis of the temporomandibular joint (TMJ) can lead to the initiation and progression of degenerative arthropathies such as osteoarthritis (OA). Cells sense and engage with their mechanical microenvironment through interactions with the extracellular matrix. In the mandibular condylar cartilage, the pericellular microenvironment is composed of type VI collagen. NG2/CSPG4 is a transmembrane proteoglycan that binds with type VI collagen, and has been implicated in the cell stress response through mechanical loading-sensitive signaling networks including ERK 1/2. The objective of this study is to define the role of NG2/CSPG4 in the initiation and progression of TMJ OA and to determine if NG2/CSPG4 engages ERK 1/2 in a mechanical loading dependent manner. In vivo, we induced TMJ OA in control and NG2/CSPG4 knockout mice using a surgical destabilization approach. In control mice, NG2/CSPG4 is depleted during the early stages of TMJ OA and NG2/CSPG4 knockout mice have more severe cartilage degeneration, elevated expression of key OA proteases, and suppression of OA matrix synthesis genes. In vitro, we characterized the transcriptome and protein from control and NG2/CSPG4 knockout cells and found significant dysregulation of the ERK 1/2 signaling axis. To characterize the mechanobiological response of NG2/CSPG4, we applied mechanical loads on cell-agarose-collagen scaffolds using a compression bioreactor and illustrate that NG2/CSPG4 knockout cells fail to mechanically activate ERK 1/2 and are associated with changes in the expression of the same key OA biomarkers measured in vivo. Together, these findings implicate NG2/CSPG4 in the mechanical homeostasis of TMJ cartilage and in the progression of degenerative arthropathies including OA.
Project description:Changes in the mechanical homeostasis of the temporomandibular joint (TMJ) can lead to the initiation and progression of degenerative arthropathies such as osteoarthritis (OA). Cells sense and engage with their mechanical microenvironment through interactions with the extracellular matrix. In the mandibular condylar cartilage, the pericellular microenvironment is composed of type VI collagen. NG2/CSPG4 is a transmembrane proteoglycan that binds with type VI collagen, and has been implicated in the cell stress response. The objective of this study is to define the role of NG2/CSPG4 in the cell stress response during serum starvation. To evaluate the role of the NG2/CSPG4, primary mandibular fibrochondrocytes from c57 BL/6 J and NG2/CSPG4 knockout mice (mixed sex) were cultured in normal and serum starvation conditions. To evaluate the role of the NG2/CSPG4 ectodomain, primary mandibular fibrochondrocytes were immortalized using hTERT. CRSIPR/Cas9 was used to truncate the NG2/CSPG4 ectodomain by targeting the type VI collagen binding region. Normal culture conditions were AMEM growth media supplemented with 10% FBS, penicillin, L-Glut, and plasmocin. Serum starvation conditions were Optimem media with no FBS, supplemented with penicillin, L-Glut, and plasmocin. Serum starvation was induced for 24 hours. RNA from the cells was isolated using the RNeasy kit (Qiagen). poly(A) RNA was fragmented using divalent cation buffer in elevated temperature. The DNA library construction is shown in the following workflow. Quality control analysis and quantification of the sequencing library were performed using Agilent Technologies 2100 Bioanalyzer High Sensitivity DNA Chip. Paired-ended sequencing was performed on Illumina’s NovaSeq 6000 sequencing system. Sequencing was done by LC Sciences. These data illustrate that in serum starvation conditions, NG2/CSPG4 knockout mandibular fibrochondrocytes and targeted truncation of the NG2/CSPG4 ectodomain alters the transcriptional profile of the cell, promoting biological processes associated with cell stress, migration, and ossiciation.
Project description:Changes in the mechanical homeostasis of the temporomandibular joint (TMJ) can lead to the initiation and progression of degenerative arthropathies such as osteoarthritis (OA). Cells sense and engage with their mechanical microenvironment through interactions with the extracellular matrix. In the mandibular condylar cartilage, the pericellular microenvironment is composed of type VI collagen. NG2/CSPG4 is a transmembrane proteoglycan that binds with type VI collagen, and has been implicated in the cell stress response. The objective of this study is to define the role of NG2/CSPG4 in the cell stress response during serum starvation. To evaluate the role of the NG2/CSPG4, primary mandibular fibrochondrocytes from c57 BL/6 J and NG2/CSPG4 knockout mice (mixed sex) were cultured in normal and serum starvation conditions. To evaluate the role of the NG2/CSPG4 ectodomain, primary mandibular fibrochondrocytes were immortalized using hTERT. CRSIPR/Cas9 was used to truncate the NG2/CSPG4 ectodomain by targeting the type VI collagen binding region. Normal culture conditions were AMEM growth media supplemented with 10% FBS, penicillin, L-Glut, and plasmocin. Serum starvation conditions were Optimem media with no FBS, supplemented with penicillin, L-Glut, and plasmocin. Serum starvation was induced for 24 hours. RNA from the cells was isolated using the RNeasy kit (Qiagen). poly(A) RNA was fragmented using divalent cation buffer in elevated temperature. The DNA library construction is shown in the following workflow. Quality control analysis and quantification of the sequencing library were performed using Agilent Technologies 2100 Bioanalyzer High Sensitivity DNA Chip. Paired-ended sequencing was performed on Illumina’s NovaSeq 6000 sequencing system. Sequencing was done by LC Sciences. These data illustrate that in serum starvation conditions, NG2/CSPG4 knockout mandibular fibrochondrocytes and targeted truncation of the NG2/CSPG4 ectodomain alters the transcriptional profile of the cell, promoting biological processes associated with cell stress, migration, and ossiciation.
Project description:Neurotransmitters have been well-documented to determine immune cell fates; however, whether and how γ-amino butyric acid (GABA) shapes the function of innate immune cells is still obscure. Here, we demonstrated that GABA orchestrates macrophage maturation and inflammation. GABA treatment during macrophage maturation inhibits interleukin (IL)-1β production from inflammatory macrophages. Mechanistically, GABA enhances succinate-FAD-lysine demethylase1 (LSD1) signaling to regulate the histone demethylation of Bcl2l11 and Dusp2, lowering the formation of NLRP3-ASC-Caspase-1 complex. Meanwhile, GABA-succinate axis lowers succinylation of mitochondrial proteins to promote mitochondrial oxidative phosphorylation (OXPHOS). We also found that GABA alleviates the LPS-induced sepsis as well as high-fat diet-induced obesity in mice. Our study proves that GABA is potential in lessening the pro-inflammatory macrophage responses associating with metabolic reprogramming and protein succinylation, thus providing a strategy for treating macrophage-related inflammatory diseases.
Project description:Ischemic stroke is a serious medical condition that leads to neurological symptoms such as loss of motor and cognitive function. Focal cerebral ischemia (FCI) occurs due to interruption of blood supply to the site of injury, leading to the death of brain cells. Cells carrying Neural-glial antigen 2 (NG2) include glial cells serving primarily as olidogendrocyte precursors and a portion of pericytes. NG2 glia proliferate rapidly after ischemia and migrate to the site of injury, participate with astrocytes in glial scar formation, and contribute to the regeneration of the brain tissue. The ability of NG2 glia to differentiate into a different cell type than oligodendrocytes has been described but is still controversial. We therefore isolated NG2 cells and their derivatives labeled with tdTomato red fluorescent protein from the cortex of Rosa26-tdTomato/Cspg4-CreERT2 mice three days after middle cerebral artery occlusion (MCAO). Sham-operated animals were used as healthy controls (CTRL). We aimed to identify NG2 cell types and their derivatives in the cortex of healthy and ischemic mice and determine their incidence as well as characteristic gene expression.