Discovery of a novel neuroprotective compound, AS1219164, by high-throughput chemical screening of a newly identified apoptotic gene marker

TMEM100 Regulates Neuropathic Pain by Reducing the Expression of Inflammatory Factors

There is no effective treatment for peripheral nerve injury-induced chronic neuropathic pain (NP), which profoundly impacts the quality of life of those affected. Transmembraneprotein100 (TMEM100) is considered to be a pain regulatory protein and is expressed in the dorsal root ganglion (DRG) of rats. However, the mechanism of pain regulation and the expression of TMEM100 following various peripheral nerve injuries are unclear. In this study, we constructed two pain models of peripheral nerve injury: tibial nerve injury (TNI) and chronic constriction injury (CCI). This study found that the Paw Withdrawal Mechanical Threshold (PWMT) and Paw Withdraw Thermal Latency (PWTL) of the rats in the two pain models decreased significantly, and the expression of TMEM100 in the DRG of two groups also decreased significantly. Furthermore, the decrease in the CCI group was more obvious than in the TNI group. There was no significant statistical significance (P > 0.05). We constructed an adeno-associated virus 6 (AAV6) vector expressing recombinant fluorescent TMEM100 protein and injected it into the sciatic nerve (SN) of two pain models: CCI and TNI. PWMT and PWTL were significantly increased in the two groups, along with the expression of TMEM100 in the spinal cord and DRG. It also significantly inhibited the activation of microglia, astrocytes, and several inflammatory mediators (TNF- α, IL-1 β, and IL-6). In summary, the results of this study suggested that TMEM100 might be a promising molecular strategy for the treatment of NP, and its anti-inflammatory effects might play an important role in pain relief.

Overexpression of Limb-Bud and Heart (LBH) promotes angiogenesis in human glioma via VEGFA-mediated ERK signalling under hypoxia

Background

Glioma is the most common primary malignant tumor in the central nervous system with frequent hypoxia and angiogenesis. Limb-Bud and Heart (LBH) is a highly conserved transcription cofactor that participates in embryonic development and tumorigenesis.

Methods

The conditioned media from LBH regulated human glioma cell lines and patient-derived glioma stem cells (GSCs) were used to treat the human brain microvessel endothelial cells (hBMECs). The function of LBH on angiogenesis were examined through methods of MTS assay, Edu assay, TUNEL assay, western blotting analysis, qPCR analysis, luciferase reporter assay and xenograft experiment.

Findings

Our study found for the first time that LBH was overexpressed in gliomas and was associated with a poor prognosis. LBH overexpression participated in the angiogenesis of gliomas via the vascular endothelial growth factor A (VEGFA)-mediated extracellular signal-regulated kinase (ERK) signalling pathway in human brain microvessel endothelial cells (hBMECs). Rapid proliferation of gliomas can lead to tissue hypoxia and hypoxia inducible factor-1 (HIF-1) activation, while HIF-1 can directly transcriptionally regulate the expression of LBH and result in a self-reinforcing cycle.

Interpretation

LBH may be a possible treatment target to break the vicious cycle in glioma treatment.

 

 

Transmembrane protein 100 is expressed in neurons and glia of dorsal root ganglia and is reduced after painful nerve injury

Introduction

Tmem100 modulates interactions between TRPA1 and TRPV1. The cell specificity of Tmem100 expression in dorsal root ganglia (DRGs) is not well defined, nor is the effect of peripheral nerve injury on Tmem100 expression.

Objective

This study was designed to determine the cell specificity of Tmem100 expression in DRG and its subcellular localization, and to examine how Tmem100 expression may be altered in painful conditions.

Methods

Dorsal root ganglion Tmem100 expression was determined by immunohistochemistry, immunoblot, and quantitative real-time PCR, and compared between various experimental rat pain models and controls.

Results

Tmem100 is expressed in both neurons and perineuronal glial cells in the rat DRG. The plasma membrane and intracellular localization of Tmem100 are identified in 83% ± 6% of IB4-positive and 48% ± 6% of calcitonin gene-related peptide-positive neurons, as well as in medium- and large-sized neurons, with its immunopositivity colocalized to TRPV1 (94% ± 5%) and TRPA1 (96% ± 3%). Tmem100 is also detected in the perineuronal satellite glial cells and in some microglia. Tmem100 protein is significantly increased in the lumbar DRGs in the complete Freund adjuvant inflammatory pain. By contrast, peripheral nerve injury by spinal nerve ligation diminishes Tmem100 expression in the injured DRG, with immunoblot and immunohistochemistry experiments showing reduced Tmem100 protein levels in both neurons and satellite glial cells of DRGs proximal to injury, whereas Tmem100 is unchanged in adjacent DRGs. The spared nerve injury model also reduces Tmem100 protein in the injured DRGs.

Conclusion

Our data demonstrate a pain pathology-dependent alteration of DRG Tmem100 protein expression, upregulated during CFA inflammatory pain but downregulated during neuropathic pain.

The expression of Transmembrane Protein 100 is regulated by alterations in calcium signaling rather than endoplasmic reticulum stress

Transmembrane protein 100 (TMEM100) comprises 134 amino acid residues and is highly conserved among vertebrates. Tmem100 has been recently reported as a key factor in angiogenesis, pain transmission, and tumor suppression. Although the importance of TMEM100 function is well supported, few studies have elucidated its expression mechanism. In the current study, we found that activating transcription factor 6α, a transcription factor activated by endoplasmic reticulum (ER) stress, enhanced Tmem100 promoter activity. Two ER stress response element-like motifs were identified in the mouse Tmem100 promoter region. However, additional experiments using another type of ER stress inducer demonstrated that calcium signaling was more important than ER stress in the regulation of TMEM100 expression. Intracellular calcium signaling controls biological processes such as cell proliferation and embryonic development. This study suggested that TMEM100 performs various functions in response to alterations in calcium signaling in addition to those in response to ER stress.

ALK1 signaling in development and disease: new paradigms

Activin A receptor like type 1 (ALK1) is a transmembrane serine/threonine receptor kinase in the transforming growth factor-beta receptor family that is expressed on endothelial cells. Defects in ALK1 signaling cause the autosomal dominant vascular disorder, hereditary hemorrhagic telangiectasia (HHT), which is characterized by development of direct connections between arteries and veins, or arteriovenous malformations (AVMs). Although previous studies have implicated ALK1 in various aspects of sprouting angiogenesis, including tip/stalk cell selection, migration, and proliferation, recent work suggests an intriguing role for ALK1 in transducing a flow-based signal that governs directed endothelial cell migration within patent, perfused vessels. In this review, we present an updated view of the mechanism of ALK1 signaling, put forth a unified hypothesis to explain the cellular missteps that lead to AVMs associated with ALK1 deficiency, and discuss emerging roles for ALK1 signaling in diseases beyond HHT.

Gene Expression-Based Screen for Parkinson's Disease Identifies GW8510 as a Neuroprotective Agent

We carried out a gene expression-based in silico screen in order to identify small molecules with gene-expression profiles that are anticorrelated with a gene-expression profile for Parkinson's disease (PD). We identified the cyclin-dependent kinase 2/5 (CDK2/5) inhibitor GW8510 as our most significant hit and characterized its effects in rodent MN9D cells and in human neuronal cells derived from induced pluripotent stem cells. GW8510 demonstrated neuroprotective ability in MN9D cells in the presence of 1-methyl-4-phenylpyridium (MPP(+)), a widely used neurotoxin model for Parkinson's disease. In order to delineate the nature and extent of GW8510's neuroprotective properties, we studied GW8510 in human neuronal cells in the context of various mechanisms of cellular stress. We found that GW8510 was protective against small-molecule mitochondrial and endoplasmic reticulum stressors. Our findings illustrate an approach to using small-molecule gene expression libraries to identify compounds with therapeutic potential in human diseases.

Novel roles of TMEM100: inhibition metastasis and proliferation of hepatocellular carcinoma

Transmembrane protein 100 (TMEM100) was activated by ALK1/TGF-β signaling. We found that TMEM100 was decreased in hepatocellular carcinoma (HCC) tissues and in highly metastatic cell lines. Overexpressed of TMEM100 inhibited invasion, migration and proliferation. Low levels of TMEM100 were associated with cirrhosis, tumor size, Tumor nodule number, TNM stage, BCLC stage, Edmondson-Steiner Stage and vein invasion. Furthermore, TMEM100 was an independent risk factor for overall survival (P = 0.03) and disease-free survival (P = 0.019). The current findings suggest that TMEM100 functions as a tumor suppressor in HCC metastasis and proliferation.

Tmem100 Is a Regulator of TRPA1-TRPV1 Complex and Contributes to Persistent Pain

TRPA1 and TRPV1 are crucial pain mediators, but how their interaction contributes to persistent pain is unknown. Here, we identify Tmem100 as a potentiating modulator of TRPA1-V1 complexes. Tmem100 is coexpressed and forms a complex with TRPA1 and TRPV1 in DRG neurons. Tmem100-deficient mice show a reduction in inflammatory mechanical hyperalgesia and TRPA1- but not TRPV1-mediated pain. Single-channel recording in a heterologous system reveals that Tmem100 selectively potentiates TRPA1 activity in a TRPV1-dependent manner. Mechanistically, Tmem100 weakens the association of TRPA1 and TRPV1, thereby releasing the inhibition of TRPA1 by TRPV1. A Tmem100 mutant, Tmem100-3Q, exerts the opposite effect; i.e., it enhances the association of TRPA1 and TRPV1 and strongly inhibits TRPA1. Strikingly, a cell-permeable peptide (CPP) containing the C-terminal sequence of Tmem100-3Q mimics its effect and inhibits persistent pain. Our study unveils a context-dependent modulation of the TRPA1-V1 complex, and Tmem100-3Q CPP is a promising pain therapy.

Distribution of TMEM100 in the mouse and human gastrointestinal tract--a novel marker of enteric nerves

Identification of markers of enteric neurons has contributed substantially to our understanding of the development, normal physiology, and pathology of the gut. Previously identified markers of the enteric nervous system can be used to label all or most neuronal structures or for examining individual cells by labeling just the nucleus or cell body. Most of these markers are excellent but have some limitations. Transmembrane protein 100 (TMEM100) is a gene at locus 17q32 encoding a 134-amino acid protein with two hypothetical transmembrane domains. TMEM100 expression has not been reported in adult mammalian tissues but does appear in the ventral neural tube of embryonic mice and plays a role in signaling pathways associated with development of the enteric nervous system. We showed that TMEM100 messenger RNA is expressed in the gastrointestinal tract and demonstrated that TMEM100 is a membrane-associated protein. Furthermore TMEM100 immunoreactivity was restricted to enteric neurons and vascular tissue in the muscularis propria of all regions of the mouse and human gastrointestinal tract. TMEM100 immunoreactivity colocalized with labeling for the pan-neuronal marker protein gene product 9.5 (PGP9.5) but not with the glial marker S100ß or Kit, a marker of interstitial cells of Cajal. The signaling molecule, bone morphogenetic protein (BMP) 4, was also expressed in enteric neurons of the human colon and co-localized with TMEM100. TMEM100 is also expressed in neuronal cell bodies and fibers in the mouse brain and dorsal root ganglia. We conclude that TMEM100 is a novel, membrane-associated marker for enteric nerves and is as effective as PGP9.5 for identifying neuronal structures in the gastrointestinal tract. The expression of TMEM100 in the enteric nervous system may reflect a role in the development and differentiation of cells through a transforming growth factor β, BMP or related signaling pathway.