Differential Upregulation of Th1/Th17-Associated Proteins and PD-L1 in Granulomatous Mycosis Fungoides.

Granulomatous Mycosis Fungoides (GMF) is a rare form of mycosis fungoides (MF) characterized by a granulomatous infiltrate associated with the neoplastic lymphoid population and is considered to have a worse prognosis compared with regular MF. The upregulation of the T helper (Th) axis, especially Th17, plays an important role in the pathogenesis of several inflammatory/infectious granulomatous cutaneous diseases, but its role in GMF is still not elucidated to date. In this study, we evaluated the immunohistochemical expression of Th1 (Tbet), Th2 (GATA-3), Th17 (RORγT), T regulatory (Foxp3), and immune checkpoint (IC) (PD-1 and PD-L1) markers in a cohort of patients with GMF and MF with large cell transformation (MFLCT). Skin biopsies from 49 patients (28 GMF and 21 MFLCT) were studied. Patients with GMF were associated with early clinical stage (p = 0.036) and lower levels of lactate dehydrogenase (p = 0.042). An increased percentage of cells positive for Tbet (p = 0.017), RORγT (p = 0.001), and PD-L1 (p = 0.011) was also observed among the GMF specimens, while a stronger PD-1 intensity was detected in cases of MFLCT. In this cohort, LCT, RORγT < 10%, Foxp3 < 10%, age, and advanced stage were associated with worse overall survival (OS) in univariate analysis. GMF demonstrated Th1 (cellular response) and Th17 (autoimmunity) phenotype, seen in early MF and granulomatous processes, respectively, which may be related to the histopathological appearance and biological behavior of GMF. Further studies involving larger series of cases and more sensitive techniques are warranted.

Direct observation of cortactin protecting Arp2/3-actin filament branch junctions from GMF-mediated destabilization.

How cells tightly control the formation and turnover of branched actin filament arrays to drive cell motility, endocytosis, and other cellular processes is still not well understood. Here, we investigated the mechanistic relationship between two binding partners of the Arp2/3 complex, glia maturation factor (GMF) and cortactin. Individually, GMF and cortactin have opposite effects on the stability of actin filament branches, but it is unknown how they work in concert with each other to govern branch turnover. Using TIRF microscopy, we observe that GMF's branch destabilizing activities are potently blocked by cortactin (IC50 = 1.3 nM) and that this inhibition requires direct interactions of cortactin with Arp2/3 complex. The simplest model that would explain these results is competition for binding Arp2/3 complex. However, we find that cortactin and GMF do not compete for free Arp2/3 complex in solution. Further, we use single molecule analysis to show that cortactin's on-rate (3 ×107 s-1 M-1) and off-rate (0.03 s-1) at branch junctions are minimally affected by excess GMF. Together, these results show that cortactin binds with high affinity to branch junctions, where it blocks the destabilizing effects of GMF, possibly by a mechanism that is allosteric in nature. In addition, the affinities we measure for cortactin at actin filament branch junctions (Kd = 0.9 nM) and filament sides (Kd = 206 nM) are approximately 20-fold stronger than previously reported. These observations contribute to an emerging view of molecular complexity in how Arp2/3 complex is regulated through the integration of multiple inputs.

Glia maturation factor beta deficiency protects against diabetic osteoporosis by suppressing osteoclast hyperactivity.

Excessive osteoclast activation, which depends on dramatic changes in actin dynamics, causes osteoporosis (OP). The molecular mechanism of osteoclast activation in OP related to type 1 diabetes (T1D) remains unclear. Glia maturation factor beta (GMFB) is considered a growth and differentiation factor for both glia and neurons. Here, we demonstrated that Gmfb deficiency effectively ameliorated the phenotype of T1D-OP in rats by inhibiting osteoclast hyperactivity. In vitro assays showed that GMFB participated in osteoclast activation rather than proliferation. Gmfb deficiency did not affect osteoclast sealing zone (SZ) formation but effectively decreased the SZ area by decreasing actin depolymerization. When GMFB was overexpressed in Gmfb-deficient osteoclasts, the size of the SZ area was enlarged in a dose-dependent manner. Moreover, decreased actin depolymerization led to a decrease in nuclear G-actin, which activated MKL1/SRF-dependent gene transcription. We found that pro-osteoclastogenic factors (Mmp9 and Mmp14) were downregulated, while anti-osteoclastogenic factors (Cftr and Fhl2) were upregulated in Gmfb KO osteoclasts. A GMFB inhibitor, DS-30, targeting the binding site of GMFB and Arp2/3, was obtained. Biocore analysis revealed a high affinity between DS-30 and GMFB in a dose-dependent manner. As expected, DS-30 strongly suppressed osteoclast hyperactivity in vivo and in vitro. In conclusion, our work identified a new therapeutic strategy for T1D-OP treatment. The discovery of GMFB inhibitors will contribute to translational research on T1D-OP.

Glia maturation factor-γ is required for initiation and maintenance of hematopoietic stem and progenitor cells.

BACKGROUND: In vertebrates, hematopoietic stem and progenitor cells (HSPCs) emerge from hemogenic endothelium in the floor of the dorsal aorta and subsequently migrate to secondary niches where they expand and differentiate into committed lineages. Glia maturation factor γ (gmfg) is a key regulator of actin dynamics that was shown to be highly expressed in hematopoietic tissue. Our goal is to investigate the role and mechanism of gmfg in embryonic HSPC development. METHODS: In-depth bioinformatics analysis of our published RNA-seq data identified gmfg as a cogent candidate gene implicated in HSPC development. Loss and gain-of-function strategies were applied to study the biological function of gmfg. Whole-mount in situ hybridization, confocal microscopy, flow cytometry, and western blotting were used to evaluate changes in the number of various hematopoietic cells and expression levels of cell proliferation, cell apoptosis and hematopoietic-related markers. RNA-seq was performed to screen signaling pathways responsible for gmfg deficiency-induced defects in HSPC initiation. The effect of gmfg on YAP sublocalization was assessed in vitro by utilizing HUVEC cell line. RESULTS: We took advantage of zebrafish embryos to illustrate that loss of gmfg impaired HSPC initiation and maintenance. In gmfg-deficient embryos, the number of hemogenic endothelium and HSPCs was significantly reduced, with the accompanying decreased number of erythrocytes, myelocytes and lymphocytes. We found that blood flow modulates gmfg expression and gmfg overexpression could partially rescue the reduction of HSPCs in the absence of blood flow. Assays in zebrafish and HUVEC showed that gmfg deficiency suppressed the activity of YAP, a well-established blood flow mediator, by preventing its shuttling from cytoplasm to nucleus. During HSPC initiation, loss of gmfg resulted in Notch inactivation and the induction of Notch intracellular domain could partially restore the HSPC loss in gmfg-deficient embryos. CONCLUSIONS: We conclude that gmfg mediates blood flow-induced HSPC maintenance via regulation of YAP, and contributes to HSPC initiation through the modulation of Notch signaling. Our findings reveal a brand-new aspect of gmfg function and highlight a novel mechanism for embryonic HSPC development.

Identification and Characterization of Glycine- and Arginine-Rich Motifs in Proteins by a Novel GAR Motif Finder Program.

Glycine- and arginine-rich (GAR) motifs with different combinations of RG/RGG repeats are present in many proteins. The nucleolar rRNA 2'-O-methyltransferase fibrillarin (FBL) contains a conserved long N-terminal GAR domain with more than 10 RGG plus RG repeats separated by specific amino acids, mostly phenylanalines. We developed a GAR motif finder (GMF) program based on the features of the GAR domain of FBL. The G(0,3)-X(0,1)-R-G(1,2)-X(0,5)-G(0,2)-X(0,1)-R-G(1,2) pattern allows the accommodation of extra-long GAR motifs with continuous RG/RGG interrupted by polyglycine or other amino acids. The program has a graphic interface and can easily output the results as .csv and .txt files. We used GMF to show the characteristics of the long GAR domains in FBL and two other nucleolar proteins, nucleolin and GAR1. GMF analyses can illustrate the similarities and also differences between the long GAR domains in the three nucleolar proteins and motifs in other typical RG/RGG-repeat-containing proteins, specifically the FET family members FUS, EWS, and TAF15 in position, motif length, RG/RGG number, and amino acid composition. We also used GMF to analyze the human proteome and focused on the ones with at least 10 RGG plus RG repeats. We showed the classification of the long GAR motifs and their putative correlation with protein/RNA interactions and liquid-liquid phase separation. The GMF algorithm can facilitate further systematic analyses of the GAR motifs in proteins and proteomes.

The Geomagnetic Field (GMF) Is Required for Lima Bean Photosynthesis and Reactive Oxygen Species Production.

Plants evolved in the presence of the Earth's magnetic field (or geomagnetic field, GMF). Variations in MF intensity and inclination are perceived by plants as an abiotic stress condition with responses at the genomic and metabolic level, with changes in growth and developmental processes. The reduction of GMF to near null magnetic field (NNMF) values by the use of a triaxial Helmholtz coils system was used to evaluate the requirement of the GMF for Lima bean (Phaseolus lunatus L.) photosynthesis and reactive oxygen species (ROS) production. The leaf area, stomatal density, chloroplast ultrastructure and some biochemical parameters including leaf carbohydrate, total carbon, protein content and δ13C were affected by NNMF conditions, as were the chlorophyll and carotenoid levels. RubisCO activity and content were also reduced in NNMF. The GMF was required for the reaction center's efficiency and for the reduction of quinones. NNMF conditions downregulated the expression of the MagR homologs PlIScA2 and PlcpIScA, implying a connection between magnetoreception and photosynthetic efficiency. Finally, we showed that the GMF induced a higher expression of genes involved in ROS production, with increased contents of both H2O2 and other peroxides. Our results show that, in Lima bean, the GMF is required for photosynthesis and that PlIScA2 and PlcpIScA may play a role in the modulation of MF-dependent responses of photosynthesis and plant oxidative stress.

Translational Significance of GMF-ß Inhibition by Indazole-4-yl-methanol in Enteric Glial Cells for Treating Multiple Sclerosis.

In the emerging context of gut-brain control of multiple sclerosis (MS), developing therapeutics targeting proinflammatory proteins controlling the gut-brain immunomodulation is welcoming. One such immunomodulator is glia maturation factor-ß (GMF-ß). GMF-ß activation following GMF-ß-ser-83 phosphorylation upregulates proinflammatory responses and exacerbates experimental autoimmune encephalomyelitis (EAE). Notably, GMF-ß-/- mice exhibited no EAE symptoms. Thus, we identified 1H-indazole-4-yl-methanol (GMFBI.1) inhibitor which blocked GMF-ß-ser-83 phosphorylation critical in EAE suppression. To establish gut GMF-ß's role in EAE in the context of gut-brain involvement in neurodegenerative diseases, we altered gut GMFBI.1 bioavailability as an index of EAE suppression. At first, we identified Miglyol 812N as a suitable biocompatible GMFBI.1 carrier compared to other FDA-approved carriers using in silico molecular docking analysis. GMFBI.1 administration in Miglyol 812N enhanced its retention/brain permeability. Subsequently, we administered GMFBI.1-Miglyol 812N by subcutaneous/oral routes at different doses with differential GMFBI.1 bioavailability in gut and brain to assess the role of local GMFBI.1 bioavailability in EAE reversal by a pharmacokinetic approach. Deprival of gut GMFBI.1 bioavailability led to partial EAE suppression despite having sufficient GMFBI.1 in circulation to inhibit brain GMF-ß activity. Restoration of gut GMFBI.1 bioavailability led to complete EAE reversal. Molecular pathology behind partial/full EAE reversal was associated with differential GMF-ß-Ser-83 phosphorylation/GM-CSF expression levels in enteric glial cells owing to GMFBI.1 bioavailability. In addition, we observed leaky gut reversal, tight junction protein ZO-1 restoration, beneficial gut microbiome repopulation, recovery from gut dysbiosis, and upregulation of Treg cells. GMFBI.1's dual gut/brain targeting of GMF-ß has therapeutical/translational potential in controlling autoimmunity in MS.

Transcriptomics and Metabolomics of Reactive Oxygen Species Modulation in Near-Null Magnetic Field-Induced Arabidopsis thaliana.

The geomagnetic field (GMF) is a natural component of Earth's biosphere. GMF reduction to near-null values (NNMF) induces gene expression modulation that generates biomolecular, morphological, and developmental changes. Here, we evaluate the effect of NNMF on gene expression and reactive oxygen species (ROS) production in time-course experiments on Arabidopsis thaliana. Plants exposed to NNMF in a triaxial Helmholtz coils system were sampled from 10 min to 96 h to evaluate differentially expressed genes (DEGs) of oxidative stress responses by gene microarray. In 24-96 h developing stages, H2O2 and polyphenols were also analyzed from roots and shoots. A total of 194 DEGs involved in oxidative reactions were selected, many of which showed a fold change ≥±2 in at least one timing point. Heatmap clustering showed DEGs both between roots/shoots and among the different time points. NNMF induced a lower H2O2 than GMF, in agreement with the expression of ROS-related genes. Forty-four polyphenols were identified, the content of which progressively decreased during NNMF exposition time. The comparison between polyphenols content and DEGs showed overlapping patterns. These results indicate that GMF reduction induces metabolomic and transcriptomic modulation of ROS-scavenging enzymes and H2O2 production in A. thaliana, which is paralleled by the regulation of antioxidant polyphenols.

Expression of GMFB in High-Grade Cervical Intraepithelial Neoplasia and Its Role in Cervical Cancer.

Cervical intraepithelial neoplasia (CIN) is a collective term for specific precancerous lesions associated with cervical cancer (CC). Although it has been affirmed with slow development of several levels of cellular changes, the existing poor prognosis calls for an urgent need to diagnose CIN at early stage and be aware of markers related to its pathogenesis and prognosis. We explored the expression level of a newly marker GMFB and its regulatory effect on CIN and CC. Patient samples and cell models were included. Bioinformatic studies were taken to predict its binding to miR-143-3p, miR-26b-5p, miR-191-5p, and miR-223-3p. Luciferase reporter and RNA pull-down assays were used to validate the prediction. Edu assay and flow cytometry were used to measure the regulation of GMFB on proliferation and apoptosis of CC cells. qRT-PCR was used for mRNA expression level detection. The results showed that GMFB was targeted by miR-143-3p, miR-26b-5p, miR-191-5p, and miR-223-3p. It had elevated expression in both CIN and CC samples. GMFB had highly prognostic value for CIN, and lymph node metastasis of CC was much associated with high GMFB expression level. Besides, silencing of GMFB inhibited CC cell proliferation and elevated cell apoptosis. In conclusion, we determined that GMFB has regulatory effect on high grade CIN and CC, which could lighten a novel way in exploring their pathogenesis and improving accuracy of prognosis.

Glia Maturation Factor-ß Supports Liver Regeneration by Remodeling Actin Network to Enhance STAT3 Proliferative Signals.

BACKGROUND & AIMS: Glia maturation factor-ß (GMFB) is a bona fide member of the actin depolymerizing factor homology family. Recently, emerging evidence suggested its implication in liver diseases, but data on its role in liver remain limited. METHODS: Assessment of GMFB in liver histology, impact on liver regeneration and hepatocyte proliferation, and the underlying molecular pathways were conducted using mouse models with acute liver injury. RESULTS: GMFB is widely distributed in normal liver. Its expression increases within 24 hours after partial hepatectomy (PHx). Adult Gmfb knockout mice and wild-type littermates are similar in gross appearance, body weight, liver function, and histology. However, compared with wild-type control, Gmfb knockout mice post-PHx develop more serious liver damage and steatosis and have delayed liver regeneration; the dominant change in liver transcriptome at 24 hours after PHx is the significantly suppressed acute inflammation pathways; the top down-regulated gene sets relate to interleukin (IL)6/Janus kinase/signal transducer and activator of transcription 3 (STAT3) signaling. Another mouse model intoxicated with carbon tetrachloride replicated these findings. Furthermore, Gmfb knockout and wild-type groups have the similar numbers of Kupffer cells, but Gmfb knockout Kupffer cells once stimulated produce less IL6, tumor necrosis factor, and IL1ß. In hepatocytes treated with IL6, GMFB associates positively with cell proliferation and STAT3/cyclin D1 activation, but without any direct interaction with STAT3. In Gmfb knockout hepatocytes, cytoskeleton-related gene expression was changed significantly, with an abnormal-appearing morphology of actin networks. In hepatocyte modeling, actin-filament turnover, STAT3 activation, and metabolite excretion show a strong reliance on the status of actin-filament organization. CONCLUSIONS: GMFB plays a significant role in liver regeneration by promoting acute inflammatory response in Kupffer cells and by intracellularly coordinating the responsive hepatocyte proliferation.

Single-molecule analysis of actin filament debranching by cofilin and GMF.

Eukaryotic cells contain branched actin networks that are essential for endocytosis, motility, and other key cellular processes. These networks, which are formed by filamentous actin and the Arp2/3 complex, must subsequently be debranched to allow network remodeling and to recycle the Arp2/3 complex. Debranching appears to be catalyzed by two different members of the actin depolymerizing factor homology protein family: cofilin and glial maturation factor (GMF). However, their mechanisms of debranching are only partially understood. Here, we used single-molecule fluorescence imaging of Arp2/3 complex and actin filaments under physiological ionic conditions to observe debranching by GMF and cofilin. We demonstrate that cofilin, like GMF, is an authentic debrancher independent of its filament-severing activity and that the debranching activities of the two proteins are additive. While GMF binds directly to the Arp2/3 complex, cofilin selectively accumulates on branch-junction daughter filaments in tropomyosin-decorated networks just prior to debranching events. Quantitative comparison of debranching rates with the known kinetics of cofilin-actin binding suggests that cofilin occupancy of a particular single actin site at the branch junction is sufficient to trigger debranching. In rare cases in which the order of departure could be resolved during GMF- or cofilin-induced debranching, the Arp2/3 complex left the branch junction bound to the pointed end of the daughter filament, suggesting that both GMF and cofilin can work by destabilizing the mother filament-Arp2/3 complex interface. Taken together, these observations suggest that GMF and cofilin promote debranching by distinct yet complementary mechanisms.

GMFG (glia maturation factor gamma) inhibits lung cancer growth by activating p53 signaling pathway.

The tumor-promoting or tumor-suppressing functions of Glia maturation factor gamma (GMFG) were described in several cancers. However, how GMFG regulates lung cancer progression is elusive. Bioinformatics analysis was employed to analyze GMFG expression in lung adenocarcinoma (LUAD) and lung squamous cancer (LUSC) as well as its significance in prognosis prediction and diagnosis in lung cancer patients. CCK8 and colony formation assays were adopted to evaluate the impact of GMFG overexpressing and depleting on lung cancer cell proliferation. And in vivo experiments were implemented. Luciferase reporter assays were used to disclose the signaling pathway mediated by GMFG in lung cancer. GMFG expression was lower in LUSC and LUAD tissues compared with normal lung tissues based on TCGA and GTEx databases. Low GMFG expression was associated with lower overall survival and shorter disease specific survival compared high GMFG expression. In vitro loss and gain functions assays demonstrated that ectopically GMFG expression dampened the lung cancer cell proliferation while GMFG knockout escalated the cell proliferation. The promoting effect of GMFG knockout on lung cancer tumorgenesis was also observed in vivo. More interesting, GMFG overexpression reinforced the p53 signaling pathway in lung cancer cells, conversely GMFG deficiency disrupted p53 signaling pathway. In conclusion, we revealed that GMFG is fundamental to p53 signaling pathway to inhibit lung cancer progression, highlighting the importance of GMFG as a p53 inducer for lung cancer patient's diagnosis and therapy.

Glia maturation factor-ß induces ferroptosis by impairing chaperone-mediated autophagic degradation of ACSL4 in early diabetic retinopathy.

Diabetic retinopathy (DR) is one of the leading causes of blindness in the world, and timely prevention and treatment are very important. Previously, we found that a neurodegenerative factor, Glia maturation factor-ß (GMFB), was upregulated in the vitreous at a very early stage of diabetes, which may play an important role in pathogenesis. Here, we found that in a high glucose environment, large amounts of GMFB protein can be secreted in the vitreous, which translocates the ATPase ATP6V1A from the lysosome, preventing its assembly and alkalinizing the lysosome in the retinal pigment epithelial (RPE) cells. ACSL4 protein can be recognized by HSC70, the receptor for chaperone-mediated autophagy, and finally digested in the lysosome. Abnormalities in the autophagy-lysosome degradation process lead to its accumulation, which catalyzes the production of lethal lipid species and finally induces ferroptosis in RPE cells. GMFB antibody, lysosome activator NKH477, CMA activator QX77, and ferroptosis inhibitor Liproxstatin-1 were all effective in preventing early diabetic retinopathy and maintaining normal visual function, which has powerful clinical application value. Our research broadens the understanding of the relationship between autophagy and ferroptosis and provides a new therapeutic target for the treatment of DR.

RNF144A exerts tumor suppressor function in breast cancer through targeting YY1 for proteasomal degradation to downregulate GMFG expression.

Ring finger protein 144A (RNF144A), a poorly characterized member of the RING-in-between-RING family of E3 ubiquitin ligases, is an emerging tumor suppressor, but its underlying mechanism remains largely elusive. To address this issue, we used Affymetrix GeneChip Human Transcriptome Array 2.0 to profile gene expression in MDA-MB-231 cells stably expressing empty vector pCDH and Flag-RNF144A, and found that 128 genes were differentially expressed between pCDH- and RNF144A-expressing cells with fold change over 1.5. We further demonstrated that RNF144A negatively regulated the protein and mRNA levels of glial maturation factor γ (GMFG). Mechanistical investigations revealed that transcription factor YY1 transcriptionally activated GMFG expression, and RNF144A interacted with YY1 and promoted its ubiquitination-dependent degradation, thus blocking YY1-induced GMFG expression. Functional rescue assays showed that ectopic expression of RNF144A suppressed the proliferative, migratory, and invasive potential of breast cancer cells, and the noted effects were partially restored by re-expression of GMFG in RNF144A-overexpressing breast cancer cells. Collectively, these findings reveal that RNF144A negatively regulates GMFG expression by targeting YY1 for proteasomal degradation, thus inhibiting the proliferation, migration, and invasion of breast cancer cells.

MicroRNA-5195-3p alleviates high glucose­induced injury in human ARPE-19 cells by targeting GMFB.

Hyperglycemia is generally considered to be an important cause of diabetic retinopathy (DR). The aim of the present study was to investigate the role of miR-5195-3p in high glucose (HG)-induced human retinal pigment epithelial ARPE-19 cell injury. Here, we first found that the expression level of miR-5195-3p was significantly downregulated in HG-stimulated ARPE-19 cells using reverse transcription quantitative PCR. Overexpression of miR-5195-3p attenuated the impaired cell viability, increased apoptosis and pro-inflammatory cytokines secretion in ARPE-19 cells under HG condition using CCK-8 assay, flow cytometry and ELISA assay, respectively. Luciferase reporter assay showed that miR-5195-3p could specifically bind to the 3'UTR of glia maturation factor-ß (GMFB). GMFB overexpression reversed, while knockdown enhanced the protective effects of miR-5195-3p overexpression against HG-induced ARPE-19 cell injury. In summary, miR-5195-3p targeting GMFB might be a potential therapeutic target for DR.

Real-Time Noninvasive Bioluminescence, Ultrasound and Photoacoustic Imaging in NFκB-RE-Luc Transgenic Mice Reveal Glia Maturation Factor-Mediated Immediate and Sustained Spatio-Temporal Activation of NFκB Signaling Post-Traumatic Brain Injury in a Gender-Specific Manner.

Neurotrauma especially traumatic brain injury (TBI) is the leading cause of death and disability worldwide. To improve upon the early diagnosis and develop precision-targeted therapies for TBI, it is critical to understand the underlying molecular mechanisms and signaling pathways. The transcription factor, nuclear factor kappa B (NFκB), which is ubiquitously expressed, plays a crucial role in the normal cell survival, proliferation, differentiation, function, as well as in disease states like neuroinflammation and neurodegeneration. Here, we hypothesized that real-time noninvasive bioluminescence molecular imaging allows rapid and precise monitoring of TBI-induced immediate and rapid spatio-temporal activation of NFκB signaling pathway in response to Glia maturation factor (GMF) upregulation which in turn leads to neuroinflammation and neurodegeneration post-TBI. To test and validate our hypothesis and to gain novel mechanistic insights, we subjected NFκB-RE-Luc transgenic male and female mice to TBI and performed real-time noninvasive bioluminescence imaging (BLI) as well as photoacoustic and ultrasound imaging (PAI). Our BLI data revealed that TBI leads to an immediate and sustained activation of NFκB signaling. Further, our BLI data suggest that especially in male NFκB-RE-Luc transgenic mice subjected to TBI, in addition to brain, there is widespread activation of NFκB signaling in multiple organs. However, in the case of the female NFκB-RE-Luc transgenic mice, TBI induces a very specific and localized activation of NFκB signaling in the brain. Further, our microRNA data suggest that TBI induces significant upregulation of mir-9-5p, mir-21a-5p, mir-34a-5p, mir-16-3p, as well as mir-155-5p within 24 h and these microRNAs can be successfully used as TBI-specific biomarkers. To the best of our knowledge, this is one of the first and unique study of its kind to report immediate and sustained activation of NFκB signaling post-TBI in a gender-specific manner by utilizing real-time non-invasive BLI and PAI in NFκB-RE-Luc transgenic mice. Our study will prove immensely beneficial to gain novel mechanistic insights underlying TBI, unravel novel therapeutic targets, as well as enable us to monitor in real-time the response to innovative TBI-specific precision-targeted gene and stem cell-based precision medicine.

Glia Maturation Factor (GMF) Regulates Microglial Expression Phenotypes and the Associated Neurological Deficits in a Mouse Model of Traumatic Brain Injury.

Traumatic brain injury (TBI) induces inflammatory responses through microglial activation and polarization towards a more inflammatory state that contributes to the deleterious secondary brain injury. Glia maturation factor (GMF) is a pro-inflammatory protein that is responsible for neuroinflammation following insult to the brain, such as in TBI. We hypothesized that the absence of GMF in GMF-knockout (GMF-KO) mice would regulate microglial activation state and the M1/M2 phenotypes following TBI. We used the weight drop model of TBI in C57BL/6 mice wild-type (WT) and GMF-KO mice. Immunofluorescence staining, Western blot, and ELISA assays were performed to confirm TBI-induced histopathological and neuroinflammatory changes. Behavioral analysis was done to check motor coordination ability and cognitive function. We demonstrated that the deletion of GMF in GMF-KO mice significantly limited lesion volume, attenuated neuronal loss, inhibited gliosis, and activated microglia adopted predominantly anti-inflammatory (M2) phenotypes. Using an ELISA method, we found a gradual decrease in pro-inflammatory cytokines (TNF-α and IL-6) and upregulation of anti-inflammatory cytokines (IL-4 and IL-10) in GMF-KO mice compared with WT mice, thus, promoting the transition of microglia towards a more predominantly anti-inflammatory (M2) phenotype. GMF-KO mice showed significant improvement in motor ability, memory, and cognition. Overall, our results demonstrate that GMF deficiency regulates microglial polarization, which ameliorates neuronal injury and behavioral impairments following TBI in mice and concludes that GMF is a regulator of neuroinflammation and an ideal therapeutic target for the treatment of TBI.

Force and phosphate release from Arp2/3 complex promote dissociation of actin filament branches.

Networks of branched actin filaments formed by Arp2/3 complex generate and experience mechanical forces during essential cellular functions, including cell motility and endocytosis. External forces regulate the assembly and architecture of branched actin networks both in vitro and in cells. Considerably less is known about how mechanical forces influence the disassembly of actin filament networks, specifically, the dissociation of branches. We used microfluidics to apply force to branches formed from purified muscle actin and fission yeast Arp2/3 complex and observed debranching events in real time with total internal reflection fluorescence microscopy. Low forces in the range of 0 pN to 2 pN on branches accelerated their dissociation from mother filaments more than two orders of magnitude, from hours to <1 min. Neither force on the mother filament nor thermal fluctuations in mother filament shape influenced debranching. Arp2/3 complex at branch junctions adopts two distinct mechanical states with different sensitivities to force, which we name "young/strong" and "old/weak." The "young/strong" state 1 has adenosine 5'-diphosphate (ADP)-P i bound to Arp2/3 complex. Phosphate release converts Arp2/3 complex into the "old/weak" state 2 with bound ADP, which is 20 times more sensitive to force than state 1. Branches with ADP-Arp2/3 complex are more sensitive to debranching by fission yeast GMF (glia maturation factor) than branches with ADP-P i -Arp2/3 complex. These findings suggest that aging of branch junctions by phosphate release from Arp2/3 complex and mechanical forces contribute to disassembling "old" actin filament branches in cells.

NLRP3 inflammasome and glia maturation factor coordinately regulate neuroinflammation and neuronal loss in MPTP mouse model of Parkinson's disease.

Neuroinflammation plays an active role in the pathogenesis of several neurodegenerative diseases, including Parkinson's disease (PD). Earlier studies from this laboratory showed that glia maturation factor (GMF), a proinflammatory mediator; is up-regulated in the brain in neurodegenerative diseases and that deficiency of GMF showed decreased production of IL-1ß and improved behavioral abnormalities in mouse model of PD. However, the mechanisms linking GMF and dopaminergic neuronal death have not been completely explored. In the present study, we have investigated the expression of NLRP3 inflammasome and caspase-1 in the substantia nigra (SN) of human PD and non-PD brains by immunohistochemistry. Wild-type (WT) and GMF-/- (GMF knock-out) mice were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine (MPTP) and the brains were isolated for neurochemical and morphological examinations. NLRP3 and caspase-1 positive cells were found significantly increased in PD when compared to non-PD control brains. Moreover, GMF co-localized with α-Synuclein within reactive astrocytes in the midbrain of PD. Mice treated with MPTP exhibit glial activation-induced inflammation, and nigrostriatal dopaminergic neurodegeneration. Interestingly, increased expression of the inflammasome components in astrocytes and microglia observed in the SN of MPTP-treated WT mice were significantly reduced in GMF-/- mice. Additionally, we show that NLRP3 activation in microglia leads to translocation of GMF and NLRP3 to the mitochondria. We conclude that downregulation of GMF may have beneficial effects in prevention of PD by modulating the cytotoxic functions of microglia and astrocytes through reduced activation of the NLRP3 inflammasome; a major contributor of neuroinflammation in the CNS.

Substrate Specific Inhibitor Designed against the Immunomodulator GMF-beta Reversed the Experimental Autoimmune Encephalomyelitis.

The concept of substrate inhibition to prevent its phosphorylation has potential in drug discovery and is envisioned to treat the autoimmune disorder multiple sclerosis (MS). Glia maturation factor-ß (GMF-ß) Ser83 phosphorylation by protein kinase A (PKA) is pivotal in the activation of GMF-ß-p38MAPK-NFκB biochemical pathway towards proinflammatory response induction in experimental autoimmune encephalomyelitis (EAE). Using structure-based drug design, we identified the small molecule inhibitor 1-H-indazole-4yl methanol (GMFBI.1) that specifically blocked Ser83 phosphorylation site on GMF-ß substrate. Using in vitro and in vivo techniques, molecular mechanism of action of GMFBI.1's direct interaction with GMF-ß substrate and prevention of its Ser83 phosphorylation was established. GMFBI.1 down regulated p38MAPK phosphorylation and NFκB expression essential for proinflammatory response. Further, GMFBI.1 administration at peak of EAE reversed clinical symptoms, immunopathology, proinflammatory cytokine response and up regulated the anti-inflammatory cytokines. Present strategy of substrate inhibition against the key immunomodulatory target has immense therapeutic potential in MS.