Proteomic analysis of underlying apoptosis mechanisms of human retinal pigment epithelial ARPE-19 cells in response to mechanical stretch.

Our previous study demonstrated mechanical stretch (MS) could induce the apoptosis of retinal pigment epithelial (RPE) cells, but the related mechanisms remained unclear. This study was to characterize the protein expression profile in RPE cell line ARPE-19 exposed to MS, cytochalasin D (CD; an inhibitor of actin polymerization) or CD + MS at 2-time points (6, 24 hr; n = 3, at each time point) by using proteomics technique. Our data highlighted that compared with control, ECE1 was continuously downregulated in ARPE-19 cells treated by MS or CD + MS from 6 to 24 hr. Function and protein-protein interaction network analyses showed ATAD2 was downregulated in all three treatment groups compared with control, but successive upregulation of RPS13 and RPL7 and downregulation of AHSG were specifically induced by MS. ATAD2 was enriched in cell cycle; AHSG was associated with membrane organization; RPS13 and RPL7 participated in ribosome biogenesis. Furthermore, transcription factor CREB1 that was upregulated in MS group at 24 hr after treatment, may negatively regulate ATAD2. The expressions of all crucial proteins in ARPE-19 cells were confirmed by western blot analysis. Overexpression of ATAD2 and AHSG were also shown to reverse the apoptosis of ARPE-19 cells induced by MS or CD + MS, with significantly decreased apoptotic rates and caspase-3 activities. Accordingly, our findings suggest downregulation of ATAD2 and AHSG may be potential contributors to the apoptosis of RPE cells induced by MS. Overexpression of them may represent underlying preventive and therapeutic strategies for MS-induced retinal disorders.

GRK3 is essential for metastatic cells and promotes prostate tumor progression.

The biochemical mechanisms that regulate the process of cancer metastasis are still poorly understood. Because kinases, and the signaling pathways they comprise, play key roles in regulation of many cellular processes, we used an unbiased RNAi in vitro screen and a focused cDNA in vivo screen against human kinases to identify those with previously undocumented roles in metastasis. We discovered that G-protein-coupled receptor kinase 3 (GRK3; or ß-adrenergic receptor kinase 2) was not only necessary for survival and proliferation of metastatic cells, but also sufficient to promote primary prostate tumor growth and metastasis upon exogenous expression in poorly metastatic cells in mouse xenograft models. Mechanistically, we found that GRK3 stimulated angiogenesis, at least in part through down-regulation of thrombospondin-1 and plasminogen activator inhibitor type 2. Furthermore, GRK3 was found to be overexpressed in human prostate cancers, especially in metastatic tumors. Taken together, these data suggest that GRK3 plays an important role in prostate cancer progression and metastasis.

Histone cross-talk connects protein phosphatase 1α (PP1α) and histone deacetylase (HDAC) pathways to regulate the functional transition of bromodomain-containing 4 (BRD4) for inducible gene expression.

Transcription elongation has been recognized as a rate-limiting step for the expression of signal-inducible genes. Through recruitment of positive transcription elongation factor P-TEFb, the bromodomain-containing protein BRD4 plays critical roles in regulating the transcription elongation of a vast array of inducible genes that are important for multiple cellular processes. The diverse biological roles of BRD4 have been proposed to rely on its functional transition between chromatin targeting and transcription regulation. The signaling pathways and the molecular mechanism for regulating this transition process, however, are largely unknown. Here, we report a novel role of phosphorylated Ser(10) of histone H3 (H3S10ph) in governing the functional transition of BRD4. We identified that the acetylated lysines 5 and 8 of nucleosomal histone H4 (H4K5ac/K8ac) is the BRD4 binding site, and the protein phosphatase PP1α and class I histone deacetylase (HDAC1/2/3) signaling pathways are essential for the stress-induced BRD4 release from chromatin. In the unstressed state, phosphorylated H3S10 prevents the deacetylation of nucleosomal H4K5ac/K8ac by HDAC1/2/3, thereby locking up the majority of BRD4 onto chromatin. Upon stress, PP1α-mediated dephosphorylation of H3S10ph allows the deacetylation of nucleosomal H4K5ac/K8ac by HDAC1/2/3, thereby leading to the release of chromatin-bound BRD4 for subsequent recruitment of P-TEFb to enhance the expression of inducible genes. Therefore, our study revealed a novel mechanism that the histone cross-talk between H3S10ph and H4K5ac/K8ac connects PP1α and HDACs to govern the functional transition of BRD4. Combined with previous studies on the regulation of P-TEFb activation, the intricate signaling network for the tight control of transcription elongation is established.

Signal-induced Brd4 release from chromatin is essential for its role transition from chromatin targeting to transcriptional regulation.

Bromodomain-containing protein Brd4 is shown to persistently associate with chromosomes during mitosis for transmitting epigenetic memory across cell divisions. During interphase, Brd4 also plays a key role in regulating the transcription of signal-inducible genes by recruiting positive transcription elongation factor b (P-TEFb) to promoters. How the chromatin-bound Brd4 transits into a transcriptional regulation mode in response to stimulation, however, is largely unknown. Here, by analyzing the dynamics of Brd4 during ultraviolet or hexamethylene bisacetamide treatment, we show that the signal-induced release of chromatin-bound Brd4 is essential for its functional transition. In untreated cells, almost all Brd4 is observed in association with interphase chromatin. Upon treatment, Brd4 is released from chromatin, mostly due to signal-triggered deacetylation of nucleosomal histone H4 at acetylated-lysine 5/8 (H4K5ac/K8ac). Through selective association with the transcriptional active form of P-TEFb that has been liberated from the inactive multi-subunit complex in response to treatment, the released Brd4 mediates the recruitment of this active P-TEFb to promoter, which enhances transcription at the stage of elongation. Thus, through signal-induced release from chromatin and selective association with the active form of P-TEFb, the chromatin-bound Brd4 switches its role to mediate the recruitment of P-TEFb for regulating the transcriptional elongation of signal-inducible genes.

[Retracted] MicroRNA­448 inhibits the progression of retinoblastoma by directly targeting ROCK1 and regulating PI3K/AKT signalling pathway.

Following the publication of this paper, it was drawn to the Editors' attention by a concerned reader that three data panels featured in the flow cytometric plots shown in Figs. 5D and 6D, and several panels from the cell invasion assays shown in Figs. 5C and 6C, were strikingly similar to data appearing in different form in other articles by different authors. Owing to the fact that the contentious data in the above article were already under consideration for publication prior to its submission to Oncology Reports, the Editor has decided that this paper should be retracted from the Journal. After having been in contact with the authors, they agreed with the decision to retract the paper. The Editor apologizes to the readership for any inconvenience caused. [Oncology Reports 39: 2402­2412, 2018; DOI: 10.3892/or.2018.6302].

Biliverdin/Bilirubin Redox Pair Protects Lens Epithelial Cells against Oxidative Stress in Age-Related Cataract by Regulating NF-κB/iNOS and Nrf2/HO-1 Pathways.

Age-related cataract (ARC) is the leading cause of vision impairment globally. It has been widely accepted that excessive reactive oxygen species (ROS) accumulation in lens epithelial cells (LECs) is a critical risk factor for ARC formation. Biliverdin (BV)/bilirubin (BR) redox pair is the active by-product of heme degradation with robust antioxidative stress and antiapoptotic effects. Thus, we purpose that BV and BR may have a therapeutic effect on ARC. In the present study, we determine the expression levels of enzymes regulating BV and BR generation in human lens anterior capsule samples. The therapeutic effect of BV/BR redox pair on ARC was assessed in hydrogen peroxide (H2O2)-damaged mouse LECs in vitro. The NF-κB/inducible nitric oxide synthase (iNOS) and nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathways were evaluated to illustrate the molecular mechanism. The results revealed that the mRNA expressions of Nrf2, HO-1, and biliverdin reductase A (BVRA) were all decreased in human samples of age-related nuclear cataract. BV/BR redox pair pretreatment protected LECs against H2O2 damage by prohibiting NF-κB p65 nuclear trafficking, ameliorating iNOS expression, reducing intracellular and mitochondrial ROS levels, and restoring glutathione (GSH) and superoxide dismutase (SOD) levels. BV and BR pretreatment also regulated the expression of apoptotic molecules (Bax, Bcl-2, and cleaved caspase-3), thus decreasing the apoptosis of LECs. In addition, BV/BR pair promoted Nrf2 nuclear accumulation and HO-1 induction, whereas the knockdown of BVRA counteracted the effect of BV on activating Nrf2/HO-1 pathway and antiapoptosis. These findings implicated that BV/BR redox pair protects LECs against H2O2-induced apoptosis by regulating NF-κB/iNOS and Nrf2/HO-1 pathways. Moreover, BVRA is responsible for BV-mediated cytoprotection by reductive conversion of BV to BR. This trial is registered with ChiCTR2000036059.

Lentinan Enhances the Function of Oxaliplatin on the Esophageal Tumors by Persuading Immunogenic Cell Death.

Objective: The focus of this research was to look at the effects of the combination of the lentinan (LNT) and oxaliplatin (Oxa) on the apoptosis of human esophageal cancer cells, as well as the underlying mechanism. Methods: LNT and Oxa were used to treat EC-109 human esophageal cancerous cells at various doses, and the cell survival rate was measured using the Cell Counting Kit-8 (CCK-8) assay. In addition, 24 h after treatment of EC-109 cells with a combination of LNT and Oxa, flow cytometry was used to analyze their apoptotic effect on these cells. Additionally, LNT on EC-109 cell apoptotic upshot was assessed via measuring the consequence of LNT on the mRNA and protein expression levels pertaining to immunogenic cell death factors CALR, HSP90, and HSP70 by qPCR (quantitative real-time polymerase chain reaction) and western blot analysis, correspondingly. Results: Cell proliferation was inhibited only when EC-109 cells were added with LNT at 1,200 µg/mL to the maximum concentrations, but the combination of LNT and Oxa at a low dose (800 µg/mL and 20 µM, respectively) significantly increased their sensitivity to Oxa and reduced their proliferation (P < 0.05), and their apoptosis was significantly increased by LNT (P < 0.05). The immunogenic cell death-related genes CALR, HSP90, and HSP70 had dramatically enhanced mRNA and protein expression levels after therapy with a combination of LNT and Oxa (P < 0.05). Conclusion: These data imply that LNT increases the susceptibility of esophageal cancerous cells to Oxa by driving EC-109 cells to display immunogenic death. Therefore, LNT combined with Oxa may be an effective method in esophageal cancer management.

CKB inhibits epithelial-mesenchymal transition and prostate cancer progression by sequestering and inhibiting AKT activation.

Epithelial-mesenchymal transition (EMT) contributes to tumor invasion, metastasis and drug resistance. AKT activation is key in a number of cellular processes. While many positive regulators for either EMT or AKT activation have been reported, few negative regulators are established. Through kinase cDNA screen, we identified brain-type creatine kinase (CKB or BCK) as a potent suppressor for both. As a ubiquitously expressed kinase in normal tissues, CKB is significantly downregulated in several solid cancer types. Lower CKB expression is significantly associated with worse prognosis. Phenotypically, CKB overexpression suppresses, while its silencing promotes, EMT and cell migration, xenograft tumor growth and metastasis of prostate cancer cells. AKT activation is one of the most prominent signaling events upon CKB silencing in prostate cancer cells, which is in line with prostate cancer TCGA data. EMT enhanced by CKB silencing is abolished by AKT inhibition. Mechanistically, CKB interacts with AKT and sequestrates it from activation by mTOR. We further elucidated that an 84aa fragment at C-terminus of CKB protein interacts with AKT's PH domain. Ectopic expression of the 84aa CKB fragment inhibits AKT activation, EMT and cell proliferation. Interestingly, molecular dynamics simulation on crystal structures of AKT and CKB independently demonstrates that AKT's PH domain and CKB's 84aa fragment establish their major interaction interface. In summary, we have discovered CKB as a negative regulator of EMT and AKT activation, revealing a new mode of their regulation . We have also demonstrated that CKB downregulation is a poor prognosticator, which is sufficient to promote prostate cancer progression.

Markedly Elevated Serum Level of T-Helper Cell 17-Related Cytokines/Chemokines in Acute Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis.

Purpose: The purpose of this study was to examine the differences in immunopathogenesis based on the cytokine/chemokine profiles in myelin oligodendrocyte glycoprotein antibody (MOG-IgG)-positive and -negative groups. Methods: We measured the levels of T-helper cell 17 (Th17) cell-related cytokines/chemokines in 74 serum samples, which were divided into four groups: healthy control (HC) group (n = 15), idiopathic demyelinating optic neuritis (IDON) group (n = 20), aquaporin 4 (AQP4)-IgG-positive optic neuritis (ON) group (n = 18), and MOG-IgG positive-ON group (n = 21). Serum IL17, IL21, IL28, IL31, CXCL1, CXCL2, CCL2, CCL11, CCL20, and LT-α were detected. Results: The serum of the MOG-IgG-positive ON patients showed an obvious elevation of Th17 cell-related cytokines/chemokines compared with that of all the MOG-IgG-negative ON patients. Serum IL17 and IL21 were significantly higher in the ON patients with MOG-IgG positive than in all the other three groups. The serum levels of IL28, IL31, CXCL1, and CCL11 were higher in the ON patients with MOG-IgG positive than in the HC group and the IDON group. The serum concentration of CCL2, CXCL2, and CCL20 in the MOG-IgG-positive and AQP4-IgG-positive group is higher than that of the HC group. No difference in serum LT-α level was found among the four groups. Adjusted multiple regression analyses showed a positive association of IL17 and IL21 levels with the serum concentration of MOG-IgG in the ON patients. Conclusion: The elevated serum level of Th17 cell-related cytokine/chemokines may play an important role in the pathogenesis of MOG-IgG-positive demyelinating ON.

Cytokines and chemokines expression in serum of patients with neuromyelitis optica.

OBJECTIVE: To study the differences in immunopathogenesis based on chemokine profile in neuromyelitis optica patients positive for AQP4 antibodies or MOG antibodies. PATIENTS AND METHODS: We measured 52 cytokines/chemokines using ELISA in 59 serum samples, which were divided into three groups according to CBA results: HCs (n=16), AQP4+ (n=20) and MOG+ (n=23). The regression equation (R 2>0.98) of the standard curve was calculated according to the standard concentration and the corresponding A value. And then the corresponding sample concentration was calculated according to the A value of the sample. RESULTS: Eleven of 52 measured serum cytokine/chemokines (CCL22/MDC, CCL13/MCP-4, CCL21/6Ckine, CCL27/CTACK, CCL8/MCP-2, CXCL14/BRAK, Contactin-1, Kallilrein 6/Neurosin, Midkine, VCAM-1 and Fas) were significantly different between MOG+ group and controls. Ten of 52 measured serum cytokine/chemokines (CCL1/I-309, CCL22/MDC, CCL28, CCL17/TARC, CCL27/CTACK, CXCL2/GRO beta, Contactin-1, Midkine, Chemerin and Synuclein-alpha) were significantly different between AQP4+ group and controls. There was no difference between serum AQP4+ and MOG+ groups for CC chemokines. All measured chemokines CXC except CXCL6/GCP-2 showed no significant differences in serum AQP4+ group compared to MOG+ group. However, there was significant difference between serum AQP4+ and MOG+ groups for C5/C5a and Midkine. C5/C5a and Midkine were significantly higher in AQP4+ group compared to MOG+ group (P<0.05). CONCLUSION: Our findings suggest that the differences of mean concentration in CXCL6/GCP-2, Midkine and C5/C5a probably reveal different immunologic mechanism between AQP4+ NMO and MOG+ NMO. This cytokine/chemokine profiling provides new insight into NMO pathogenesis associated with MOG antibody seropositivity and provides guidance to monitor inflammation and response to treatment in a way.

Simultaneous bilateral optic neuritis in China: clinical, serological and prognostic characteristics.

PURPOSE: To analyse the clinical characteristics of simultaneous bilateral ON patients in China. METHODS: This retrospective study was done on 51 primary bilateral ON patients between April 2008 and July 2016 at the Chinese People's Liberation Army General Hospital. Fifty eight primary unilateral ON patients formed the control group. Demographic data, clinical course, serum autoantibody status, connective tissue disorders, magnetic resonance imaging and visual functions were compared. RESULTS: The mean age at disease onset in the bilateral group was younger than that of the unilateral group (p = 0.001). Cerebrospinal fluid (CSF) total cell count and CSF total protein were significantly higher in the bilateral group (p = 0.001, p = 0.025). Aquaporin-4 (AQP4) antibodies were detected in 39% and 21% of the bilateral and unilateral patients, respectively (p = 0.03). Twenty two percent of the bilateral patients fulfilled the diagnosis of neuromyelitis optica (NMO); 7% in the unilateral group did so (p = 0.03). Serum autoantibodies (ANA, SSA, SSB, etc.) were found in 49% of the bilateral patients and 29% of the unilateral patients (p = 0.035). After treatment, the bilateral patients were significantly more prone to severe visual disability eventually than their unilateral counterparts (p = 0.002). Patients with MOG-IgG (myelin oligodendrocyte glycoprotein-IgG) represented 26% of the patients negative for AQP4-IgG. Myelin oligodendrocyte glycoprotein-IgG (MOG-IgG) sero-positive patients were more likely to recover than the other patients (p < 0.001). CONCLUSION: Simultaneous bilateral ON is a severe disorder closely related to serum AQP4-IgG and MOG-IgG, which are more likely to involve younger people and incur severe visual disability eventually. Myelin oligodendrocyte glycoprotein-IgG (MOG-IgG) sero-positive patients have higher risk of ON relapses and better visual prognosis.

MEIS2C and MEIS2D promote tumor progression via Wnt/ß-catenin and hippo/YAP signaling in hepatocellular carcinoma.

BACKGROUND: MEIS2 has been identified as one of the key transcription factors in the gene regulatory network in the development and pathogenesis of human cancers. Our study aims to identify the regulatory mechanisms of MEIS2 in hepatocellular carcinoma (HCC), which could be targeted to develop new therapeutic strategies. METHODS: The variation of MEIS2 levels were assayed in a cohort of HCC patients. The proliferation, clone-formation, migration, and invasion abilities of HCC cells were measured to analyze the effects of MEIS2C and MEIS2D (MEIS2C/D) knockdown with small hairpin RNAs in vitro and in vivo. Chromatin immunoprecipitation (ChIP) was performed to identify MEIS2 binding site. Immunoprecipitation and immunofluorescence assays were employed to detect proteins regulated by MEIS2. RESULTS: The expression of MEIS2C/D was increased in the HCC specimens when compared with the adjacent noncancerous liver (ANL) tissues. Moreover, MEIS2C/D expression negatively correlated with the prognosis of HCC patients. On the other hand, knockdown of MEIS2C/D could inhibit proliferation and diminish migration and invasion of hepatoma cells in vitro and in vivo. Mechanistically, MESI2C activated Wnt/ß-catenin pathway in cooperation with Parafibromin (CDC73), while MEIS2D suppressed Hippo pathway by promoting YAP nuclear translocation via miR-1307-3p/LATS1 axis. Notably, CDC73 could directly either interact with MEIS2C/ß-catenin or MEIS2D/YAP complex, depending on its tyrosine-phosphorylation status. CONCLUSIONS: Our studies indicate that MEISC/D promote HCC development via Wnt/ß-catenin and Hippo/YAP signaling pathways, highlighting the complex molecular network of MEIS2C/D in HCC pathogenesis. These results suggest that MEISC/D may serve as a potential novel therapeutic target for HCC.

MicroRNA­448 inhibits the progression of retinoblastoma by directly targeting ROCK1 and regulating PI3K/AKT signalling pathway.

Retinoblastoma (RB) is the most common primary intraocular malignancy during infancy and childhood worldwide. Numerous microRNAs (miRNAs) contribute to RB initiation and progression through the regulation of cell proliferation, cycle, apoptosis, migration, invasion and metastasis. Therefore, further investigation concerning the expression, roles and associated mechanisms of RB­related miRNAs may be beneficial to develop novel strategies for patients with this malignancy. Recently, miRNA­448 (miR­448) has been reported to be aberrantly expressed and to play an important role in several types of human cancer. However, the expression patterns and biological roles of miR­448 in RB have not been studied. The aim of the present study was to detect the expression levels of miR­448 and investigate its functions in RB and its associated molecular mechanisms. In the present study, miR­448 was significantly downregulated in RB tissues and cell lines. Upregulation of miR­448 decreased cell proliferation and invasion and increased apoptosis in RB cells. Additionally, ρ­associated coiled­coil containing protein kinase 1 (ROCK1) was validated as a novel direct target gene of miR­448 in RB. ROCK1 was overexpressed in RB tissues and inversely correlated with miR­448 expression. Furthermore, ROCK1 silencing induced effects on the proliferation, invasion and apoptosis of RB cells similar to those observed following miR­448 overexpression. Moreover, restoration of miR­448 expression markedly reversed the effects of miR­448 overexpression on RB cells, further supporting the hypothesis that ROCK1 is a direct functional target of miR­448 in RB. Importantly, miR­448 targeted ROCK1 to inhibit the activation of the PI3K/AKT signalling pathway in RB. These results demonstrated that miR­448 may serve as a tumour suppressor in RB by directly targeting ROCK1 and regulating the PI3K/AKT signalling pathway, thereby suggesting that miR­448 may be an effective therapeutic target for treating this aggressive cancer.

Distinct clinical characteristics of atypical optic neuritis with seronegative aquaporin-4 antibody among Chinese patients.

OBJECTIVE: To evaluate the clinical features and prognosis of atypical optic neuritis (ON) with seronegative aquaporin-4 (AQP4) antibody in Chinese patients. METHODS: All patients with first or relapsing ON were recruited from the Neuro-ophthalmology Department of the Chinese People's Liberation Army General Hospital from January 2013 to December 2014 and assigned to one of three groups based on diagnosis: atypical ON, typical ON and neuromyelitis optica spectrum disorder (NMOSD)-ON. RESULTS: A total of 173 patients were included in the cohort. Fifty patients (28.9%) were AQP4-Ab-positive and diagnosed with NMOSD-ON. Of 123 patients with seronegative AQP4-Ab, 37 (30.1%) patients had atypical ON, with male predominance (25, 67.6%). The atypical ON group (compared with the typical ON and NMOSD-ON groups) had a significantly lower female:male ratio (1:2.1 vs 1.8:1 and 9:1, respectively, p=0.001 and p<0.001), an older mean age of onset (44.8, 13-71 years vs 36.9, 13-73 years and 36.2, 13-66 years, p=0.003 and p=0.004), a lower rate of good (≥0.5) visual recovery (6.7% vs 79.8% and 30.9%, p<0.001 and p<0.001) and (compared with the NMOSD-ON group) a lower recurrence rate during a 2-year follow-up (29.3% vs 60%, p=0.009). However, none developed to multiple sclerosis or neuromyelitis optica in the atypical ON group. CONCLUSIONS: Atypical ON with seronegative AQP4-Ab had unique clinical features in this Chinese cohort, including male predominance, an older age of onset, worse visual acuity recovery and resistance to corticosteroid therapy. This condition may be a distinct nosological entity with an unusual clinical and therapeutic profile.

Optic Neuritis in the Older Chinese Population: A 5-Year Follow-Up Study.

OBJECTIVE: This study aims to describe the clinical manifestations and outcomes in a cohort of older Chinese patients. METHOD: A retrospective study of patients aged ≥ 45 years who had a first episode of optic neuritis (ON) between May 2008 and November 2012. Clinical features at onset and last follow-up were analyzed within subgroups (age 45-65 years and age ≥ 65 years). RESULTS: 76 patients (99 eyes) were included, of which 58% were females. The mean age at presentation was 55.53 ± 8.29 years (range: 45-83 years). Vision loss was severe at presentation, with initial best corrected vision activity (BCVA) < 20/200 in 93% and final BCVA < 20/200 in 53% of patients at 5-year follow-up. Final BCVA significantly correlated with the initial BCVA and peripapillary retinal nerve fiber layer. At last follow-up, 14.5% were diagnosed with neuromyelitis optica spectrum disorder (NMOSD), 1.3% were diagnosed with multiple sclerosis (MS), 5.2% with chronic relapsing inflammatory optic neuropathy, 1.3% with infectious ON, and 19.7% with autoimmune ON. None of the elderly group (≥65 years) developed NMOSD or MS. CONCLUSION: Chinese patients in the age group ≥ 65 years with ON are less likely to develop NMOSD or MS. Notwithstanding, they had more severe visual loss at onset and poor recovery.

The poor recovery of neuromyelitis optica spectrum disorder is associated with a lower level of CXCL12 in the human brain.

Neuromyelitis optica spectrum disorders (NMOSDs) are blindness-causing neuritis. In NMOSD patients, NMO-IgG evokes astrocytopathy that in turn causes demyelination. While measurement of NMO-IgG titer will help neurologists make the diagnosis of NMOSDs, it is not sufficient to evaluate the severity of astrocytopathy. In this study, we compared the different levels of an astrocyte biomarker in cerebrospinal fluid of NMOSD patients with good or poor recovery, and then linked their differences to the changes in remyelinating promoter (CXCL12) levels. Our results indicate that NMO-IgG down-regulated CXCL12 and impaired the remyelinating process, this may be a mechanism contributing to the poor recovery of NMOSDs.

PP2B and PP1alpha cooperatively disrupt 7SK snRNP to release P-TEFb for transcription in response to Ca2+ signaling.

The positive transcription elongation factor b (P-TEFb), consisting of Cdk9 and cyclin T, stimulates RNA polymerase II elongation and cotranscriptional pre-mRNA processing. To accommodate different growth conditions and transcriptional demands, a reservoir of P-TEFb is kept in an inactive state in the multisubunit 7SK snRNP. Under certain stress or disease conditions, P-TEFb is released to activate transcription, although the signaling pathway(s) that controls this is largely unknown. Here, through analyzing the UV- or hexamethylene bisacetamide (HMBA)-induced release of P-TEFb from 7SK snRNP, an essential role for the calcium ion (Ca2+)-calmodulin-protein phosphatase 2B (PP2B) signaling pathway is revealed. However, Ca2+ signaling alone is insufficient, and PP2B must act sequentially and cooperatively with protein phosphatase 1alpha (PP1alpha) to disrupt 7SK snRNP. Activated by UV/HMBA and facilitated by a PP2B-induced conformational change in 7SK snRNP, PP1alpha releases P-TEFb through dephosphorylating phospho-Thr186 in the Cdk9 T-loop. This event is also necessary for the subsequent recruitment of P-TEFb by the bromodomain protein Brd4 to the preinitiation complex, where Cdk9 remains unphosphorylated and inactive until after the synthesis of a short RNA. Thus, through cooperatively dephosphorylating Cdk9 in response to Ca2+ signaling, PP2B and PP1alpha alter the P-TEFb functional equilibrium through releasing P-TEFb from 7SK snRNP for transcription.