Rho GDP Dissociation Inhibitor Research Articles

MON-463 Cilia-Dependent Hedgehog Signaling in Adamantinomatous AND Neutrophil-Related Innate Immune Responses in Papillary Craniopharyngiomas Mediate Tumorigenesis

Craniopharyngiomas are rare benign epithelial neoplasms of the sellar region. There are two variants based on epidemiological and histomorphological difference: adamantinomatous (ACPs) and papillary craniopharyngiomas (PCPs). ACPs occur in children and adults while PCPs occur almost exclusively in adults. ACPs are characterized by cystic cavities lined by the ciliated epithelium, infiltrative tumor borders and calcification, which are rarely found in PCPs. Although recent genetic analyses identified BRAF V600E mutation in PCPs and CTNNB1 mutations in ACPs, the distinct molecular pathogenesis of each variant remains to be elucidated. Here, we performed the RNA sequencing and proteomic profiling on 6 ACP and 6 PCP using fresh frozen tumor samples to unveil the subtype-specific tumorigenesis. The transcriptome analysis revealed that 3,921 genes were upregulated in ACPs and 1,743 genes were upregulated in PCPs (P<0.05). Gene ontology, pathway analysis, and gene set enrichment analysis for differential expressed genes (DEGs) were carried out. Cilium morphogenesis or assembly-related genes, Hedgehog pathway and Wnt pathway were significantly up-regulated in ACPs. Regulation of intrinsic apoptotic signaling pathway, natural killer cell-mediated cytotoxicity and p53 signaling pathway were highly expressed in PCPs. Using proteomics, we extracted 980 differentially expressed proteins (DEPs): 345 up-regulated proteins in ACPs and 635 up-regulated proteins in PCPs (P<0.05). Up-regulated pathways in ACPs were cyclin-dependent kinase 5 signaling and Rho GDP-dissociation inhibitor signaling whereas up-regulated pathways in PCPs were CD28 signaling in T helper cells, N-formyl-l-methionyl-l-leucyl-phenylalanine signaling in neutrophils, and phagocytosis/endocytosis. We further analyzed co-expressed DEGs and DEPs between ACPs and PCPs. Pathways of neutrophil degranulation and innate immune systems were highly activated in PCPs. Taken together, our integrative analysis of transcriptomic and proteomic data discovered the novel tumorigenesis of ACPs and PCPs. Cilia-dependent hedgehog signaling in ACP and neutrophil-related innate immune responses in PCP may mediate tumorigenesis after initial genetic alteration.

Proteomic characterization of early lung response to breast cancer metastasis in mice

IntroductionThe tumor-promoting rearrangement of the lungs facilitates the process of cancer cell survival in a foreign microenvironment and enables their protection against immune defense. The study aimed to define the fingerprint of the early rearrangement of the lungs via the proteomic profiling of the lung tissue in the experimental model of tumor metastasis in a murine 4T1 mammary adenocarcinoma. Materials and methodsThe studies were performed on 7-8-week-old BALB/c female mice. Viable 4T1 cancer cells were orthotopically inoculated into the right mammary fat pad. The experiment was performed in the early phase of the tumor metastasis one and two weeks after cancer cell inoculation. The comparative analysis of protein profiles was carried out with the aid of the two-dimensional difference in gel electrophoresis (2D-DIGE). Proteins, of which expression differed significantly, were identified using nano-liquid chromatography coupled to a high-resolution mass spectrometry (nanoLC/hybrid ion trap- Orbitrap XL Discovery). ResultsPalpable primary tumors were noted in the 2nd week after cancer cell inoculation. The investigated period preceded the formation of numerous macrometastases in the lungs, however the metastasis-promoting changes were visible very early. Primary tumor-induced inflammation developed in the lungs as early as after the 1st week and progressed during the 2nd week, accompanied by increased concentration of 2-OH-E+, an oxidative stress marker, and imbalance in nitric oxide metabolites, pointing to endothelium dysfunction. The early proteomic changes in the lungs in the 1st week after 4T1 cell inoculation resulted in the reorganization of lung tissue structure [actin, cytoplasmic 1 (Actb), tubulin beta chain (Tubb5), lamin-B1 (Lmnb1), serine protease inhibitor A3K (Serpina3k)] and activation of defense mechanisms [selenium-binding protein 1 (Selenbp1), endoplasmin (Hsp90b1), stress 70 protein, mitochondrial (Hspa9), heat shock protein HSP 90-beta (Hsp90ab1)], but also modifications in metabolic pathways [glucose-6-phosphate 1-dehydrogenase X (G6pdx), ATP synthase subunit beta, mitochondrial (Atp5b), L-lactate dehydrogenase B chain (Ldhb)]. Further development of the solid tumor after the 2nd week following cancer cell inoculation, secretion of prolific tumor-derived factors as well as the presence of the increasing number of circulating cancer cells and extravasation processes further impose reorganization of the lung tissue [Actb, vimentin (Vim), clathrin light chain A (Clta)], altering additional metabolic pathways [annexin A5 (Anxa5), Rho GDP-dissociation inhibitor 2 (Arhgdib), complement 1 Q subcomponent-binding protein, mitochondrial (C1qbp), 14-3-3 protein zeta/delta (Ywhaz), peroxiredoxin-6 (Prdx6), chitinase-like protein 4 (Chi3l4), reticulocalbin-1 (Rcn1), EF-hand domain-containing protein D2 (Efhd2), calumenin (Calu)]. Interestingly, many of differentially expressed proteins were involved in calcium homeostasis (Rcn1, Efhd2, Calu, Actb, Vim, Lmnb1, Clta, Tubb5, Serpina3k, Hsp90b1, Hsp90ab1, Hspa9. G6pdx, Atp5b, Anxa5, Arhgdib, Ywhaz). ConclusionThe analysis enabled revealing the importance of calcium signaling during the early phase of metastasis development, early cytoskeleton and extracellular matrix reorganization, activation of defense mechanisms and metabolic adaptations. It seems that the tissue response is an interplay between pro- and anti-metastatic mechanisms accompanied by inflammation, oxidative stress and dysfunction of the barrier endothelial cells.

RhoGDIβ affects HeLa cell spindle orientation following UVC irradiation.

The molecular signals that regulate mitotic spindle orientation to determine the proper division axis play a critical role in the development and maintenance of tissue homeostasis. However, deregulation of signaling events can result in spindle misorientation, which in turn can trigger developmental defects and cancer progression. Little is known about the cellular signaling pathway involved in the misorientation of proliferating cells that evade apoptosis after DNA damage. In this study, we found that perturbations to spindle orientation were induced in ultraviolet C (UVC)-irradiated surviving cells. N-terminal truncated Rho GDP-dissociation inhibitor β (RhoGDIβ), which is produced by UVC irradiation, distorted the spindle orientation of HeLa cells cultured on Matrigel. The short hairpin RNA-mediated knockdown of RhoGDIβ significantly attenuated UVC-induced misorientation. Subsequent expression of wild-type RhoGDIβ, but not a noncleavable mutant, RhoGDIβ (D19A), again led to a relative increase in spindle misorientation in response to UVC. Our findings revealed that RhoGDIβ impacts spindle orientation in response to DNA damage.

ROCK inhibitors alleviate myofibroblast transdifferentiation and vascular remodeling via decreasing TGFβ1-mediated RhoGDI expression.

The aim of this study was to investigate the effects of the Rho GDP dissociation inhibitor (RhoGDI) on TGFβ1-mediated vascular adventitia myofibroblast transdifferentiation and on the inhibition of ROCK inhibitors. Myofibroblast transdifferentiation and vascular remodeling model were induced by TGFβ1 in vitro and by balloon injury in vivo. H&E (Hematoxylin & Eosin) and PSR (Picrosirius Red) staining were used to observe vascular morphology while immunofluorescence, immunohistochemistry, and Western blotting were used to measure protein expression. Fasudil treatment reduced the expression of TGFβ1, RhoGDI1, and RhoGDI2 in addition to vascular remodeling in the rat balloon injury model. TGFβ1 induced the expression of α-SMA, TGFβRI, phospho-TGFβRI, RhoGDI1, RhoGDI2, and collagen secretion in human aortic adventitial fibroblasts (HAAFs). These effects were diminished after treatment with Y27632. Suppressing both RhoGDI1 and RhoGDI2 expression also blocked TGFβ1-induced α-SMA expression and collagen secretion in HAAFs. Moreover, TGFβR inhibition blocked TGFβ1-mediated collagen secretion and the expression of α-SMA, RhoGDI1, and RhoGDI2. These data suggested that ROCK inhibitors alleviate myofibroblast transdifferentiation and vascular remodeling by decreasing TGFβ1-mediated expression of RhoGDI.

FRET biosensor allows spatio-temporal observation of shear stress-induced polar RhoGDI\u03b1 activation

Rho GDP-dissociation inhibitor α (RhoGDIα) is a known negative regulator of the Rho family that shuts off GDP/GTP cycling and cytoplasm/membrane translocation to regulate cell migration. However, to our knowledge, no reports are available that focus on how the RhoGDIα-Rho GTPases complex is activated by laminar flow through exploring the activation of RhoGDIα itself. Here, we constructed a new biosensor using fluorescence resonance energy transfer (FRET) technology to measure the spatio-temporal activation of RhoGDIα in its binding with Rho GTPases in living HeLa cells. Using this biosensor, we find that the dissociation of the RhoGDIα-Rho GTPases complex is increased by shear stress, and its dissociation rate varies with subcellular location. Moreover, this process is mediated by membrane fluidity, cytoskeleton and Src activity, which indicates that the regulation of RhoGDIα activation under shear stress application represents a relatively separate pathway from the shear stress-induced Rho pathway.

Proteomics Analysis of Myocardial Tissues in a Mouse Model of Coronary Microembolization.

Coronary microembolization (CME) is an important clinical problem, and it is related to poor outcome. The specific molecular mechanisms of CME are not fully understood. In the present study, we established a mice model of CME. Isobaric tags for relative and absolute quantitation (iTRAQ) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technologies identified 249 differentially expressed proteins in the myocardial tissues of CME mice as compared with sham-operated mice. Bioinformatics analysis demonstrated that these differentially expressed proteins were enriched in several energy metabolism or cytoskeleton organization related processes or pathways. Quantitative PCR and Western blotting validation experiments revealed that succinate dehydrogenase (SDHA and SDHB) were upregulated, Rho GDP dissociation inhibitor α (RhoGDIα) and Filamin-A (FLNA) were downregulated significantly in CME mice. These findings indicated that the alternations of the cytoskeleton and energy metabolism pathways play important roles in the pathogenesis of CME, future studies are warranted to verify if targeting these molecules might be useful to alleviate CME injury or not.

STAT3-coordinated migration facilitates the dissemination of diffuse large B-cell lymphomas

The motile characteristics and mechanisms that drive the dissemination of diffuse large B-cell lymphoma (DLBCL) are elusive. Here, we show that DLBCL initiates dissemination through activating STAT3-mediated amoeboid migration. Mechanistically, STAT3 activates RHOH transcription, which competes with the RhoGDP dissociation inhibitor RhoGDIγ to activate RhoA. In addition, activated STAT3 regulates microtubule dynamics and releases ARHGEF2 to activate RhoA. Both the JAK inhibitor ruxolitinib and the microtubule stabilizer Taxol suppress DLBCL cell dissemination in vivo. A clinical DLBCL sample analysis shows that STAT3-driven amoeboid movement is particularly important for the transition from stage I to stage II. This study elucidates the mechanism of DLBCL dissemination and progression and highlights the potential of combating advanced DLBCL with a JAK/STAT inhibitor or microtubule stabilizer to reduce DLBCL motility; these findings may have a great impact on the development of patient-tailored treatments for DLBCL.

Moderate-Intensity Exercise Induces Neurogenesis and Improves Cognition in Old Mice by Upregulating Hippocampal Hippocalcin, Otub1, and Spectrin-α.

Exercise increases the levels of neurogenic factors and enhances neurogenesis, memory, and learning. However, the molecular link between exercise and neurogenesis is not clear. The purpose of this study was to examine the effects of exercise intensity on cognitive function and protein expression in the hippocampus of old mice. To compare the effects of aerobic exercise intensity on cognition in old mice, we exposed 18-month-old mice to low- and moderate-intensity treadmill exercise for 4weeks. Moderate-intensity exercise improved cognitive function in the old mice, while low-intensity exercise did not. To investigate the underlying mechanisms, two-dimensional electrophoresis was used to examine protein expression. Using peptide fingerprinting mass spectrometry, we identified 19 proteins that were upregulated in the hippocampus following exercise training, and seven of these proteins were normalized by the control value. Among them, the levels of 14-3-3 zeta and heat shock protein 70, which have been shown to be induced by exercise training and related to neurogenesis, were dramatically increased by moderate exercise. Hippocalcin, α-spectrin, ovarian tumor domain-containing ubiquitin aldehyde-binding protein 1 (otub1), mu-crystallin, serine racemase, and rho GDP dissociation inhibitor 1, which are related to neurogenesis, neuroprotection, and synaptic strength, were upregulated in the hippocampus by moderate exercise. In addition, we confirmed that neurogenic markers, including doublecortin and the neuronal nuclei antigen, and hippocalcin, otub1, and spectrin-α are potential molecular links between hippocampal neurogenesis and exercise in the elderly. Thus, these results showed that steady moderate-intensity exercise delayed the declines in cognitive function in the elderly through the activation of multiple factors.

Grl1 Protein is a Candidate K Antigen in Tetrahymena thermophila

In Tetrahymena, K antigens associate only with mature basal bodies and are expected to play important roles in the morphogenesis and function of the membrane skeleton around basal bodies, but these proteins have not been identified and their functions are unknown. Commercially available anti-human Rho GDP-dissociation inhibitor α (RhoGDIα) antibody (sc-33201) was accidentally found to show very similar immunofluorescence staining patterns to those of anti-K antigen antibodies, such as 424A8 and 10D12 mouse monoclonal antibodies, in Tetrahymena. A 40kDa protein recognized by this antibody was partially purified and identified as granule lattice protein 1 (Grl1p) by matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry. In immunoblotting experiments this antibody was suggested to recognize endogenous Grl1p. The three-dimensional structure of proGrl1p protein predicted by I-TASSER was similar to a spectrin family protein. Grl1 may be a K antigen and a spectrin-like protein in Tetrahymena.

Expression of Rho GDP dissociation inhibitor alpha in papillary thyroid carcinoma and its clinical significance

Objective To observe the level of Rho GDP dissociation inhibitor (GDI) alpha (RhoGDIa) expression in papillary thyroid carcinoma (PTC) and explore its clinical significance. Methods The levels of RhoGDIa and microRNA (miRNA, miR)-151-5p expression in 200 cases of PTC tissues and paired normal tissues were detected by real-time quantitative polymerase chain reaction (Real-time PCR), respectively. The relationship between RhoGDIa expression and the clinicopathological features in PTC patients, and between RhoGDIa expression and miR-151-5p levels in PTC tissues was investigated. Results As compared with normal tissues adjacent to cancer, the expression of RhoGDIa mRNA was decreased in 76.5% (153/200) PTC tissues and that of miR-151-5p was increased in 72.5% (145/200) PTC tissues, respectively. The correlation analysis showed that there was a significantly negative correlation between the miR-151-5p level and the expression of RhoGDIa mRNA in PTC tissues (r=-0.925, P=0.000). As compared with PTC without lymph node metastasis, the miR-151-5p level was significantly up-regulated and the expression of RhoGDIa protein was significantly down-regulated in those PTC with lymph node metastasis, and the expression abundance of miR-151-5p was negatively correlated with the level of RhoGDIa protein. The low expression of RhoGDIa mRNA was significantly correlated with gender (P=0.000), number of lesions (P=0.004), local invasion (P=0.002), lymph node metastasis (P=0.000) and clinical stage (P=0.000) in PTC patients. Conclusion RhoGDIa was down-regulated in PTC tissues and closely related to tumor progression, and its expression may be negatively regulated by miR-151-5p. Key words: Papillary thyroid carcinoma; Rho GDP dissociation inhibitor alpha; MicroRNA-151-5p; Lymph node metastasis

Secretoneurin A Directly Regulates the Proteome of Goldfish Radial Glial Cells In Vitro.

Radial glial cells (RGCs) are the main macroglia in the teleost brain and have established roles in neurogenesis and neurosteroidogenesis. They are the only brain cell type expressing aromatase B (cyp19a1b), the enzyme that synthesizes estrogens from androgen precursors. There are few studies on the regulation of RGC functions, but our previous investigations demonstrated that dopamine stimulates cyp19a1b expression in goldfish RGCs, while secretoneurin A (SNa) inhibits the expression of this enzyme. Here, we determine the range of proteins and cellular processes responsive to SNa treatments in these steroidogenic cells. The focus here is on SNa, because this peptide is derived from selective processing of secretogranin II in magnocellular cells embedded within the RGC-rich preoptic nucleus. Primary cultures of RGCs were treated (24 h) with 10, 100, or 1,000 nM SNa. By using isobaric tagging for relative and absolute quantitation and a Hybrid Quadrupole Obritrap Mass Spectrometry system, a total of 1,363 unique proteins were identified in RGCs, and 609 proteins were significantly regulated by SNa at one or more concentrations. Proteins that showed differential expression with all three concentrations of SNa included H1 histone, glutamyl-prolyl-tRNA synthetase, Rho GDP dissociation inhibitor γ, vimentin A2, and small nuclear ribonucleoprotein-associated protein. At 10, 100, and 1,000 nM SNa, there were 5, 195, and 489 proteins that were downregulated, respectively, whereas the number of upregulated proteins were 72, 44, and 51, respectively. Subnetwork enrichment analysis of differentially regulated proteins revealed that processes such as actin organization, cytoskeleton organization and biogenesis, apoptosis, mRNA processing, RNA splicing, translation, cell growth, and proliferation are regulated by SNa based on the proteomic response. Moreover, we observed that, at the low concentration of SNa, there was an increase in the abundance of proteins involved in cell growth, proliferation, and migration, whereas higher concentration of SNa appeared to downregulate proteins involved in these processes, indicating a dose-dependent proteome response. At the highest concentration of SNa, proteins linked to the etiology of diseases of the central nervous system (brain injuries, Alzheimer disease, Parkinson’s disease, cerebral infraction, brain ischemia) were also differentially regulated. These data implicate SNa in the control of cell proliferation and neurogenesis.

Identification of antibody reactive proteins in pancreatic cancer using 2D immunoblotting and mass spectrometry.

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy characterized by early invasiveness and resistance to treatment. Surgery in early stages is the only effective treatment, thus finding new biomarkers for the early detection of PDAC remains a major challenge. The present study aimed to compare the immunoproteome between PDAC patients and healthy controls using serological proteome analysis method. Firstly, cell lysates from two different pancreatic cancer cell lines were separated by two dimensional (2D) gels, and then transferred onto membranes probed with sera from 20PDAC patients and 10healthy controls. Proteins differentially reacting with autoantibodies in PDAC patients and control groups and were identified using mass spectrometry. This process led to the identification of 18 pancreatic immunoreactive antigens such as laminin, superoxide dismutase, ATP synthase, Rho GDP-dissociation inhibitorII, septin, glyceraldehyde 3-phosphate-dehydrogenase, phosphoglycerate mutaseB, tubulinβ8 channel and prohibit in. In the present study, we identified 18immunoreactive proteins in PDAC. While the identified proteins were critically involved in PDAC pathogenesis, further investigation in a large scale population will determine the applicability of these potential biomarkers for the early diagnosis or treatment of the disease.

Epigenetic alterations of the Igf2 promoter and the effect of miR‑483‑5p on its target gene expression in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is one of the most widespread malignancies in China. MicroRNAs (miRNAs/miRs) are endogenous evolutionarily-conserved small non-coding RNAs that are able to regulate ESCC formation and deterioration by negatively regulating specific target genes. In the present study, the expression levels of miR-483-5p and its associated mRNAs were measured by quantitative polymerase chain reaction (PCR) analysis, and the methylation levels of the insulin-like growth factor 2 (Igf2) promoter were detected via the methylation-specific PCR method in serum and tissues from patients with ESCC. The results demonstrated that the expression level of miR-483-5p was significantly upregulated in preoperative serum and cancer tissues from patients with ESCC (P<0.01), and the miR-483-5p expression levels were correlated with the tumor, node, metastasis stage (P<0.05) and lymph node metastasis (P<0.05). In addition, the mRNA levels of miR-483-5p target genes (Rho GDP dissociation inhibitor α, activated leukocyte cell adhesion molecule, and suppressor of cytokine signaling 3) in cancer tissues were significantly decreased compared with adjacent non-cancerous tissues. These results indicated that miR-483-5p and its target genes may be involved in the developmental process of ESCC. The Igf2 levels in cancer tissues were significantly increased compared with adjacent non-cancerous tissues (P<0.01). Additionally, the methylation levels of the Igf2 promoter region were 31.82 and 54.55% in cancer tissues and adjacent non-cancerous tissues, respectively, suggesting that low methylation of the Igf2 gene promoter region may promote the expression of Igf2 and miR-483-5p; this, in turn, induces the degradation of miR-483-5p target genes, and leads to the upregulation of oncogenes and the downregulation of tumor suppressors, which promotes the development of ESCC.

The intracellular microbial sensor NLRP4 directs Rho-actin signaling to facilitate Group A Streptococcus-containing autophagosome-like vacuole formation

ABSTRACTXenophagy, also known as antibacterial autophagy, functions as a crucial defense system that can utilize intracellular pattern recognition sensors, such as NLRP4, to recognize and selectively eliminate bacterial pathogens. However, little is known about how NLRP4 regulates xenophagy. Here, we report that NLRP4 binds ARHGDIA (Rho GDP dissociation inhibitor α) to regulate Rho GTPase signaling and facilitate actin-mediated xenophagy. Specifically, NLRP4 is recruited to Group A Streptococcus (GAS) and colocalizes with GAS-containing autophagosome-like vacuoles (GcAVs), where it regulates ARHGDIA-Rho GTPase recruitment to promote autophagosome formation. The interaction between NLRP4, ARHGDIA, and Rho GTPases is regulated by ARHGDIA Tyr156 phosphorylation, which acts as a gate to induce Rho-mediated xenophagy. Moreover, ARHGDIA and Rho GTPase are involved in actin-mediated ATG9A recruitment to phagophores, facilitating elongation to form autophagosomes. Collectively, these findings demonstrate that NLRP4 functions as a Rho receptor complex to direct actin dynamics regulating xenophagy.

Effect of carboxyl-terminal truncated HBx mediated down-regulation of RhoGDIα expression on the metastasis and invasion of hepatocellular carcinoma

Objective To investigate the mechanism of natural carboxyl-terminal truncated HBx (with 31 amino acids deleted at the C-terminal end) (HBxΔ31)-dependent down-regulation of Rho GDP dissociation inhibitor alpha (RhoGDIα) expression and its role in enhancing hepatocellular carcinoma (HCC) metastasis. Methods HepG2 cells with stable expression of wild type HBx and its deletion mutant HBxΔ31 protein were selected as the study subjects. The effects of HBx and HBxΔ31 on RhoGDIα expression in HepG2 cells was detected using real-time quantitative reverse transcription PCR (RT-qPCR) and Western blot analysis. A series of deleted and mutated variants of the RhoGDIα promoter were made and individually co-transfected with HBx-and HBxΔ31-expressing vectors or control empty vector into HepG2 cells. The luciferase reporter assay was used to identify the cis-regulatory elements of the RhoGDIα promoter in response to HBxΔ31 regulation. The interaction between Myc-associated zinc finger protein (MAZ) and HBxΔ31 was examined by co-immunoprecipitation experiment. Eelectrophoretic mobility shift assay (EMSA) was performed to determine interaction of MAZ with the RhoGDIα promoter in HBxΔ31-expressing HepG2 cells. The impact of reduced RhoGDIα expression by HBxΔ31 on cell-invasive activity was analyzed by the Matrigel cell invasion assay. In addition, the effects of silencing of shRNA-mediated RhoGDIα in HepG2 or introduction of RhoGDIα by transfection in HBxΔ31-expressing HepG2 cells on cell-invasion were investigated. Results HBxΔ31, but not HBx, suppressed RhoGDIα expression at transcriptional levels. Analysis of the deletion and mutation of RhoGDIα promoter showed that the HBxΔ31 repressive element localized between nt-460 and-242 bp of RhoGDIα promoter and that the transcription factor MAZ binding sites was required for RhoGDIα promoter inactivation regulated by HBxΔ31. In addition, HBxΔ31 represses RhoGDIα expression by enhancing MAZ binding to its promoter through directly associating with MAZ. The cell-migratory and cell-invasive activity were significantly increased in sh-RhoGDIα-expressing HepG2 cells, as compared to control cells (migrated cells number: 58 ± 5 vs. 98 ± 7, invaded cells number: 55 ± 6 vs. 113 ± 6, t= 18.91 and t= 20.12, both P < 0.01). However, ectopic expression of RhoGDIα in HBxΔ31-expressing HepG2 cells significantly decreased cell migration and invasion (migrated cells number: 40 ± 4 vs. 115 ± 5, invaded cells number: 42 ± 4 vs. 102 ± 4, t= 18.14 and t= 16.31, both P < 0.001). Conclusion Carboxyl-terminal truncated HBx deregulates RhoGDIα expression through MAZ, in turn which promotes the invasion and metastasis of HCC. Key words: Carcinoma, hepatocellular; Sequence deletion; Hepatitis B virus; Gnanine nucleotide dissociation inhibitors; Neoplasm metastasis

Kindlin-2 Association with Rho GDP-Dissociation Inhibitor α Suppresses Rac1 Activation and Podocyte Injury

Alteration of podocyte behavior is critically involved in the development and progression of many forms of human glomerular diseases. The molecular mechanisms that control podocyte behavior, however, are not well understood. Here, we investigated the role of Kindlin-2, a component of cell-matrix adhesions, in podocyte behavior in vivo Ablation of Kindlin-2 in podocytes resulted in alteration of actin cytoskeletal organization, reduction of the levels of slit diaphragm proteins, effacement of podocyte foot processes, and ultimately massive proteinuria and death due to kidney failure. Through proteomic analyses and in vitro coimmunoprecipitation experiments, we identified Rho GDP-dissociation inhibitor α (RhoGDIα) as a Kindlin-2-associated protein. Loss of Kindlin-2 in podocytes significantly reduced the expression of RhoGDIα and resulted in the dissociation of Rac1 from RhoGDIα, leading to Rac1 hyperactivation and increased motility of podocytes. Inhibition of Rac1 activation effectively suppressed podocyte motility and alleviated the podocyte defects and proteinuria induced by the loss of Kindlin-2 in vivo Our results identify a novel Kindlin-2-RhoGDIα-Rac1 signaling axis that is critical for regulation of podocyte structure and function in vivo and provide evidence that it may serve as a useful target for therapeutic control of podocyte injury and associated glomerular diseases.

Proteome analysis of irradiated endothelial cells reveals persistent alteration in protein degradation and the RhoGDI and NO signalling pathways

Purpose: Epidemiological studies indicate that radiation doses as low as 0.5 Gy increase the risk of cardiovascular disease decades after the exposure. The aim of the present study was to investigate whether this radiation dose causes late molecular alterations in endothelial cells that could support the population-based data.Materials and methods: Human coronary artery endothelial cells were irradiated at 0.5 Gy (X-ray) and radiation-induced changes in the proteome were investigated after different time intervals (1, 7 and 14 d) using ICPL technology. Key changes identified by proteomics and bioinformatics were validated by immunoblotting and ELISA.Results: The radiation-induced alteration of the endothelial proteome was characterized by sustained perturbation of Rho GDP-dissociation inhibitor (RhoGDI) and nitric oxide (NO) signalling pathways. At later time-points, this was accompanied by reduced proteasome activity, enhanced protein carbonylation indicating augmented oxidative stress, and senescence.Conclusions: These molecular changes are indicative of long-term premature endothelial dysfunction and provide a mechanistic framework to the epidemiological data showing increased risk of cardiovascular disease at 0.5 Gy.

Increased dermal collagen bundle alignment in systemic sclerosis is associated with a cell migration signature and role of Arhgdib in directed fibroblast migration on aligned ECMs.

Systemic sclerosis (SSc) is a devastating disease affecting the skin and internal organs. Dermal fibrosis manifests early and Modified Rodnan Skin Scores (MRSS) correlate with disease progression. Transcriptomics of SSc skin biopsies suggest the role of the in vivo microenvironment in maintaining the pathological myofibroblasts. Therefore, defining the structural changes in dermal collagen in SSc patients could inform our understanding of fibrosis pathogenesis. Here, we report a method for quantitative whole-slide image analysis of dermal collagen from SSc patients, and our findings of more aligned dermal collagen bundles in diffuse cutaneous SSc (dcSSc) patients. Using the bleomycin-induced mouse model of SSc, we identified a distinct high dermal collagen bundle alignment gene signature, characterized by a concerted upregulation in cell migration, adhesion, and guidance pathways, and downregulation of spindle, replication, and cytokinesis pathways. Furthermore, increased bundle alignment induced a cell migration gene signature in fibroblasts in vitro, and these cells demonstrated increased directed migration on aligned ECM fibers that is dependent on expression of Arhgdib (Rho GDP-dissociation inhibitor 2). Our results indicate that increased cell migration is a cellular response to the increased collagen bundle alignment featured in fibrotic skin. Moreover, many of the cell migration genes identified in our study are shared with human SSc skin and may be new targets for therapeutic intervention.

Poly(ADP-ribosylated) proteins in mononuclear cells from patients with type 2 diabetes identified by proteomic studies.

In diabetes, hyperglycemia increases reactive oxygen species that induce DNA damage and poly(ADP-ribose)polymerase activation. The aim of this study is to characterize the proteomic profile and the role of poly(ADP-ribosylation) in patients with type 2 diabetes. A proteomic platform based on 2DE and MALDI-ToF spectrometry was applied to peripheral blood mononuclear cells obtained from two different cohorts in which diabetic (n=14) and normoglycemic patients (n=11) were enrolled. Proteomic maps identified WD repeat protein, 78-kDa glucose-regulated protein precursor and myosin regulatory light chain 2, as unique proteins in diabetic patients; vimentin, elongation factor 2, annexin A1, glutathione S-transferase P, moesin and cofilin-1 as unique in the normoglycemic; and calreticulin, rho GDP-dissociation inhibitor 2, protein disulfide isomerase and tropomyosin alpha-4-chain as differentially expressed between the two cohorts. An enrichment in PARylation in diabetic patients was observed in particular, affecting GAPDH and α-Enolase leading to a decrease in their enzymatic activity. As the GAPDH and α-Enolase are involved in energy metabolism, protein synthesis and DNA repair, loss of their function or change in their activity can significantly contribute to the molecular mechanisms responsible for the development of type 2 diabetes. These data along with the proteomic profile associated with the disease may provide new insight into the pathophysiology of type 2 diabetes.

Cross-species gene modules emerge from a systems biology approach to osteoarthritis

Complexities in degenerative disorders, such as osteoarthritis, arise from multiscale biological, environmental, and temporal perturbations. Animal models serve to provide controlled representations of the natural history of degenerative disorders, but in themselves represent an additional layer of complexity. Comparing transcriptomic networks arising from gene co-expression data across species can facilitate an understanding of the preservation of functional gene modules and establish associations with disease phenotypes. This study demonstrates the preservation of osteoarthritis-associated gene modules, described by immune system and system development processes, across human and rat studies. Class prediction analysis establishes a minimal gene signature, including the expression of the Rho GDP dissociation inhibitor ARHGDIB, which consistently defined healthy human cartilage from osteoarthritic cartilage in an independent data set. The age of human clinical samples remains a strong confounder in defining the underlying gene regulatory mechanisms in osteoarthritis; however, defining preserved gene models across species may facilitate standardization of animal models of osteoarthritis to better represent human disease and control for ageing phenomena.