REST is up-regulated by epidermal growth factor in HeLa cells and inhibits apoptosis by influencing histone H3 acetylation

Integrated Platform for Large-Scale Quantitative Profiling of Phosphotyrosine Signaling Complexes Based on Cofractionation/Mass Spectrometry and Complex-Centric Algorithm

The scarcity and dynamic nature of phosphotyrosine (pTyr)-modified proteins pose a challenge for researching protein complexes with pTyr modification, which are assembled through multiple protein-protein interactions. We developed an integrated complex-centric platform for large-scale quantitative profiling of pTyr signaling complexes based on cofractionation/mass spectrometry (CoFrac-MS) and a complex-centric algorithm. We initially constructed a trifunctional probe based on pTyr superbinder (SH2-S) for specifically binding and isolation of intact pTyr protein complexes. Then, the CoFrac-MS strategy was employed for the identification of pTyr protein complexes by integrating ion exchange chromatography in conjunction with data independent acquisition mass spectrometry. Furthermore, we developed a novel complex-centric algorithm for quantifying protein complexes based on the protein complex elution curve. Utilizing this algorithm, we effectively quantified 216 putative protein complexes. We further screened 21 regulated pTyr protein complexes related to the epidermal growth factor signal. Our study engenders a comprehensive framework for the intricate examination of pTyr protein complexes and presents, for the foremost occasion, a quantitative landscape delineating the composition of pTyr protein complexes in HeLa cells.

Leukocyte Integrin Antagonists as a Novel Option to Treat Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a complex multifactorial degenerative disease that leads to irreversible blindness. AMD affects the macula, the central part of the retina responsible for sharp central vision. Retinal pigment epithelium (RPE) is the main cellular type affected in dry AMD. RPE cells form a monolayer between the choroid and the neuroretina and are in close functional relationship with photoreceptors; moreover, RPE cells are part of the blood retina barrier that is disrupted in ocular diseases such as AMD. During ocular inflammation lymphocytes and macrophages are recruited, contact RPE and produce pro-inflammatory cytokines, which play an important role in AMD pathogenesis. The interaction between RPE and immune cells is mediated by leukocyte integrins, heterodimeric transmembrane receptors, and adhesion molecules, including VCAM-1 and ICAM-1. Within this frame, this study aimed to characterize RPE-leukocytes interaction and to investigate any potentially beneficial effects induced by integrin antagonists (DS-70, MN27 and SR714), developed in previous studies. ARPE-19 cells were co-cultured for different incubation times with Jurkat cells and apoptosis and necrosis levels were analyzed by flow cytometry. Moreover, we measured the mRNA levels of the pro-inflammatory cytokine IL-1β and the expression of adhesion molecules VCAM-1 and ICAM-1. We found that RPE-lymphocyte interaction increased apoptosis and necrosis levels in RPE cells and the expression of IL-1β. This interaction was mediated by the binding of α₄β₁ and α_Lβ₂ integrins to VCAM-1 and ICAM-1, respectively. The blockade of RPE-lymphocyte interaction with blocking antibodies highlighted the pivotal role played by integrins. Therefore, α₄β₁ and α_Lβ₂ integrin antagonists were employed to disrupt RPE-lymphocyte crosstalk. Small molecule integrin antagonists proved to be effective in reducing RPE cell death and expression of IL-1β, demonstrating that integrin antagonists could protect RPE cells from detrimental effects induced by the interaction with immune cells recruited to the retina. Overall, the leukocyte integrin antagonists employed in the present study may represent a novel opportunity to develop new drugs to fight dry AMD.

Integrin-mediated adhesive properties of neutrophils are reduced by hyperbaric oxygen therapy in patients with chronic non-healing wound

In recent years, several studies suggested that the ability of hyperbaric oxygen therapy (HBOT) to promote healing in patients with diabetic ulcers and chronic wounds is due to the reduction of inflammatory cytokines and to a significant decrease in neutrophils recruitment to the damaged area. α4 and β2 integrins are receptors mediating the neutrophil adhesion to the endothelium and the comprehension of the effects of hyperbaric oxygenation on their expression and functions in neutrophils could be of great importance for the design of novel therapeutic protocols focused on anti-inflammatory agents. In this study, the α4 and β2 integrins' expression and functions have been evaluated in human primary neutrophils obtained from patients with chronic non-healing wounds and undergoing a prolonged HBOT (150 kPa per 90 minutes). The effect of a peptidomimetic α4β1 integrin antagonist has been also analyzed under these conditions. A statistically significant decrease (68%) in β2 integrin expression on neutrophils was observed during the treatment with HBO and maintained one month after the last treatment, while α4 integrin levels remained unchanged. However, cell adhesion function of both neutrophilic integrins α4β1 and β2 was significantly reduced 70 and 67%, respectively), but α4β1 integrin was still sensitive to antagonist inhibition in the presence of fibronectin, suggesting that a combined therapy between HBOT and integrin antagonists could have greater antinflammatory efficacy.

Production and characterization of monoclonal antibodies against the DNA binding domain of the RE1-silencing transcription factor

The use of monoclonal antibodies for the detection of cellular biomarkers during carcinogenesis provides new strategies for cancer diagnosis or prognosis in patients. Loss of the Restrictive Element 1-Silencing Transcription (REST) factor has been observed in previous molecular and immunological approaches in aggressive breast cancer, small cell lung cancer, liver carcinoma, and colo-rectal cancer; however, for clinic diagnosis, monoclonal antibodies for REST recognition are unavailable. The goal of this work was to design, produce and characterize monoclonal antibodies against the REST DNA binding damain (DBD) that would be suitable for immunoassays. We searched for conserved domains, and immunogenic and antigenic sites in the REST structure via in silico analysis. For mice immunization, we used a recombinant REST DBD purified by affinity chromatography, and then Hybridomas were generated by mouse spleen fusion with myeloma cells. Finally, for monoclonal antibody characterization, we performed enzyme-linked immunosorbent (ELISA), western blot, dot blot, immunocytochemistry (ICC) and immunoprecipitation assays. Results showed that the DBD is conserved in REST isoforms and contains immunogenic and antigenic sites. We generated three clones producing monoclonal antibodies against REST DBD, one of them specifically recognized native REST and was suitable for ICC in samples from patients.

Regulation of REST levels overcomes dysregulation of neural stem cell differentiation caused by disruption of polyubiquitin gene Ubb

Reduced levels of cellular ubiquitin (Ub) caused by disruption of the polyubiquitin gene Ubb lead to dysregulated differentiation of neural stem/progenitor cells (NSCs) and apoptosis in cells cultured in vitro. However, the underlying mechanisms responsible for these phenotypes in Ub-deficient cells have not been studied extensively. In the present study, we found that levels of repressor element-1 silencing transcription factor (REST) are elevated in Ubb^-/- cells. To determine whether dysregulation of NSC differentiation is caused by the increased REST levels, we investigated the effect of reduced REST levels in Ubb^-/- cells. Rest knockdown was found to increase the expression of the neuronal marker βIII-tubulin (TUJ1) and restore the expression pattern of the early neuronal marker α-internexin (α-INX) in Ubb^-/- cells. Furthermore, Rest knockdown reduced Ub deficiency-induced apoptosis in cells cultured in vitro. Therefore, our study validates that cellular Ub levels are crucial for precise control of the levels of regulatory proteins such as REST during neurogenesis. We propose that regulation of Rest levels is a promising approach to overcome dysregulation of NSC differentiation caused by disruption of the polyubiquitin gene Ubb.

Demethylation of Repressor Element-1 Silencing Transcription (REST) Suppresses the Malignant Phenotype of Breast Cancer via MMP9

Breast cancer is the leading cause of cancer deaths in females all over the world, mainly resulting from metastasis. Previous studies have revealed that repressor element-1 (RE-1) silencing transcription (REST) acted as a tumor suppressor in breast cancer. However, the mechanism by which REST is regulated remains unknown, and its role in the metastasis in breast cancer cells remains unclear. In the present study, we showed that the expression of REST was lower in breast cancer samples than that of adjacent samples by immunohistochemical analysis, which may be due to hypermethylation of the REST promoter. Low REST levels are significantly associated with malignant progression in breast cancer patients. Additionally, we elucidated the functions of REST on proliferation and invasion in breast cancer cells. Lentivirus transfection was used to overexpress REST in human breast MDA-MB-231 cells. Then the biologic consequences of overexpressing REST in regard to cell proliferation, apoptosis, and invasion were determined. Furthermore, we also determined matrix metalloproteinase-9 (MMP9) as a target of REST. These results demonstrate that downregulation of REST, a tumor suppressor in breast cancer, is associated with hypermethylation. Induced REST expression is capable of attenuating invasion ability of breast cancer cells, which may be a novel strategy for metastatic breast cancer treatment.

Activated 5'flanking region of NANOGP8 in a self-renewal environment is associated with increased sphere formation and tumor growth of prostate cancer cells

INTRODUCTION

NANOGP8 is a retrogene which encodes a full-length protein similar to the NANOG1 gene. The expression of NANOGP8 has been documented in several cancers and is related to cell proliferation and tumor development. However, the regulation of NANOGP8 expression has not been investigated. Therefore, the role of NANOGP8 in cell proliferation has not been completely understood.

METHODS

We evaluate the expression of NANOG1 and NANOGP8 in prostate cancer cell lines and primary cultures of prostate tissues. We investigate clonogenicity, sphere formation, and xenograft tumor growth of prostate cancer cells with an activated 5'flanking region of NANOGP8. We examine the role of NANOGP8 in cell cycle progression.

RESULTS

In the prostate cells the NANOG RNA was transcribed from NANOGP8 and not from NANOG1. Cells with the activated 5'flanking region of NANOGP8 exhibited enhanced clonogenicity, sphere formation, and xenograft tumor growth. The sphere culture and tumor initiation mouse mode promoted the activation of the 5'flanking region of NANOGP8. Forced expression of NANOGP8 increased the entry into the cell cycle.

DISCUSSION

In prostate cells NANOGP8 is a predominant molecule of NANOG. The activation of 5'flanking sequence of NANOGP8 could play a role in the regulation of the stem-like properties of cancer stem cells and prostate tumor initiation and development. The microenvironment favoring cancer stem cells could promote the activation of the 5'flanking region of NANOGP8.