Purpose: To analyze tear protein variations in patients suffering from dry eye symptoms in the presence of tear film instability but without epithelial defects. Methods: Five microlitres of non-stimulated tears from 60 patients, suffering from evaporative dry eye (EDE) with a break-up time (BUT) o10 s, and from 30 healthy subjects as control (no symptoms, BUT 410 s) were collected. Tear proteins were separated by mono and bi-dimensional SDS-PAGE electrophoresis and characterized by immunoblotting and enzymatic digestion. Digested peptides were analyzed by liquid chromatography coupled to electrospray ionization quadrupole-time of flight mass spectrometry followed by comparative data analysis into Swiss-Prot human protein database using Mascot. Statistical analysis were performed by applying a t-test for independent data and a MannWhitney test for unpaired data (Po0.05). Results: In EDE patients vs controls, a significant decrease in levels of lactoferrin (data in % ± SD): 20.15 ± 2.64 vs 24.56 ± 3.46 (P ¼ 0.001), lipocalin-1: 14.98±2.70 vs 17.73±2.96 (P ¼ 0.0001), and lipophilin A-C: 2.89±1.06 vs 3.63±1.37 (P ¼ 0.006) was revealed, while a significant increase was observed for serum albumin: 9.45 ± 1.87 vs 3.46 ± 1.87 (P ¼ 0.0001). No changes for lysozyme and zinc a-2 glycoprotein (P ¼ 0.07 and 0.7, respectively) were shown. Proteomic analysis showed a downregulation of lipophilin A and C and lipocalin-1 in patients, which is suggested to be associated with post-translational modifications. Conclusions: Data show that tear protein changes anticipate the onset of more extensive clinical signs in early stage dry eye disease.

Prohibitins (PHBs) are a highly conserved class of proteins first discovered as inhibitors of cellular proliferation. Since then PHBs have been found to have a significant role in transcription, nuclear signaling, mitochondrial structural integrity, cell division, and cellular membrane metabolism, placing these proteins among the key regulators of pathologies such as cancer, neuromuscular degeneration, and other metabolic diseases. The human genome encodes two PHB proteins, prohibitin 1 (PHB1) and prohibitin 2 (PHB2), which function not only as a heterodimeric complex, but also independently. While many previous reviews have focused on the better characterized prohibitin, PHB1, this review focuses on PHB2 and new data concerning its cellular functions both in complex with PHB1 and independent of PHB1. V C 2015 IUBMB Life, 67(4): [239][240][241][242][243][244][245][246][247][248][249][250][251][252][253][254] 2015

microRNAs (miRNAs) are a group of highly conserved small non-coding RNAs that were found to enhance mRNA degradation or inhibit post-transcriptional translation. Accumulating evidence indicates that miRNAs contribute to tumorigenesis and cancer metastasis. microRNA-210 has been largely studied in the past several years and has been identified as a major miRNA induced under hypoxia. A variety of miR-210 targets have been identified pointing to its role, not only in mitochondrial metabolism, but also in angiogenesis, the DNA damage response, cell proliferation, and apoptosis. Based on earlier research findings, this review aims to provide a current overview on the involvement of miRNA-210 in biological processes and diseases.

BackgroundBeyond its possible correlation with stemness of tumor cells, CD133/prominin1 is considered an important marker in breast cancer, since it correlates with tumor size, metastasis and clinical stage of triple-negative breast cancers (TNBC), to date the highest risk breast neoplasia.MethodsTo study the correlation between the levels of CD133 expression and the biology of breast-derived cells, CD133low and CD133high cell subpopulations isolated from triple negative MDA-MB-231 cells were compared in terms of malignant properties and protein expression.ResultsHigh expression of CD133 characterizes cells with larger adhesion area, lower proliferation rate and reduced migration speed, indicative of a less undifferentiated phenotype. Conversely, when compared with CD133low cells, CD133high cells show higher invasive capability and increased expression of proteins involved in metastasis and drug-resistance of breast tumors. Among the signalling proteins examined, PLC-β2 expression inversely correlates with the levels of CD133 and has a role in inducing the CD133high cells to CD133low cells conversion, suggesting that, in TNBC cells, the de-regulation of this PLC isoform is responsible of the switch from an early to a mature tumoral phenotype also by reducing the expression of CD133.ConclusionsSince CD133 plays a role in determining the invasiveness of CD133high cells, it may constitute an attractive target to reduce the metastatic potential of TNBC. In addition, our data showing that the forced up-regulation of PLC-β2 counteracts the invasiveness of CD133-positive MDA-MB-231 cells might contribute to identify unexplored key steps responsible for the TNBC high malignancy, to be considered for potential therapeutic strategies.

Energetically speaking, ribosome biogenesis is by far the most costly process of the cell and, therefore, must be highly regulated in order to avoid unnecessary energy expenditure. Not only must ribosomal RNA (rRNA) synthesis, ribosomal protein (RP) transcription, translation, and nuclear import, as well as ribosome assembly, be tightly controlled, these events must be coordinated with other cellular events, such as cell division and differentiation. In addition, ribosome biogenesis must respond rapidly to environmental cues mediated by internal and cell surface receptors, or stress (oxidative stress, DNA damage, amino acid depletion, etc.). This review examines some of the well-studied pathways known to control ribosome biogenesis (PI3K-AKT-mTOR, RB-p53, MYC) and how they may interact with some of the less well studied pathways (eIF2α kinase and RNA editing/splicing) in higher eukaryotes to regulate ribosome biogenesis, assembly, and protein translation in a dynamic manner.

The double-stranded RNA-dependent kinase PKR has been described for many years as strictly a pro-apoptotic kinase. Recent data suggest that the main purpose of this kinase is damage control and repair following stress and, if all else fails, apoptosis. Aberrant activation of PKR has been reported in numerous neurodegenerative diseases and cancer. Although a subset of myelodysplastic syndromes (MDS) and chronic lymphocytic leukemia contain low levels of PKR expression and activity, elevated PKR activity and/or expression have been detected in a wide range of hematologic malignancies, from bone marrow failure disorders to acute leukemia. With the recent findings that cancers containing elevated PKR activity are highly sensitive to PKR inhibition, we explore the role of PKR in hematologic malignancies, signal transduction pathways affected by PKR, and how PKR may contribute to leukemic transformation.

Overexpression of Vav1 promotes the overcoming of the differentiation blockade that characterizes acute promyelocytic leukemia cells. At variance, down-modulation of Vav1 prevents ATRA-induced maturation, and in particular, the inhibition of its tyrosine phosphorylation prevents the neutrophil differentiation-related changes of cell morphology. These findings allowed to identify Vav1 as a crucial protein in the ATRA-dependent differentiation of tumoral promyelocytes. By means of a proteomic approach, here we have investigated a possible role for Vav1 in modulating protein expression during ATRA treatment of tumoral promyelocytes. We have performed high-resolution 2-DE coupled with mass spectra analysis of HL-60 and NB4 promyelocytic cell lines induced to differentiate with ATRA when the amounts or the tyrosine phosphorylation of Vav1 were forcedly reduced. We have found that the down-regulation of Vav1 affects the expression level of a number of proteins, including cell cycle/apoptosis- and cytoskeleton-related proteins. In particular, the expression of 14-3-3epsilon, alpha-enolase, alpha-tubulin and splice isoform 2 of alpha3 proteasome subunit changed as a consequence of the down-modulation of Vav1 during the differentiation of both HL-60 and NB4 cell lines, suggesting that these proteins may constitute a common part of the ATRA-induced pathway during maturation of APL-derived promyelocytes. These results indicate an unprecedented role for Vav1 in the maturation of myeloid cells as a regulator of protein expression.

A number of cancers possess constitutive activity of the dsRNA-dependent kinase, PKR. Inhibition of PKR in these cancers leads to tumor cell death. We recently reported the increased presence of PKR phosphorylated on Thr451 (p-T451 PKR) in clinical samples from myelodysplastic syndrome (MDS) patients and acute leukemia cell lines. Whereas p-T451 PKR in low-risk patient samples or PTEN-positive acute leukemia cell lines was mostly cytoplasmic, in high-risk patient samples and acute leukemia cell lines deficient in PTEN, p-T451 PKR was mainly nuclear. As nuclear activity of PKR has not been previously characterized, we examined the status of nuclear PKR in acute leukemia cell lines. Using antibodies to N-terminus, C-terminus and the kinase domain in conjunction with a proteomics approach, we found that PKR exists in diverse molecular weight forms in the nucleus. Analysis of PKR transcripts by reverse transcriptase-PCR, and PKR-derived peptides by MS/MS revealed that these forms were the result of post-translational modifications (PTMs). Biochemical analysis demonstrated that nuclear PKR is an active kinase that can respond to stress. Given the association of PKR with PTEN and the Fanconi complex, these results indicate that PKR likely has other previously unrecognized roles in nuclear signaling that may contribute to leukemic development.