Cyclophilin C Participates in the US2-Mediated Degradation of Major Histocompatibility Complex Class I Molecules

Do variations in the HLA-E ligand encoded by UL40 distinguish individuals susceptible to HCMV disease?

Human cytomegalovirus (HCMV) is carried lifelong by ∼80 % of adults worldwide, generating distinct disease syndromes in transplant recipients, people with HIV (PWH) and neonates. Amino acids 15-23 encoded by the HCMV gene UL40 match positions 3-11 of HLA-A and HLA-C, and constitute a "signal peptide" able to stabilise cell surface HLA-E as a restriction element and a ligand of NKG2A and NKG2C. We present next generation sequencing of UL40 amplified from 15 Australian renal transplant recipients (RTR), six healthy adults and four neonates, and 21 Indonesian PWH. We found no groupwise associations between the presence of multiple sequences and HCMV burden (highest in PWH) or HCMV-associated symptoms in neonates. Homology between UL40 and corresponding HLA-C and HLA-A peptides in 11 RTR revealed perfect matches with HLA-C in three individuals, all carrying HCMV encoding only VMAPRTLIL - a peptide previously associated with viremia. However indices of the burden of HCMV did not segregate in our cohort.

Ppic modulates CCl4-induced liver fibrosis and TGF-β-caused mouse hepatic stellate cell activation and regulated by miR-137-3p

Hepatic stellate cell activation, characterized by hyperproliferation and increased release of collagens, is a critical event during the initiation and development of hepatic fibrosis. The deregulated genes among different expression profiles based on online datasets were analyzed, attempting to identify novel potential biomarkers and treatment targets for hepatic fibrosis. The abnormal upregulation of mouse peptidylprolyl isomerase C (Ppic) within the CCl₄-caused hepatic fibrosis model in mice was identified according to bioinformatics and experimental analyses. The knockdown of Ppic in the CCl₄-caused liver fibrosis murine model significantly improved CCl₄-caused liver damage, decreased the fibrotic area, reduced ECM deposition, and reduced the hydroxyproline levels. The knockdown of Ppic in TGF-β-stimulated mouse hepatic stellate cells inhibited cell proliferation and decreased ECM levels. Through direct targeting, miR-137-3p negatively regulated Ppic expression. Contrastingly to Ppic knockdown, miR-137-3p inhibition further promoted cell proliferation and boosted ECM levels; the effects of miR-137-3p inhibition could be partially reversed by Ppic knockdown. Altogether, mmu-miR-137-3p directly targets Ppic and forms a regulatory axis with Ppic, modulating CCl₄-caused hepatic fibrosis in mice and TGF-β-caused mouse hepatic stellate cell activation.

Cyclophilins A, B, and C Role in Human T Lymphocytes Upon Inflammatory Conditions

Cyclophilins (Cyps) are a group of peptidyl-prolyl cis/trans isomerases that play crucial roles in regulatory mechanisms of cellular physiology and pathology in several inflammatory conditions. Their receptor, CD147, also participates in the development and progression of the inflammatory response. Nevertheless, the main function of Cyps and their receptor are yet to be deciphered. The release of CypA and the expression of the CD147 receptor in activated T lymphocytes were already described, however, no data are available about other Cyps in these cells. Therefore, in the present work intra and extracellular CypA, B and C levels were measured followed by induced inflammatory conditions. After activation of T lymphocytes by incubation with concanavalin A, both intra and extracellular Cyps levels and the CD147 membrane receptor expression were increased leading to cell migration towards circulating CypA and CypB as chemoattractants. When CypA was modulated by natural and synthetic compounds, the inflammatory cascade was avoided including T cell migration. Our results strengthen the relationship between CypA, B, and C, their receptor, and the inflammatory process in human T lymphocytes, associating CypC with these cells for the first time.

TMEM33 regulates intracellular calcium homeostasis in renal tubular epithelial cells

Mutations in the polycystins cause autosomal dominant polycystic kidney disease (ADPKD). Here we show that transmembrane protein 33 (TMEM33) interacts with the ion channel polycystin-2 (PC2) at the endoplasmic reticulum (ER) membrane, enhancing its opening over the whole physiological calcium range in ER liposomes fused to planar bilayers. Consequently, TMEM33 reduces intracellular calcium content in a PC2-dependent manner, impairs lysosomal calcium refilling, causes cathepsins translocation, inhibition of autophagic flux upon ER stress, as well as sensitization to apoptosis. Invalidation of TMEM33 in the mouse exerts a potent protection against renal ER stress. By contrast, TMEM33 does not influence pkd2-dependent renal cystogenesis in the zebrafish. Together, our results identify a key role for TMEM33 in the regulation of intracellular calcium homeostasis of renal proximal convoluted tubule cells and establish a causal link between TMEM33 and acute kidney injury.

Comparison of the MHC I Immunopeptidome Repertoire of B-Cell Lymphoblasts Using Two Isolation Methods

Significant technological advances in both affinity chromatography and mass spectrometry have facilitated the identification of peptides associated with the major histocompatibility complex class I (MHC I) molecules, and enabled a greater understanding of the dynamic nature of the immunopeptidome of normal and neoplastic cells. While the isolation of MHC I-associated peptides (MIPs) typically used mild acid elution (MAE) or immunoprecipitation (IP), limited information currently exists regarding their respective analytical merits. Here, a comparison of these approaches for the isolation of two different B-cell lymphoblast cell models is presented, and it is reported on the recovery, reproducibility, scalability, and complementarity of identification from each method. Both approaches yielded reproducible datasets for peptide extracts obtained from 2 to 100 million cells, with 2016 to 5093 MIPs, respectively. The IP typically provides up to 6.4-fold increase in MIPs compared to the MAE. The comprehensiveness of these immunopeptidome analyses is extended using personalized genomic database of B-cell lymphoblasts, and it is discovered that 0.4% of their respective MIP repertoire harbored nonsynonymous single nucleotide variations (also known as minor histocompatibility antigens, MiHAs).

PPIC, EMP3 and CHI3L1 Are Novel Prognostic Markers for High Grade Glioma

Current treatment methods for patients diagnosed with gliomas have shown limited success. This is partly due to the lack of prognostic genes available to accurately predict disease outcomes. The aim of this study was to investigate novel prognostic genes based on the molecular profile of tumor samples and their correlation with clinical parameters. In the current study, microarray data (GSE4412 and GSE7696) downloaded from Gene Expression Omnibus were used to identify differentially expressed prognostic genes (DEPGs) by significant analysis of microarray (SAM) between long-term survivors (>2 years) and short-term survivors (≤2 years). DEPGs generated from these two datasets were intersected to obtain a list of common DEPGs. The expression of a subset of common DEPGs was then independently validated by real-time reverse transcription quantitative PCR (qPCR). Survival value of the common DEPGs was validated using known survival data from the GSE4412 and TCGA dataset. After intersecting DEPGs generated from the above two datasets, three genes were identified which may potentially be used to determine glioma patient prognosis. Independent validation with glioma patients tissue (n = 70) and normal brain tissue (n = 19) found PPIC, EMP3 and CHI3L1 were up-regulated in glioma tissue. Survival value validation showed that the three genes correlated with patient survival by Kaplan-Meir analysis, including grades, age and therapy.