Novel Role of UHRF1 in DNA methylation-mediated repression of latent HIV-1

The multiplicity, heterogeneity and dynamic nature of HIV-1 latency mechanisms are reflected in the current lack of functional cure for HIV-1 and in the various reported ex vivo potencies of latency-reversing agents. Here, we investigated the molecular mechanisms underlying the potency of the DNA methylation inhibitor 5-aza-2'-deoxycytidine (5-AzadC) in HIV-1 latency reversal. Doing so, we uncovered specific demethylation CpG signatures induced by 5-AzadC in the HIV-1 promoter. By analyzing the binding modalities to these CpG, we revealed the recruitment of the epigenetic integrator UHRF1 to the HIV-1 promoter. We further demonstrated the role of UHRF1 in DNA methylation-mediated silencing of the latent HIV-1 promoter. As a proof-of-concept to this molecular characterization, we showed that pharmacological downregulation of UHRF1 in ex vivo HIV+ patient cell cultures resulted in potent reactivation of latent HIV-1. Together, we identify UHRF1 as a novel actor in HIV-1 gene silencing and highlight that it constitutes a new molecular target for HIV-1 curative strategies.

Effect of rapamycin on mitochondria and lysosomes in fibroblasts from patients with mtDNA mutations

Maintaining mitochondrial function and dynamics is crucial for cellular health. In muscle, defects in mitochondria result in severe myopathies where accumulation of damaged mitochondria causes deterioration and dysfunction. Importantly, understanding the role of mitochondria in disease is a necessity to determine future therapeutics. One of the most common myopathies is mitochondrial encephalopathy lactic acidosis stroke-like episodes (MELAS), which has no current treatment. Recently, MELAS patients treated with rapamycin exhibited improved clinical outcomes. However, the cellular mechanisms of rapamycin effects in MELAS patients are currently unknown. In this study, we used cultured skin fibroblasts as a window into the mitochondrial dysfunction evident in MELAS cells, as well as to study the mechanisms of rapamycin action, compared to control, healthy individuals. We observed that mitochondria from patients were fragmented, had a 3-fold decline in the average speed of motility, a 2-fold reduced mitochondrial membrane potential and a 1.5-2-fold decline in basal respiration. Despite the reduction in mitochondrial function, mitochondrial import protein Tim23 was elevated in patient cell lines. MELAS fibroblasts exhibited increased MnSOD levels and lysosomal function when compared to healthy controls. Treatment of MELAS fibroblasts with rapamycin for 24 hrs resulted in increased mitochondrial respiration compared to control cells, a higher lysosome content, and a greater localization of mitochondria to lysosomes. Our studies suggest that rapamycin has the potential to improve cellular health even in the presence of mtDNA defects, primarily via an increase in lysosomal content.

Vers une thérapie génique pour la progéria ?

Hutchinson-Gilford Progeria (acute premature aging) is caused by a de novo point mutation in the lamin A gene. Recently, this mutation has been accurately corrected by base editing in patient cell lines and in a mouse model, resulting in nearly complete reversal to a normal phenotype. This success opens the perspective for clinical applications in Progeria and other diseases.

Effect of rapamycin on mitochondria and lysosomes in fibroblasts from patients with mtDNA mutations

Maintaining mitochondrial function and dynamics is crucial for cellular health. In muscle, defects in mitochondria result in severe myopathies where accumulation of damaged mitochondria causes deterioration and dysfunction. Importantly, understanding the role of mitochondria in disease is a necessity to determine future therapeutics. One of the most common myopathies is mitochondrial encephalopathy lactic acidosis stroke-like episodes (MELAS), which has no current treatment. Recently, MELAS patients treated with rapamycin exhibited improved clinical outcomes. However, the cellular mechanisms of rapamycin effects in MELAS patients are currently unknown. In this study, we used cultured skin fibroblasts as a window into the mitochondrial dysfunction evident in MELAS cells, as well as to study the mechanisms of rapamycin action, compared to control, healthy individuals. We observed that mitochondria from patients were fragmented, had a 3-fold decline in the average speed of motility, a 2-fold reduced mitochondrial membrane potential and a 1.5-2-fold decline in basal respiration. Despite the reduction in mitochondrial function, mitochondrial import protein Tim23 was elevated in patient cell lines. MELAS fibroblasts had increased MnSOD, p62 and lysosomal function when compared to healthy controls. Treatment of MELAS fibroblasts with rapamycin for 24 hrs resulted in increased mitochondrial respiration compared to control cells, a higher lysosome content, and a greater localization of mitochondria to lysosomes. Despite the reduction in mitochondrial function, mitochondrial import protein Tim23 was elevated in patient cell lines. MELAS fibroblasts had increased MnSOD, p62 and lysosomal function when compared to healthy controls. Treatment of MELAS fibroblasts with rapamycin for 24 hrs resulted in increased mitochondrial respiration compared to control cells, a higher lysosome content, and a greater localization of mitochondria to lysosomes.Our studies suggest that rapamycin has the potential to improve cellular health even in the presence of mtDNA defects, primarily via an increase in lysosomal content.

Ubiquitin and SUMO conjugation as biomarkers of acute myeloid leukemias response to chemotherapies

Ubiquitin and the ubiquitin-like SUMO are covalently conjugated to thousands of proteins to modulate their function and fate. Many of the enzymes involved in their conjugation are dysregulated in cancers and involved in cancer cell response to therapies. We describe here the identification of biomarkers of the activity of these enzymes and their use to predict acute myeloid leukemias (AML) response to standard chemotherapy (daunorubicin-DNR and cytarabine-Ara-C). We compared the ability of extracts from chemosensitive and chemoresistant AML cells to conjugate ubiquitin or SUMO-1 on 9,000 proteins spotted on protein arrays. We identified 122 proteins whose conjugation by these posttranslational modifiers marks AML resistance to DNR and/or Ara-C. Based on this signature, we defined a statistical score predicting AML patient response to standard chemotherapy. We finally developed a miniaturized assay allowing for easy assessment of modification levels of the selected biomarkers and validated it in patient cell extracts. Thus, our work identifies a new type of ubiquitin-based biomarkers that could be used to predict cancer patient response to treatments.

Role of Resveratrol in Transmitochondrial AMD RPE Cells

Resveratrol is a phytoalexin, stilbenoid compound with antioxidant properties attributable to its bioactive trans-resveratrol content. This study characterized the effects of over-the-counter (OTC) resveratrol nutritional supplements and a HPLC-purified resveratrol formulation, in human transmitochondrial age-related macular degeneration (AMD) retinal pigment epithelial (RPE) patient cell lines. These cell lines, which were created by fusing blood platelets obtained from dry and wet AMD patients with mitochondria-deficient (Rho0) ARPE-19 cells, had identical nuclei (derived from ARPE-19 cells) but different mitochondria that were derived from AMD patients. After resveratrol treatment, the levels of cell viability and reactive oxygen species production were measured. Results demonstrated that treatment with different resveratrol formulations improved cell viability and decreased reactive oxygen species generation in each AMD patient cell line. Although further studies are required to establish the cytoprotective potential of resveratrol under different physiological conditions, this novel study established the positive effects of OTC resveratrol supplements in macular degeneration patient cybrid cell lines in vitro.

Ubiquitin and SUMO conjugation as biomarkers of Acute Myeloid Leukemias response to chemotherapies

Ubiquitin and the ubiquitin-like SUMO are covalently conjugated to thousands of proteins to modulate their function and fate. Many of the enzymes involved in their conjugation are dysregulated in cancers and involved in cancer cells response to therapies. We describe here the identification of biomarkers of the activity of these enzymes and their use to predict Acute Myeloid Leukemias (AML) response to standard chemotherapy (daunorubicine-DNR and cytarabine-Ara-C). We compared the ability of extracts from chemosensitive and chemoresistant AML cells to conjugate ubiquitin or SUMO-1 on 9000 proteins spotted on protein-arrays. We identified 122 proteins whose conjugation by these post-translational modifiers marks AML resistance to DNR and/or Ara-C. Based on this modifomic signature, we defined a statistical score able to predict AML patient response to standard chemotherapy. We finally developed a miniaturized assay to easily assess the modification level of the selected biomarkers and validated it in patient cell extracts. Thus, our work identifies a new type of ubiquitin-based biomarkers that could be used to predict cancer patients response to treatments.Summary blurbThis study describes the identification of a new class of biomarkers of cancer response to therapies based on protein modification by Ubiquitin and SUMO and provides the tools to analyze them in Acute Myeloid Leukemia patient samples.

Мodern Approaches to the Treatment and Prevention of Recurrent of Ophthalmic Herpes. Review

The review focuses on modern treatment aspects and prevention of ophthalmic herpes.The generalized experience of the clinical nucleoside administration, the basic antiviral drugs in the treatment of this pathology, is presented in detail. Information about indications, side effects and various schemes for their systemic and local application is provided. Questions on the duration of nucleoside administration in various clinical forms of eye herpes are considered. A meta-analysis of the comparative therapeutic nucleoside efficacy based on the results of more than 100 placebo-controlled randomized trials is presented. Special attention is paid to the rare but severe eye pathology, the acute retinal necrosis. Also data on the indications and contraindications of corticosteroids and on the current view of immunotherapy of ophthalmic herpes is presented. The question of the modern approach to the disease prevention recurrences is considered in detail, particularly, the results of the nucleoside administration have a high level of evidence, and, herpetic vaccines in the rehabilitation of patients with herpes infection are not widely used due to the lack of reliable methods for evaluating the efficacy. The information on the search for new effective drugs that have a targeted effect on certain patient cell receptors that can inhibit the penetration and spread of the herpes virus that can cause a controlled immune response is provided. Expanding the arsenal of effective and safe antiviral therapy will definitely optimize the treatment of ophthalmic herpes and prevent the occurrence of its recurrence and severe outcomes.