A new senolytic drug discovered

Accumulation of senescent cells may drive age-associated alterations and pathologies. Stem cells may undergo senescence, what plays a crucial role in organismal aging. Senolytics are promising therapeutics that can preferentially eliminate senescent cells. We previously demonstrated that dasatinib and quercetin are ineffective in the setting of liver diseases and regeneration (see: https://biosignaling.biomedcentral.com/articles/10.1186/s12964-021-00731-0.). Identifying new effective senolytics is important.

Together with groups from Italy (San Giovanni Rotondo, Catania, Palermo), Czech Republic (Brno, Olomouc), USA (Los Angeles, New York), Denmark (Copenhagen), Sweden (Stockholm), researchers from the TRANSTEM performed a high-throughput automatized screening (HTS) of the commercial LOPAC®Pfizer library on aphidicolin-induced senescent human fibroblasts, to identify novel senolytics.

The team discovered the nociceptin receptor FQ opioid receptor (NOP) selective ligand 1-[1-(1-methylcyclooctyl)-4-piperidinyl]-2-[(3R)-3-piperidinyl]-1H-benzimidazole (MCOPPB, a compound previously studied as potential anxiolytic) as the best scoring hit. The ability of MCOPPB to eliminate senescent cells in in vitro models was further tested in mice and in C. elegans. MCOPPB reduced the senescence cell burden in peripheral tissues but not in the central nervous system containing stem cell compartments. Mice and worms exposed to MCOPPB also exhibited locomotion and lipid storage changes.

Thus study uncovers MCOPPB as a NOP ligand that, apart from anxiolytic effects, also shows tissue-specific senolytic effects. Further studies are warranted to understand the effects of MCOPPB on the stem cell compartment in various tissues during age progression.

Fulltext article: Raffaele M, Kovacovicova K, Biagini T, Lo Re O, Frohlich J, Giallongo S, Nhan JD, Giannone AG, Cabibi D, Ivanov M, Tonchev AB, Mistrik M, Lacey M, Dzubak P, Gurska S, Hajduch M, Bartek J, Mazza T, Micale V, Curran SP, Vinciguerra M. (2022) Nociceptin/orphanin FQ opioid receptor (NOP) selective ligand MCOPPB links anxiolytic and senolytic effects.  Geroscience. Feb;44(1):463-483. https://link.springer.com/article/10.1007/s11357-021-00487-y

A rejuvenating factor affecting adipose tissue plasticity.

GDF11 is a member of the TGF-β superfamily that was recently implicated as potential “rejuvenating” factor, which can ameliorate metabolic disorders. The role of GDF11 signaling in the glucose homeostasis and in the differentiation of white adipose tissue is unknown.

Together with groups from Italy (Brescia, Catania), Czech Republic (Brno), Germany (Ulm), Spain (Madrid, Barcelona) and USA (New York), researchers from the TRANSTEM administered GDF11 treatment in ob/ob mice and showed improved glucose/insulin homeostasis, decreased weight gain and white adipocyte size. Furthermore, GDF11 treatment inhibited adipogenesis in pre-adipocytes by ALK5-SMAD2/3 activation in cooperation with the WNT/β-catenin pathway, whose inhibition resulted in adipogenic differentiation.

The team showed evidence that link GDF11 to adipogenic differentiation, glucose, and insulin homeostasis, which are pointing towards potential beneficial effects of GDF11-based “anti-obesity” therapy.

Fulltext article: Frohlich, J, Kovacovicova, K, Raffaele, M, Virglova, T, Cizkova, E, Kucera, J, Bienertova-Vasku, J, Wabitsch, M, Peyrou, M, Bonomini, F, Rezzani, R, Chaldakov, GN, Tonchev, AB, Di Rosa, M, Blavet, N, Hejret, V, Vinciguerra, M. GDF11 inhibits adipogenesis and improves mature adipocytes metabolic function via WNT/β-catenin and ALK5/SMAD2/3 pathways.  (2022) Cell Proliferation. Aug 3;e13310. https://onlinelibrary.wiley.com/doi/full/10.1111/cpr.13310

Increasing the efficiency of production of reprogrammed iPSCs

DDR efficiency could increase the yield of induced pluripotent stem cells (iPSC) upon reprogramming from somatic cells. The epigenetic mechanisms governing DDR during iPSC reprogramming are not completely understood. The goal was to evaluate the splicing isoforms of histone variant macroH2A1, macroH2A1.1, and macroH2A1.2, as potential regulators of DDR during iPSC reprogramming.

Together with groups from Italy (Rome), United Kingdom (Liverpool), Estonia (Tallinn) and Czech Republic (Brno), researchers from the TRANSTEM team used GFP-Trap one-step isolation of mtagGFP-macroH2A1.1 or mtagGFP-macroH2A1.2 fusion proteins from overexpressing human cell lines, followed by liquid chromatography-tandem mass spectrometry analysis, to uncover macroH2A1.1 exclusive interaction with Poly-ADP Ribose Polymerase 1 (PARP1) and X-ray cross-complementing protein 1 (XRCC1). MacroH2A1.1 overexpression in U2OS-GFP reporter cells enhanced specifically nonhomologous end joining (NHEJ) repair pathway, while macroH2A1.1 knock-out (KO) mice showed an impaired DDR capacity. The exclusive interaction of macroH2A1.1, but not macroH2A1.2, with PARP1/XRCC1, was confirmed in human umbilical vein endothelial cells (HUVEC) undergoing reprogramming into iPSC through episomal vectors. In HUVEC, macroH2A1.1 overexpression activated transcriptional programs that enhanced DDR and reprogramming. Consistently, macroH2A1.1 but not macroH2A1.2 overexpression improved iPSC reprogramming.

MacroH2A1 splicing isoform macroH2A1.1 was proposed as a promising epigenetic target to improve iPSC genome stability and therapeutic potential.

Fulltext citation: Giallongo S, Reháková D, Biagini T, Lo Re O, Raina P, Lochmanová G, Zdráhal Z, Resnick I, Pata P, Pata I, Mistrík M, de Magalhães JP, Mazza T, Koutná I, Vinciguerra M. Histone Variant macroH2A1.1 Enhances Nonhomologous End Joining-dependent DNA Double-strand-break Repair and Reprogramming Efficiency of Human iPSCs. Stem Cells, Volume 40, Issue 1, January 2022, Pages 35–48, https://doi.org/10.1093/stmcls/sxab004

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A new class of anti-aging drugs improves liver diseases and regeneration

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and can progress into fibrosis and cirrhosis, with impaired liver regeneration. Senolytics are promising agents that target selectively senescent cells. Whether senolytics dasatinib and quercetin (D + Q) have an effect on the age-associated spectrum of NAFLD-is unknown.

Together with groups from Czech Republic (Brno), United Kingdom (London) and Italy (Palermo), researchers from the TRANSTEM team utilized an established model of age- and obesity-associated liver cancer, the low dose diethylnitrosamine (DEN)/high fat diet (HFD), a regimen promoting liver inflammation and tumorigenesis over a long period of 9 months. Four groups of mice each were created: group 1 included control untreated mice; group 2 included mice treated with D + Q; group 3 included mice undergoing the DEN/HFD protocol; group 4 included mice undergoing the DEN/HFD protocol with the administration of D + Q.

Unexpectedly, D + Q worsened liver disease progression in the DEN/HFD mouse model, slightly increasing histological damage and tumorigenesis, while having no effect on senescent cells removal.

In summary, senolytics compounds are ineffective against age-associated NAFLD-induced liver cancer.

Fulltext citation: Raffaele, M, Kovacovicova, K, Frohlich, J, Lo Re, O, Giallongo, S, Oben, JA, Faldyna, M, Leva, L, Giannone, AG, Cabibi, D, Vinciguerra, M (2021) Mild exacerbation of obesity- and age- dependent liver disease progression by senolytic cocktail dasatinib+quercetin. Cell Communication and Signaling 19(1):44. https://biosignaling.biomedcentral.com/articles/10.1186/s12964-021-00731-0.

See accompanying/attached video abstract.

Unveiling the structural bases of two sister histones modulating production of reprogrammed iPSCs

MacroH2A1 is a histone H2A variant containing a domain highly similar to H2A and a large non-histone (macro) domain. MacroH2A1, in turn, is present in two alternatively exon-spliced isoforms: macroH2A1.1 and macroH2A1.2, which regulate cell plasticity and proliferation in a remarkably distinct manner (see also our Stem Cell 2022 paper: https://doi.org/10.1093/stmcls/sxab004. No study has analyzed extensively, and in parallel, the post-translational modifications (PTM) pattern of macroH2A1.1 and macroH2A1.2 in the same experimental setting, which could facilitate the understanding of their distinct biological functions in health and disease.

Together with groups from Czech Republic (Brno) and from Italy (San Giovanni Rotondo, Rome), researchers from the TRANSTEM team used mass spectrometry-based approach to identify the sites for phosphorylation, acetylation, and methylation in green fluorescent protein (GFP)-tagged macroH2A1.1 and macroH2A1.2 expressed in human hepatoma cells. The impact of selected PTMs on macroH2A1.1 and macroH2A1.2 structure and function were demonstrated using computational analyses.

Quantitative comparison of histone marks between the two isoforms revealed significant differences in the levels of phosphorylated T129 and S170. The computational analysis provided evidence that the phosphorylation status in the intrinsically disordered linker region in macroH2A1 isoforms might represent a key regulatory element contributing to their distinct biological responses.

Taken together, these results report different PTMs on the two macroH2A1 splicing isoforms as responsible for their distinct features and distribution in the cell and during iPSCs reprogramming.

Fulltext citation: Giallongo S, Lo Re O, Lochmanová G, Parca L, Petrizzelli F, Zdráhal Z, Mazza T, Vinciguerra M. (2021) Phosphorylation within Intrinsic Disordered Region Discriminates Histone Variant macroH2A1 Splicing Isoforms-macroH2A1.1 and macroH2A1.2. Biology (Basel). ul 13;10(7):659. doi: https://www.mdpi.com/2079-7737/10/7/659.

A new mouse model for hyper-sociality and regeneration of the hippocampus

Gene expression and epigenetic processes in several brain regions regulate physiological processes such as cognitive functions and social behavior. MacroH2A1.1 is a ubiquitous variant of histone H2A that regulates cell stemness and differentiation in various organs. Whether macroH2A1.1 has a modulatory role in emotional behavior is unknown. 

Together with groups from Italy (Rome, Catania) and Czech Republic (Brno), researchers from the TRANSTEM team employed macroH2A1.1 knock-out (−/−) mice to perform a comprehensive battery of behavioral tests, and an assessment of hippocampal synaptic plasticity (long- term potentiation) accompanied by whole hippocampus RNA sequencing. MacroH2A1.1−/− mice exhibit a stunning enhancement both of sociability and of active stress- coping behavior, reflected by the increased social behavior in social activity tests and higher mobility time in the forced swim test, respectively. They also display an increased hippocampal synaptic plasticity, accompanied by significant neurotransmission transcriptional networks changes. These results suggest that systemic depletion of histone macroH2A1.1 supports an epigenetic control necessary for hippocampal function and social behavior.

This mouse model can be used for studies on hypersociability and on autism.

Fulltext citation: Chiodi,V, Domenici MR, Biagini T, De Simone R, Tartaglione AM, Di Rosa, M, Lo Re O, Mazza T, Micale V, Vinciguerra M. Systemic depletion of histone macroH2A1.1 boosts hippocampal synaptic plasticity and social behaviour in mice. FASEB Journal 2021; 35:e21793. https://doi.org/10.1096/fj.202100569R

Transcriptomic atlas of adult primate brain progenitor cells

The adult brain retains capability to regenerate via stem cells known as neural stem/progenitor cells. The research onto the molecular signals which regulate neuronal production by stem cells is an intensely studied topic. However, currently it largely remains unknown how these mechanisms operate in the primate brain.

Together with groups from Germany, Japan and China, MU-Varna researchers from the TRANSTEM team have published the first transcriptomic analysis of gene expression in the neural stem niche of the adult brain of macaque monkeys. In order to uncover genes which could potentially activate the process of neurogenesis in the main stem cell zone of the adult brain, known as the subventricular zone, we compared the changes in the gene expression before and after ischemic insult, known as a strong activator of neurogenesis. Our results uncovered 500 genes up-regulated after ischemia in the subventricular zone. Some of these genes were already known as stem cell-related from data in mice, while others seemed to be specific for the primate brain. We also employed an in situ gene expression analysis on histological sections of 150 genes, the data available in a public database: www.monkey-niche.org. The results are published in Frontiers in Cell and Developmental Biology.

Fulltext citation: Chongtham MC, Wang H, Thaller C, Hsiao NH, Vachkov IH, Pavlov SP, Williamson LH, Yamashima T, Stoykova A, Yan J, Eichele G, Tonchev AB. Transcriptome Response and Spatial Pattern of Gene Expression in the Primate Subventricular Zone Neurogenic Niche After Cerebral Ischemia. Front Cell Dev Biol. 2020 Dec 3;8:584314. doi: https://doi.org/10.3389/fcell.2020.584314

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