AG-Leiter: Prof. Dr. Michael Ott

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Recent Submissions

  • MicroRNA-125b-5p mimic inhibits acute liver failure.

    Yang, Dakai; Yuan, Qinggong; Balakrishnan, Asha; Bantel, Heike; Klusmann, Jan-Henning; Manns, Michael P; Ott, Michael; Cantz, Tobias; Sharma, Amar Deep; Twincore Centre of Experimental and Clinical Infection Research; a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover 30625, Germany. (2016)
    The lack of broad-spectrum anti-acute liver failure (ALF) therapeutic agents contributes to ALF-related mortality. MicroRNAs (miRNAs) are suggested to be potent serum biomarkers for ALF, but their functional and therapeutic relevance in ALF are unclear. Here we show an unbiased approach, using two complementary miRNA screens, to identify miRNAs that can attenuate ALF. We identify miR-125b-5p as a regulator of cell death that attenuates paracetamol-induced and FAS-induced toxicity in mouse and human hepatocytes. Importantly, administration of miR-125b-5p mimic in mouse liver prevents injury and improves survival in models of ALF. Functional studies show that miR-125b-5p ameliorates ALF by directly regulating kelch-like ECH-associated protein 1, in turn elevating expression of nuclear factor-E2-related factor 2, a known regulator in ALF. Collectively, our findings establish miR-125b-5p as an important regulator of paracetamol-induced and FAS-induced cell death. Thus, miR-125b-5p mimic may serve as a broad-spectrum therapeutic attenuator of cell death during ALF.
  • Concise review: cell therapies for hereditary metabolic liver diseases-concepts, clinical results, and future developments.

    Cantz, Tobias; Sharma, Amar Deep; Ott, Michael; TWINCORE, Centre for Experimental and Clinical Infection Research, Feodor-Lynen Str. 7, 30625, Hannover, Germany. (2015-04)
    The concept of cell-based therapies for inherited metabolic liver diseases has been introduced for now more than 40 years in animal experiments, but controlled clinical data in humans are still not available. In the era of dynamic developments in stem cell science, the "right" cell for transplantation is considered as an important key for successful treatment. Do we aim to transplant mature hepatocytes or do we consider the liver as a stem/progenitor-driven organ and replenish the diseased liver with genetically normal stem/progenitor cells? Although conflicting results from cell tracing and transplantation experiments have recently emerged about the existence and role of stem/progenitor cells in the liver, their overall contribution to parenchymal cell homeostasis and tissue repair is limited. Accordingly, engraftment and repopulation efficacies of extrahepatic and liver-derived stem/progenitor cell types are considered to be lower compared to mature hepatocytes. On the basis of these results, we will discuss the current clinical cell transplantation programs for inherited metabolic liver diseases and future developments in liver cell therapy. Stem Cells 2015;33:1055-1062.
  • E-N-cadherin heterodimers define novel adherens junctions connecting endoderm-derived cells.

    Straub, Beate K; Rickelt, Steffen; Zimbelmann, Ralf; Grund, Christine; Kuhn, Caecilia; Iken, Marcus; Ott, Michael; Schirmacher, Peter; Franke, Werner W (2011-11-28)
    Intercellular junctions play a pivotal role in tissue development and function and also in tumorigenesis. In epithelial cells, decrease or loss of E-cadherin, the hallmark molecule of adherens junctions (AJs), and increase of N-cadherin are widely thought to promote carcinoma progression and metastasis. In this paper, we show that this "cadherin switch" hypothesis does not hold for diverse endoderm-derived cells and cells of tumors derived from them. We show that the cadherins in a major portion of AJs in these cells can be chemically cross-linked in E-N heterodimers. We also show that cells possessing E-N heterodimer AJs can form semistable hemihomotypic AJs with purely N-cadherin-based AJs of mesenchymally derived cells, including stroma cells. We conclude that these heterodimers are the major AJ constituents of several endoderm-derived tissues and tumors and that the prevailing concept of antagonistic roles of these two cadherins in developmental and tumor biology has to be reconsidered.