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Anger M, Radonova L, Horakova A, Sekach D, Charousova M. Impact of Global Transcriptional Silencing on Cell Cycle Regulation and Chromosome Segregation in Early Mammalian Embryos. Int J Mol Sci 2021; 22:9073. [PMID: 34445775 PMCID: PMC8396661 DOI: 10.3390/ijms22169073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/14/2021] [Accepted: 08/18/2021] [Indexed: 11/17/2022] Open
Abstract
The onset of an early development is, in mammals, characterized by profound changes of multiple aspects of cellular morphology and behavior. These are including, but not limited to, fertilization and the merging of parental genomes with a subsequent transition from the meiotic into the mitotic cycle, followed by global changes of chromatin epigenetic modifications, a gradual decrease in cell size and the initiation of gene expression from the newly formed embryonic genome. Some of these important, and sometimes also dramatic, changes are executed within the period during which the gene transcription is globally silenced or not progressed, and the regulation of most cellular activities, including those mentioned above, relies on controlled translation. It is known that the blastomeres within an early embryo are prone to chromosome segregation errors, which might, when affecting a significant proportion of a cell within the embryo, compromise its further development. In this review, we discuss how the absence of transcription affects the transition from the oocyte to the embryo and what impact global transcriptional silencing might have on the basic cell cycle and chromosome segregation controlling mechanisms.
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Affiliation(s)
- Martin Anger
- Central European Institute of Technology, Department of Genetics and Reproduction, Veterinary Research Institute, 621 00 Brno, Czech Republic; (L.R.); (A.H.); (D.S.); (M.C.)
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RHEB1 insufficiency in aged male mice is associated with stress-induced seizures. GeroScience 2017; 39:557-570. [PMID: 28891034 DOI: 10.1007/s11357-017-9997-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
The mechanistic target of rapamycin (mTOR), a protein kinase, is a central regulator of mammalian metabolism and physiology. Protein mTOR complex 1 (mTORC1) functions as a major sensor for the nutrient, energy, and redox state of a cell and is activated by ras homolog enriched in brain (RHEB1), a GTP-binding protein. Increased activation of mTORC1 pathway has been associated with developmental abnormalities, certain form of epilepsy (tuberous sclerosis), and cancer. Clinically, those mTOR-related disorders are treated with the mTOR inhibitor rapamycin and its rapalogs. Because the effects of chronic interference with mTOR signaling in the aged brain are yet unknown, we used a genetic strategy to interfere with mTORC1 signaling selectively by introducing mutations of Rheb1 into the mouse. We created conventional knockout (Rheb1 +/- ) and gene trap (Rheb1 Δ/+ ) mutant mouse lines. Rheb1-insufficient mice with different combinations of mutant alleles were monitored over a time span of 2 years. The mice did not show any behavioral/neurological changes during the first 18 months of age. However, after aging (> 18 months of age), both the Rheb1 +/- and Rheb1 Δ /- hybrid males developed rare stress-induced seizures, whereas Rheb1 +/- and Rheb1 Δ /- females and Rheb1 Δ/+ and Rheb1 Δ/Δ mice of both genders did not show any abnormality. Our findings suggest that chronic intervention with mTORC1 signaling in the aged brain might be associated with major adverse events.
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Tian Q, Smart JL, Clement JH, Wang Y, Derkatch A, Schubert H, Danilchik MV, Marks DL, Fedorov LM. RHEB1 expression in embryonic and postnatal mouse. Histochem Cell Biol 2015; 145:561-72. [PMID: 26708151 DOI: 10.1007/s00418-015-1394-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2015] [Indexed: 12/16/2022]
Abstract
Ras homolog enriched in brain (RHEB1) is a member within the superfamily of GTP-binding proteins encoded by the RAS oncogenes. RHEB1 is located at the crossroad of several important pathways including the insulin-signaling pathways and thus plays an important role in different physiological processes. To understand better the physiological relevance of RHEB1 protein, the expression pattern of RHEB1 was analyzed in both embryonic (at E3.5-E16.5) and adult (1-month old) mice. RHEB1 immunostaining and X-gal staining were used for wild-type and Rheb1 gene trap mutant mice, respectively. These independent methods revealed similar RHEB1 expression patterns during both embryonic and postnatal developments. Ubiquitous uniform RHEB1/β-gal and/or RHEB1 expression was seen in preimplantation embryos at E3.5 and postimplantation embryos up to E12.5. Between stages E13.5 and E16.5, RHEB1 expression levels became complex: In particular, strong expression was identified in neural tissues, including the neuroepithelial layer of the mesencephalon, telencephalon, and neural tube of CNS and dorsal root ganglia. In addition, strong expression was seen in certain peripheral tissues including heart, intestine, muscle, and urinary bladder. Postnatal mice have broad spatial RHEB1 expression in different regions of the cerebral cortex, subcortical regions (including hippocampus), olfactory bulb, medulla oblongata, and cerebellum (particularly in Purkinje cells). Significant RHEB1 expression was also viewed in internal organs including the heart, intestine, urinary bladder, and muscle. Moreover, adult animals have complex tissue- and organ-specific RHEB1 expression patterns with different intensities observed throughout postnatal development. Its expression level is in general comparable in CNS and other organs of mouse. Thus, the expression pattern of RHEB1 suggests that it likely plays a ubiquitous role in the development of the early embryo with more tissue-specific roles in later development.
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Affiliation(s)
- Qi Tian
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | | | - Joachim H Clement
- Department of Hematology and Oncology, Jena University Hospital, 07747, Jena, Germany
| | - Yingming Wang
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | - Alex Derkatch
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA
| | | | - Michael V Danilchik
- Department of Integrative Biosciences, Oregon Health and Science University, Portland, OR, USA
| | - Daniel L Marks
- Department of Pediatrics, Oregon Health and Science University, Portland, OR, USA
| | - Lev M Fedorov
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR, 97239, USA.
- Friedrich-Schiller-University, 07740, Jena, Germany.
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Schmid M, Steinlein C, Tian Q, Hanlon Newell AE, Gessler M, Olson SB, Rosenwald A, Kneitz B, Fedorov LM. Mosaic variegated aneuploidy in mouse BubR1 deficient embryos and pregnancy loss in human. Chromosome Res 2014; 22:375-92. [DOI: 10.1007/s10577-014-9432-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 12/23/2022]
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