Requirement of mitoses for the reversal of X-inactivation in cell hybrids between murine embryonal carcinoma cells and normal female thymocytes

Journal Article · Fri Apr 01 00:00:00 EST 1988 · Experimental Cell Research; (United States)

DOI:https://doi.org/10.1016/0014-4827(88)90200-5· OSTI ID:5323991

Takagi, N ^[1]

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1. Hokkaido Univ., Sapporo (Japan)

By means of a 5-bromodeoxyuridine (BrdU) incorporation and acridine orange fluorescence staining method the authors studied reactivation of the inactivated X chromosome (X{sub i}) in newly formed cell hybrids between the near-diploid HPRT-deficient OTF9-63 murine embryonal carcinoma cell (ECC) with an XO sex chromosome constitution and the normal female mouse thymocyte. Synchronization of the late replicating S chromosome in such hybrid cells, indicative of reactivation, was found for the first time on Day 3, and the frequency of reactivation was attained 90% on Day 5. Inhibition of cell cycle progression either by methylglyoxal bis(guanylhydrazone) dihydrochloride, an inhibitor of polyamine metabolism, or by isoleucine-deficient medium after cell fusion delayed reactivation of the X{sub i}, which implied that the number of cell division cycles traversed by individual cells rather than the length of time after cell fusion is critical for the reactivation. Double-labeling experiments using ({sup 3}H)thymidine and BrdU indicated that hybrid cells had undergone three or four mitoses before reactivation of the X{sub i}. Most probably reactivation of the X{sub i} is consequent to reversion of the thymocyte genome to an undifferentiated state under the influence of OTF9 genome. DNA demethylation or dilution of X{sub i}-specific factors by mitoses may be involved in this process.

• OSTI ID: 5323991
• Journal Information: Experimental Cell Research; (United States), Vol. 175:2; ISSN 0014-4827
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
X CHROMOSOME
INACTIVATION
METABOLIC ACTIVATION
ACRIDINE ORANGE
AUTORADIOGRAPHY
BUDR
CARCINOMAS
DOUBLE LABELLING
EMBRYONIC CELLS
FLUORESCENCE
HYPOXANTHINE PHOSPHORIBOSYLTRANSFERASE
MICE
MITOSIS
THYMIDINE
THYMOCYTES
TRITIUM COMPOUNDS
TUMOR CELLS
ACRIDINES
AMINES
ANIMAL CELLS
ANIMALS
ANTIMETABOLITES
AROMATICS
AZAARENES
AZINES
BROMOURACILS
CELL DIVISION
CHROMOSOMES
DISEASES
DRUGS
DYES
ENZYMES
GLYCOSYL TRANSFERASES
HETEROCHROMOSOMES
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
LABELLING
LUMINESCENCE
MAMMALS
NEOPLASMS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PENTOSYL TRANSFERASES
PYRIDINES
PYRIMIDINES
RIBOSIDES
RODENTS
SOMATIC CELLS
TRANSFERASES
URACILS
VERTEBRATES
550401* - Genetics- Tracer Techniques
550301 - Cytology- Tracer Techniques