Analysis of spreading of inactivation in eight X autosome translocations utilizing the high resolution RBG technique

Keitges, Elisabeth A.; Palmer, Catherine G.

doi:10.1007/bf00291884

Cited by 51 publications

(38 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At least at the cytological level, X inactivation can spread over quite long distances, into autosomal material, in both murine and human X;autosome translocations (e.g., see Disteche et al 1979;Mattei et al 1982;Keitges and Palmer 1986). In addition, ectopic copies of the mouse Xist gene can lead to inactivation of at least some autosomal loci (Lee and Jaenisch 1997).…”

Section: Discussionmentioning

confidence: 99%

“…Using this difference in the timing of DNA synthesis, late-replication banding analyses of X;autosome translocations in both mouse and human have revealed that translocated autosomal material becomes later replicating compared with its intact autosomal counterpart and thus appears more like the adjacent inactive X chromosome (Eicher 1970;Disteche et al 1979;Mattei et al 1982;Keitges and Palmer 1986). Additionally, latereplication studies have suggested that the spreading of inactivation into autosomal sequences may be incomplete and discontinuous (Disteche et al 1984;Keitges and Palmer 1986;Schanz and Steinbach 1989). The indirect, subjective nature and low resolution of late-replication banding, however, makes it difficult to draw more than general conclusions about the spreading of X inactivation into autosomal DNA.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Spreading of X Inactivation into Autosomal Material of an X;autosome Translocation: Evidence for a Difference between Autosomal and X‐Chromosomal DNA

1998

Am. J Hum. Genet.

View full text Add to dashboard Cite

SummaryX inactivation involves initiation, propagation, and maintenance of genetic inactivation. Studies of replication timing in X;autosome translocations have suggested that X inactivation may spread into adjacent autosomal DNA. To examine the inactivation of autosomal material at the molecular level, we assessed the transcriptional activity of X-linked and autosomal loci spanning an inactive translocation in a phenotypically normal female with a karyotype of 46,X,der(X)t(X;4)(q22;q24). Since 4q duplications usually manifest dysmorphic features and severe growth and mental retardation, the normal phenotype of this individual suggested the spreading of X inactivation throughout the autosomal material. Consistent with this model, reverse transcription-PCR analysis of 20 transcribed sequences spanning 4q24-qter revealed that three known genes and 11 expressed sequence tags (ESTs) were not expressed in a somatic-cell hybrid that carries the translocation chromosome. However, three ESTs and three known genes were expressed from the t(X;4) chromosome and thus "escaped" X inactivation. This direct assay of expression demonstrated that the spreading of inactivation from the adjoining X chromosome was incomplete and noncontiguous. These findings are broadly consistent with the existence of genes known to escape inactivation on normal inactive X chromosomes. However, the fact that a high proportion (30%) of tested autosomal genes escaped inactivation may indicate that autosomal material lacks X chromosome-specific features that are associated with the spreading and/or maintenance of inactivation.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Spreading of X Inactivation into Autosomal Material of an X;autosome Translocation: Evidence for a Difference between Autosomal and X‐Chromosomal DNA

1998

Am. J Hum. Genet.

View full text Add to dashboard Cite

show abstract

“…As for X-autosome translocation, however, there are many instances that the early replicating regions of translocated autosomal segment replicated in the late S phase due to the "spreading effect" of translocated X chromosome (Camargo and Cervenka, 1984;Keitges and Palmer, 1986). This suggests that each chromosomal region has a feasibility of changing replication timing according to the function of the chromosome in which it is localized.…”

Section: Discussionmentioning

confidence: 99%

“…The X-autosomal translocation is known to change the timing of replication in each chromosomal region accompanied with the change of transcriptional activity (Camargo and Cervenka, 1984;Keitges and Palmer, 1986). Also in plants, changes in transcription have been reported to be caused by chromosome translocation, such as the transcription of nucleolar organizing regions (NOR) in translocation lines of wheat (Rieger et al, 1979).…”

Section: Introductionmentioning

confidence: 99%

Characterization of the late replication banding patterns in barley chromosomes.

1997

View full text Add to dashboard Cite

Replicating DNA regions on barley chromosomes were investigated by a replication banding technique. Of all chromosomal regions, the late replicating regions, in which DNA replicated in the last third of S phase, were detected as exceptionally distinct bands. Each late replicating region had its own timing and duration to replicate, which were not influenced by any translocations. This suggested that the late replication was highly associated with the structure of its related chromosomal region. By using the series of translocated chromosome lines, the late replication banding patterns of seven barley chromosomes were identified. The late replication banding pattern was similar to the C-banding pattern. The relationships of the late replicating regions with heterochromatin and C-banding regions are also discussed.

show abstract

“…(16)(17)(18) A compelling argument has been made for the role of LINE-1 elements, enriched on the mammalian X chromosome, in supporting the spread of silencing. (19,20) The Drosophila X chromosome is enriched in particular satellite sequences and repeats, (21)(22)(23) as is the C. elegans X chromosome.…”

Section: How Important Is Spreading?mentioning

confidence: 99%

Worm chromosomes call for recognition!

Rattner¹,

Meller²

2004

BioEssays

View full text Add to dashboard Cite

SummaryMany organisms face a dilemma rooted in the unequal numbers of X chromosomes carried by the two sexes and the need to maintain equivalent expression of X-linked genes. Several strategies have arisen to cope with this problem. All rely on accurately targeting epigenetic modifications to entire chromosomes. Targeting results from the action of recognition elements that attract modification and may rely on spreading of modification in cis along the affected chromosome. A recent report describing the first X chromosome recognition element from C. elegans opens the way to defining the relative contributions of these factors to the compensation of Xlinked gene expression in worms. (1) Extrachromosomal arrays composed of a C. elegans recognition element attract proteins that modify the C. elegans X chromosomes and interact genetically with mutations disrupting compensation. Moreover, examination of X:A translocations provides the first evidence for spreading of modification along C. elegans X chromosomes. Dosage compensation: one problem with different solutions One of the primary distinctions between the sexes of many species is the number of sex chromosomes. The heterogametic sex (XY or X0) typically results in male development, and female or hermaphrodite development occurs in the sex carrying two copies of the same chromosome (XX). As most X-linked genes encode functions that are required equally in both sexes, inequality in the number of sex chromosomes poses a fundamental challenge: the need for a mechanism that ensures the production of similar amounts of X-linked gene products regardless of the number of X chromosomes present. At least three different solutions have independently evolved in mammals, flies and the worm C. elegans. These strategies, grouped under the term 'dosage compensation', appear different at a first glance but present remarkable similarities. In mammals, dosage compensation between XY males and XX females occurs by the transcriptional silencing of one randomly chosen X chromosome in each female cell. (2) In flies, XY males increase transcription from most X-linked genes. (3) Hermaphrodite worms (XX) continue to transcribe both X chromosomes, but at half the rate of the single male X. (4) These divergent strategies arrive at a similar outcome: both sexes express similar amounts of most X-linked gene products. Each mechanism is based on the recruitment of chromatin-modifying factors to the X chromosome. These factors achieve a stable, epigenetic modification of chromatin structure resulting in altered gene expression, the central feature of dosage compensation.Targeting the X chromosome A shared requirement of each system is the need to accurately target modification to an entire chromosome, or in C. elegans, a pair of X chromosomes. An element of danger is implicit in the mammalian strategy as silencing is directed to one chromosome, but the identical homologue must remain active. This dilemma is solved by designating a single X inactivation center (Xic) to direct X inactivation in ci...

show abstract

Analysis of spreading of inactivation in eight X autosome translocations utilizing the high resolution RBG technique

Cited by 51 publications

References 18 publications

The Spreading of X Inactivation into Autosomal Material of an X;autosome Translocation: Evidence for a Difference between Autosomal and X‐Chromosomal DNA

The Spreading of X Inactivation into Autosomal Material of an X;autosome Translocation: Evidence for a Difference between Autosomal and X‐Chromosomal DNA

Characterization of the late replication banding patterns in barley chromosomes.

Worm chromosomes call for recognition!

Contact Info

Product

Resources

About