Sequence and chromosomal context effects on variegated expression of keratin 5/lacZ constructs in stratified epithelia of transgenic mice.

The expression of transgene loci in mammals often occurs in a heterocellular fashion resulting in variegated patterns of expression. We have examined the effect of chromosomal integration site, copy number, and transcriptionally activating sequences on the variegation of a keratin 5-lacZ (K5Z) construct in the stratified epithelia of transgenic mice. lacZ expression in these mice is always mosaic, and the beta-gal activity per cell is usually higher in the lines with a higher proportion of expressing cells. Similar constructs, in which cDNAs were exchanged by lacZ sequences, showed no variegation. Also, when a strongly active, nonvariegating construct was coinjected with K5Z, most transgenic lines showed an almost homogeneous lacZ expression. The comparison of transgene arrays of different copies inserted at the same locus (obtained by using a lox/Cre system) showed that the reduction of copy number does not lead to an increase in the proportion of cells that express the transgene. Finally, in most of the variegating or nonexpressing lines the transgenes were located both at intermediate positions and at peritelomeric regions in the long chromosome arms. These findings suggest that the probability and efficiency of expression of K5Z genes depend on both long range chromosomal influences and on sequences in the transgene array.

[1]  S. Elgin,et al.  Silencing at Drosophila telomeres: nuclear organization and chromatin structure play critical roles , 1999, The EMBO journal.

[2]  L. Manuelidis.  Heterochromatic features of an 11-megabase transgene in brain cells. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[3]  L. Doyon,et al.  In transgenic mice , 1994 .

[4]  D. Kioussis,et al.  Locus control regions: overcoming heterochromatin-induced gene inactivation in mammals. , 1997, Current opinion in genetics & development.

[5]  R. Allshire,et al.  Position effect variegation at fission yeast centromeres , 1994, Cell.

[6]  Mark Groudine,et al.  A Functional Enhancer Suppresses Silencing of a Transgene and Prevents Its Localization Close to Centromeric Heterochromatin , 1999, Cell.

[7]  E. Whitelaw,et al.  Position-dependent variegation of globin transgene expression in mice. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[8]  R. Lathe,et al.  Variegated transgene expression in mouse mammary gland is determined by the transgene integration locus. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[9]  D. Scalzo,et al.  Transcriptional enhancers act in cis to suppress position-effect variegation. , 1996, Genes & development.

[10]  J. Yanowitz,et al.  Stringent sequence requirements for the formation of human telomeres. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[11]  D. Kioussis,et al.  Locus Control Region Function and Heterochromatin-Induced Position Effect Variegation , 1996, Science.

[12]  M. C. Huber,et al.  Genomic position effects lead to an inefficient reorganization of nucleosomes in the 5'-regulatory region of the chicken lysozyme locus in transgenic mice. , 1996, Nucleic acids research.

[13]  K. Skorecki,et al.  Position effect of human telomeric repeats on replication timing. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[14]  S. Henikoff.  Position-effect variegation after 60 years. , 1990, Trends in genetics : TIG.

[15]  J. Miyazaki,et al.  Site-specific recombination of a transgene in fertilized eggs by transient expression of Cre recombinase. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[16]  C. Conti,et al.  Deregulated expression of E2F1 induces hyperplasia and cooperates with ras in skin tumor development , 1998, Oncogene.

[17]  R. Kothary,et al.  The beta‐globin locus control region enhances transcription of but does not confer position‐independent expression onto the lacZ gene in transgenic mice. , 1996, The EMBO journal.

[18]  P. Meyer,et al.  Differences in DNA-methylation are associated with a paramutation phenomenon in transgenic petunia. , 1993, The Plant journal : for cell and molecular biology.

[19]  J. Mullins,et al.  Variegated expression of a mouse steroid 21-hydroxylase/beta- galactosidase transgene suggests centripetal migration of adrenocortical cells. , 1996, Molecular endocrinology.

[20]  E. Bouhassira,et al.  Transcriptional behavior of LCR enhancer elements integrated at the same chromosomal locus by recombinase-mediated cassette exchange. , 1997, Blood.

[21]  E. Whitelaw,et al.  A globin enhancer acts by increasing the proportion of erythrocytes expressing a linked transgene , 1997, Molecular and cellular biology.

[22]  K Weber,et al.  Intermediate filaments: structure, dynamics, function, and disease. , 1994, Annual review of biochemistry.

[23]  David G Johnson,et al.  E2F4 and E2F1 Have Similar Proliferative Properties but Different Apoptotic and Oncogenic Properties In Vivo , 2000, Molecular and Cellular Biology.

[24]  D. Kioussis,et al.  Random activation of a transgene under the control of a hybrid hCD2 locus control region/Ig enhancer regulatory element. , 1995, The EMBO journal.

[25]  I. Thorey,et al.  Embryonic expression of human keratin 18 and K18-beta-galactosidase fusion genes in transgenic mice. , 1993, Developmental biology.

[26]  F. Yull,et al.  Mammalian cDNA and prokaryotic reporter sequences silence adjacent transgenes in transgenic mice. , 1997, Nucleic acids research.

[27]  David Garrick,et al.  Repeat-induced gene silencing in mammals , 1998, Nature Genetics.

[28]  S. Porter,et al.  A distal tyrosinase upstream element stimulates gene expression in neural-crest-derived melanocytes of transgenic mice: position-independent and mosaic expression. , 1994, Development.

[29]  M. Vidal,et al.  Tissue-specific and efficient expression of the human simple epithelial keratin 8 gene in transgenic mice. , 1995, Journal of cell science.

[30]  M. Rieger,et al.  Identification of an orthologous mammalian cytokeratin gene. High degree of intron sequence conservation during evolution of human cytokeratin 10. , 1988, Journal of molecular biology.

[31]  F. Larcher,et al.  Expression of cyclin D1 in epithelial tissues of transgenic mice results in epidermal hyperproliferation and severe thymic hyperplasia. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[32]  Steven Henikoff,et al.  Expansions of transgene repeats cause heterochromatin formation and gene silencing in Drosophila , 1994, Cell.

[33]  J. Strouboulis,et al.  Heterochromatin Effects on the Frequency and Duration of LCR-Mediated Gene Transcription , 1996, Cell.

[34]  E. Whitelaw,et al.  Variegated expression of a globin transgene correlates with chromatin accessibility but not methylation status. , 1996, Nucleic acids research.

[35]  A. E. Sippel,et al.  A nuclear DNA attachment element mediates elevated and position-independent gene activity , 1989, Nature.

[36]  C. Goodman,et al.  The Molecular Biology of Axon Guidance , 1996, Science.

[37]  S. Henikoff,et al.  Copy number and orientation determine the susceptibility of a gene to silencing by nearby heterochromatin in Drosophila. , 1996, Genetics.

[38]  S. Smerdon,et al.  Human HMG box transcription factor HBP1: a role in hCD2 LCR function , 1999, The EMBO journal.

[39]  M. Vidal,et al.  Sequences 5' of the bovine keratin 5 gene direct tissue- and cell-type-specific expression of a lacZ gene in the adult and during development. , 1994, Differentiation; research in biological diversity.

[40]  L. Hennighausen,et al.  Matrix-attachment regions can impart position-independent regulation of a tissue-specific gene in transgenic mice. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[41]  T. Ley,et al.  Stochastic, stage-specific mechanisms account for the variegation of a human globin transgene. , 1998, Nucleic acids research.

[42]  Barbara L. Billington,et al.  Position effect at S. cerevisiae telomeres: Reversible repression of Pol II transcription , 1990, Cell.