Pretreatment with glucocorticoid is essential for lactogenic induction of the bovine β-casein/cat expression in HC11 cells

1998 ◽  
Vol 24 (1) ◽  
pp. 65-77 ◽  
Author(s):  
C. S. Lee ◽  
K. Kim ◽  
D. Y. Yu ◽  
K K. Lee
Keyword(s):  
Hc11 Cells ◽  
Cat Expression

scholarly journals p53-dependent and p53-independent activation of apoptosis in mammary epithelial cells reveals a survival function of EGF and insulin.

1995 ◽  
Vol 128 (6) ◽  
pp. 1185-1196 ◽  
Author(s):  
G R Merlo ◽  
F Basolo ◽  
L Fiore ◽  
L Duboc ◽  
N E Hynes
Keyword(s):  
Mammary Epithelial Cells ◽  
P53 Protein ◽  
Survival Function ◽  
Mammary Epithelial ◽  
Nuclear Accumulation ◽  
Temperature Sensitive ◽  
Dna Damaging Agents ◽  
A Cells ◽  
Hc11 Cells ◽  
P53 Tumor Suppressor Protein

The p53 tumor suppressor protein has been implicated as a mediator of programmed cell death (PCD). A series of nontransformed mammary epithelial cell (MEC) lines were used to correlate p53 function with activation of PCD. Treatment of MECs expressing mutant, inactive, or no p53 with DNA-damaging agents did not induce apoptosis. Upon introduction of temperature-sensitive p53 into HC11 cells, which lack wild-type (wt) p53, PCD was observed after mitomycin treatment at 32 degrees, when the ts p53 protein is in wt conformation. Thus, wt p53 mediates activation of PCD in response to mitomycin in HC11 cells. Treatment of the MCF10-A cells, which express wt p53, with various DNA-damaging agents led to nuclear accumulation of p53. Only mitomycin treatment led to an increase in the number of apoptotic nuclei. ErbB-2-transformed MCF10-A cells responded to mitomycin, cisplatin, and 5-Fl-uracil, suggesting that signaling from activated ErbB-2 enhances the cells ability to respond to DNA damage. A combination of high cell density and serum-free medium induces apoptosis in all MECs tested, irrespective of their p53 status. Under these conditions, EGF or insulin act as survival factors in preventing PCD. These data might elucidate some aspects of breast involution and tumorigenesis.

Ecdysterone regulatory elements function as both transcriptional activators and repressors

1991 ◽  
Vol 11 (4) ◽  
pp. 1846-1853
Author(s):  
L Dobens ◽  
K Rudolph ◽  
E M Berger
Keyword(s):  
Regulatory Element ◽  
Regulatory Elements ◽  
Upstream Region ◽  
Transcriptional Activators ◽  
Reporter Plasmid ◽  
Bacterial Gene ◽  
Simplex Virus ◽  
Very High ◽  
Cat Gene ◽  
Cat Expression

A synthetic, 23-bp ecdysterone regulatory element (EcRE), derived from the upstream region of the Drosophila melanogaster hsp27 gene, was inserted adjacent to the herpes simplex virus thymidine kinase promoter fused to a bacterial gene for chloramphenicol acetyltransferase (CAT). Hybrid constructs were transfected into Drosophila S3 cells and assayed for ecdysterone-inducible CAT expression. In the absence of ecdysterone a tandem pair of EcREs repressed the high constitutive level of CAT activity found after transfection with the parent reporter plasmid alone. After hormone addition very high levels of CAT activity were observed. Insertion of the EcRE pair 3' of the CAT gene also led to high levels of ecdysterone-induced CAT expression, but the repression of high constitutive levels of CAT activity failed to occur. The EcRE-CAT construct was cotransfected with plasmids containing tandem 10-mers or 40-mers of the EcRE but lacking a reporter gene. These additional EcREs led to a reduced level of ecdysterone-induced CAT activity and to an elevation of basal CAT activity in the absence of hormone. The data suggest that the receptor binds to the EcRE in the absence of hormone, blocking basal transcription from a constitutive promoter. In the presence of ecdysterone, receptor-hormone binding to the EcRE leads to greatly enhanced transcription.

scholarly journals Repression of the Drosophila proliferating-cell nuclear antigen gene promoter by zerknüllt protein

1991 ◽  
Vol 11 (10) ◽  
pp. 4909-4917
Author(s):  
M Yamaguchi ◽  
F Hirose ◽  
Y Nishida ◽  
A Matsukage
Keyword(s):  
Proliferating Cell Nuclear Antigen ◽  
Regulatory Region ◽  
Ectopic Expression ◽  
Gene Promoter ◽  
Nuclear Antigen ◽  
Target Sequence ◽  
Transient Expression Assay ◽  
Rnase Protection ◽  
Proliferating Cell ◽  
Cat Expression

A 631-bp fragment containing the 5'-flanking region of the Drosophila melanogaster proliferating-cell nuclear antigen (PCNA) gene was placed upstream of the chloramphenicol acetyltransferase (CAT) gene of a CAT vector. A transient expression assay of CAT activity in Drosophila Kc cells transfected with this plasmid and a set of 5'-deletion derivatives revealed that the promoter function resided within a 192-bp region (-168 to +24 with respect to the transcription initiation site). Cotransfection with a zerknüllt (zen)-expressing plasmid specifically repressed CAT expression. However, cotransfection with expression plasmids for a nonfunctional zen mutation, even-skipped, or bicoid showed no significant effect on CAT expression. RNase protection analysis revealed that the repression by zen was at the transcription step. The target sequence of zen was mapped within the 34-bp region (-119 to -86) of the PCNA gene promoter, even though it lacked zen protein-binding sites. Transgenic flies carrying the PCNA gene regulatory region (-607 to +137 or -168 to +137) fused with lacZ were established. When these flies were crossed with the zen mutant, ectopic expression of lacZ was observed in the dorsal region of gastrulating embryos carrying the transgene with either construct. These results indicate that zen indirectly represses PCNA gene expression, probably by regulating the expression of some transcription factor(s) that binds to the PCNA gene promoter.

Transcription termination at the chicken beta H-globin gene

1988 ◽  
Vol 8 (12) ◽  
pp. 5369-5377
Author(s):  
T M Pribyl ◽  
H G Martinson
Keyword(s):  
Rna Polymerase Ii ◽  
Inverted Repeat ◽  
Transcription Termination ◽  
Globin Gene ◽  
H Gene ◽  
Delta G ◽  
A Site ◽  
Cat Expression

We characterized the transcription termination region of the chicken beta H-globin gene. First we located the region by nuclear runon transcription in vitro. Then we sequenced and subcloned it into a chloramphenicol acetyltransferase (CAT) expression vector for assay in vivo. The region of beta H termination contains two interesting elements located about 1 kilobase downstream of the beta H gene poly(A) site. Either element alone can block CAT expression if inserted between the promoter and the poly(A) site of the cat gene in pRSVcat. The first element in the termination region is an unusually large inverted repeat in the DNA (delta G = -71 kcal). The second element, 200 base pairs further downstream, is an RNA polymerase II promoter which directs transcription back upstream on the complementary strand. This transcription converges on and collides with that from the beta H gene at or near the inverted repeat where transcription from both directions stops. We propose that the inverted repeat is a strong pause site which positions the converging polymerases for mutual site-specific termination.

Transient activity assays of the Trypanosoma brucei variant surface glycoprotein gene promoter: control of gene expression at the posttranscriptional level

1991 ◽  
Vol 11 (1) ◽  
pp. 338-343
Author(s):  
D Jefferies ◽  
P Tebabi ◽  
E Pays
Keyword(s):  
Trypanosoma Brucei ◽  
Gene Promoter ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Gene Promoters ◽  
Control Of Gene Expression ◽  
Transient Activity ◽  
Expression Site ◽  
Cat Gene ◽  
Cat Expression

The putative promoter of the variant surface glycoprotein (VSG) gene of Trypanosoma brucei was cloned into a plasmid containing the chloramphenicol acetyltransferase (CAT) gene. After electroporation into trypanosomes, this construct directed the expression of the CAT reporter gene. The essential region for promoter activity was found to reside within 88 bp upstream of the putative transcription start site. Transcription of the CAT construct occurred at approximately the same level in both bloodstream and procyclic forms and was resistant to alpha-amanitin. However, CAT expression appeared to be modulated in the two forms of the parasite. Sequences 3' to the gene seemed to be important in this respect, as CAT activity in bloodstream forms was readily detectable only when the 3' region of a VSG cDNA was placed downstream of the CAT gene. Two separate VSG gene promoter sequences, both cloned from T. brucei AnTat 1.3A, were equally able to direct CAT expression, which suggests that there are a number of potential VSG gene promoters in the genome, although usually only one expression site is fully active at any one time.

Expression of the K-fgf proto-oncogene is controlled by 3' regulatory elements which are specific for embryonal carcinoma cells

1990 ◽  
Vol 10 (6) ◽  
pp. 2475-2484
Author(s):  
A M Curatola ◽  
C Basilico
Keyword(s):  
Dna Sequences ◽  
Embryonal Carcinoma ◽  
Protein S ◽  
Cell Types ◽  
Regulatory Elements ◽  
Developmentally Regulated ◽  
Cis Acting ◽  
Dna Elements ◽  
Ec Cells ◽  
Cat Expression

Expression of the K-fgf/hst proto-oncogene appears to be restricted to cells in the early stages of development, such as embryonal carcinoma (EC) cells. When EC cells are induced to differentiate, K-fgf expression is drastically repressed. To identify cis-acting DNA elements responsible for this type of regulation, we constructed a plasmid in which cat gene expression was driven by about 1 kilobase of upstream K-fgf human DNA sequences, including the putative promoter, and transfected it into undifferentiated F9 EC cells or HeLa cells as prototypes of cells which express or do not express, respectively, the K-fgf proto-oncogene. This plasmid was essentially inactive in both cell types, and the addition of more than 8 kilobases of DNA sequences upstream of the K-fgf promoter did not lead to any increase in chloramphenicol acetyltransferase (CAT) expression. On the other hand, when we inserted in this plasmid DNA sequences which are 3' of the human K-fgf coding sequences, we could detect a significant stimulation of CAT activity. Analysis of these sequences led to the identification of enhancerlike DNA elements which are part of the 3' noncoding region of K-fgf exon 3 and promote CAT expression only in undifferentiated mouse F9 or human NT2/D1 EC cells, but not in HeLa, 3T3, or differentiated F9 cells, therefore mimicking the physiological expression of the K-fgf proto-oncogene. Similar elements are also present in the 3' region of the murine K-fgf proto-oncogene, in a region showing high homology to the human K-fgf sequences. These regulatory elements can promote CAT expression from heterologous promoters in an EC-specific manner, suggesting that they interact with a specific cellular transacting protein(s) whose expression is developmentally regulated.

Approximately 1 kilobase of sequence 5' to the two myosin light-chain 1f/3f gene cap sites is sufficient for differentiation-dependent expression

1988 ◽  
Vol 8 (3) ◽  
pp. 1361-1365
Author(s):  
R Billeter ◽  
W Quitschke ◽  
B M Paterson
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Cis Acting ◽  
Rous Sarcoma ◽  
Fast Myosin ◽  
Sequence Elements ◽  
Sarcoma Virus ◽  
Flanking Sequences ◽  
Transcriptional Start Sites ◽  
Cat Expression

Approximately 1 kilobase of genomic DNA from the chicken fast myosin light-chain 1f/3f gene 5' to the transcriptional start sites for each light-chain mRNA was sufficient for differentiation-dependent, tissue-restricted expression. This was determined in primary chick myoblast cultures transfected with the chloramphenicol acetyltransferase (CAT) expression vector p8CAT containing these 5'-flanking sequences. The expression of CAT activity from both light-chain promoters was 10- to 20-fold higher in differentiated myotubes than in fibroblasts or myoblasts grown in bromodeoxyuridine. In contrast, the beta-actin and Rous sarcoma virus promoters joined to the CAT gene were expressed equally in all cell backgrounds tested. Even though the relative timing of light-chain 1f and 3f expression was altered, tissue-restricted, differentiation-dependent expression of the light-chain mRNAs was maintained with these 5' cis-acting sequence elements.

Co-localization of apoptosis-regulating proteins in mouse mammary epithelial HC11 cells exposed to TGF-β1

2003 ◽  
Vol 82 (6) ◽  
pp. 303-312 ◽  
Author(s):  
Olga Kolek ◽  
Barbara Gajkowska ◽  
Michał Marek Godlewski ◽  
Tomasz Motyl
Keyword(s):  
Mammary Epithelial ◽  
Hc11 Cells ◽  
Tgf Β1

scholarly journals Selective Response to Insulin Versus Insulin-Like Growth Factor-I and -II and Up-Regulation of Insulin Receptor Splice Variant B in the Differentiated Mouse Mammary Epithelium

Endocrinology ◽  
2009 ◽  
Vol 150 (6) ◽  
pp. 2924-2933 ◽  
Author(s):  
Chiara Berlato ◽  
Wolfgang Doppler
Keyword(s):  
Mammary Gland ◽  
Insulin Receptor ◽  
Lactate Production ◽  
Terminal Differentiation ◽  
Mammary Epithelium ◽  
Epithelial Cell Line ◽  
Human Form ◽  
Igf Binding Proteins ◽  
Stage Of Development ◽  
Hc11 Cells

The terminal differentiation of the mouse mammary gland epithelium during lactation has been shown to require IGFs and/or superphysiological levels of insulin. It has been suggested that IGF receptor I (IGF-IR), in addition to its well-established role in the mammary gland during puberty and pregnancy, serves as the principal mediator of IGFs at this stage of development. However, our analysis of the expression levels of IGF-IR and the two insulin receptor (IR) splice variants, IR-A and IR-B, has revealed a 3- to 4-fold up-regulation of IR-B transcripts and a 6-fold down-regulation of IGF-IR transcripts and protein during terminal differentiation in the developing mammary gland. IR-B expression was also more than 10-fold up-regulated in murine mammary epithelial cell line HC11 during differentiation in vitro. As already described for the human form, murine IR-B cloned from HC11 exhibited selectivity for insulin as compared with IGFs. When differentiated HC11 cells were stimulated by 10 nm insulin, a concentration that is unable to activate IGF-IR, induction of milk protein and lipid synthetic enzyme gene expression, lactate production, and phosphorylation of Akt were observed. In contrast, on differentiated HC11 cells 10 nm IGF-I or 10 nm IGF-II were able to exert growth-promoting effects only. The lack of response of differentiated cells to low levels of IGFs could not be explained by inactivation of IGFs by IGF binding proteins. Our results suggest a previously unrecognized predominant role for IR-B in the differentiated mammary epithelium.

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