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Davis SR, Ward HE, Kelly V, Palmer D, Ankersmit-Udy AE, Lopdell TJ, Berry SD, Littlejohn MD, Tiplady K, Adams LF, Carnie K, Burrett A, Thomas N, Snell RG, Spelman RJ, Lehnert K. Screening for phenotypic outliers identifies an unusually low concentration of a β-lactoglobulin B protein isoform in bovine milk caused by a synonymous SNP. Genet Sel Evol 2022; 54:22. [PMID: 35296234 PMCID: PMC8925192 DOI: 10.1186/s12711-022-00711-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 02/28/2022] [Indexed: 12/12/2022] Open
Abstract
Background Milk samples from 10,641 dairy cattle were screened by a mass spectrometry method for extreme concentrations of the A or B isoforms of the whey protein, β-lactoglobulin (BLG), to identify causative genetic variation driving changes in BLG concentration. Results A cohort of cows, from a single sire family, was identified that produced milk containing a low concentration of the BLG B protein isoform. A genome-wide association study (GWAS) of BLG B protein isoform concentration in milk from AB heterozygous cows, detected a group of highly significant single nucleotide polymorphisms (SNPs) within or close to the BLG gene. Among these was a synonymous G/A variation at position + 78 bp in exon 1 of the BLG gene (chr11:103256256G > A). The effect of the A allele of this SNP (which we named B’) on BLG expression was evaluated in a luciferase reporter assay in transfected CHO-K1 and MCF-7 cells. In both cell types, the presence of the B’ allele in a plasmid containing the bovine BLG gene from -922 to + 898 bp (relative to the transcription initiation site) resulted in a 60% relative reduction in mRNA expression, compared to the plasmid containing the wild-type B sequence allele. Examination of a mammary RNAseq dataset (n = 391) identified 14 heterozygous carriers of the B’ allele which were homozygous for the BLG B protein isoform (BB’). The level of expression of the BLG B’ allele was 41.9 ± 1.0% of that of the wild-type BLG B allele. Milk samples from three cows, homozygous for the A allele at chr11:103,256,256 (B’B’), were analysed (HPLC) and showed BLG concentrations of 1.04, 1.26 and 1.83 g/L relative to a mean of 4.84 g/L in milk from 16 herd contemporaries of mixed (A and B) BLG genotypes. The mechanism by which B’ downregulates milk BLG concentration remains to be determined. Conclusions High-throughput screening and identification of outliers, enabled the discovery of a synonymous G > A mutation in exon 1 of the B allele of the BLG gene (B’), which reduced the milk concentration of β-lactoglobulin B protein isoform, by more than 50%. Milk from cows carrying the B’ allele is expected to have improved processing characteristics, particularly for cheese-making. Supplementary Information The online version contains supplementary material available at 10.1186/s12711-022-00711-z.
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Affiliation(s)
- Stephen R Davis
- Research & Development, Livestock Improvement Corporation, Ruakura Road, Hamilton, New Zealand. .,ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand.
| | - Hamish E Ward
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
| | - Van Kelly
- School of Biological Sciences, University of Auckland, Symonds Street, Auckland, New Zealand
| | - David Palmer
- School of Biological Sciences, University of Auckland, Symonds Street, Auckland, New Zealand
| | - Alexandra E Ankersmit-Udy
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
| | - Thomas J Lopdell
- Research & Development, Livestock Improvement Corporation, Ruakura Road, Hamilton, New Zealand
| | - Sarah D Berry
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
| | - Mathew D Littlejohn
- Research & Development, Livestock Improvement Corporation, Ruakura Road, Hamilton, New Zealand
| | - Kathryn Tiplady
- Research & Development, Livestock Improvement Corporation, Ruakura Road, Hamilton, New Zealand
| | - Linda F Adams
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
| | - Katie Carnie
- Research & Development, Livestock Improvement Corporation, Ruakura Road, Hamilton, New Zealand
| | - Alayna Burrett
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
| | - Natalie Thomas
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
| | - Russell G Snell
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Symonds Street, Auckland, New Zealand
| | - Richard J Spelman
- Research & Development, Livestock Improvement Corporation, Ruakura Road, Hamilton, New Zealand
| | - Klaus Lehnert
- ViaLactia Biosciences Ltd., a subsidiary (now closed) of Fonterra Co-Operative Ltd., Fanshawe Street, Auckland, New Zealand
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Shepelev MV, Kalinichenko SV, Deykin AV, Korobko IV. Production of Recombinant Proteins in the Milk of Transgenic Animals: Current State and Prospects. Acta Naturae 2018; 10:40-47. [PMID: 30397525 PMCID: PMC6209402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The use of transgenic animals as bioreactors for the synthesis of the recombinant proteins secreted into milk is a current trend in the development of biotechnologies. Advances in genetic engineering, in particular the emergence of targeted genome editing technologies, have provided new opportunities and significantly improved efficiency in the generation of animals that produce recombinant proteins in milk, including economically important animals. Here, we present a retrospective review of technologies for generating transgenic animals, with emphasis on the creation of animals that produce recombinant proteins in milk. The current state and prospects for the development of this area of biotechnology are discussed in relation to the emergence of novel genome editing technologies. Experimental and practical techniques are briefly discussed.
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Affiliation(s)
- M. V. Shepelev
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova Str., 34/5, Moscow, 119334, Russia
| | - S. V. Kalinichenko
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova Str., 34/5, Moscow, 119334, Russia
| | - A. V. Deykin
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova Str., 34/5, Moscow, 119334, Russia
| | - I. V. Korobko
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova Str., 34/5, Moscow, 119334, Russia
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3
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The extremely high level expression of human serum albumin in the milk of transgenic mice. Transgenic Res 2012; 21:1359-66. [DOI: 10.1007/s11248-012-9612-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 03/09/2012] [Indexed: 10/28/2022]
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4
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Iavnilovitch E, Eilon T, Groner B, Barash I. Expression of a carboxy terminally truncated Stat5 with no transactivation domain in the mammary glands of transgenic mice inhibits cell proliferation during pregnancy, delays onset of milk secretion, and induces apoptosis upon involution. Mol Reprod Dev 2006; 73:841-9. [PMID: 16596634 DOI: 10.1002/mrd.20479] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Signal transducer and activator of transcription (Stat5) is a transcription factor, which transduces extracellular cytokine and growth-factor signals to the nuclei of mammalian cells. As a major mediator of prolactin action, it is involved in the regulation of the development, function, and survival of mammary epithelial cells. The carboxyl terminal of Stat5 encodes a transactivation domain (TAD), which interacts with coactivators and is crucial for the transcriptional induction of Stat5 target genes. To study the role of the Stat5 TAD in mediating Stat5 functions, a carboxy terminally truncated Stat5 variant (Stat5Delta750) was directed for expression in the mammary glands of transgenic mice by regulatory sequences of the beta-lactoglobulin (BLG) gene. Expression of Stat5Delta750 in mammary tissue reduced the rates of cell proliferation at mid and late pregnancy. Subsequently, morphological signs of milk secretion upon parturition were delayed. In double-transgenic mice, expression of Stat5Delta750 drastically decreased BLG/luciferase activity during lactation, but did not affect the expression and secretion of the endogenous beta-casein or alpha-lactalbumin into the milk. Expression of Stat5Delta750 also caused an increase in the number of apoptotic cells during mammary involution by a factor of 3 relative to control glands. Our data established a role for the Stat5 TAD in mediating the effects of Stat5 on mammary development, regulation of milk protein gene activity, and cell survival. The full effects of Stat5Delta750 may be partially buffered by the expression of endogenous wild-type Stat5 and the formation of truncated and wild-type heterodimers.
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5
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Reichenstein M, German T, Barash I. BLG-e1 - a novel regulatory element in the distal region of the beta-lactoglobulin gene promoter. FEBS Lett 2005; 579:2097-104. [PMID: 15811325 DOI: 10.1016/j.febslet.2005.02.061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2005] [Revised: 02/16/2005] [Accepted: 02/20/2005] [Indexed: 10/25/2022]
Abstract
beta-Lactoglobulin (BLG) is a major ruminant milk protein. A regulatory element, termed BLG-e1, was defined in the distal region of the ovine BLG gene promoter. This 299-bp element lacks the established cis-regulatory sequences that affect milk-protein gene expression. Nevertheless, it alters the binding of downstream BLG sequences to histone H4 and the sensitivity of the histone-DNA complexes to trichostatin A treatment. In mammary cells cultured under favorable lactogenic conditions, BLG-e1 acts as a potent, position-independent silencer of BLG/luciferase expression, and similarly affects the promoter activity of the mouse whey acidic protein gene. Intragenic sequences upstream of BLG exon 2 reverse the silencing effect of BLG-e1 in vitro and in transgenic mice.
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Affiliation(s)
- Moshe Reichenstein
- Institute of Animal Science, ARO, The Volcani Center, P.O. Box 6, Bet-Dagan 50250, Israel
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6
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Sohn BH, Chang HG, Kang HS, Yoon H, Bae YS, Lee KK, Kim SJ. High level expression of the bioactive human interleukin-10 in milk of transgenic mice. J Biotechnol 2003; 103:11-9. [PMID: 12770500 DOI: 10.1016/s0168-1656(03)00072-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human interleukin-10 (hIL-10) has wide spectrum of anti-inflammatory activities and has shown a potential to be used for treatment of inflammatory or immune illness. In this study, transgenic mice that over-express human interleukin-10 (IL-10) in their milk were generated using a bovine beta-casein/human IL-10 hybrid gene. After cloning of the IL-10 gene, a 22 kb hybrid gene was constructed by linking a 10 kb promoter sequence of the bovine beta-casein gene to the cloned 12 kb IL-10 gene. In six of the eight transgenic mice, the transgene RNA was expressed only in the mammary gland and in the other two mice, it was also slightly expressed in the lung. The highest human IL-10 level in milk was 1620 microg x ml(-1). Notably, transgenes in all the eight transgenic mice were expressed regardless of the integration site even though no correlation was shown between the copy numbers of the transgene and expression level. These results suggest that the genomic sequence of the human IL-10 gene can induce the IL-10 expression at high levels under the control of the bovine beta-casein promoter.
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Affiliation(s)
- Bo Hwa Sohn
- Department of Biological Sciences, Ewha Womans University, Seoul 120-750, South Korea
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7
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Reichenstein M, Gottlieb H, Damari GM, Iavnilovitch E, Barash I. A new beta-lactoglobulin-based vector targets luciferase cDNA expression to the mammary gland of transgenic mice. Transgenic Res 2001; 10:445-56. [PMID: 11708654 DOI: 10.1023/a:1012064922126] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A beta-lactoglobulin (BLG)/luciferase gene vector (p907), composed of a luciferase intronless gene inserted between the second and sixth BLG exons was constructed. Stable transfections of CID-9 cells with this vector, as well as with a series of additional vectors, were performed to define regulatory regions within the BLG sequence, and the contribution of the SV40 polyadenylation (PA) site to luciferase expression. A relatively low level of luciferase activity was supported by vector p907. It was partially rescued by vector p906, in which the BLG 3' region, downstream of the luciferase cDNA, was replaced with the SV40 PA site. Flanking the SV40 region of vector p906, at its 3' end, with BLG sequences of exon 6/intron 6/exon 7 and the 3' region of the gene resulted in vector p904. This vector supported the highest luciferase activity, 10 times or 2.5 times higher than that measured in cells transfected with vectors p907 and p906, respectively. The induced activity supported by vector p904 is attributed to interaction between the SV40 PA site and elements of the distal part of the BLG 3' flanking sequences. The BLG 5' regulatory region of vector p904 encompasses a 3-kb promoter sequences. Deletion of 935 bp of its proximal end resulted in a 60% decrease in luciferase activity. Reduced activity was also seen with vector p915 lacking sequences of exon 1/intron 1/exon 2. This decrease could not be rescued with heterologous sequences of insulin intron 1, inserted upstream of the luciferase cDNA. Two sets of transgenic mice carrying vectors p907 and p904 were generated. Vector p907 supported only marginal luciferase activity in the mammary gland of all transgenic mice tested and luciferase RNA could not be detected by northern analysis. In contrast, 50% of the transgenic mice carrying vector p904 expressed luciferase RNA in the mammary gland and tissue-specific, hormonal-dependent activity was determined. However, the new p904 vector was not able to insulate the transgene from surrounding host DNA sequences, as reflected by its copy number-independent manner of expression. Nevertheless, vector p904 may represent a valuable tool for the expression of cDNAs in the mammary gland of transgenic animals.
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Affiliation(s)
- M Reichenstein
- Institute of Animal Science, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
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8
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Abstract
The production of recombinant human proteins in the milk of transgenic dairy animals offers a safe, renewable source of commercially important proteins that cannot be produced as efficiently in adequate quantities by other methods. A decade of success in expressing a variety of proteins in livestock has brought three human recombinant proteins to human clinical trials. Recent progress has drawn on molecular biology and reproductive physiology to improve the efficiency of producing and reproducing useful transgenic founder animals, and to improve the expression of heterologous proteins in their milk.
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9
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Broide RS, Grifman M, Loewenstein A, Grisaru D, Timberg R, Stone J, Shani M, Patrick JW, Soreq H. Manipulations of ACHE gene expression suggest non-catalytic involvement of acetylcholinesterase in the functioning of mammalian photoreceptors but not in retinal degeneration. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 71:137-48. [PMID: 10521568 DOI: 10.1016/s0169-328x(99)00169-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To explore role(s) of acetylcholinesterase (AChE) in functioning and diseased photoreceptors, we studied normal (rd/+) and degenerating (rd/rd) murine retinas. All retinal neurons, expressed AChEmRNA throughout fetal development. AChE and c-Fos mRNAs peaked at post-natal days 10-12, when apoptosis of rd/rd photoreceptors begins. Moreover, c-Fos and AChEmRNA were co-overexpressed in rd/rd mice producing transgenic human (h), and host (m) AChE, but not in rd/+ mice. However, mAChE overexpression also occurred in transgenics expressing human serum albumin. Drastic variations in AChE catalytic activity were ineffective during development. Neither transgenic excess nor diisopropylfluorophosphonate (DFP) inhibition (80%) affected the rd phenotype; nor did DFP exposure induce photoreceptor degeneration or affect other key cholinergic proteins in rd/+ mice, unlike reports of adult mice and despite massive induction under DFP of c-Fos70 years). Therefore, the extreme retinal sensitivity to AChE modulation may reflect non-catalytic function(s) of AChE in adult photoreceptors. These findings exclude AChE as causing the rd phenotype, suggest that its primary function(s) in mammalian retinal development are non-catalytic ones and indicate special role(s) for the AChE protein in adult photoreceptors.
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Affiliation(s)
- R S Broide
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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10
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Barash I, Faerman A, Richenstein M, Kari R, Damary GM, Shani M, Bissell MJ. In vivo and in vitro expression of human serum albumin genomic sequences in mammary epithelial cells with beta-lactoglobulin and whey acidic protein promoters. Mol Reprod Dev 1999; 52:241-52. [PMID: 10206655 DOI: 10.1002/(sici)1098-2795(199903)52:3<241::aid-mrd1>3.0.co;2-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The expression pattern of human serum albumin (HSA) in transgenic mice carrying various HSA genomic sequences driven either by the mouse whey acidic protein (WAP) or the sheep beta-lactoglobulin (BLG) promoters, was compared. The pattern of HSA expression in both WAP/HSA and BLG/HSA transgenic lines was copy number independent, and the major site of ectopic expression was the skeletal muscle. Although an equal proportion of expressors was determined in both sets of mice (approximately 25% secreting >0.1 mg/ml), the highest level of HSA secreted into the milk in the WAP/HSA transgenic lines was one order of magnitude lower than in the BLG/HSA lines. Despite this difference, the HSA expression patterns in the mammary gland were similar and consisted of two levels of variegated expression. Studies using mammary explant cultures revealed a comparable responsiveness to the lactogenic hormones insulin, hydrocortisone, and prolactin, although the WAP/HSA gene constructs were more sensitive to the hydrocortisone effect than were the BLG/HSA vectors. When HSA vectors were stably transfected into the mouse mammary cell line CID-9, they displayed a hierarchy of expression, dependent upon the specific complement of HSA introns included. Nevertheless, the expression of HSA in four out of five WAP/HSA constructs was similar to their BLG/HSA counterparts. This construct-dependent, and promoter-independent, hierarchy was also found following transfection into the newly established Golda-1 ovine mammary epithelial cell line.
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Affiliation(s)
- I Barash
- Institute of Animal Science, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
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11
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Lubon H. Transgenic animal bioreactors in biotechnology and production of blood proteins. BIOTECHNOLOGY ANNUAL REVIEW 1999; 4:1-54. [PMID: 9890137 DOI: 10.1016/s1387-2656(08)70066-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The regulatory elements of genes used to target the tissue-specific expression of heterologous human proteins have been studied in vitro and in transgenic mice. Hybrid genes exhibiting the desired performance have been introduced into large animals. Complex proteins like protein C, factor IX, factor VIII, fibrinogen and hemoglobin, in addition to simpler proteins like alpha 1-antitrypsin, antithrombin III, albumin and tissue plasminogen activator have been produced in transgenic livestock. The amount of functional protein secreted when the transgene is expressed at high levels may be limited by the required posttranslational modifications in host tissues. This can be overcome by engineering the transgenic bioreactor to express the appropriate modifying enzymes. Genetically engineered livestock are thus rapidly becoming a choice for the production of recombinant human blood proteins.
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Affiliation(s)
- H Lubon
- Plasma Derivatives Department, American Red Cross, Rockville, Maryland, USA.
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12
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Zinovieva N, Lassnig C, Schams D, Besenfelder U, Wolf E, Müller S, Frenyo L, Seregi J, Müller M, Brem G. Stable production of human insulin-like growth factor 1 (IGF-1) in the milk of hemi- and homozygous transgenic rabbits over several generations. Transgenic Res 1998; 7:437-47. [PMID: 10341452 DOI: 10.1023/a:1008831028620] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
One transgenic rabbit line was generated carrying a fusion gene consisting of the cDNA for human IGF-1 fused to a mammary gland specific expression cassette derived from bovine alpha-S1-casein sequences. Transgene expression was shown to be strictly tissue and lactation period specific. The transgenic rabbit line was bred for six generations. All transgenic animals showed stable production of biologically active IGF-1 over the generations and no apparent effect on the physiological or reproductive performance was observed. The absence of adverse effects on homozygous transgenic rabbits suggested the absence of insertional mutagenesis. Eight hemizygous transgenic offspring analysed produced on average 363 +/- 12 micrograms/ml (ranging from 223 +/- 61 to 484 +/- 39 micrograms/ml) mature human IGF-1 in their milk, whereas three homozygous animals produced on average 543 +/- 41 micrograms/ml (ranging from 360 +/- 15 to 678 +/- 80 micrograms/ml). Homozygous hulGF-1 females clearly showed a significantly increased production performance of the recombinant protein.
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Affiliation(s)
- N Zinovieva
- Research Center for Milk and Food Weihenstephan, TU Munich, Freising-Weihenstephan
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13
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Sokol DL, Passey RJ, MacKinlay AG, Murray JD. Regulation of CAT protein by ribozyme and antisense mRNA in transgenic mice. Transgenic Res 1998; 7:41-50. [PMID: 9556913 DOI: 10.1023/a:1008803905445] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Transgenic mouse lines were engineered to express stably antisense mRNA or antisense mRNA containing catalytic ribozyme (rbz) structures complementary to bacterial chloramphenicol acetyltransferase (CAT) gene transcripts. One transgenic line expressed antisense mRNA that specifically targeted full-length CAT coding sequences (ACAT). Another transgenic line expressed full-length antisense CAT mRNA which was modified by mutagensis to include four rbz cassettes (rbz-ACAT) in order to compare antisense versus antisense-rbz function in vivo. Preliminary data were also collected from a transgenic mouse line expressing antisense mRNA targeting 72% of the 5' region of CAT coding sequences (5' ACAT). All constructs contained similar control elements in their design. Promoter elements were derived from the bovine alpha s1-casein gene, while the small t intron and 3' control sequences were derived from SV40. The ability of these various constructs to down-regulate CAT protein levels was compared by analysis of CAT protein production in lactating double-hemizygous transgenic female mice. Every double-hemizygous mouse analysed expressed mRNA from the alpha s1-casein-CAT construct (Clarke et al., 1994) and equivalent levels of mRNA from one of the three antisense constructs. Transgenic mouse lines expressing both ACAT and CAT mRNA down-regulated CAT protein levels by 90% of that found in the CAT only transgenic population. Similarly, double-hemizygous transgenic lines expressing both rbz-ACAT and CAT mRNA regulated CAT protein levels by 87%. Preliminary data suggests that expression of mRNA from 5' ACAT/CAT double-hemizygote mice allowed approximately 67% down-regulation of normal CAT protein levels. We conclude that incorporation of multiple ribozymes within the full-length antisense CAT construct does not enhance the effectiveness of antisense mRNA in the down-regulation of CAT protein production in our system.
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Affiliation(s)
- D L Sokol
- Department of Pathology, University of Pennsylvania, Philadelphia 19104, USA
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14
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Rijnkels M, Kooiman PM, Platenburg GJ, van Dixhoorn M, Nuijens JH, de Boer HA, Pieper FR. High-level expression of bovine alpha s1-casein in milk of transgenic mice. Transgenic Res 1998; 7:5-14. [PMID: 9556911 DOI: 10.1023/a:1008892720466] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The bovine alpha s1-casein gene, isolated from a cosmid library, was introduced into the murine germline. Transgene expression occurred in all transgenic mice, and was confined to the lactating mammary gland. Half of the mouse lines (five out of ten) expressed at relatively high expression levels (> 1 mg ml-1). The highest levels of expression were obtained with a transgene containing 14.2 kb of 5' flanking sequence, in two cases expression levels comparable to (10 mg ml-1) or well above (20 mg ml-1) alpha s1-casein levels in bovine milk were obtained. Transcription initiation occurred at the same site in the bovine alpha s1-casein gene in transgenic mouse as in the cow. A marked induction of expression occurred at parturition rather than at mid-pregnancy, and thus resembled the bovine rather than the murine developmental expression pattern. Bovine alpha s1-casein specific immunoblotting and RIA were developed for characterization and quantification of the recombinant protein. Using these assays, the properties of the recombinant protein could not be distinguished from those of the natural bovine protein. In spite of the high-level tissue-specific and correctly regulated developmental expression of the transgene, expression levels were integration-site dependent. This may indicate that not all cis-acting regulatory elements involved in bovine alpha s1-casein expression were included in the transgene.
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Affiliation(s)
- M Rijnkels
- Medical Biotechnology Dept, Leiden Institute of Chemistry, Leiden University, Netherlands
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Kim J, Yu MH, Kim K. Repression participates in mammary tissue-specific activation of the caprine beta-lactoglobulin promoter. Mol Cell Endocrinol 1997; 133:161-8. [PMID: 9406862 DOI: 10.1016/s0303-7207(97)00163-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Activation of the beta-lactoglobulin (BLG) gene promoter is restricted to overtly differentiated mammary tissue. To understand the mechanism underlying such tissue-specificity, activity of the caprine BLG promoter was analyzed comparatively in cultured mammary HC11 cells and non-mammary HeLa and CV-1 cells. The BLG promoter flanked by the 5'-regulatory sequence below -205 was strongly activated in the cells, regardless of the cell type. In non-mammary HeLa and CV-1 cells, this activation was repressed completely by the upper regulatory sequence. Weak repression was also observed in mammary HC11 cells kept non-confluent. As the mammary HC11 cells grew confluent and maintained the stabilized state, however, repression by the upper regulatory sequence was switched to activation. The repressive upstream flanking sequence was strongly recognized by the binding factors in non-mammary HeLa and CV-1 cells in an in vitro binding assay. Binding intensity and competition strength of the upstream regulatory regions were in a close correlation to their transcriptional repression activities in the cultured cells. The results suggest that the restricted activation of the caprine BLG promoter in differentiated mammary tissue is guaranteed by repression in non-mammary and undifferentiated mammary cells.
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Affiliation(s)
- J Kim
- Korea Research Institute of Bioscience and Biotechnology, KIST, Yusong, Taejon, South Korea
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Webster J, Donofrio G, Wallace R, Clark AJ, Whitelaw CB. Intronic sequences modulate the sensitivity of beta-lactoglobulin transgenes to position effects. Gene X 1997; 193:239-43. [PMID: 9256082 DOI: 10.1016/s0378-1119(97)00128-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have analysed the expression of beta-lactoglobulin (BLG) gene constructs with combinations of introns deleted to further define the role of intronic regions in directing position-independent mammary expression of BLG transgenes. Intron removal had no obvious effect on hormonal induction of BLG expression in vitro but dramatically reduced expression in vivo, in that removal of intron pairs always resulted in a proportion of the transgenic lines generated failing to express the transgene in the mammary gland. Position-dependent expression was seen for all intron-deleted transgenes regardless of which introns were removed and the ability of the intron-deleted transgenes to be expressed bore no relationship to transgene copy number. Thus, intron removal per se increases the sensitivity of BLG transgenes to position effects.
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Affiliation(s)
- J Webster
- Division of Molecular Biology, Roslin Institute (Edinburgh), Midlothian, UK
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Ibáñez E, Folch JM, Vidal F, Coll A, Santaló J, Egozcue J, Sánchez A. Expression of caprine beta-lactoglobulin in the milk of transgenic mice. Transgenic Res 1997; 6:69-74. [PMID: 9032979 DOI: 10.1023/a:1018409217315] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A 14.5 kb-long transgene containing the complete caprine beta-lactoglobulin gene transcription unit as well as 6.1 kb and 3.7 kb of the 5'- and 3'-flanking regions, respectively, was microinjected into pronuclear stage mouse embryos. Four lines of transgenic mice were obtained, three of them expressing the transgene in their mammary glands during lactation. Western blot analysis of caprine beta-lactoglobulin in the milk of hemizygous transgenic animals demonstrated the presence of the exogenous protein at concentrations up to 0.5 mg ml-1 of mouse milk.
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Affiliation(s)
- E Ibáñez
- Departament de Biologia Cellular i Fisiologia, Facultat de Ciències, Universitat Autònoma de Barcelona, Spain
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Barash I, Ilan N, Kari R, Hurwitz DR, Shani M. Co-integration of beta-lactoglobulin/human serum albumin hybrid genes with the entire beta-lactoglobulin gene or the matrix attachment region element: repression of human serum albumin and beta-lactoglobulin expression in the mammary gland and dual regulation of the transgenes. Mol Reprod Dev 1996; 45:421-30. [PMID: 8956279 DOI: 10.1002/(sici)1098-2795(199612)45:4<421::aid-mrd3>3.0.co;2-t] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effect of co-integration of the entire beta-lactoglobulin (BLG) gene or matrix attachment region (MAR) sequences on the expression of various BLG/ human serum albumin (HSA) gene constructs was tested in transgenic mice. These former sequences were chosen because of their reported ability to insulate transgenes from the neighboring host genomic DNA sequences and/or to provide a more permissive transcriptional environment. When introduced alone, a cDNA-based BLG/HSA construct was expressed in 60% of transgenic strains and HSA was secreted at levels up to 0.3 mg/ml into the milk. Upon co-integration with either the entire BLG gene or MAR element, HSA RNA and protein expression were completely abrogated. While the co-integrated BLG gene suppressed the proportion of expresser strains carrying cDNA as well as genomic BLG/HSA constructs, the MAR element only exerted its negative effect on the cDNA-based BLG/HSA construct. In transgenics expressing both HSA and BLG, the tissue specificity and developmental patterns of BLG expression were altered and resembled the less stringent pattern of the BLG/HSA expression. These results demonstrate that rescue of transgene expression through co-integration with BLG or MAR sequences do not apply universally.
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Affiliation(s)
- I Barash
- Institute of Animal Science, Volcani Center, Bet Dagan, Israel
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Davisson RL, Nuutinen N, Coleman ST, Sigmund CD. Inappropriate splicing of a chimeric gene containing a large internal exon results in exon skipping in transgenic mice. Nucleic Acids Res 1996; 24:4023-8. [PMID: 8918807 PMCID: PMC146210 DOI: 10.1093/nar/24.20.4023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We generated transgenic mice containing a chimeric construct consisting of the alpha-cardiac myosin heavy chain (alpha cMHC) promoter and the human renin (hRen) gene in order to target hRen synthesis specifically to the heart. The construct consisted of three segments: (i) an alpha cMHC DNA segment including 4.5 kb of 5' flanking DNA and an additional 1.1 kb of genomic DNA encompassing exons I-III (non-coding) and the first two introns; (ii) a partial hRen cDNA consisting of exons I-VI; and (iii) a hRen genomic segment containing exons VII through IX, their intervening introns, and 400 bp of 3' flanking DNA. This results in the formation of a 909 bp internal fusion exon consisting of alpha cMHC, polylinker, and hRen sequences. Despite the presence of splice acceptor and donor sites bracketing this exon, transcription of this transgene resulted in a major alternatively spliced mRNA lacking the exon and therefore a majority of the hRen coding sequence. Cloning and sequencing of RT-PCR products from several heart samples from two independent transgenic lines confirmed accurate and faithful splicing of alpha cMHC exon II to hRen exon VII thus bypassing the internal fusion exon. All other exons (alpha cMHC exons I and II and hRen exons VII, VIII and IX) were appropriately spliced. These results are consistent with the hypothesis on exon definition which states that internal exons have a size limitation. Moreover, the results demonstrate that transgenes present in the genome at independent insertion sites and in either a single copy or multiple copies can be subject to exon skipping. The implications for transgene design will be discussed.
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Affiliation(s)
- R L Davisson
- Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA
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