Expression of the whey acidic protein in transgenic pigs impairs mammary development (original) (raw)
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FEBS Letters, 1992
We have investigated whether DNA regions present in lhc rabbit whey acidic protein (WAP) promoter/S' flankingsqucnce could polentiallyconfix. in viva, high level expression of reparlcr genes. Transgcnic mice were generated expressing a varianl of human a,-anrhrypsin. which has inhibitory activity against plasma kallikrein under lhc control or a 17.6 kbp DNA fraymcnt located upstream or the rabbi1 WAP gene. Up IO IO mg/ml oI' aclive and correctly processed recombinant protein were detected in mouse milk, thus suggesting that lhc far upsiream DNA sequences from the rabbit WAP gene mighi be useful for engineering elIicicnt prolein production in the mammary glands of lransgcnic animals.
Physiology and Genetic Aspects of the Regulation of Expression Milk Protein Genes
The Journal of Microbiology, Biotechnology and Food Sciences, 2017
For the genetic improvement of milk composition and milk yield, both the typing of different protein variants and knowledge about the regulation of expression of the different milk protein genes are important. Some of the processing properties of milk are dependent on the milk composition. Information about the DNA sequence and genes involved in the expression of the milk protein genes, therefore, is big importance for genetic improvement of these traits in animals breeding programmes.In recent years more data has become available concerning the regulation of expression of the milk protein genes and as might have been expected from the complex multihormonal control of these genes it appears to be rather complex. Although several mammary gland specific factors that play a role in expression of some of these genes have been identified, none of these factors has been shown to be involved in the expression of all or the majority of the milk protein genes.
Regulation of mouse mammary cell differentiation by extracellular milk proteins
Experimental Physiology, 1991
Differentiation of mammary epithelial cells prepared from pregnant mice was stimulated by culture on floating collagen gels in the presence of lactogenic hormones. Differentiation was measured by the induction of casein synthesis and fatty acid synthetase activity, both of which increased by up to 15-fold during 12 days of culture. Addition of a 10-30 kDa fraction of goat whey proteins to culture medium from day 3 inhibited casein synthesis by > 20 % compared with control cultures on days 4-12, and prevented further induction of fatty acid synthetase activity. Inhibition of secretory cell differentiation by this fraction, which is known to inhibit milk synthesis acutely in explant culture and lactating goats, suggests that similar autocrine mechanisms may mediate the sequential local effects on milk yield and cell differentiation elicited by manipulation of milking frequency or efficiency.
Transgenic Research, 1996
Transgenic mice were produced by microinjection of a DNA construct composed of the bovine K-casein (K-CN) cDNA under the control of the goat Jj-CN 5' promoter elements and 3' flanking regions into pronuclear-stage embryos. The gene construct targeted the expression of bovine K-CN RNA to the mammary gland and secretion of bovine K-CN in the milk. In the three lines studied (BC-7, BC-31 and BC-67) the transgene was stably integrated and propagated as a Mendelian locus. Expression of the bovine protein in lactating mice from the three transgenic lines was demonstrated by northern and western blots. In ten different tissues analysed by northern blotting, expression was confined to the mammary gland of lactating transgenic mice from line BC-7, with low-level expression also observed in the salivary gland of lines BC-31 and BC-67. Transgene expression in the mammary gland paralleled normal casein gene expression during lactation and was not observed in virgin females. The level of bovine K-CN mRNA expression on day 10 of lactation in hemizygous transgenic females in relation to endogenous mRNA of whey acid protein (WAP) gene expression was 14%, 69% and 127% in lines BC-7, BC-31 and BC-67, respectively. No association between transgene copy number and expression was observed. The bovine K-CN concentration in milk on day 10 of lactation ranged from 0.94 to 3.85 mg of protein per ml of milk. The bovine K-CN expressed in mouse milk had the same molecular mass and immunoactivity with polyclonal antibodies as did K-CN from bovine milk. A high degree of variation in the production of bovine K-CN within each of the transgenic lines was observed.
Synthesis of milk proteins in a cell-free system isolated from lactating bovine mammary tissue
Archives of Biochemistry and Biophysics, 1969
Cell-free milk protein synthesis as measured by W-leucine incorporation has been accomplished using partially defined components from lactating bovine mammary tissue. Incorporation of 14C-leucine into trichloroacetic acid-precipitable protein and into specific milk proteins has been demonstrated. This synthesis is dependent on the presence of microsomes and an energy source and was partially dependent on the addition of sRNA and an aminoacyl-sRNA synthetase preparation. Incorporation was inhibited by ribonuclease, puromycin, cycloheximide, and sodium fluoride, but not by chloramphenicol and deoxyribonuclease. No stimulation is observed when various lactogenic hormones are added to the system. After addition of carrier, the isolatedcr-lactalbumin,P-lactoglobulin, K-, olg-, and&caseins were radioactive in about the same proportion as their abundance in milk and the isotope content remained relatively constant upon reisolation. Verification of or,-casein synthesis was obtained by a combination of radioautography and immunodiffusion procedures.
Cell biology international …, 1992
Development of the MAC-T bovine mammary epithelial cell line by stable transfection with simian virus-40 large Tantigen should greatly assist study of possible intrinsic (local) and extrinsic (systemic) factors regulating bovine mammary epithelial cell development, differentiation, and function. This study evaluated the influence of mammary secretion whey proteins alpha-lactalbumin (ALA), betalactoglobulin (BLG), lactoferrin (LF), transferrin (TF) and serum albumin (SA) on MAC-T cell proliferation in the absence and presence of 10% fetal bovine serum (FBS). Concentration of whey proteins in culture ranged from 0 to 625 ~g/ml. MAC-T cell proliferation in the absence of FBS was significantly lower than in presence of 10% FBS. Alpha-lactalbumin and LF significantly decreased MAC-T proliferation in both the absence and presence of 10% FBS. Transferrin significantly increased MAC-T cell proliferation only in the absence of FBS. There were no significant differences in MAC-T cell proliferation cultured in the presence of BLG or SA. These experiments illustrate the potential usefulness of MAC-T cells for the study of factors involved in mammary cell proliferation. Results identified ALA, LF and TF as possible intrinsic factors associated with regulation of mammary epithelial cell proliferation.
Functional aspect of colostrum and whey proteins in human milk
The colostrum serum in the human milk has a variety of proteins that characterize and contribute exclusively to the quality of nutrition. In addition to being an important source of special amino acids required for rapid growth of the baby, many of these proteins have specific functions; such as assisting in the absorption of the fluids, defending against viral and bacterial infections, and stimulating the development of the intestinal mucosa by increasing the immunocompetence of the neonate. Some proteins such as the bile, a salt-stimulated lipase, the α-amylase and α1-antitrypsin, exert their function in the gastrointestinal tract, helping the absorption of the micronutrients and macronutrients milk, because they are relatively resistant to digestive enzymes. Furthermore, other proteins such as lactoferrin, secretory immunoglobulin A, lactoperoxidase, haptocorrin, and lactaderina bioactive peptides are formed during digestion, human milk proteins may inhibit the growth of pathogen...