Tissue distribution of the cellular binding protein for the mouse mammary tumour virus

1991 ◽  
Vol 7 (3) ◽  
pp. 169-174 ◽  
Author(s):  
F. F. Bolander ◽  
M. E. Blackstone
Keyword(s):  
Salivary Gland ◽  
Mammary Gland ◽  
Binding Protein ◽  
Mammary Epithelium ◽  
Late Pregnancy ◽  
Cell Surface Receptor ◽  
Mammary Tumour ◽  
Isolated Cells ◽  
Mouse Mammary Tumour Virus ◽  
Mouse Tissues

ABSTRACT The envelope protein, gp52, of the mouse mammary tumour virus (MMTV) binds to a cell-surface receptor as a first step in infection. A protein with characteristics of this receptor was measured on freshly isolated cells using, as ligand, 125I-labelled gp52 purified from C3H/HeN mice. The gp52-binding protein was found in all mouse tissues examined, but was present at highest concentrations in the mammary gland and spleen where it reached 4.2±0.3 (s.e.m.) pmol/mg protein; the dissociation constant was 30±7 pm. Binding to mammary epithelium could be displaced by either the RIII or 34I-R strains of MMTV, and binding was blocked by antibodies to gp52. Levels in the liver and adrenal glands were only 25% of those in the mammary gland, while the concentrations in the ovary and salivary gland were intermediate. Scatchard analyses of the binding data suggested that there was only a single set of high-affinity binding sites. During late pregnancy and lactation, receptor levels in mammary epithelium rose threefold, while those in the liver and salivary gland were unchanged. This induction would result in the mammary gland having 12 times the gp52-binding protein than other tissues and may result in the preferential reinfection of this tissue during lactation, with subsequent tumour formation.

Developmental and hormonal regulation of a mouse mammary tumour virus glycoprotein in normal mouse mammary epithelium

1990 ◽  
Vol 4 (2) ◽  
pp. 101-106 ◽  
Author(s):  
F. F. Bolander ◽  
M. E. Blackstone
Keyword(s):  
Hormonal Regulation ◽  
Normal Mouse ◽  
Mammary Epithelium ◽  
Late Pregnancy ◽  
Mammary Tumour ◽  
Mammary Tissue ◽  
Response Curves ◽  
Mouse Mammary Tumour Virus ◽  
Pregnancy And Lactation ◽  
Rna Accumulation

ABSTRACT A radioimmunoassay was developed and validated for the major glycoprotein (gp58) of the mouse mammary tumour virus (MMTV). Using this assay, the expression of gp58 during pregnancy and lactation was found to parallel that for MMTV RNA. In particular, there was a very rapid induction in late pregnancy and a decline in late lactation, although some residual expression persisted well into involution. In cultures of normal mouse mammary tissue, induction of gp58 occurred after a 24-h lag period and began to reach a plateau after 3 days. Both the insulin and prolactin dose—response curves for gp58 resembled those for MMTV RNA; in contrast, the effects of steroid hormones on gp58 and MMTV RNA were disparate. Although progesterone stimulated the RNA, it only slightly increased gp58 levels; however, the presence of cortisol greatly augmented this stimulation, despite the inability of cortisol to induce RNA at physiological concentrations. These results suggest that insulin, prolactin and progesterone act primarily at the level of RNA accumulation in normal mammary epithelium, while cortisol affects some more distal event.

Cyclic AMP and calcium in mouse mammary tumour virus expression: effects and post-transcriptional site of action

1990 ◽  
Vol 5 (1) ◽  
pp. 27-31 ◽  
Author(s):  
F. F. Bolander ◽  
M. E. Blackstone ◽  
B. M. Bradham
Keyword(s):  
Cyclic Amp ◽  
Second Messengers ◽  
Calcium Ionophore ◽  
Mammary Epithelium ◽  
Calcium Ionophore A23187 ◽  
Mammary Tumour ◽  
Ionophore A23187 ◽  
Mouse Mammary Tumour Virus ◽  
Low Concentrations ◽  
Virus Expression

ABSTRACT The role of cyclic AMP (cAMP), calcium, calmodulin and protein kinase C (PKC) in the expression of both mouse mammary tumour virus (MMTV) RNA and an MMTV glycoprotein, gp58, was investigated in normal mammary epithelium in culture. None of these second messengers had any effect on MMTV RNA. Dibutyryl cAMP alone had no effect on gp58 levels but, at low concentrations (0·05–0·1 mm), it nearly doubled the induction seen with insulin, cortisol and prolactin; higher concentrations were inhibitory. Although a calcium ionophore (A23187), either alone or with hormones, was ineffective, a calcium channel blocker (verapamil) reduced hormonal induction of gp58 by 80%, and a calmodulin inhibitor (W-13) reduced it by 90%. Two PKC activators, a phorbol ester and a diacylglyceride, were ineffective alone, with hormones or with the calcium ionophore. The following conclusions can be made: (1) cAMP, calcium and calmodulin play an important role in MMTV expression, (2) these second messengers all act post-transcriptionally, since they do not affect MMTV RNA, and (3) PKC does not appear to have a role in MMTV production in normal mammary epithelium.

scholarly journals Mammary Gland Structures Are Not Affected by an Increased Growth Rate of Yearling Ewes Post-Weaning but Are Associated with Growth Rates of Singletons

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 884
Author(s):  
Emmanuelle Haslin ◽  
Rene A. Corner-Thomas ◽  
Paul R. Kenyon ◽  
Adrian J. Molenaar ◽  
Stephen T. Morris ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mammary Gland ◽  
Live Weight ◽  
Late Pregnancy ◽  
Control Group ◽  
Early Lactation ◽  
Fat Pad ◽  
Negative Effects ◽  
Lamb Growth ◽  
Heavy Group

The experiment aimed to examine the impacts of an increased growth rate of ewes between three and seven months of age on udder development using ultrasound and to establish whether ultrasonography could be used to identify ewe mammary structures that may be indirect indicators of singleton growth to weaning. Udder dimensions, depths of gland cistern (GC), parenchyma (PAR) and fat pad (FP) were measured in late pregnancy (P107), early lactation (L29), and at weaning (L100) in 59 single-bearing yearling ewes selected from two treatments. The ‘heavy’ group (n = 31) was preferentially fed prior to breeding achieving an average breeding live-weight of 47.9 ± 0.38 kg at seven months of age. The ‘control’ group (n = 28) had an average breeding live-weight of 44.9 ± 0.49 kg. Udder dimensions, GC, PAR and FP did not differ between treatments. Lamb growth to L100 was positively associated (p < 0.05) with PAR at P107 and GC at L29. There was no evidence of negative effects of the live-weight gain treatments on udder development of yearling ewes as measured by ultrasonography. The results suggest that this ultrasound method has the potential to identify pregnant yearling ewes which would wean heavier singletons.

The transfer of transthyretin and receptor-binding properties from the plasma retinol-binding protein to the epididymal retinoic acid-binding protein

2002 ◽  
Vol 362 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Manickavasagam SUNDARAM ◽  
Daan M. F. van AALTEN ◽  
John B. C. FINDLAY ◽  
Asipu SIVAPRASADARAO
Keyword(s):  
Retinoic Acid ◽  
Binding Protein ◽  
Binding Pocket ◽  
Retinol Binding Protein ◽  
Cell Surface Receptor ◽  
Acid Binding Protein ◽  
The Family ◽  
Surface Receptor ◽  
A Cell ◽  
Plasma Retinol

Members of the lipocalin superfamily share a common structural fold, but differ from each other with respect to the molecules with which they interact. They all contain eight β-strands (A—H) that fold to form a well-defined β-barrel, which harbours a binding pocket for hydrophobic ligands. These strands are connected by loops that vary in size and structure and make up the closed and open ends of the pocket. In addition to binding ligands, some members of the family interact with other macromolecules, the specificity of which is thought to be associated with the variable loop regions. Here, we have investigated whether the macromolecular-recognition properties can be transferred from one member of the family to another. For this, we chose the prototypical lipocalin, the plasma retinol-binding protein (RBP) and its close structural homologue the epididymal retinoic acid-binding protein (ERABP). RBP exhibits three molecular-recognition properties: it binds to retinol, to transthyretin (TTR) and to a cell-surface receptor. ERABP binds retinoic acid, but whether it interacts with other macromolecules is not known. Here, we show that ERABP does not bind to TTR and the RBP receptor, but when the loops of RBP near the open end of the pocket (L-1, L-2 and L-3, connecting β-strands A—B, C—D and E—F, respectively) were substituted into the corresponding regions of ERABP, the resulting chimaera acquired the ability to bind TTR and the receptor. L-2 and L-3 were found to be the major determinants of the receptor- and TTR-binding specificities respectively. Thus we demonstrate that lipocalins serve as excellent scaffolds for engineering novel biological functions.

Targeting heparanase to the mammary epithelium enhances mammary gland development and promotes tumor growth and metastasis

2018 ◽  
Vol 65 ◽  
pp. 91-103 ◽  
Author(s):  
Ilanit Boyango ◽  
Uri Barash ◽  
Liat Fux ◽  
Inna Naroditsky ◽  
Neta Ilan ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Tumor Growth ◽  
Mammary Gland Development ◽  
Mammary Epithelium ◽  
Tumor Growth And Metastasis ◽  
Gland Development

CHANGES IN THE COMPOSITION AND YIELD OF THE MAMMARY SECRETION OF COWS DURING THE INITIATION OF LACTATION

1973 ◽  
Vol 59 (2) ◽  
pp. 231-247 ◽  
Author(s):  
P. E. HARTMANN
Keyword(s):  
Mammary Gland ◽  
Late Pregnancy ◽  
The Other ◽  
Small Samples ◽  
Dry Period ◽  
Abrupt Increase ◽  
Milk Samples ◽  
Casein Protein ◽  
Two Phases

SUMMARY Mammary secretion (1·2–2·0 ml) was collected from the milk sinus of each mammary gland (quarter) of two pregnant heifers and eight pregnant cows (dry period 49–229 days), first at weekly intervals from 40 days before parturition, then with increasing frequency as parturition approached. The progressive changes in the concentration of lactose, glucose, casein, non-casein protein and fat in the mammary secretion were determined. Calves were separated from the cows immediately after birth and the yield and composition of milk from individual quarters were determined for 5 days after parturition. Two quarters (milked quarters) of each of a further five cows were milked throughout pregnancy, while the other two quarters (unmilked quarters) of each cow were allowed to involute (dry off) 63– 104 days before parturition. Small samples (5–10 ml) of secretion were collected from the unmilked quarters, first at weekly intervals after drying off and then every second day from 10 to 15 days before parturition. On the days that the unmilked quarters were sampled, corresponding composite milk samples were collected from the milked quarters and the progressive changes in the yield of milk, lactose and fat were determined. The changes in the concentration of lactose and glucose in the mammary secretion, during drying off in late lactation, were determined in an additional five cows. In most cows allowed a usual dry period, and in the unmilked quarters of cows in which two quarters were milked throughout pregnancy, the concentration of lactose gradually increased from about 8 to 12 days before parturition to reach levels of about half those found in normal milk just before parturition. However, in some cows the concentration of lactose was low until 1–2 days before parturition and then increased abruptly, whereas in others the concentration of lactose increased slowly from as early as 32 days before parturition. A further rapid increase in the concentration of lactose in the mammary secretion occurred between 0 and 4 days before parturition in all cows. This latter increase was accompanied by an abrupt increase in the yield of milk, lactose and fat in the milked quarters of the cows in which two quarters were milked throughout pregnancy. These observations suggest that the initiation of lactation in the cow develops in two phases, a limited secretion of milk constituents occurs in late pregnancy and then 0–4 days before parturition copious secretion (lactogenesis) occurs.

Nucleotide sequences at host–proviral junctions for mouse mammary tumour virus

Nature ◽  
1981 ◽  
Vol 289 (5795) ◽  
pp. 253-258 ◽  
Author(s):  
John E. Majors ◽  
Harold E. Varmus
Keyword(s):  
Nucleotide Sequences ◽  
Mammary Tumour ◽  
Mouse Mammary Tumour Virus

Neurotransmitter Control of Secretion

1987 ◽  
Vol 66 (1_suppl) ◽  
pp. 628-632 ◽  
Author(s):  
B. J. Baum
Keyword(s):  
Plasma Membrane ◽  
Salivary Gland ◽  
Salivary Secretion ◽  
Cell Surface Receptor ◽  
Specific Cell ◽  
Neural Signal ◽  
N Protein ◽  
Transduction Mechanisms ◽  
Surface Receptor ◽  
Specific Cell Surface

It is very well established that the principal control of salivary secretion is derived from autonomic innervation. Transmission of a neural signal to a salivary gland acinar cell occurs chemically via neurotransmitters, the first messengers of a secretory response. Neurotransmitters bind to specific cell surface receptor proteins, an event which activates precise transduction mechanisms which then transfer the neural signal to the inside of the cell. There are two major transduction mechanisms operative in salivary gland acinar cells. One involves the generation of cAMP, the other involves the breakdown of plasma membrane polyphosphoinositides. For both mechanisms, the appropriate stimulated receptor activates a second plasma membrane protein, termed an N (or G) protein. The N protein requires GTP to activate an enzyme (adenylate cyclase or phospholipase C), which then catalyzes the formation of a second messenger (cAMP and inositol trisphosphatel diacylglyeerol, respectively). This action provides the intracellular signal for secretory events (protein, fluid, electrolyte secretion) to begin.

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