Disease relevance of LOC424533

• Here we demonstrate that this single gene defect in the restricted-ovulator hen has detrimental consequences for the binding not only of very low density lipoprotein but also of vitellogenin to the 95-kDa receptor normally present in oocytes [1].
• This construct consists of DNA sequences from -626 to -590 upstream of the start of transcription of the chicken vitellogenin gene linked to the herpes simplex virus thymidine kinase promoter driving the transcription of the bacterial chloramphenicol acetyltransferase gene [2].
• A series of overlapping recombinant clones, which cover the vitellogenin gene, has been isolated from a phage-lambda linked chicken gene library [3].
• Organization, sequence and nuclease hypersensitivity of repetitive elements flanking the chicken apoVLDLII gene: extended sequence similarity to elements flanking the chicken vitellogenin gene [4].
• Two phage lambda recombinant DNA clones covering the entire sequence of an avian vitellogenin gene, plus flanking regions, have been isolated from an erythrocyte DNA gene library and characterized by R-loop and restriction mapping [5].

High impact information on LOC424533

• Whereas none of these nuclease-hypersensitive sites is observed in erythrocytes, brain, or fibroblasts, a subset is present in differentiated oviduct cells that have estrogen receptors, but do not express VTG II [6].
• It has a high affinity for estradiol (Kd = 0.5 x 10(-9) M), and the affinities of various steroids for the receptor correlate well with their ability to induce vitellogenin synthesis [7].
• This paper describes an estrogen receptor which is found in both the nucleus and cytoplasm of liver cells from male Xenopus laevis, and which seems to be involved in the induction of vitellogenin synthesis [7].
• Here we define a palindromic sequence of 15 base pairs, modelled after a sequence element shared by the vitellogenin genes of frog and chicken, which confers oestrogen inducibility on a heterologous promoter and can be converted into a glucocorticoid-responsive element by substitution of one or two bases at homologous positions in the palindrome [8].
• Measurement of hepatic apolipoprotein II and vitellogenin II messenger RNA during chicken embryogenesis showed that these genes acquire estrogen responsiveness at different stages of development [9].

Chemical compound and disease context of LOC424533

• 3. Mature female patterns of plasma vitellogenin and VLDL were induced by injection of oestradiol 17 beta (5 mg/kg body weight per day for 3 days) into adult cockerels [10].

Biological context of LOC424533

• In oviparous vertebrates vitellogenin, the precursor of the major yolk proteins, is synthesized in the liver of mature females under the control of estrogen [11].
• In contrast, the corresponding introns of the Xenopus and the chicken vitellogenin gene show no significant sequence homology [11].
• Sequence homologies within the 5' end region of the estrogen-controlled vitellogenin gene in Xenopus and chicken [11].
• It remains to be demonstrated which of these conserved sequences, if any, are involved in the hormone-regulated expression of the vitellogenin genes [11].
• The structural organization and the coding nucleotide sequence of the Xenopus laevis A2 and the chicken major vitellogenin genes have been compared [12].

Anatomical context of LOC424533

• These results suggest that after incorporation from serum via a specific receptor vitellogenin II is cleaved in the oocyte into four fragments, heavy and light chain lipovitellins, phosvitin and YGP40, and that YGP40 is released into the yolk plasma before or during compartmentation of lipovitellin-phosvitin complex into the yolk granule [13].
• The amino acid sequence of the egg yolk storage protein phosvitin has been deduced from the nucleotide sequence of part of the chicken vitellogenin gene [14].
• Using this technique we show that vitellogenin II gene sequences are selectively associated with the nuclear matrix of liver but not with oviduct of laying hens [15].
• Association of transcriptionally active vitellogenin II gene with the nuclear matrix of chicken liver [15].
• We also demonstrate that the size and number of polysomes increase and decrease in a coordinated fashion with the rate of vitellogenin synthesis [16].

Associations of LOC424533 with chemical compounds

• Another yolk plasma glycoprotein of 42 kDa is suggested to be one of the proteolytic products of the minor vitellogenin (vitellogenin I) [13].
• Isolation of chicken vitellogenin I and III cDNAs and the developmental regulation of five estrogen-responsive genes in the embryonic liver [17].
• They encode the 1850-amino acid pre-peptide of vitellogenin, which is the precursor of the mature yolk proteins, the serine-rich and heavily phosphorylated phosvitin and the lipovitellin [18].
• Addition of the antiestrogen tamoxifen (0.1 microM) to the system decreased vitellogenin mRNA synthesis by about 45% without affecting total RNA synthesis [19].
• Genomic sequencing was used to study the extent of cytosine methylation of four CpG sites within the regulatory region of the estradiol-inducible avian vitellogenin II gene [20].

Physical interactions of LOC424533

• VBP binds to one of the most important positive elements in the VTGII promoter and appears to play a pivotal role in the estrogen-dependent regulation of this gene [21].
• Estrogen and progesterone receptor-binding sites on the chicken vitellogenin II gene: synergism of steroid hormone action [2].
• Depleting the estradiol receptors from the cell and nuclear extracts by means of estradiol-receptor antibodies covalently bound to Matrex beads reduced the stimulation of the vitellogenin gene by 40% [19].
• Genomic sequencing reveals a positive correlation between the kinetics of strand-specific DNA demethylation of the overlapping estradiol/glucocorticoid-receptor binding sites and the rate of avian vitellogenin mRNA synthesis [20].

Co-localisations of LOC424533

• Furthermore, addition of growth hormone or prolactin to cultured cockerel hepatocyte monolayers resulted in the synthesis and secretion of a polypeptide that comigrates with authentic vitellogenin on polyacrylamide gels [22].

Regulatory relationships of LOC424533

• Although most of these mutations compromised VTGII promoter function, one dramatically increased expression in LMH cells and also rendered the VTGII promoter capable of being activated by cis-linked EREs in fibroblasts cotransfected with an estrogen receptor expression vector [23].
• Strikingly, the constitutive HS site located 5.5 kb upstream of the VTGIII gene and a previously identified HS site located within the coordinately regulated VTGII gene mapped to nearly identical copies of a 72 bp sequence [24].
• Does vitellogenin inhibit lipoprotein lipase in the laying hen [25]?

Other interactions of LOC424533

• Chicken vitellogenin, a serum lipoprotein specific for laying hens, has been thought to be proteolytically cleaved into the heavy and light chain lipovitellins and phosvitin, the major yolk granule proteins, during or after transportation into oocyte [13].
• Precursor-product relationship between chicken vitellogenin and the yolk proteins: the 40 kDa yolk plasma glycoprotein is derived from the C-terminal cysteine-rich domain of vitellogenin II [13].
• Third, as has been described previously for the VTGII and apoVLDLII genes, we demonstrate that a single injection of estradiol effects a long-term reprogramming event (hepatic memory) that allows a faster onset of the rapid accumulation of both VTGI and VTGIII RNAs following a subsequent rechallenge by estradiol [17].
• We have used the newly isolated clones, as well as the yolk protein cDNAs previously available [VTGII, apolipoprotein II (apoVLDLII), and apolipoprotein B], as probes to examine several aspects of the regulation of these genes by estradiol [17].
• We have precisely determined the positions of the first three exons for the major chicken vitellogenin gene (VTG II) by a combination of S1 nuclease protection, primer extension and DNA sequencing experiments [26].

Analytical, diagnostic and therapeutic context of LOC424533

• Gel filtration analysis of vitellogenin II digested with cathepsin D showed that YGP40 dissociated from lipovitellin-phosvitin complex after the proteolytic cleavage [13].
• Identification and sequence analysis of the 5' end of the major chicken vitellogenin gene [26].
• However, when serum was obtained from cockerels injected with estradiol 4 days before blood collection and included in the culture medium, the cultures secreted a protein identified immunologically as vitellogenin by affinity chromatography [22].
• The messenger RNA that specifies vitellogenin has been purified more than 800-fold from rooster liver polysomal RNA by a combination of methods, including immunoprecipitation of polysomes and chromatography of RNA on poly(U)-Sepharose [27].
• Here we have applied ligand and immunoblotting to visualize the Xenopus laevis oocyte receptor for vitellogenin as a protein with an apparent Mr of 115,000 in sodium dodecyl sulfate-polyacrylamide gels under nonreducing conditions [28].

References