High impact information on vitellogenin

• We have produced strains carrying a synthetic fusion of parts of two vitellogenin genes, vit-2 and vit-6, integrated into the Caenorhabditis elegans genome [1].
• However, in two strains the transgene integrated by homologous recombination into the endogenous vit-2 gene [1].
• In both cases the reciprocal exchange between the chromosome and the injected circular plasmid containing a promoter deletion led to switching of the plasmid-borne promoter and the endogenous promoter, with a reduction in vit-2 expression [1].
• Regulation of vitellogenin gene expression in transgenic Caenorhabditis elegans: short sequences required for activation of the vit-2 promoter [2].
• The major proteins were identified as vitellogenins. rme-2 mutants, which lack the vitellogenin receptor, fail to accumulate dehydroergosterol in oocytes and embryos and instead accumulate dehydroergosterol in the body cavity along with vitellogenin [3].

Biological context of vitellogenin

• The nucleotide sequence of a nematode vitellogenin gene [4].
• The C. elegans vitellogenin genes: short sequence repeats in the promoter regions and homology to the vertebrate genes [5].
• Regulated expression of a vitellogenin fusion gene in transgenic nematodes [6].
• The four introns of vit-6 are all in different places from the four introns of vit-5, but three of these eight positions are identical or close to intron locations in the vertebrate vitellogenin genes [7].
• As a first step we examined gene expression patterns and vitellogenin responses of this organism to vertebrate steroids, in liquid culture [8].

Anatomical context of vitellogenin

• All strains synthesize substantial amounts of a novel vitellogenin-like polypeptide of 155 kDa that accumulates in the intestine and pseudocoelom, but is not transported efficiently into oocytes [6].
• Although deletion of the CAAT box, the conserved nematode box, and several other sequences had little effect on vitellogenin promoter activity, deletion or mutation of a short sequence related to the NF1 transcription activator reduced estrogen-dependent transcription 10-20-fold in both cell lines [9].
• The VA element is not liver-specific, since VA deletions, mutations, and insertions elicited similar effects on vitellogenin promoter activity in the cell lines derived from hepatocytes and fibroblasts [9].
• Fat body synthesis of vitellogenin was significantly reduced as early as 8 h post-infection in comparison with sham-injected flies [10].
• In nematodes in which protein carbonyls increased with age, one of the carbonylated proteins was identified as vitellogenin, an egg-yolk protein [11].

Associations of vitellogenin with chemical compounds

• Many cysteine residues have been conserved, suggesting that vitellogenin structure has been maintained over a long evolutionary distance and is dependent upon disulfide bonds [7].
• Western blotting showed the expected number and size of vitellogenin translation products after estrogen exposure [8].
• Testosterone (10(-5) M) increased the synthesis of vitellogenin, but progesterone-treated cultures (10(-5) M) had less vitellogenin [8].
• Although divergence is high, conservation among insect, vertebrate, and nematode Vg sequences is widespread with a preponderance of glycine, proline, and cysteine residues among strictly conserved amino acids, establishing conclusively that Vgs from the three phyla are homologous [12].
• In fact, multiple predicted sterol regulatory elements or related regulatory sequences responding to sterols were found to be located at the 5'-flanking regions in vit-2 and lrp-1 genes, and their transcriptional activities fluctuated highly in response to changes in sterol concentration [13].

Other interactions of vitellogenin

• Caenorhabditis elegans vitellogenins are encoded by a family of six genes, one of which, vit-5, has been previously sequenced and shown to be surprisingly closely related to the vertebrate vitellogenin genes [7].
• The GATA motif (WGATAR) is found in the promoter regions of numerous Caenorhabditis elegans genes, including two intestine-specific genes, vit-2 and ges-1, in which it has been shown to be required for promoter function [14].

Analytical, diagnostic and therapeutic context of vitellogenin

• We describe the molecular cloning and characterization of a fragment of the vitellogenin gene from the spruce terminal weevil [15].
• The effects of resistance on vitellogenin gene expression were studied to confirm our earlier findings and to provide a sensitive bioassay for identifying resistance factors [15].
• Comparative sequence analysis also suggests the possibility that the first 70 bases of the vitellogenin mRNAs can be folded into stable secondary structures [16].
• In situ hybridization analysis revealed that putative vitellogenin mRNA was expressed strongly in the follicle cells in the ovary [17].
• The amount of protein in the 200 kDa band of vitellogenin, determined using densitometry, rapidly increased between 12 and 25 hours after eclosion [18].

References