title: Vitellogenin receptor mutation leads to the oogenesis mutant phenotype "scanty vitellin" of the silkworm, Bombyx mori.
abstract: BACKGROUND
  The vitellogenin receptor (VgR) mediates the uptake of vitellogenin (Vg) from the hemolymph by developing oocytes.
  
  
  RESULTS
  VgR with the mutational EGF1 domain can bind ligand proteins but cannot be dissociated under acidic conditions. The mutant is lethal in embryos.
  
  
  CONCLUSIONS
  Bombyx mori VgR (BmVgR) has an important role in egg formation and embryonic development.
  
  
  CONCLUSIONS
  BmVgR is a potential target for pest control. In insects, the vitellogenin receptor (VgR) mediates the uptake of vitellogenin (Vg) from the hemolymph by developing oocytes. The oogenesis mutant scanty vitellin (vit) of Bombyx mori (Bm) lacks vitellin and 30-kDa proteins, but B. mori egg-specific protein and BmVg are normal. The vit eggs are white and smaller compared with the pale yellow eggs of the wild type and are embryonic lethal. This study found that a mutation in the B. mori VgR gene (BmVgR) is responsible for the vit phenotype. We cloned the cDNA sequences encoding WT and vit BmVgR. The functional domains of BmVgR are similar to those of other low-density lipoprotein receptors. When compared with the wild type, a 235-bp genomic sequence in vit BmVgR is substituted for a 7-bp sequence. This mutation has resulted in a 50-amino acid deletion in the third Class B region of the first epidermal growth factor (EGF1) domain. BmVgR is expressed specifically in oocytes, and the transcriptional level is changed dramatically and consistently with maturation of oocytes during the previtellogenic periods. Linkage analysis confirmed that BmVgR is mutated in the vit mutant. The coimmunoprecipitation assay confirmed that mutated BmVgR is able to bind BmVg but that BmVg cannot be dissociated under acidic conditions. The WT phenotype determined by RNA interference was similar to that of the vit phenotype for nutritional deficiency, such as BmVg and 30-kDa proteins. These results showed that BmVgR has an important role in transporting proteins for egg formation and embryonic development in B. mori.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Lin
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Yan-Xia
authors.initials: YX
authors.lastname: Wang
authors.forename: Juan
authors.initials: J
authors.lastname: Luo
authors.forename: Susumu
authors.initials: S
authors.lastname: Katsuma
authors.forename: Cong-Wen
authors.initials: CW
authors.lastname: Yang
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Banno
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kusakabe
authors.forename: Toru
authors.initials: T
authors.lastname: Shimada
authors.forename: Qing-You
authors.initials: QY
authors.lastname: Xia
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000196:embryology / Q000235:genetics*; D003001:Cloning, Molecular; D004527:Egg Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D047108:Embryonic Development; D005260:Female; D055785:Gene Knockdown Techniques; D008040:Genetic Linkage; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D009866:Oogenesis; D009928:Organ Specificity; D010053:Ovary / Q000196:embryology; D010063:Ovum / Q000378:metabolism / Q000502:physiology; D010641:Phenotype; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D034622:RNA Interference; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D014158:Transcription, Genetic; D047048:Vitellins / Q000378:metabolism; D014819:Vitellogenins / Q000378:metabolism
chemical_list: D004527:Egg Proteins; D019476:Insect Proteins; D021382:Protein Sorting Signals; D011956:Receptors, Cell Surface; D047048:Vitellins; D014819:Vitellogenins; C030474:vitellogenin receptor
keywords: Development; Lipid Transport; Lipids; Low-density Lipoprotein Receptor; Mutation; Oogenesis; Receptor Endocytosis; Silkworm; Vitellogenin Receptor