Dataset Information

LBD1 of Vitellogenin Receptor Specifically Binds to the Female-Specific Storage Protein SP1 via LBR1 and LBR3.

ABSTRACT: Storage proteins are the major protein synthesized in the fat body, released into hemolymph and re-sequestered into the fat body before pupation in most insect species. Storage proteins are important amino acid and nutrition resources during the non-feeding pupal period and play essential roles for the metamorphosis and oogenesis of insects. The sequestration of storage protein is a selective, specific receptor-mediated process. However, to date, the potential receptor mediating the sequestration of storage protein has not been determined in Bombyx mori. In this study, we expressed and purified the first ligand binding domain of Bombyx mori vitellogenin receptor (BmVgR), LBD1, and found LBD1 could bind with an unknown protein from the hemolymph of the ultimate silkworm larval instar via pull-down assay. This unknown protein was subsequently identified to be the female-specific storage protein SP1 by mass spectrometry. Furthermore, far western blotting assay, immunoprecipitation and isothermal titration calorimetry analysis demonstrated LBD1 specifically bound with the female-specific SP1, rather than another unisex storage protein SP2. The specific binding of LBD1 with SP1 was dependent on the presence of Ca2+ as it was essential for the proper conformation of LBD1. Deletion mutagenesis and ITC analysis revealed the first and third ligand binding repeats LBR1 and LBR3 were indispensable for the binding of LBD1 with SP1, and LBR2 and LBR4 also had a certain contribution to the specific binding. Our results implied BmVgR may mediate the sequestration of SP1 from hemolymph into the fat body during the larval-pupal transformation of Bombyx mori.

SUBMITTER: Liu L

PROVIDER: S-EPMC5026343 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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LBD1 of Vitellogenin Receptor Specifically Binds to the Female-Specific Storage Protein SP1 via LBR1 and LBR3.

Liu Lina L Wang Yejing Y Li Yu Y Lin Ying Y Hou Yong Y Zhang Yan Y Wei Shuguang S Zhao Peng P Zhao Ping P He Huawei H

PloS one 20160916 9

Storage proteins are the major protein synthesized in the fat body, released into hemolymph and re-sequestered into the fat body before pupation in most insect species. Storage proteins are important amino acid and nutrition resources during the non-feeding pupal period and play essential roles for the metamorphosis and oogenesis of insects. The sequestration of storage protein is a selective, specific receptor-mediated process. However, to date, the potential receptor mediating the sequestratio ...[more]

PMID: 27637099

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Project description:ObjectiveThe dominant-negative P467L mutation in peroxisome proliferator activated receptor-? (PPAR?) was identified in insulin-resistant patients with hyperglycemia and lipodystrophy. In contrast, mice carrying the corresponding Pparg-P465L mutation have normal insulin sensitivity, with mild hyperinsulinemia. We hypothesized that murine Pparg-P465L mutation leads to covert insulin resistance, which is masked by hyperinsulinemia and increased pancreatic islet mass, to retain normal plasma glucose.Research design and methodsWe introduced in Pparg(P465L/+) mice an Ins2-Akita mutation that causes improper protein folding and islet apoptosis to lower plasma insulin.ResultsUnlike Ins2(Akita/+) littermates, male Pparg(P465L/+)Ins2(Akita/+) mice have drastically reduced life span with enhanced type 1 diabetes. Hyperglycemia in Ins2(Akita/+) females is mild. However, Pparg(P465L/+)Ins2(Akita/+) females have aggravated hyperglycemia, smaller islets, and reduced plasma insulin. In an insulin tolerance test, they showed smaller reduction in plasma glucose, indicating impaired insulin sensitivity. Although gluconeogenesis is enhanced in Pparg(P465L/+)Ins2(Akita/+) mice compared with Ins2(Akita/+), exogenous insulin equally suppressed gluconeogenesis in hepatocytes, suggesting that Pparg(P465L/+)Ins2(Akita/+) livers are insulin sensitive. Expression of genes regulating insulin sensitivity and glycogen and triglyceride contents suggest that skeletal muscles are equally insulin sensitive. In contrast, adipose tissue and isolated adipocytes from Pparg(P465L/+)Ins2(Akita/+) mice have impaired glucose uptake in response to exogenous insulin. Pparg(P465L/+)Ins2(Akita/+) mice have smaller fat depots composed of larger adipocytes, suggesting impaired lipid storage with subsequent hepatomegaly and hypertriglyceridemia.ConclusionsPPARg-P465L mutation worsens hyperglycemia in Ins2(Akita/+) mice primarily because of adipose-specific insulin resistance and altered storage function. This underscores the important interplay between insulin and PPAR? in adipose tissues in diabetes.

Dataset Information

LBD1 of Vitellogenin Receptor Specifically Binds to the Female-Specific Storage Protein SP1 via LBR1 and LBR3.

Publications

LBD1 of Vitellogenin Receptor Specifically Binds to the Female-Specific Storage Protein SP1 via LBR1 and LBR3.

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