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Subunit cleavage of mosquito pro-vitellogenin by a subtilisin-like convertase.

ABSTRACT: The eukaryotic convertase family plays an important role in posttranslational proteolytic processing and activation of many pro- and polypeptides that have at their cleavage sites the paired basic motif, RX(K/R)R. Recent studies have revealed that the cleavage site of insect pro-vitellogenins (pro-Vg) also contains this motif. To identify and characterize the insect pro-Vg processing enzyme, Vg convertase (VC), its cDNA was cloned from a vitellogenic female fat body cDNA library of the mosquito, Aedes aegypti. The 3735-bp-long VC cDNA has an open reading frame encoding a 115-kDa protein. In vitro transcription/translation of VC cDNA revealed that this 115-kDa protein becomes 140 kDa after co- and posttranslational modifications. The VC deduced amino acid sequence has high similarity to and a domain structure characteristic of furin-like convertases. Northern blot analysis showed that a single 4.2-kb transcript was expressed in the fat body during the first 18 hr of the Vg synthetic period. Coexpression of VC cDNA with mosquito Vg cDNA resulted in correct cleavage of pro-Vg. Thus, this newly identified convertase is, indeed, a functional fat body-specific enzyme for pro-Vg cleavage.

SUBMITTER: Chen JS

PROVIDER: S-EPMC39211 | biostudies-other | 1996 Jun

REPOSITORIES: biostudies-other

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Subunit cleavage of mosquito pro-vitellogenin by a subtilisin-like convertase.

Chen J S JS Raikhel A S AS

Proceedings of the National Academy of Sciences of the United States of America 19960601 12

The eukaryotic convertase family plays an important role in posttranslational proteolytic processing and activation of many pro- and polypeptides that have at their cleavage sites the paired basic motif, RX(K/R)R. Recent studies have revealed that the cleavage site of insect pro-vitellogenins (pro-Vg) also contains this motif. To identify and characterize the insect pro-Vg processing enzyme, Vg convertase (VC), its cDNA was cloned from a vitellogenic female fat body cDNA library of the mosquito, ...[more]

PMID: 8650241

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Project description:Proprotein convertase subtilisin/kexins (PCSKs) constitute a family of nine related proteases: PCSK1-7, MBTPS1, and PCSK9. Apart from PCSK9, little is known about PCSKs in cardiovascular disease. Here, we aimed to investigate the expression landscape and druggability potential of the entire PCSK family for CVD. We applied an integrative approach, combining genetic, transcriptomic and proteomic data from three vascular biobanks comprising carotid atherosclerosis, thoracic and abdominal aneurysms, with patient clinical parameters and immunohistochemistry of vascular biopsies. Apart from PCSK4, all PCSK family members lie in genetic regions containing variants associated with human cardiovascular traits. Transcriptomic analyses revealed that FURIN, PCSK5, MBTPS1 were downregulated, while PCSK6/7 were upregulated in plaques vs. control arteries. In abdominal aneurysms, FURIN, PCSK5, PCSK7, MBTPS1 were downregulated, while PCSK6 was enriched in diseased media. In thoracic aneurysms, only FURIN was significantly upregulated. Network analyses of the upstream and downstream pathways related to PCSKs were performed on the omics data from vascular biopsies, revealing mechanistic relationships between this protein family and disease. Cell type correlation analyses and immunohistochemistry showed that PCSK transcripts and protein levels parallel each other, except for PCSK9 where transcript was not detected, while protein was abundant in vascular biopsies. Correlations to clinical parameters revealed a positive association between FURIN plaque levels and serum LDL, while PCSK6 was negatively associated with Hb. PCSK5/6/7 were all positively associated with adverse cardiovascular events. Our results show that PCSK6 is abundant in plaques and abdominal aneurysms, while FURIN upregulation is characteristic for thoracic aneurysms. PCSK9 protein, but not the transcript, was present in vascular lesions, suggesting its accumulation from circulation. Integrating our results lead to the development of a novel 'molecular' 5D framework. Here, we conducted the first integrative study of the proprotein convertase family in this context. Our results using this translational pipeline, revealed primarily PCSK6, followed by PCSK5, PCSK7 and FURIN, as proprotein convertases with the highest novel therapeutic potential.

Project description:Background and aimsCardiac natriuretic peptides (NPs) exert several metabolic effects, including some on lipid metabolism. Higher NPs levels are likely to be associated with a favorable lipid profile. In in vitro studies, NPs have been found to modulate low-density lipoprotein receptor (LDLR) trafficking by preventing proprotein convertase subtilisin/kexin type 9 (PCSK9) overexpression. The aim of our study is to investigate a possible association between plasma levels of PCSK9 and N-terminal pro B-type natriuretic peptide (NT-proBNP) in vivo.MethodsWe performed a cross-sectional study on 160 consecutive older male and female patients hospitalized for medical conditions. Patients taking lipid-lowering drugs and patients with an admission diagnosis of acute heart failure were excluded. Fasting blood samples were collected after clinical stabilization of the acute illness, the day before discharge.ResultsThe mean age was 87.8 ± 6.4 years with a female prevalence (62.5%). The median NT-proBNP was 2340 (814-5397) pg/mL. The mean plasma PCSK9 was 275.2 ± 113.2 ng/mL. We found an inverse correlation between plasma PCSK9 and NT-proBNP (r = -0.280; p = 0.001). This association was confirmed after taking into account NT-proBNP tertiles (plasma PCSK9 levels: 317.4 ± 123.6 ng/mL in the first tertile, 283.3 ± 101.8 ng/mL in the second tertile, 231.3 ± 99.0 ng/mL in the third tertile, p = 0.001) and even after an adjustment for confounding factors (beta = -0.361, p = 0.001 for ln(NT-proBNP); beta = -0.330, p = 0.001 for NT-proBNP tertiles). The strength of the correlation between plasma PCSK9 and NT-proBNP was likely greater in patients affected by type 2 diabetes mellitus (r = -0.483; p = 0.006) and in male patients (r = -0.431, p = 0.001).ConclusionThe inverse association found between PCSK9 and NT-proBNP plasma levels in our real-life clinical study supports the hypothesis that NPs may play a role in cholesterol metabolism, possibly through an inhibitory action on circulating PCSK9 concentrations, thus increasing the availability of LDLR.

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Subunit cleavage of mosquito pro-vitellogenin by a subtilisin-like convertase.

Publications

Subunit cleavage of mosquito pro-vitellogenin by a subtilisin-like convertase.

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