The signal peptide region of vacuolating cytotoxin-A gene of Helicobacter pylori in patients with gastrointestinal disorders

IntroductionHereditary haemochromatosis (HH) caused by a homozygous p.C282Y mutation in haemochromatosis (HFE) gene has been well documented. However, less is known about the causative non-HFE mutation. We aimed to assess mutation patterns of haemochromatosis-related genes in Chinese patients with primary iron overload.MethodsPatients were preanalysed for mutations in the classic HH-related genes: HFE, HJV, HAMP, TFR2 and SLC40A1. Whole exome sequencing was conducted for cases with variants in HJV signal peptide region. Representative variants were analysed for biological function.ResultsNone of the cases analysed harboured the HFE p.C282Y; however, 21 of 22 primary iron-overload cases harboured at least one non-synonymous variant in the non-HFE genes. Specifically, p.E3D or p.Q6H variants in the HJV signal peptide region were identified in nine cases (40.9%). In two of three probands with the HJV p.E3D, exome sequencing identified accompanying variants in BMP/SMAD pathway genes, including TMPRSS6 p.T331M and BMP4 p.R269Q, and interestingly, SUGP2 p.R639Q was identified in all the three cases. Pedigree analysis showed a similar pattern of combination of heterozygous mutations in cases with HJV p.E3D or p.Q6H, with SUGP2 p.R639Q or HJV p.C321X being common mutation. In vitro siRNA interference of SUGP2 showed a novel role of downregulating the BMP/SMAD pathway. Site-directed mutagenesis of HJV p.Q6H/p.C321X in cell lines resulted in loss of membrane localisation of mutant HJV, and downregulation of p-SMAD1/5 and HAMP.ConclusionCompound heterozygous mutations of HJV or combined heterozygous mutations of BMP/SMAD pathway genes, marked by HJV variants in the signal peptide region, may represent a novel aetiological factor for HH.

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Expression of a Tranosema rostrale polydnavirus gene in the spruce budworm, Choristoneura fumiferana

Microbiology ◽

10.1099/0022-1317-81-7-1871 ◽

2000 ◽

Vol 81 (7) ◽

pp. 1871-1880 ◽

Cited By ~ 37

Author(s):

Catherine Béliveau ◽

Marlène Laforge ◽

Michel Cusson ◽

Guy Bellemare

Keyword(s):

Signal Peptide ◽

Fat Body ◽

Choristoneura Fumiferana ◽

Northern Analysis ◽

Juvenile Hormone Esterase ◽

Signal Peptide Region ◽

Putative Signal Peptide ◽

Cysteine Rich Protein ◽

Cellular Immune ◽

Peptide Region

The endoparasitic wasp Tranosema rostrale (Ichneumonidae) transmits a polydnavirus (PDV) to its host, Choristoneura fumiferana, during oviposition. Unlike most other PDVs examined, the virus of T. rostrale (TrPDV) does not appear to play an important role in suppressing the host cellular immune response. However, it inhibits host metamorphosis. In the present study, TrPDV gene expression was examined in parasitized and virus-injected last-instar caterpillars. Northern analysis with viral DNA as a probe revealed only one detectable mRNA, of about 650 bp. The corresponding cDNA, termed TrV1, was cloned and sequenced and found to encode a protein of 103 amino acids which, following cleavage of the putative signal peptide, has a predicted molecular mass of 9·3 kDa. This protein displays limited similarity to the VHv1.4 cysteine-rich protein from the PDV of Campoletis sonorensis, mostly within the signal peptide region. By using a TrV1-specific probe, the TrV1 gene was localized to segment G of the TrPDV genome. The cuticle and fat body were identified as the principal sites of TrV1 transcription, with little transcription observed in haemocytes and midgut. Western analysis of proteins extracted from selected tissues of parasitized insects suggested that the TrV1 protein is secreted in the haemolymph. As observed for other PDVs, injection of TrPDV did not suppress transcription of the gene that encodes juvenile hormone esterase, the activity of which is inhibited by the virus. We speculate that the TrV1 protein may play a role in the inhibition of C. fumiferana metamorphosis.

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