Juvenile hemochromatosis is an early-onset autosomal recessive disorder of iron overload resulting in cardiomyopathy, diabetes and hypogonadism that presents in the teens and early 20s (refs. 1,2). ...Juvenile hemochromatosis has previously been linked to the centromeric region of chromosome 1q (refs. 3-6), a region that is incomplete in the human genome assembly. Here we report the positional cloning of the locus associated with juvenile hemochromatosis and the identification of a new gene crucial to iron metabolism. We finely mapped the recombinant interval in families of Greek descent and identified multiple deleterious mutations in a transcription unit of previously unknown function (LOC148738), now called HFE2, whose protein product we call hemojuvelin. Analysis of Greek, Canadian and French families indicated that one mutation, the amino acid substitution G320V, was observed in all three populations and accounted for two-thirds of the mutations found. HFE2 transcript expression was restricted to liver, heart and skeletal muscle, similar to that of hepcidin, a key protein implicated in iron metabolism. Urinary hepcidin levels were depressed in individuals with juvenile hemochromatosis, suggesting that hemojuvelin is probably not the hepcidin receptor. Rather, HFE2 seems to modulate hepcidin expression.
Congenital indifference to pain (CIP) is a rare condition in which patients have severely impaired pain perception, but are otherwise essentially normal. We identified and collected DNA from ...individuals from nine families of seven different nationalities in which the affected individuals meet the diagnostic criteria for CIP. Using homozygosity mapping and haplotype sharing methods, we narrowed the CIP locus to chromosome 2q24–q31, a region known to contain a cluster of voltage‐gated sodium channel genes. From these prioritized candidate sodium channels, we identified 10 mutations in the SCN9A gene encoding the sodium channel protein Nav1.7. The mutations completely co‐segregated with the disease phenotype, and nine of these SCN9A mutations resulted in truncation and loss‐of‐function of the Nav1.7 channel. These genetic data further support the evidence that Nav1.7 plays an essential role in mediating pain in humans, and that SCN9A mutations identified in multiple different populations underlie CIP.
Rhizosphere bacteria from Lodgepole pine (Pinus contorta) seedlings were characterized from forest soils which differed in disturbance and geographic source. Soil disturbance treatments included ...whole-tree harvesting with and without heavy soil compaction and whole-tree harvesting with complete surface organic matter removal and heavy soil compaction from British Columbia (BC) Ministry of Forests Long-Term Soil Productivity installations in three biogeoclimatic subzones in central BC, Canada. Bacterial community members were characterized by DNA sequence analysis of 16S rRNA gene fragments following direct DNA isolation from soil, polymerase chain reaction amplification and cloning. Phylogenetic analyses revealed that 85% of 709 16S rDNA clones were classified as alpha-, beta-, gamma-, and delta-Proteobacteria, Actinobacteria, Cytophaga-Flexibacter-Bacteroides group, Acidobacterium, Verrucomicrobia, and candidate divisions OP10 and TM6. Members of the Proteobacteria and Acidobacterium represented 55% and 19% of the clone library, respectively, whereas the remaining bacterial divisions each comprised less than 4% of the clone library. One hundred and six 16S rDNA clones could not be classified into known bacterial divisions. No significant differences were detected for soil disturbance treatment or site effects on the proportions of 16S rDNA clones affiliated with Proteobacteria and Acidobacterium. Phylogenetic analyses revealed that it was common for 16S rRNA gene fragments from different soil disturbance treatments and geographic locations to be closely related.
Bacteria from forest soils were characterized by DNA sequence analysis of cloned 16S rRNA gene fragments (16S clones). Surface organic matter and mineral soil samples from a British Columbia Ministry ...of Forests Long-Term Soil Productivity (LTSP) installation were collected during winter and summer from two disturbance treatments: whole-tree harvesting with no soil compaction (plot N) and whole-tree harvesting plus complete surface organic matter removal with heavy soil compaction (plot S). Phylogenetic analyses revealed that 87% of 580 16S clones were classified as Proteobacteria, Actinobacteria, Acidobacterium, Verrucomicrobia, Bacillus/Clostridium group, Cytophaga-Flexibacter-Bacteroides group, green nonsulfur bacteria, Planctomyces, and candidate divisions TM6 and OP10. Seventy-five 16S clones could not be classified into known bacterial divisions, and five 16S clones were related to chloroplast DNA. Members of Proteobacteria represented 46% of the clone library. A higher proportion of 16S clones affiliated with γ-Proteobacteria were from plot N compared with plot S. 16S rRNA gene fragments amplified with Pseudomonas-specific primers and cloned (Ps clones) were examined from mineral-soil samples from plots N and S from three LTSP installations. A significantly greater proportion of sequenced Ps clones from plot N contained Pseudomonas 16S rRNA gene fragments compared with Ps clones from plot S.Key words: bacterial diversity, 16S rRNA gene, forest soil.
Brunham LR, Tietjen I, Bochem AE, Singaraja RR, Franchini PL, Radomski C, Mattice M, Legendre A, Hovingh GK, Kastelein JJP, Hayden MR. Novel mutations in scavenger receptor BI associated with high ...HDL cholesterol in humans.
The scavenger receptor class B, member 1 (SR‐BI), is a key cellular receptor for high‐density lipoprotein (HDL) in mice, but its relevance to human physiology has not been well established. Recently a family was reported with a mutation in the gene encoding SR‐BI and high HDL cholesterol (HDL‐C). Here we report two additional individuals with extremely high HDL‐C (greater than the 90th percentile for age and gender) with rare mutations in the gene encoding SR‐BI. These mutations segregate with high HDL‐C in family members of each proband and are associated with a 37% increase in plasma HDL‐C in heterozygous individuals carrying them. Both mutations occur at highly conserved positions in the large extracellular loop region of SR‐BI and are predicted to impair the function of the SR‐BI protein. Our findings, combined with the prior report of a single mutation in the gene encoding SR‐BI, further validate that mutations in SR‐BI are a rare but recurring cause of elevated HDL‐C in humans.
Hereditary sensory and autonomic neuropathy (HSAN) type II is an autosomal recessive disorder characterized by impairment of pain, temperature, and touch sensation owing to reduction or absence of ...peripheral sensory neurons. We identified two large pedigrees segregating the disorder in an isolated population living in Newfoundland and performed a 5-cM genome scan. Linkage analysis identified a locus mapping to 12p13.33 with a maximum LOD score of 8.4. Haplotype sharing defined a candidate interval of 1.06 Mb containing all or part of seven annotated genes, sequencing of which failed to detect causative mutations. Comparative genomics revealed a conserved ORF corresponding to a novel gene in which we found three different truncating mutations among five families including patients from rural Quebec and Nova Scotia. This gene, termed “HSN2,” consists of a single exon located within intron 8 of the
PRKWNK1 gene and is transcribed from the same strand. The HSN2 protein may play a role in the development and/or maintenance of peripheral sensory neurons or their supporting Schwann cells.
The AmpC beta-lactamase gene and a small portion of the regulatory ampR sequence of Enterobacter aerogenes 97B were cloned and sequenced. The beta-lactamase had an isoelectric point of 8 and ...conferred cephalosporin and cephamycin resistance on the host. The sequence of the cloned gene is most closely related to those of the ampC genes of E. cloacae and C. freundii.
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Stearoyl-CoA desaturase-1 (SCD1) plays an important role in lipid metabolism. Inhibition of SCD1 activity represents a potential novel approach for the treatment of metabolic diseases ...such as obesity, type 2 diabetes and dyslipidemia, as well as skin diseases, acne and cancer. Herein, we report the synthesis and structure–activity relationships (SAR) of a series of novel triazolone derivatives, culminating in the identification of pyrazolyltriazolone 17a, a potent SCD1 inhibitor, which reduced plasma C16:1/C16:0 triglycerides desaturation index (DI) in an acute Lewis rat model in a dose dependent manner, with an ED50 of 4.6mg/kg. In preliminary safety studies, compound 17a did not demonstrate adverse effects related to SCD1 inhibition after repeat dosing at 100mg/kg. Together, these data suggest that sufficient safety margins can be achieved with certain SCD1 inhibitors, thus allowing exploration of clinical utility in metabolic disease settings.
Juvenile hemochromatosis (JH) is an autosomal recessive condition that leads to significant morbidity due to early onset systemic iron overload. The majority of families with JH link to chromosome 1q ...and were recently found to have mutations in the HFE2 gene encoding hemojuvelin; however, several JH families have been reported to have mutations in the HAMP gene encoding hepcidin. Here, we report a multiply consanguineous family with a father and daughter showing iron overload consistent with JH. Sequence analysis of HAMP revealed homozygosity for amino acid substitution C78T due to a c.233G > A mutation. This mutation disrupts one of eight highly conserved cysteines that are believed to be critical for the function of the active enzyme. This finding adds support to the importance of the role of these conserved cysteines in the activity of hepcidin.
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