Cyclic di-GMP is Essential for the Survival of the Lyme Disease Spirochete in Ticks

Cyclic dimeric GMP (c-di-GMP) is a bacterial second messenger that modulates many biological processes. Although its role in bacterial pathogenesis during mammalian infection has been documented, the role of c-di-GMP in a pathogen's life cycle within a vector host is less understood. The enzootic cycle of the Lyme disease pathogen Borrelia burgdorferi involves both a mammalian host and an Ixodes tick vector. The B. burgdorferi genome encodes a single copy of the diguanylate cyclase gene (rrp1), which is responsible for c-di-GMP synthesis. To determine the role of c-di-GMP in the life cycle of B. burgdorferi, an Rrp1-deficient B. burgdorferi strain was generated. The rrp1 mutant remains infectious in the mammalian host but cannot survive in the tick vector. Microarray analyses revealed that expression of a four-gene operon involved in glycerol transport and metabolism, bb0240-bb0243, was significantly downregulated by abrogation of Rrp1. In vitro, the rrp1 mutant is impaired in growth in the media containing glycerol as the carbon source (BSK-glycerol). To determine the contribution of the glycerol metabolic pathway to the rrp1 mutant phenotype, a glp mutant, in which the entire bb0240-bb0243 operon is not expressed, was generated. Similar to the rrp1 mutant, the glp mutant has a growth defect in BSK-glycerol medium. In vivo, the glp mutant is also infectious in mice but has reduced survival in ticks. Constitutive expression of the bb0240-bb0243 operon in the rrp1 mutant fully rescues the growth defect in BSK-glycerol medium and partially restores survival of the rrp1 mutant in ticks. Thus, c-di-GMP appears to govern a catabolic switch in B. burgdorferi and plays a vital role in the tick part of the spirochetal enzootic cycle. This work provides the first evidence that c-di-GMP is essential for a pathogen's survival in its vector host

A first-in-human phase I, dose-escalation, multicentre study of HSP990 administered orally in adult patients with advanced solid malignancies

Heat-shock protein 990 (HSP990) is a potent and selective synthetic small-molecule HSP90 inhibitor. The primary objectives of this phase I first-in-human study were to determine dose-limiting toxicities (DLTs), maximum-tolerated dose (MTD) and recommended phase II dose (RP2D). Secondary objectives included characterisation of the safety profile, pharmacokinetics (PKs) and pharmacodynamics (PDs). Heat-shock protein 990 was administered orally once or two times weekly on a 28-day cycle schedule in patients with advanced solid tumours. Dose escalation was guided by a Bayesian logistic regression model with overdose control. A total of 64 patients were enrolled. Fifty-three patients received HSP990 once weekly at 2.5, 5, 10, 20, 30, 50 or 60 mg, whereas 11 patients received HSP990 two times weekly at 25 mg. Median duration of exposure was 8 weeks (range 1-116 weeks) and 12 patients remained on treatment for >16 weeks. Dose-limiting toxicities occurred in seven patients and included diarrhoea, QTc prolongation, ALT/AST elevations and central neurological toxicities. The most common drug-related adverse events were diarrhoea, fatigue and decreased appetite. Further dose escalation beyond 60 mg once weekly was not possible owing to neurological toxicity. Rapid absorption, no drug accumulation and large interpatient variability in PK exposures were observed. No objective responses were seen; 25 patients had a best overall response of stable disease. Heat-shock protein 990 is relatively well tolerated, with neurological toxicity being the most relevant DLT. The single agent MTD/RP2D of HSP990 was declared at 50 mg once weekly

The Gene Curation Coalition: a global effort to harmonize gene-disease evidence resources

Purpose: Several groups and resources provide information that pertains to the validity of gene–disease relationships used in genomic medicine and research; however, universal standards and terminologies to define the evidence base for the role of a gene in disease and a single harmonized resource were lacking. To tackle this issue, the Gene Curation Coalition (GenCC) was formed. Methods: The GenCC drafted harmonized definitions for differing levels of gene–disease validity on the basis of existing resources, and performed a modified Delphi survey with 3 rounds to narrow the list of terms. The GenCC also developed a unified database to display curated gene–disease validity assertions from its members. Results: On the basis of 241 survey responses from the genetics community, a consensus term set was chosen for grading gene–disease validity and database submissions. As of December 2021, the database contained 15,241 gene–disease assertions on 4569 unique genes from 12 submitters. When comparing submissions to the database from distinct sources, conflicts in assertions of gene–disease validity ranged from 5.3% to 13.4%. Conclusion: Terminology standardization, sharing of gene–disease validity classifications, and resolution of curation conflicts will facilitate collaborations across international curation efforts and in turn, improve consistency in genetic testing and variant interpretation