Combating mutations in genetic disease and drug resistance: understanding molecular mechanisms to guide drug design

Introduction: Mutations introduce diversity into genomes, leading to selective changes and driving evolution. These changes have contributed to the emergence of many of the current major health concerns of the 21st century, from the development of genetic diseases and cancers to the rise and spread of drug resistance. The experimental systematic testing of all mutations in a system of interest is impractical and not cost-effective, which has created interest in the development of computational tools to understand the molecular consequences of mutations to aid and guide rational experimentation.

Areas covered: Here, the authors discuss the recent development of computational methods to understand the effects of coding mutations to protein function and interactions, particularly in the context of the 3D structure of the protein.

Expert opinion: While significant progress has been made in terms of innovative tools to understand and quantify the different range of effects in which a mutation or a set of mutations can give rise to a phenotype, a great gap still exists when integrating these predictions and drawing causality conclusions linking variants. This often requires a detailed understanding of the system being perturbed. However, as part of the drug development process it can be used preemptively in a similar fashion to pharmacokinetics predictions, to guide development of therapeutics to help guide the design and analysis of clinical trials, patient treatment and public health policy strategies.     

Luteinizing hormone beta mutation and hypogonadism in men and women

Selective luteinizing hormone deficiency due to mutations in the luteinizing hormone beta-subunit gene (LHB) is a rare cause of hypogonadism. We describe the clinical features of a consanguineous family in which three siblings, two men and one woman, had hypogonadism related to isolated luteinizing hormone deficiency. These subjects have a newly discovered homozygous mutation of a 5' splice site in LHB: IVS2+1G-->C. This mutation disrupts the splicing of messenger RNA (mRNA), generating a gross abnormality in the processing of the luteinizing hormone beta-subunit mRNA, which abrogates the secretion of luteinizing hormone. We also determined that the female phenotype of this LHB mutation is characterized by normal pubertal development, secondary amenorrhea, and infertility.     

Induction of apoptosis in rat lymphocytes by starvation

The aim of the present study was to investigate whether fasting for 24 and 48 h induces apoptosis of rat mesenteric lymph node lymphocytes similar to that observed previously in diabetic patients and alloxan-induced diabetic rats. Several features of lymphocyte death were evaluated by flow cytometry. Plasma levels of glucose, NEFAs (non-esterified fatty acids) and ketone bodies (acetoacetate and beta-hydroxybutyrate) were determined in rats fasted for 24 and 48 h. Lymphocytes obtained from fasted rats had an increase in DNA fragmentation and phosphatidylserine externalization after 48 h of culture, although there was no loss of membrane integrity in lymphocytes even after 48 h of culture. Cytochrome c release from the mitochondrial intermembrane space into the cytosol was increased significantly in lymphocytes from fasted rats cultured for 24 h, whereas the levels of bcl-2 and bax proteins were not affected. Activities of caspases 3, 6, 8 and 9 were increased significantly in lymphocytes from rats fasted for 24 h, whereas only an increase in caspase 3 and 9 activities were observed in rats fasted for 48 h. In conclusion, fasting for 24 and 48 h caused a significant increase in the proportion of lymphocytes undergoing apoptosis. The occurrence of apoptosis was observed by DNA fragmentation, phosphatidylserine externalization, cytochrome c release from the mitochondria and activation of the caspase cascade. These findings support the hypothesis that conditions that raise plasma fatty acids levels (e.g. diabetes and starvation) may impair immune function by causing lymphocyte death.     

Anti‐inflammatory effects of haptoglobin on LPS‐stimulated macrophages: Role of HMGB1 signaling and implications in chronic wound healing

Nonhealing wounds possess elevated numbers of pro‐inflammatory M1 macrophages, which fail to transition to anti‐inflammatory M2 phenotypes that promote healing. Hemoglobin (Hb) and haptoglobin (Hp) proteins, when complexed (Hb‐Hp), can elicit M2‐like macrophages through the heme oxygenase‐1 (HO‐1) pathway. Despite the fact that nonhealing wounds are chronically inflamed, previous studies have focused on non‐inflammatory systems, and do not thoroughly compare the effects of complexed vs individual proteins. We aimed to investigate the effect of Hb/Hp treatments on macrophage phenotype in an inflammatory, lipopolysaccharide (LPS)‐stimulated environment, similar to chronic wounds. Human M1 macrophages were cultured in vitro and stimulated with LPS. Concurrently, Hp, Hb, or Hb‐Hp complexes were delivered. The next day, 27 proteins related to inflammation were measured in the supernatants. Hp treatment decreased a majority of inflammatory factors, Hb increased many, and Hb‐Hp had intermediate trends, indicating that Hp attenuated overall inflammation to the greatest extent. From this data, Ingenuity Pathway Analysis software identified high motility group box 1 (HMGB1) as a key canonical pathway—strongly down‐regulated from Hp, strongly up‐regulated from Hb, and slightly activated from Hb‐Hp. HMGB1 measurements in macrophage supernatants confirmed this trend. In vivo results in diabetic mice with biopsy punch wounds demonstrated accelerated wound closure with Hp treatment, and delayed wound closure with Hb treatment. This work specifically studied Hb/Hp effects on macrophages in a highly inflammatory environment relevant to chronic wound healing. Results show that Hp—and not Hb‐Hp, which is known to be superior in noninflammatory conditions—reduces inflammation in LPS‐stimulated macrophages, and HMGB1 signaling is also implicated. Overall, Hp treatment on M1 macrophages in vitro reduced the inflammatory secretion profile, and also exhibited benefits in in silico and in vivo wound‐healing models.     

Natural history of intraventricular meningiomas: systematic review

Review the data published on the subject to create a more comprehensive natural history of intraventricular meningiomas (IVMs). A Medline search up to March 2018 using “intraventricular meningioma” returned 98 papers. As a first selection step, we adopted the following inclusion criteria: series and case reports about IVMs, as well as papers written in other languages, but abstracts written in English were evaluated. Six hundred eighty-one tumors were evaluated from 98 papers. The majority of the tumors were located in the lateral ventricles (602–88.4%), fourth ventricle (59–8.7%), and third ventricle (20–2.9%). These tumors accounted for a mortality rate of 4.0% (25 deaths) and a recurrence rate of 5.3% (26 recurrences). The majority of the tumors were grade I (89.8%) and consisted of the following subtypes: fibrous, 39.7% (n = 171); transitional, 22.0% (n = 95); meningothelial, 18.6% (n = 80); angiomatosus, 3.2% (n = 14); psammomatous, 2.6% (n = 11); and others, 13.9% (n = 60). Forty-five patients (7.4%) presented with grade II (GII) tumors, and 17 patients (2.8%) presented with grade III (GIII) tumors. These tumors follow the histopathological distribution of meningiomas in general, with the exception of the higher prevalence of the fibrous subtype, possibly due to its embryonic origin. Recurrence and mortality were lower than in other localizations likely due to a complete surgical resection rate than in the convexity and skull base, which suggests that GTR is the gold standard for the management of IVMs.