Regulating apoptosis in mammalian cell cultures

Cell culture technology has become a widely accepted method used to derive therapeutic and diagnostic protein products. Mammalian cells adapted to grow in bioreactors now play an integral role in the development of these biologicals. A major limiting factor determining the output efficiency of mammalian cell cultures however, is apoptosis or programmed cell death. Methods to delay apoptosis and increase the longevity of cell cultures can lead to more economical processes. Researchers have shown that both genetic and chemical strategies to block apoptotic signals can increase cell culture productivity. Here, we discuss various strategies which have been implemented to improve cellular viabilities and productivities in batch cultures.     

Bioactivity of glycogen phosphorylase inhibitors that bind to the purine nucleoside site

The bioactivity in hepatocytes of glycogen phosphorylase inhibitors that bind to the active site, the allosteric activator site and the indole carboxamide site has been described. However, the pharmacological potential of the purine nucleoside inhibitor site has remained unexplored. We report the chemical synthesis and bioactivity in hepatocytes of four new olefin derivatives of flavopiridol (1-4) that bind to the purine site. Flavopiridol and 1-4 counteracted the activation of phosphorylase in hepatocytes caused by AICAR (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside), which is metabolised to an AMP analogue. Unlike an indole carboxamide inhibitor, the analogues 1 and 4 suppressed the basal rate of glycogenolysis in hepatocytes by allosteric inhibition rather than by inactivation of phosphorylase, and accordingly caused negligible stimulation of glycogen synthesis. However, they counteracted the stimulation of glycogenolysis by dibutyryl cAMP by both allosteric inhibition and inactivation of phosphorylase. Cumulatively, the results show key differences between purine site and indole carboxamide site inhibitors in terms of (i) relative roles of dephosphorylation of phosphorylase-a as compared with allosteric inhibition, (ii) counteraction of the efficacy of the inhibitors on glycogenolysis by dibutyryl-cAMP and (iii) stimulation of glycogen synthesis.     

Ecpagloxylon mathiesenii gen. nov. et sp. nov., a Jurassic wood from Greenland with several primitive angiosperm features

Fossil wood specimens from the late Early–early Middle Jurassic of Jameson Land, Eastern Greenland, have several unexpected features: tracheids of irregular size and shape, thinly pitted ray cell walls, heterogeneous rays, partially scalariform radial pitting, both areolate and simple pits, and pitted elements associated with rays. These characters diverge markedly from those typical of Jurassic wood, which usually conform to those of modern conifers. Although this combination of features is not encountered in any extant angiosperm, each has been documented in one or several extant homoxylous angiosperms, particularly Amborella, Trochodendron, and Tetracentron. As these wood specimens are not found in connection with any reproductive part, it is impossible to confidently assign them to the angiosperms. If a Jurassic angiosperm did exist, however, it might well have had a similar wood. This material is an early bench-mark in the evolution that led from homoxylous conifer-like wood to that of the angiosperms. Its particular biogeography (Arctic) could renew the discussion about the area of origin of the angiosperms.     

A variant in MCF2L is associated with osteoarthritis

Osteoarthritis (OA) is a prevalent, heritable degenerative joint disease with a substantial public health impact. We used a 1000-Genomes-Project-based imputation in a genome-wide association scan for osteoarthritis (3177 OA cases and 4894 controls) to detect a previously unidentified risk locus. We discovered a small disease-associated set of variants on chromosome 13. Through large-scale replication, we establish a robust association with SNPs in MCF2L (rs11842874, combined odds ratio [95% confidence interval] 1.17 [1.11–1.23], p = 2.1 × 10⁻⁸) across a total of 19,041 OA cases and 24,504 controls of European descent. This risk locus represents the third established signal for OA overall. MCF2L regulates a nerve growth factor (NGF), and treatment with a humanized monoclonal antibody against NGF is associated with reduction in pain and improvement in function for knee OA patients.     

Influence of vitamin D receptor genotype on bone mineral density in postmenopausal women: a twin study in Britain.

OBJECTIVES--To investigate the possible association between vitamin D receptor genotype and bone mineral density in a large group of postmenopausal twins. DESIGN--Cross sectional twin study. SETTING--Twin population based in Britain. SUBJECTS--95 dizygotic (non-identical) pairs of twins and 87 monozygotic (identical) pairs of twins aged 50-69 years, postmenopausal, and free of diseases affecting bone, recruited from a national register of twins and with a media campaign. MAIN OUTCOME MEASURES--Bone mineral density measured at the hip, lumbar spine, forearm, and for the whole body by dual energy x ray absorptiometry in relation to differences in the vitamin D receptor genotype. RESULTS--At all sites the values of bone density among dizygotic twins were more similar in those of the same vitamin D receptor genotype than in those of differing genotype, and the values in the former were closer to the correlations seen in monozygotic twins. Women with the genotype that made them at risk of osteoporotic fracture had an adjusted bone mineral density that was significantly lower by SD 0.5 to 0.6 at the hip, lumbar spine, and for the whole body. The results could not be explained by differences in age, weight, years since menopause, or use of hormone replacement therapy. CONCLUSIONS--The findings that in postmenopausal women in Britain bone density-particularly at the hip and spine-is genetically linked and specifically associated with the vitamin D receptor genotypes should lead to novel approaches to the prevention and treatment of osteoporosis.