Kinase-dead mutation: A novel strategy for improving soybean resistance to soybean cyst nematode Heterodera glycines

Protein kinases phosphorylate proteins for functional changes and are involved in nearly all cellular processes, thereby regulating almost all aspects of plant growth and development, and responses to biotic and abiotic stresses. We generated two independent co-expression networks of soybean genes using control and stress response gene expression data and identified 392 differentially highly interconnected kinase hub genes among the two networks. Of these 392 kinases, 90 genes were identified as “syncytium highly connected hubs”, potentially essential for activating kinase signalling pathways in the nematode feeding site. Overexpression of wild-type coding sequences of five syncytium highly connected kinase hub genes using transgenic soybean hairy roots enhanced plant susceptibility to soybean cyst nematode (SCN; Heterodera glycines) Hg Type 0 (race 3). In contrast, overexpression of kinase-dead variants of these five syncytium kinase hub genes significantly enhanced soybean resistance to SCN. Additionally, three of the five tested kinase hub genes enhanced soybean resistance to SCN Hg Type 1.2.5.7 (race 2), highlighting the potential of the kinase-dead approach to generate effective and durable resistance against a wide range of SCN Hg types. Subcellular localization analysis revealed that kinase-dead mutations do not alter protein cellular localization, confirming the structure–function of the kinase-inactive variants in producing loss-of-function phenotypes causing significant decrease in nematode susceptibility. Because many protein kinases are highly conserved and are involved in plant responses to various biotic and abiotic stresses, our approach of identifying kinase hub genes and their inactivation using kinase-dead mutation could be translated for biotic and abiotic stress tolerance.     

Chronic administration of pioglitazone attenuates intracerebroventricular streptozotocin induced-memory impairment in rats

Memory impairment induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) in rats is associated with impaired brain glucose and energy metabolism, oxidative stress and impaired cholinergic neurotransmission. Treatment with antioxidants and cholinergic agonists has been reported to produce beneficial effect in this model. However, no reports are available on drugs that improve glucose utilization and metabolism. In the present study, we evaluated the effects of pioglitazone on cognitive performance, oxidative stress and glucose utilization in ICV STZ injected rats (3 mg/kg, on day 1 and 3). Pioglitazone (10 and 30 mg/kg) was administered per oral (p.o.) for 14 days, starting 5 days prior to STZ injection. Cognitive performance was assessed using step-through passive avoidance and Morris water maze task. Malondialdehyde (MDA) and glutathione levels in brain were estimated as parameters of oxidative stress. Glucose utilization by brain was assessed as the amount of glucose consumed from the media by the brain. ICV STZ injected rats showed a severe deficit in learning and memory associated with increased MDA levels (+67.5%), decreased glutathione levels (-29.2%) and impaired cerebral glucose utilization (-44.4%). In contrast pioglitazone treatment improved cognitive performance, lowered oxidative stress and improved cerebral glucose utilization in ICV STZ rats. The present study demonstrates the beneficial effects of pioglitazone in the ICV STZ induced cognitive deficits, which can be exploited for the dementia associated with diabetes and age-related neurodegenerative disorder, where oxidative stress and impaired glucose and energy metabolism are involved.     

New PPARgamma ligands based on barbituric acid: virtual screening, synthesis and receptor binding studies

A new series of PPARgamma ligands based on barbituric acid (BA) has been designed employing virtual screening and molecular docking approach. To validate the computational approach, designed molecules were synthesized and evaluated in in vitro radioligand binding studies. Out of the total 14 molecules, 6 were found to bind to the murine PPARgamma with IC(50) ranging from 0.1 to 2.5 microM as compared to reference standard, pioglitazone (IC(50)=0.7 microM).     

New PPARgamma ligands based on 2-hydroxy-1,4-naphthoquinone: computer-aided design, synthesis, and receptor-binding studies

FlexX-based molecular docking study was employed to identify 2-hydroxy-1,4-naphthoquinone as a new 'acidic head group' for the design of a novel series of PPARgamma ligands. To provide the proof of concept, designed molecules were synthesized and evaluated in a standard radioligand-binding assay. Out of eight molecules, four were found to bind to the murine PPARgamma with IC(50) ranging from 0.2 to 56.2 microM as compared to standard pioglitazone, with IC(50) of 0.7 microM.