Differential effects of prenylation and s-acylation on type I and II ROPS membrane interaction and function

Prenylation primarily by geranylgeranylation is required for membrane attachment and function of type I Rho of Plants (ROPs) and Gγ proteins, while type II ROPs are attached to the plasma membrane by S-acylation. Yet, it is not known how prenylation affects ROP membrane interaction dynamics and what are the functional redundancy and specificity of type I and type II ROPs. Here, we have used the expression of ROPs in mammalian cells together with geranylgeranylation and CaaX prenylation-deficient mutants to answer these questions. Our results show that the mechanism of type II ROP S-acylation and membrane attachment is unique to plants and likely responsible for the viability of plants in the absence of CaaX prenylation activity. The prenylation of ROPs determines their steady-state distribution between the plasma membrane and the cytosol but has little effect on membrane interaction dynamics. In addition, the prenyl group type has only minor effects on ROP function. Phenotypic analysis of the CaaX prenylation-deficient pluripetala mutant epidermal cells revealed that type I ROPs affect cell structure primarily on the adaxial side, while type II ROPs are functional and induce a novel cell division phenotype in this genetic background. Taken together, our studies show how prenyl and S-acyl lipid modifications affect ROP subcellular distribution, membrane interaction dynamics, and function.     

Trans fatty acids induce vascular inflammation and reduce vascular nitric oxide production in endothelial cells

Intake of trans fatty acids (TFA), which are consumed by eating foods made from partially hydrogenated vegetable oils, is associated with a higher risk of cardiovascular disease. This relation can be explained by many factors including TFA's negative effect on endothelial function and reduced nitric oxide (NO) bioavailability. In this study we investigated the effects of three different TFA (2 common isomers of C18 found in partially hydrogenated vegetable oil and a C18 isomer found from ruminant-derived-dairy products and meat) on endothelial NF-κB activation and nitric oxide (NO) production. Human endothelial cells were treated with increasing concentrations of Elaidic (trans-C18:1 (9 trans)), Linoelaidic (trans-C18:2 (9 trans, 12 trans)), and Transvaccenic (trans-C18:1 (11 trans)) for 3 h. Both Elaidic and Linoelaidic acids were associated with increasing NF-κB activation as measured by IL-6 levels and phosphorylation of IκBα, and impairment of endothelial insulin signaling and NO production, whereas Transvaccenic acid was not associated with these responses. We also measured superoxide production, which has been hypothesized to be necessary in fatty acid-dependent activation of NF-κB. Both Elaidic acid and Linoelaidic acid are associated with increased superoxide production, whereas Transvaccenic acid (which did not induce inflammatory responses) did not increase superoxide production. We observed differential activation of endothelial superoxide production, NF-κB activation, and reduction in NO production by different C18 isomers suggesting that the location and number of trans double bonds effect endothelial NF-κB activation.     

Additive Genetic Variation in Schizophrenia Risk Is Shared by Populations of African and European Descent

To investigate the extent to which the proportion of schizophrenia’s additive genetic variation tagged by SNPs is shared by populations of European and African descent, we analyzed the largest combined African descent (AD [n = 2,142]) and European descent (ED [n = 4,990]) schizophrenia case-control genome-wide association study (GWAS) data set available, the Molecular Genetics of Schizophrenia (MGS) data set. We show how a method that uses genomic similarities at measured SNPs to estimate the additive genetic correlation (SNP correlation [SNP-r_g]) between traits can be extended to estimate SNP-r_g for the same trait between ethnicities. We estimated SNP-r_g for schizophrenia between the MGS ED and MGS AD samples to be 0.66 (SE = 0.23), which is significantly different from 0 (p_{(SNP-rg = 0)} = 0.0003), but not 1 (p_{(SNP-rg = 1)} = 0.26). We re-estimated SNP-r_g between an independent ED data set (n = 6,665) and the MGS AD sample to be 0.61 (SE = 0.21, p_{(SNP-rg = 0)} = 0.0003, p_{(SNP-rg = 1)} = 0.16). These results suggest that many schizophrenia risk alleles are shared across ethnic groups and predate African-European divergence.     

Dimensions of responsibility in medical genetics: exploring the complexity of the “duty to recontact”

Discussion of a “duty to recontact” emerged as technological advances left professionals considering getting back in touch with patients they had seen in the past. While there has been much discussion of the duty to recontact as a matter of theory and ethics, there has been rather little empirically based analysis of what this “duty” consists of. Drawing on interviews with 34 professionals working in, or closely with, genetics services, this paper explores what the “duty to recontact” means for healthcare professionals involved in genetics. Using a discourse analytic framework, the paper identifies three system generated discourses on recontact (governance, legal and responsibilizing discourses) and three lifeworld discourses (situating recontact as a formal duty; more loosely as an obligation; and as a personal sense of responsibility). In summary, the paper shows that the “duty” to recontact involves a complex interplay of system responsibilities with professional duties, responsibilities and obligations.     

Low Dose Focused Ultrasound Induces Enhanced Tumor Accumulation of Natural Killer Cells

Natural killer (NK) cells play a vital antitumor role as part of the innate immune system. Efficacy of adoptive transfer of NK cells depends on their ability to recognize and target tumors. We investigated whether low dose focused ultrasound with microbubbles (ldbFUS) could facilitate the targeting and accumulation of NK cells in a mouse xenograft of human colorectal adenocarcinoma (carcinoembryonic antigen (CEA)-expressing LS-174T implanted in NOD.Cg-Prkdc^scidIl2rg^tm1Wjl/SzJ (NSG) mice) in the presence of an anti-CEA immunocytokine (ICK), hT84.66/M5A-IL-2 (M5A-IL-2). Human NK cells were labeled with an FDA-approved ultra-small superparamagnetic iron oxide particle, ferumoxytol. Simultaneous with the intravenous injection of microbubbles, focused ultrasound was applied to the tumor. In vivo longitudinal magnetic resonance imaging (MRI) identified enhanced accumulation of NK cells in the ensonified tumor, which was validated by endpoint histology. Significant accumulation of NK cells was observed up to 24 hrs at the tumor site when ensonified with 0.50 MPa peak acoustic pressure ldbFUS, whereas tumors treated with at 0.25 MPa showed no detectable NK cell accumulation. These clinically translatable results show that ldbFUS of the tumor mass can potentiate tumor homing of NK cells that can be evaluated non-invasively using MRI.     

A Pilot Feasibility Study of Neurofeedback for Children with Autism

Neurofeedback (NFB) is an emerging treatment for children with autism spectrum disorder (ASD). This pilot study examined the feasibility of NFB for children with ASD. Ten children ages 7–12 with high functioning ASD and attention difficulties received a NFB attention training intervention. A standardized checklist captured feasibility, including focus during exercises and academic tasks, as well as off-task behaviors. Active behaviors and vocalizations were the most frequent off-task behaviors. Positive reinforcement and breaks including calm breathing exercises were the most common supports. Low motivation was associated with higher feasibility challenges, yet parental involvement and accommodations were helpful. This pilot study shows that it is feasible to conduct NFB sessions with children with high functioning autism and attention difficulties.     

Pharmacokinetics of nateglinide enantiomers and their metabolites in Goto‐Kakizaki rats,a model for type 2 diabetes mellitus

The pharmacokinetics of (?)‐N‐(trans‐4‐isopropylcyclohexanecarbonyl)‐D ‐phenylalanine (nateglinide) and its enantiomer (L‐enantiomer) was studied in Goto‐Kakizaki (GK) rats after intravenous administration of nateglinide or L‐enantiomer at a dose of 40 μmol/kg body weight. Nateglinide, its L‐enantiomer and their metabolites in serum, bile and urine were determined. The total clearance (CL_tot) and the volume of distribution (V_d) was slightly higher for nateglinide than those for L‐enantiomer in control rats, although the differences were not statistically significant. The cumulative excretions of L‐M1 (major metabolite of L‐enantiomer) and L‐M2 (major metabolite of L‐enantiomer) into bile were almost the same as that of M1 (major metabolite of nateglinide)and M2 (major metabolite of nateglinide). In GK rats, CL_tot and V_d were higher for nateglinide than those for L‐enantiomer. The cumulative excretion of L‐M1 and L‐M2 were not different from those of M1 and M2, respectively, into bile or urine. CL_tot and V_d for nateglinide or L‐enantiomer in GK rats were not different from those in control rats. The total excretion of M1, M2, L‐M1, and L‐M2 into bile or urine in GK rats was not substantially different from that of control rats. These results suggest that the L‐enantiomer of nateglinide shows higher CL_tot and V_d compared with nateglinide, especially in the diabetic state. Chirality, 2010. © 2009 Wiley‐Liss, Inc.     

The retromer complex

The retromer complex has been conserved throughout evolution as a retrieval agent for a variety of membrane receptors, in order to prevent their delivery to the degradative pathway. The consequence of this is that retromer biology has implications in areas as diverse as Wnt signalling and amyloid plaque accumulation; clearly it is imperative that we improve our understanding of how retromer fulfils its role in these biological processes.