The role of CDC48 in the retro-translocation of non-ubiquitinated toxin substrates in plant cells

When the catalytic A subunits of the castor bean toxins ricin and Ricinus communis agglutinin (denoted as RTA and RCA A, respectively) are delivered into the endoplasmic reticulum (ER) of tobacco protoplasts, they become substrates for ER-associated protein degradation (ERAD). As such, these orphan polypeptides are retro-translocated to the cytosol, where a significant proportion of each protein is degraded by proteasomes. Here we begin to characterise the ERAD pathway in plant cells, showing that retro-translocation of these lysine-deficient glycoproteins requires the ATPase activity of cytosolic CDC48. Lysine polyubiquitination is not obligatory for this step. We also show that while RCA A is found in a mannose-untrimmed form prior to its retro-translocation, a significant proportion of newly synthesised RTA cycles via the Golgi and becomes modified by downstream glycosylation enzymes. Despite these differences, both proteins are similarly retro-translocated

Arabidopsis R-SNARE Proteins VAMP721 and VAMP722 Are Required for Cell Plate Formation

Background: Cell plate formation during plant cytokinesis is facilitated by SNARE complex-mediated vesicle fusion at the cell-division plane. However, our knowledge regarding R-SNARE components of membrane fusion machinery for cell plate formation remains quite limited. Methodology/Principal Findings: We report the in vivo function of Arabidopsis VAMP721 and VAMP722, two closely sequence-related R-SNAREs, in cell plate formation. Double homozygous vamp721vamp722 mutant seedlings showed lethal dwarf phenotypes and were characterized by rudimentary roots, cotyledons and hypocotyls. Furthermore, cell wall stubs and incomplete cytokinesis were frequently observed in vamp721vamp722 seedlings. Confocal images revealed that green fluorescent protein-tagged VAMP721 and VAMP722 were preferentially localized to the expanding cell plates in dividing cells. Drug treatments and co-localization analyses demonstrated that punctuate organelles labeled with VAMP721 and VAMP722 represented early endosomes overlapped with VHA-a1-labeled TGN, which were distinct from Golgi stacks and prevacuolar compartments. In addition, protein traffic to the plasma membrane, but not to the vacuole, was severely disrupted in vamp721vamp722 seedlings by subcellular localization of marker proteins. Conclusion/Significance: These observations suggest that VAMP721 and VAMP722 are involved in secretory trafficking to the plasma membrane via TGN/early endosomal compartment, which contributes substantially to cell plate formatio

Response of cell wall composition and RNA-seq transcriptome to methyl-jasmonate in Brachypodium distachyon callus

Main conclusion: Methyl-jasmonate induces large increases in p-coumarate linked to arabinoxylan in Brachypodium and in abundance of GT61 and BAHD family transcripts consistent with a role in synthesis of this linkage. Jasmonic acid (JA) signalling is required for many stress responses in plants, inducing large changes in the transcriptome, including up-regulation of transcripts associated with lignification. However, less is known about the response to JA of grass cell walls and the monocot-specific features of arabinoxylan (AX) synthesis and acylation by ferulic acid (FA) and para-coumaric acid (pCA). Here, we show that methyl-jasmonate (MeJA) induces moderate increases in FA monomer, > 50% increases in FA dimers, and five–sixfold increases in pCA ester-linked to cell walls in Brachypodium callus. Direct measurement of arabinose acylated by pCA (Araf-pCA) indicated that most or all the increase in cell-wall pCA was due to pCA ester-linked to AX. Analysis of the RNA-seq transcriptome of the callus response showed that these cell-wall changes were accompanied by up-regulation of members of the GT61 and BAHD gene families implicated in AX decoration and acylation; two BAHD paralogues were among the most up-regulated cell-wall genes (seven and fivefold) after 24 h exposure to MeJA. Similar responses to JA of orthologous BAHD and GT61 transcripts are present in the RiceXPro public expression data set for rice seedlings, showing that they are not specific to Brachypodium or to callus. The large response of AX-pCA to MeJA may, therefore, indicate an important role for this linkage in response of primary cell walls of grasses to JA signalling

Progressive multifocal leukoencephalopathy genetic risk variants for pharmacovigilance of immunosuppressant therapies

BackgroundProgressive multifocal leukoencephalopathy (PML) is a rare and often lethal brain disorder caused by the common, typically benign polyomavirus 2, also known as JC virus (JCV). In a small percentage of immunosuppressed individuals, JCV is reactivated and infects the brain, causing devastating neurological defects. A wide range of immunosuppressed groups can develop PML, such as patients with: HIV/AIDS, hematological malignancies (e.g., leukemias, lymphomas, and multiple myeloma), autoimmune disorders (e.g., psoriasis, rheumatoid arthritis, and systemic lupus erythematosus), and organ transplants. In some patients, iatrogenic (i.e., drug-induced) PML occurs as a serious adverse event from exposure to immunosuppressant therapies used to treat their disease (e.g., hematological malignancies and multiple sclerosis). While JCV infection and immunosuppression are necessary, they are not sufficient to cause PML.MethodsWe hypothesized that patients may also have a genetic susceptibility from the presence of rare deleterious genetic variants in immune-relevant genes (e.g., those that cause inborn errors of immunity). In our prior genetic study of 184 PML cases, we discovered 19 candidate PML risk variants. In the current study of another 152 cases, we validated 4 of 19 variants in both population controls (gnomAD 3.1) and matched controls (JCV+ multiple sclerosis patients on a PML-linked drug ≥ 2 years).ResultsThe four variants, found in immune system genes with strong biological links, are: C8B, 1-57409459-C-A, rs139498867; LY9 (alias SLAMF3), 1-160769595-AG-A, rs763811636; FCN2, 9-137779251-G-A, rs76267164; STXBP2, 19-7712287-G-C, rs35490401. Carriers of any one of these variants are shown to be at high risk of PML when drug-exposed PML cases are compared to drug-exposed matched controls: P value = 3.50E-06, OR = 8.7 [3.7–20.6]. Measures of clinical validity and utility compare favorably to other genetic risk tests, such as BRCA1 and BRCA2 screening for breast cancer risk and HLA-B*15:02 pharmacogenetic screening for pharmacovigilance of carbamazepine to prevent Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.ConclusionFor the first time, a PML genetic risk test can be implemented for screening patients taking or considering treatment with a PML-linked drug in order to decrease the incidence of PML and enable safer use of highly effective therapies used to treat their underlying disease

Evolutionary social psychology: Prospects and pitfalls

The principles of evolutionary psychology and the traditional assumptions of social psychology are highly compatible. Both disciplines trace observed behavioral variability to situational variability. Both assume that psychological mechanisms sensitive to social information are central to causal accounts of social behavior. Questions about the origins and functions of these psychological mechanisms are indispensable for understanding social behavior. Evolutionary psychology provides conceptual tools for addressing these questions. Several pitfalls must be avoided by practitioners of evolutionary social psychology. Specifically, we must jettison notions of genetic determinism and behavioral unmodifiability, eliminate false dichotomies between “genetic” and “learned,” and place cross-cultural variability in a sensible theoretical context. Attending to the reliable phenomena discovered by traditional social psychology and the conceptual frameworks provided by modern evolutionary psychology will produce the most informed evolutionary social psychology.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45364/1/11031_2004_Article_BF00996185.pd

The Influence of Superficial Pre-cooling on a Static Stretching Regimen: A Randomized Trial

Background: The influence of superficial precooling on range of motion (ROM) as part of a stretching program has not been extensively studied. It is not clear if the analgesic effect can benefit a stretching program. Hypotheses: Superficial precooling will result in greater gains in ROM as part of a stretching program, compared with stretching without a precooling intervention. Superficial precooling will also result in greater retention in ROM gains following cessation of stretching, compared with stretching without a precooling intervention. Study Design: Prospective randomized single-blind test-retest design. Methods: Twenty-nine participants were randomly assigned to 1 of 2 static stretching protocols: a standard protocol (n, 14; age, 24.6 ± 5.4 years) or a precool protocol (n, 15; age, 25.1 ± 7.3 years). These samples allowed for 80% power for statistical significance testing. Both groups performed static hamstring stretching daily for 4 weeks. The precool group applied ice to the hamstring for 10 minutes before stretching. Both groups stretched for 4 weeks and then stopped stretching for the last 4 weeks. Hip ROM measures were obtained each week for 8 weeks. Results: For the standard group, mean hip ROM increased from 71.4° ± 18.5° to 90.6° ± 20.5° and for the precool group, 71.5° ± 22.3° to 91.8° ± 20.9°. For the standard group, mean hip ROM decreased from 90.6° ± 20.5° to 83.9° ± 20.3° and for the precool group, 91.8° ± 20.9 to 85.0° ± 19.4°. There were no differences between groups at any time in the study (P \u3e .05). Conclusions: Precooling had no beneficial effects on ROM or on retention of ROM. Clinical Relevance: Cold application, before stretching, does not provide any benefit to a stretching program

Cell wall composition and digestibility alterations in Brachypodium distachyon achieved through reduced expression of the UDP-arabinopyranose mutase

Nucleotide-activated sugars are essential substrates for plant cell-wall carbohydrate-polymer biosynthesis. The most prevalent grass cell wall sugars are glucose (Glc), xylose (Xyl), and arabinose (Ara). These sugars are biosynthetically related via the UDP-sugar interconversion pathway. We sought to target and generate UDP-sugar interconversion pathway transgenic Brachypodium distachyon lines resulting in cell wall carbohydrate composition changes with improved digestibility and normal plant stature. Both RNAi-mediated gene-suppression and constitutive gene-expression approaches were performed. Cell walls from 336 T0 transgenic plants with normal appearance were screened for complete carbohydrate composition. RNAi mutants of BdRGP1, a UDP-arabinopyranose mutase, resulted in large alterations in cell wall carbohydrate composition with significant decreases in cell wall Ara content but with minimal change in plant stature. Five independent RNAi-RGP1 T1 plant lines were used for in-depth analysis of plant cell walls. Real-time PCR analysis indicated that gene expression levels for BdRGP1, BdRGP2 and BdRGP3 were reduced in RNAi-RGP1 plants to 15-20% of controls. Cell wall Ara content was reduced by 23-51% of control levels. No alterations in cell wall Xyl and Glc content were observed. Corresponding decreases in cell wall ferulic acid (FA) and ferulic acid-dimers (FA-dimers) were observed. Additionally, cell wall p-coumarates (pCA) were decreased. We demonstrate the cell wall pCA decrease corresponds to Ara-coupled pCA. Xylanase-mediated digestibility of RNAi-RGP1 Brachypodium cell walls resulted in a near two-fold increase of released total carbohydrate. However, cellulolytic hydrolysis of cell wall material was inhibited in leaves of RNAi-RGP1 mutants. Our results indicate that targeted manipulation of UDP-sugar biosynthesis can result in biomass with substantially altered compositions and highlights the complex effect cell wall composition has on digestibility