Identification and characterization of extensive intra-molecular associations between 3′-UTRs and their ORFs

During eukaryotic translation, mRNAs may form intra-molecular interactions between distant domains. The 5′-cap and the polyA tail were shown to interact through their associated proteins, and this can induce physical compaction of the mRNA in vitro. However, the stability of this intra-molecular association in translating mRNAs and whether additional contacts exist in vivo are largely unknown. To explore this, we applied a novel approach in which several endogenous polysomal mRNAs from Saccharomyces cerevisiae were cleaved near their stop codon and the resulting 3′-UTR fragments were tested either for co-sedimentation or co-immunoprecipitation (co-IP) with their ORFs. In all cases a significant fraction of the 3′-UTR fragments sedimented similarly to their ORF-containing fragments, yet the extent of co-sedimentation differed between mRNAs. Similar observations were obtained by a co-IP assay. Interestingly, various treatments that are expected to interfere with the cap to polyA interactions had no effect on the co-sedimentation pattern. Moreover, the 3′-UTR appeared to co-sediment with different regions from within the ORF. Taken together, these results indicate extensive physical associations between 3′-UTRs and their ORFs that vary between genes. This implies that polyribosomal mRNAs are in a compact configuration in vivo

Paroxysmal Dystonia as the Initial Manifestation of Multiple Sclerosis

• Paroxysmal dystonia was the initial manifestation of multiple sclerosis (MS) in eight patients. The disorder was generally characterized by dystonic posturing of unilateral extremities, averaging less than one minute in duration. Facial grimacing and dysarthria occurred in two of the eight patients. This paroxysmal phenomenon was frequently the cause of diagnostic confusion. The time elapsing before other neurological symptoms of MS developed was as long as ten years

Wnt signaling enhances neurogenesis and improves neurological function after focal ischemic injury.

Stroke potently stimulates cell proliferation in the subventricular zone of the lateral ventricles with subsequent neuroblast migration to the injured striatum and cortex. However, most of the cells do not survive and mature. Extracellular Wnt proteins promote adult neurogenesis in the neurogenic niches. The aim of the study was to examine the efficacy of Wnt signaling on neurogenesis and functional outcome after focal ischemic injury. Lentivirus expressing Wnt3a-HA (LV-Wnt3a-HA) or GFP (LV-GFP) was injected into the striatum or subventricular zone of mice. Five days later, focal ischemic injury was induced by injection of the vasoconstrictor endothelin-1 into the striatum of the same hemisphere. Treatment with LV-Wnt3a-HA into the striatum significantly enhanced functional recovery after ischemic injury and increased the number of BrdU-positive cells that differentiated into mature neurons in the ischemic striatum by day 28. Treatment with LV-Wnt3a-HA into the subventricular zone significantly enhanced functional recovery from the second day after injury and increased the number of immature neurons in the striatum and subventricular zone. This was accompanied by reduced dissemination of the neuronal injury. Our data indicate that Wnt signaling appears to contribute to functional recovery after ischemic injury by increasing neurogenesis or neuronal survival in the striatum

Schematic representation of the experimental design.

<p>A. Experimental protocol. B. Diagram of the brain section. Lentiviral vector was injected into either the striatum (blue syringe) or SVZ (red syringe). The ischemic area in the striatum is circled in black.</p

Effect of LV-Wnt3a-HA treatment on functional recovery.

<p>A–B. LV-Wnt3a-HA injection into the striatum significantly improved functional performance at 28 days after injury on the cylinder test (A; <i>p</i><0.05) but not on the corner test (B). C–D. LV-Wnt3a-HA treatment into the SVZ significantly improved functional recovery from day 2 after injury on the cylinder test (C; <i>p</i><0.05) and on day 21 after injury on the corner test (D; <i>p</i><0.05). Data are given as mean ± SEM.</p

Neuroprotection in the ischemic striatum following LV-Wnt3a-HA injection into the SVZ 2 days after injury.

<p>A. DNA strand breaks are labeled by TUNEL staining and NeuN immunohistochemistry in the ischemic striatum. B. Wnt3a-HA significantly reduced the number of DNA fragmented cells in the striatum (<i>p</i><0.05). C. DCX⁺ cells manifest extensive expression of BDNF in the ischemic striatum. D. Quantification of BDNF levels in the striatum using ELISA (<i>p</i><0.05).</p

Effect of Wnt3a-HA treatment on neurogenesis 28 days after injury.

<p>A. A co-localized BrdU/NeuN cell is shown in the striatum. B–D. Wnt3a-HA injection into the striatum led to a significant increase in the number of newborn neurons in the striatum (<i>p</i><0.01). Treatment with Wnt3a-HA into the SVZ did not change the number of newborn neurons in the striatum. Number of newborn neurons (B), proliferating progenitors (C) and NeuN⁺/BrdU⁺ (D) cells in the striatum and SVZ.</p

Effect of LV-Wnt3a-HA injection into the SVZ on the proliferation and differentiation of progenitor cells to neuroblasts 2 days after injury.

<p>A. EdU⁺ and DCX⁺ cells were detected in the ischemic striatum. B-D. Wnt3a-HA significantly increased the number of DCX⁺ cells in the striatum (<i>p</i><0.01). EdU⁺DCX⁺ cells were hardly detected in the striatum. Number of newborn DCX⁺ (B), proliferating progenitors (C) and DCX⁺/EdU⁺ (D) cells in the striatum. E. EdU⁺ and DCX⁺ cells were found in the SVZ. D-H. Wnt3a-HA significantly increased the number of DCX⁺ and EdU⁺DCX⁺ cells in the SVZ (<i>p</i><0.01). Number of newborn DCX⁺ (F), proliferating progenitors (G) and DCX⁺/EdU⁺ (H) cells in the SVZ.</p