1. With and without the 3 Mints
Angela Ho, Wade Morishita, Deniz Atasoy, Xinran Liu, Katsuhiko Tabuchi, Robert E. Hammer, Robert C. Malenka, and Thomas C. Sdhof
You can tell a lot about a protein by what it hangs out with. The three Mints (also called X11-like proteins) bind to multiple synaptic proteins, and knock-out studies have suggested that they may indeed be necessary in synaptic transmission. But different isoforms can complement each others function; thus, it has been difficult to come to firm conclusions using single knock-outs. This week, Ho et al. deleted the Mints using constitutive and conditional knock-out strategies. Deletion of Mint 1 and 2, the two isoforms specifically expressed in neurons, caused most mice to die at birth. The 20% that survived had ataxia and reduced body weight. In the double knock-outs, whole-cell recording of hippocampal neurons revealed lowered synaptic strength, a twofold decrease in the frequency of miniature EPSCs, and enhanced paired-pulse facilitation, indicative of a presynaptic action of Mint 1 and 2. Similar results were obtained with acute ablation of Mint 1/2/3.
2. Born-Again Neurons in Mice and Men
John J. Ohab, Sheila Fleming, Armin Blesch, and S. Thomas Carmichael and Jadranka Macas, Christian Nern, Karl H. Plate, and Stefan Momma
Stroke doesnt only cause cell death, but it also attempts at recovery through neuronal regeneration in tissues near the infarct, according to two separate studies published this week. Using histological analyses in a large collection of postmortem human brains, Macas et al. found increased numbers of neuronal precursor cells, even in patients of advanced age who had suffered ischemia. Because recent studies have coupled neurogenesis to the formation of new blood vessels, Ohab et al. tested the link in a model of focal stroke in mice. These authors showed that stroke induced the long-distance migration of thousands of newly
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Society for Neuroscience