A molecular brake that modulates spliceosome pausing at detained introns contributes to neurodegeneration

Emerging evidence suggests that intron-detaining transcripts (IDTs) are a nucleus-detained and polyadenylated mRNA pool for cell to quickly and effectively respond to environmental stimuli and stress. However, the underlying mechanisms of detained intron (DI) splicing are still largely unknown. Here, we suggest that post-transcriptional DI splicing is paused at the Bact state, an active spliceosome but not catalytically primed, which depends on Smad Nuclear Interacting Protein 1 (SNIP1) and RNPS1 (a serine-rich RNA binding protein) interaction. RNPS1 and Bact components preferentially dock at DIs and the RNPS1 docking is sufficient to trigger spliceosome pausing. Haploinsufficiency of Snip1 attenuates neurodegeneration and globally rescues IDT accumulation caused by a previously reported mutant U2 snRNA, a basal spliceosomal component. Snip1 conditional knockout in the cerebellum decreases DI splicing efficiency and causes neurodegeneration. Therefore, we suggest that SNIP1 and RNPS1 form a molecular brake to promote spliceosome pausing, and that its misregulation contributes to neurodegeneration.

Effects of exposure to aluminum on some metal elements contents in hippocampus of rat / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the effects of exposure to aluminum (Al) on Zn, Fe, Cu and Ca contents in hippocampus of rats.</p><p><b>METHODS</b>AlCl(3).6H(2)O was administered orally through diet (8% of body weight) to SD rats at doses of 0 (A), 11.2 (B), 55.9 (C), 111.9 (D) mg Al(3+)/kg BW for successive 90 days. Then Al, Zn, Fe, Cu and Ca contents in hippocampi of rats were determined by atomic absorption spectrophotometry.</p><p><b>RESULTS</b>After oral exposure to Al, the Al content in hippocampus of rat increased significantly with a remarkable dose-effect relationship (r = 0.731, P < 0.001), The Zn, Fe, Ca and Cu contents in these four groups are as follows: Group A (18.29 +/- 2.48, 24.86 +/- 1.97, 48.69 +/- 22.08, 4.53 +/- 0.99) mg/g, Group B (17.22 +/- 2.06, 27.54 +/- 2.87, 42.79 +/- 14.42, 4.06 +/- 0.41) mg/g, Group C (14.46 +/- 1.90, 20.18 +/- 2.79, 29.95 +/- 7.33, 3.98 +/- 0.25) mg/g, Group D (15.85 +/- 2.54, 20.96 +/- 2.83, 36.14 +/- 12.66, 4.53 +/- 0.58) mg/g. Compared with the control group A, the Zn and Fe contents in group B and group C decreased significantly (P < 0.05), and the Ca content in group C also decreased significantly.</p><p><b>CONCLUSION</b>Oral exposure to Al may result in accumulation of Al in hippocampus of brain and thus affect some essential elements (Zn, Fe, Cu and Ca) contents in the hippocampus at different degrees.</p>