The role of the yeast cleavage and polyadenylation factor subunit Ydh1p/Cft2p in pre-mRNA 3' end formation

Cleavage and polyadenylation factor (CPF) is a multi‐protein complex that functions in pre‐mRNA 3′‐end formation and in the RNA polymerase II (RNAP II) transcription cycle. Ydh1p/Cft2p is an essential component of CPF but its precise role in 3′‐end processing remained unclear. We found that mutations in YDH1 inhibited both the cleavage and the polyadenylation steps of the 3′‐end formation reaction in vitro. Recently, we demonstrated that an important function of CPF lies in the recognition of poly(A) site sequences and RNA binding analyses suggesting that Ydh1p/Cft2p interacts with the poly(A) site region. Here we show that mutant ydh1 strains are deficient in the recognition of the ACT1 cleavage site in vivo. The C‐terminal domain (CTD) of RNAP II plays a major role in coupling 3′‐end processing and transcription. We provide evidence that Ydh1p/Cft2p interacts with the CTD of RNAP II, several other subunits of CPF and with Pcf11p, a component of CF IA. We propose that Ydh1p/Cft2p contributes to the formation of important interaction surfaces that mediate the dynamic association of CPF with RNAP II, the recognition of poly(A) site sequences and the assembly of the polyadenylation machinery on the RNA substrate.

Functional (GT)n polymorphisms in promoter region of N-methyl-d-aspartate receptor 2A subunit (GRIN2A) gene affect hippocampal and amygdala volumes

The glutamate system including N-methyl-d-aspartate (NMDA) affects synaptic formation, plasticity and maintenance. Recent studies have shown a variable (GT)n polymorphism in the promoter region of the NMDA subunit gene (GRIN2A) and a length-dependent inhibition of transcriptional activity by the (GT)n repeat. In the present study, we examined whether the GRIN2A polymorphism is associated with regional brain volume especially in medial temporal lobe structures, in which the NMDA-dependent synaptic processes have been most extensively studied. Gray matter regions of interest (ROIs) for the bilateral amygdala and hippocampus were outlined manually on the magnetic resonance images of 144 healthy individuals. In addition, voxel-based morphometry (VBM) was conducted to explore the association of genotype with regional gray matter volume from everywhere in the brain in the same sample. The manually measured hippocampal and amygdala volumes were significantly larger in subjects with short allele carriers (n = 89) than in those with homozygous long alleles (n = 55) when individual differences in intracranial volume were accounted for. The VBM showed no significant association between the genotype and regional gray matter volume in any brain region. These findings suggest that the functional GRIN2A (GT)n polymorphism could weakly but significantly impact on human medial temporal lobe volume in a length-dependent manner, providing in vivo evidence of the role of the NMDA receptor in human brain development.

The COMPASS subunit Spp1 links histone methylation to initiation of meiotic recombination

During meiosis, combinatorial associations of genetic traits arise from homologous recombination between parental chromosomes. Histone H3 lysine 4 trimethylation marks meiotic recombination hotspots in yeast and mammals, but how this ubiquitous chromatin modification relates to the initiation of double-strand breaks (DSBs) dependent on Spo11 remains unknown. Here, we show that the tethering of a PHD-containing protein, Spp1 (a component of the COMPASS complex), to recombinationally cold regions is sufficient to induce DSB formation. Furthermore, we found that Spp1 physically interacts with Mer2, a key protein of the differentiated chromosomal axis required for DSB formation. Thus, by interacting with H3K4me3 and Mer2, Spp1 promotes recruitment of potential meiotic DSB sites to the chromosomal axis, allowing Spo11 cleavage at nearby nucleosome-depleted regions.