FMRP is an RNA-binding protein that represses the translation of specific mRNAs. In neurons, its depletion determines the exaggerated translation of mRNAs leading to dendritic and axonal aberrant development, two peculiar features of Fragile X syndrome patients. However, how FMRP binds to translational machinery to regulate the translation of its mRNA targets is not yet fully understood. Here, we show that FMRP localizes on translational machinery by interacting with the ribosomal binding protein, Receptor for Activated C Kinase 1 (RACK1). The binding of FMRP to RACK1 removes the translational repressive activity of FMRP and promotes the translation of PSD-95 mRNA, one specific target of FMRP. This binding also results in a reduction in the level of FMRP phosphorylation. We also find that the morphological abnormalities induced by Fmr1 siRNA in cortical neurons are rescued by the overexpression of a mutant form of RACK1 that cannot bind ribosomes. Thus, these results provide a new mechanism underlying FMRP activity that contributes to altered development in FXS. Moreover, these data confirm the role of ribosomal RACK1 as a ribosomal scaffold for RNA binding proteins.

Success of meat production and selection for improvement of meat quality is among the primary aims in animal production. Meat quality traits are economically important in swine; however, the underlying genetic nature is very complex. Therefore, an improved pork production strongly depends on identifying and studying how genetic variations contribute to modulate gene expression. Promoters are key regions in gene modulation as they harbour several binding motifs to transcription regulatory factors. Therefore, polymorphisms in these regions are likely to deeply affect RNA levels and consequently protein synthesis. In this study, we report the identification of single nucleotide polymorphisms (SNPs) in promoter regions of candidate genes involved in development, cellular differentiation and muscle growth in Sus scrofa. We identified SNPs in the promoter regions of genes belonging to the Myogenic Regulatory Factors (MRF) gene family (the Myogenic Differentiation gene, MYOD1) and to Growth and Differentiation Factors (GDF) gene family (Myostatin gene, MSTN, GDF8), in Casertana and Large White breeds. The purpose of this study was to investigate if polymorphisms in the promoters could affect the transcriptional activity of these genes. With this aim, we evaluated in vitro the functional activity of the luciferase reporter gene luc2 activity, driven by two constructs carrying different promoter haplotypes. We tested the effects of the G302A (U12574) transition on the promoter efficiency in MYOD1 gene. We ascertained a difference in transcription efficiency for the two variants. A stronger activity of the A-carrying construct is more evident in C2C12. The luciferase expression driven by the MYOD1-A allelic variant displayed a 3.8-fold increased transcriptional activity. We investigated the activity of two haplotype variants (AY527152) in the promoter of GDF8 gene. The haploptype-1 (A435-A447-A879) up-regulated the expression of the reporter gene by a two-fold increase, and hence presumably of the GDF8 gene, in both CHO and C2C12 cultured cells. In vitro the MYOD1-A allelic variant could up-regulate the expression of MYOD1 gene. Additionally, we could assess a different response of in vitro gene expression according to cell type used to transfect constructs, suggesting that MyoD activation is regulated by mechanisms that are specific of myoblasts.

Telomeres are specialized nucleoprotein structures that have two important functions: (i) protection of the chromosomal ends from deleterious events such as chromosome fusion and degradation; (ii) counteraction of the “end replication problem” by allowing telomerase-dependent or, more rarely, telomerase-independent telomere elongation. The DNA sequences underlying these activities are short simple tandem repeats, which in vertebrate consist of a variable number of TTAGGG. Telomeres dysfunction may be caused either by the absence of telomerase activity or by mutations in telomeric proteins involved in telomere length and structure regulation. Additionally, increasing experimental evidence suggests that telomeres take part in the complex network regulating cell proliferation. Accordingly, telomeres are involved in biological process such as aging and tumor progression. In this study we determined the telomere length in two bovine Italian cattle breeds, Chianina and Maremmana, which are characterized by high longevity and range breeding. In order to account for possible variation among different tissues, we have determined telomere length in different organs such as spleen, lung and liver. Overall, the median telomere length was significant lower in Chianina (11 ± 0.69 kb) than in Maremmana (12.05 ± 1.57 kb). Moreover, telomere length variation among individuals was very low in Chianina but rather high in Maremmana. These data suggest that telomere length is influenced by the breeds. This hypothesis is confirmed by the different history of these Italian breeds. Indeed, Chianina has a long history and its size was maintained by the Breeders Association without necessity to crossbreed with other breeds, whereas the population of Maremmana underwent a dramatic shrinkage in the recent past. Therefore, breeders have crossed Maremmana with other breeds, like Charolais, and have relaxed the rules for the inclusion in the herd book.

Translation initiation of most mammalian mRNAs is mediated by a 5 ' cap structure that binds eukaryotic initiation factor 4E (eIF4E). Notably, most mRNAs are still capped when eIF4E is inhibited, suggesting alternative mechanisms likely mediate cap-dependent mRNA translation without functional eIF4F. Here we found that, when eIF4E is inhibited, the ribosomal scaffold RACK1 recruits eIF3d on the 43S pre-initiation complex. Moreover, we found that it is just PKCBII in its active form that promotes the binding of RACK1 to eIF3d. These studies disclose a previously unknown role of ribosomal RACK1 for eIF3d specialized translation.