Project description:Mutant and non-mutant footpad. McGowan et al. in press Keywords: Mutant vs. non-mutant The tissue (footpad epidermis) is from a conditional heterozygous null deletion of Rps6. One copy of Rps6 was deleted from keratinocytes in the skin using the K5.Cre transgene. K5Cre x Rps6^loxP
Project description:Mutant and non-mutant footpad. McGowan et al. in press Keywords: Mutant vs. non-mutant The tissue (footpad epidermis) is from a conditional heterozygous null deletion of Rps6. One copy of Rps6 was deleted from keratinocytes in the skin using the K5.Cre transgene.
Project description:Targeted depletion of ribosomal protein S6 (Rps6) from hepatoblasts of the developing liver results in neonatal sub-lethal hepatic failure due to inhibition of bile duct development and widespread induction of hepatocyte death triggering regeneration. Overexpression of c-Myc is hepatoprotective in the context of Rps6-deficiency and eliminates the need for DS6 livers to regenerate by preventing hepatocyte death. Microarrays were used to identify the transcriptional program associated with loss of hepatic Rps6 and to identify mRNAs associated with c-Myc's hepatoprotective effect in DS6 livers
Project description:Transcriptional analysis of concequent lack of rpS6 kinase activity in mice livers hepatocytes due to deletion of S6 kinases 1 and 2 (S6K1 and S6K2).
Project description:Phosphorylation of Ribosomal Protein S6 (RPS6) was the first post-translational modification of the ribosome to be identified and is a commonly-used readout for mTORC1 activity. Although the cellular and organismal functions of RPS6 phosphorylation are known, its molecular consequences on translation are less well understood. Here we use selective ribosome footprinting to analyze the location of ribosomes containing phosphorylated RPS6 on endogenous mRNAs in cells. We find that RPS6 becomes progressively dephosphorylated on ribosomes as they translate an mRNA. As a consequence, average RPS6 phosphorylation is higher on mRNAs with short coding sequences (CDSs) compared to mRNAs with long CDSs. Loss of RPS6 phosphorylation causes a correspondingly larger drop in translation efficiency of mRNAs with short CDSs than long CDSs. Interestingly, mRNAs with 5’ TOP motifs are translated well also in the absence of RPS6 phosphorylation despite short CDS lengths, suggesting they are translated via a different mode. In sum this provides a dynamic view of RPS6 phosphorylation on ribosomes as they translate mRNAs and the functional consequence on translation.
Project description:There is a fundamental gap in understanding the consequences of tau-ribosome interactions. Tau oligomers and filaments hinder protein synthesis in vitro, and they associate strongly with ribosomes in vivo. Here, we investigated the consequences of tau interactions with ribosomes in vivo and in human brain tissues to identify tau as a direct modulator of ribosomal selectivity. We performed microarrays and nascent proteomics to measure changes in protein synthesis using rTg4510 tau transgenic mice. We determined that tau expression differentially shifts the transcriptome and the proteome and that the synthesis of ribosomal proteins is reversibly dependent on tau levels. We further extended these results to human brains and show that tau pathologically interacts with ribosomal protein S6 (rpS6 or S6). Consequently, synthesis of ribosomal proteins coded by 5’TOP-mRNAs was reduced under tauopathic conditions in Alzheimer’s disease brains. Our data establish tau as a driver of RNA translation selectivity. Moreover, considering that regulation of protein synthesis is critical to learning and memory, aberrant tau-ribosome interactions in disease could explain the linkage between virtually every tauopathy and cognitive impairment and memory decline.
Project description:Sex in birds is genetically determined, molecular mechanism of which is not well-understood. Their Z sex chromosome (chrZ) lacks whole chromosome inactivation as known for mammalian chrX. To investigate the extent of chrZ dosage compensation and its role in somatic cell’s sex specification, we used a highly-quantitative method and analyzed transcriptional activities of male and female fibroblasts from seven birds. Our data indicate for the first time that ¾ of chrZ genes are strictly compensated, similar to that observed in chrX. We also describe non-compensated chrZ genes and identify Ribosomal Protein S6 (RPS6) as a candidate for universal, sex-dimorphic genes in birds.
