Project description:Erythropoiesis is essential to mammals and is regulated at multiple steps by both extracellular and intracellular factors. Many transcriptional regulatory networks in erythroid differentiation have been well characterized. However, our understanding of post-transcriptional regulatory circuitries in this developmental process is still limited. Using genomic approaches, we identified a sequence-specific RNA-binding protein, Cpeb4, which is dramatically induced in terminal erythroid differentiation (TED) by two erythroid important transcription factors, Gata1/Tal1. Cpeb4 belongs to the cytoplasmic polyadenylation element binding (CPEB) protein family that regulates translation of target mRNAs in early embryonic development, neuronal synapse, and cancer. Using primary mouse fetal liver erythroblasts, we found that Cpeb4 is required for terminal erythropoiesis by repressing the translation of a set of mRNAs highly expressed in progenitor cells. This translational repression occurs by the interaction with a general translational initiation factor, eIF3. Interestingly, Cpeb4 also binds its own mRNA and represses its translation, thus forming a negative regulatory circuitry to limit Cpeb4 protein level. This mechanism ensures that the translation repressor, Cpeb4, does not interfere with the translation of other mRNAs in differentiating erythroblasts. Our study characterized a translational regulatorycircuitry that controls TED and revealed that Cpeb4 is required for somatic cell differentiation. We used microarray to identify mRNAs associated with Cpeb4 in mouse fetal liver erythroblasts. Cpeb4 associated mRNAs were isolated from mouse fetal liver erythroblasts using anti-Cpeb4 antibody for immunoprecipitation followed by RNA extraction. Then Affymetrix microarrays were used to identify and quantify the mRNAs associated with Cpeb4.
Project description:LoVo cells were cultured in sEV-depleted (160,000xg, 16h) complete medium and the supernatant were collected after 72h. sEVs were purified and centrifuged at 100,000xg for 2.5h using a Beckman SW41Ti rotor to know the miRNA in LoVo cells and LoVo-Small Extracellular Vesicles
Project description:The Cytoplasmic Polyadenylation Element Binding (CPEB)-family of RNA-binding proteins regulates pre-mRNA processing and translation of CPE-containing mRNAs in early embryonic development and synaptic activity. However, the specific functions of each CPEB in the adult organism are poorly understood. Here we show that CPEB4 is required to suppress high fat diet- and aging-induced endoplasmic reticulum (ER) stress, and its subsequent hepatic steatosis. Stress-activated expression of CPEB4 in the liver is controlled through a double layer of regulation. First, Cpeb4 is transcriptionally regulated by the circadian clock and then, its mRNA translation is regulated by the Unfolded Protein Response (UPR) through the upstream Open Reading Frames (uORFs) present in its 5’ UTR. Thus, CPEB4 is synthesized only upon ER-stress but the amplitude of the induction is circadian. In turn, CPEB4 activates a second wave of UPR-translation required to maintain ER and mitochondrial homeostasis. Our results suggest that combined transcriptional and translational regulation of CPEB4 generates a “circadian mediator”, which coordinates the hepatic UPR activity with periods of high ER protein-folding demand preventing non-alcoholic fatty liver disease (NAFLD).
Project description:The differential expression of mRNA in LoVo-P cells compared with LoVo-C cells was successfully detected using the Arraystar Human LncRNA/mRNAArray V4.0, that used for the global profiling of 20730 human mRNA and 40173 long non-coding RNA (LncRNA) transcripts.
Project description:We performed CPEB4 RIP-seq on freshly isolated muscle stem cells. We found that CPEB4 associated genes are enriched in metabolic relevant pathways such as some mitochondrial protein coding genes
Project description:The Cytoplasmic Polyadenylation Element Binding (CPEB)-family of RNA-binding proteins regulates pre-mRNA processing and translation of CPE-containing mRNAs in early embryonic development and synaptic activity. However, the specific functions of each CPEB in the adult organism are poorly understood. Here we show that CPEB4 is required to suppress high fat diet- and aging-induced endoplasmic reticulum (ER) stress, and its subsequent hepatic steatosis. Stress-activated expression of CPEB4 in the liver is controlled through a double layer of regulation. First, Cpeb4 is transcriptionally regulated by the circadian clock and then, its mRNA translation is regulated by the Unfolded Protein Response (UPR) through the upstream Open Reading Frames (uORFs) present in its 5’ UTR. Thus, CPEB4 is synthesized only upon ER-stress but the amplitude of the induction is circadian. In turn, CPEB4 activates a second wave of UPR-translation required to maintain ER and mitochondrial homeostasis. Our results suggest that combined transcriptional and translational regulation of CPEB4 generates a “circadian mediator”, which coordinates the hepatic UPR activity with periods of high ER protein-folding demand preventing non-alcoholic fatty liver disease (NAFLD).
Project description:Immediate early genes (IEGs) represent a unique class of genes with rapid induction kinetics and transient expression patterns, which requires IEG mRNAs to be short-lived. Here, we establish cytoplasmic polyadenylation element-binding protein 4 (CPEB4) as a major determinant of IEG mRNA instability. We identified human CPEB4 as an RNA-binding protein (RBP) with enhanced association to poly(A) RNA upon inhibition of class I histone deacetylases (HDACs), which is known to cause widespread degradation of poly(A)-containing mRNA. Photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) analysis using endogenously tagged CBEP4 in HeLa cells revealed that CPEB4 preferentially binds to the 3' untranslated region (UTR) of IEG mRNAs, at U-rich sequence motifs located in close proximity to the poly(A) site. By transcriptome-wide mRNA decay measurements, we found that the strength of CPEB4 binding correlates with short mRNA half-lives, and that loss of CBEP4 expression leads to the stabilization of IEG mRNAs. Further, we demonstrate that CPEB4 mediates mRNA degradation by recruitment of the evolutionarily conserved CCR4-NOT complex, the major eukaryotic deadenylase. While CPEB4 is primarily known for its ability to stimulate cytoplasmic polyadenylation, our findings establish an additional function for CPEB4 as an RBP that enhances the degradation of short-lived IEG mRNAs.