Project description:We compared the poly(A) tail length status of mRNAs of HeLa cells expressing a CPEB1 shRNA (CPEB1 knockdown) versus a control shRNA, and expressing a CPEB4 shRNA (CPEB4 knockdown) versus a control shRNA. Results provide insight into the extent of gene regulation mediated by CPEB1 and CPEB4 activity during mitotic cell cycle progression. The different shRNA expressing cells were synchronized with double thymidine blockade (12 hours with 2 mM thymidine, 12 hours release, and 12 hours with 2 mM thymidine), and samples were taken after 8 hours release (G2/M phase). For each shRNA expressing HeLa cell line total RNA was purified by two different procedures: poly(U) chromatography and oligo(dT)-chromatography. Poly(U)-chromatography (Jacobson, 1987): 100 μg of total RNA were bound to poly(U)-sepharose (Sigma) and eluted at 35ºC to isolate mRNAs with short poly(A) tail (<30As, SHORT fraction). Oligo(dT) chromatography: mRNAs were purified independently of their poly(A) tail length with Ambion Poly(A)Purist kit from 20 μg total RNA (ALL fraction). Jacobson, A. Purification and fractionation of poly(A)+ RNA. Methods in Enzymology (1987) 152: 254-261. Keywords: knock-down experiment
Project description:Cytoplasmic polyadenylation element binding protein 1 (CPEB1) regulates polyadenylation and subsequent translation of CPE-containing mRNAs, which contributes to various physiological and pathological phenomena. To clarify changes in gene expression profiles caused by dysregulation of CPEB1 expression, we performed microarray analyses and revealed that reduced CPEB1 expression altered the expression levels of numerous genes. These findings indicate that accurate post-transcriptional regulation of CPEB1 expression contributes to the maintenance of global gene expression partially through modulating lncRNA expression.
Project description:To identify CPEB1 and CPEB4 regulated RNA we performed CPEB1 and CPEB4 RNA immunoprecipitation (RIP) followed by microarray hybridization analysis with striatal (St) RNA from wild-type (WT) and R6/1 mice (HD mice).
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 CPEB4 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.
Project description:Mutations or decreased expression of RNA-binding proteins (mRBPs) can lead to cardiomyopathies in humans. Here we defined RBPs in healthy and diseased primary cardiomyocytes at a system-wide level by RNA Interactome Capture. This identified 67 novel cardiomyocyte specific RBPs including several contractile proteins. Furthermore, we identified Cytoplasmic polyadenylation element binding protein 4 (Cpeb4) as a dynamic mRBP in diseased cardiomyocytes, regulating cardiac growth both in vitro and in vivo. To study Cpeb4 in cardiomyocytes, we identified mRNAs bound to and regulated by Cpeb4. Cpeb4 regulates cardiac remodeling by differential expression of transcription factors. Among Cpeb4 target mRNAs, two Zinc finger transcription factors (Zeb1 and Zbtb20) were identified. We show that Cpeb4 regulates the translation of these mRNAs and that Cpeb4 depletion increases their expression. Thus, Cpeb4 emerges as critical regulator of cardiomyocyte function by differential binding of specific mRNAs in response to pathological growth stimulation.
Project description:Mutations or decreased expression of RNA-binding proteins (RBPs) can lead to cardiomyopathies in humans. Here we defined RBPs in healthy and diseased primary cardiomyocytes at a system-wide level by RNA Interactome Capture. This identified 67 novel cardiomyocyte specific RBPs including several contractile proteins. Furthermore, we identified Cytoplasmic polyadenylation element binding protein 4 (Cpeb4) as a dynamic RBP in diseased cardiomyocytes, regulating cardiac growth both in vitro and in vivo. To study Cpeb4 in cardiomyocytes, we identified mRNAs bound to and regulated by Cpeb4. Cpeb4 regulates cardiac remodeling by differential expression of transcription factors. Among Cpeb4 target mRNAs, two Zinc finger transcription factors (Zeb1 and Zbtb20) were identified. We show that Cpeb4 regulates the translation of these mRNAs and that Cpeb4 depletion increases their expression. Thus, Cpeb4 emerges as critical regulator of cardiomyocyte function by differential binding of specific mRNAs in response to pathological growth stimulation.
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:Sequencial functions of CPEB1 and CPEB4 in the localization of repressed mRNAs to the mitotic spindle and their subsequent phase-specific activation to promote cell phase transitions and correct chromosome segregation
Project description:Here we show sequential functions of CPEB1 and CPEB4 in the localization of repressed mRNAs to the mitotic spindle and their subsequent phase -specific activation to promote cell phase transitions and correct chromosome segregation.