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.
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:Staufen1 (STAU1) is an RNA-binding protein involved in maturation, localization, translation and decay of mRNAs. STAU1 expression is modulated during the cell cycle and decreases during mitosis. In prometaphase, STAU155 binds specific classes of mRNAs that code for proteins implicated in transcription and cell cycle regulation. In this paper, we report that STAU155 co-localizes with microtubules on the mitotic spindle in human colorectal cancer cell line HCT116, and map the molecular determinant required for this association within the N-terminal 88 amino acids (aa 25-37). Interestingly, STAU1 co-purifies with ribosomal proteins and co-localizes with active sites of translation on the mitotic spindle. To characterize STAU1-dependent mRNA transport and localization on the spindle, we used RNAseq analysis to identify spindle-associated mRNAs on purified spindles of wild-type and STAU1-KO CRISPR cell lines. Our datasets identify 161 protein-coding transcripts that are less abundant on the mitotic spindle of STAU1-KO cells compared to WT, and 660 that are more abundant. Altogether, these data demonstrate that STAU1 controls the transport and the localization of specific sub-populations of mRNAs to the mitotic spindle of cancer cells and suggest that at least some spindle-localized mRNAs undergo local translation during mitosis.
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: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:Messenger RNA stability, localization, and translation are largely determined by sequences in their 3M-bM-^@M-2 untranslated regions (3M-bM-^@M-^YUTRs), which recruit regulatory proteins and RNAs. More than half of the mammalian genes generate multiple mRNA isoforms differing in their 3M-bM-^@M-2UTRs and therefore in their regulatory elements. The Cytoplasmic Polyadenylation Element Binding protein 1 (CPEB1) binds to cognate sites in 3M-bM-^@M-^Y UTRs and regulates translation. CPEB1 can shuttle to the nucleus and we report its co-localization with splicing factors. CPEB1 knock down leads to changes in alternative splicing, and we show that alternative 3M-bM-^@M-^Y splice site linked to alternative polyadenylation of the bub-3 pre-mRNA, important for cell proliferation, is regulated by CPEB1 at least in part by preventing 3M-bM-^@M-^Y splice site recognition by U2AF. RNA-Seq experiments reveal that CPEB1 mediates 3M-bM-^@M-^Y UTR shortening of hundreds of mRNAs, leading to changes in their translation efficiency. Three total RNA from three biological replicates were labeled and hybridized versus its own control in direct and dye-swap hybridizations.
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.
Project description:CPEB1 regulates cellular function by post-transcriptionally controlling its targeted transcripts' translation. After bound to CPEs, CPEB1 recruits cytoplasmic poly (A) polymerase GLD2 to elongate the poly (A) tail for the maintenance of mRNA stability. The stability of mRNA is positively correlated with translational output. It is unexamined whether CPEB1 interacts with translation machinery to regulation translation. Previous reports demonstrate that phosphorylation is required for its regulation on translation. However, it is not well understood whether phosphorylation is essential for CPEB1 interaction with translation machinery or not. Here, we performed mass spectrometry on C2 cells transfected with CPEB1-mVenus or CPEB1 (T171A, S177A)-mVenus after IgG or mVenus antibody immunoprecipitation. After analysis, we identify CPEB1 interacting proteins and the phosphorylation dependent interacting proteins such as ribosomal proteins. Thus, our data suggest that CPEB1 regulate translation by interacting with translation machinery in a phosphorylation dependent manner.