Project description:14-3-3 proteins facilitate cytoplasmic-nuclear shuttling of transcription factors.Adipocyte differentiation requires the function of critical transcription factors to drive the development of a mature adipocyte. The aim of the study was to investigate if 14-3-3ζ is required for the adipogenic transcriptional program. Examination of the transcriptome in siCon- and si14-3-3ζ-transfected 3T3-L1 cells undergoing differentiation at t=0, 24, and 48 hours.
Project description:14-3-3 proteins facilitate cytoplasmic-nuclear shuttling of transcription factors.Adipocyte differentiation requires the function of critical transcription factors to drive the development of a mature adipocyte. The aim of the study was to investigate if 14-3-3ζ is required for the adipogenic transcriptional program.
Project description:Nuclear entry of transcription factor HIPPI is mediated by its interacting partner Huntingtin Interacting Protein 1 (HIP1), a nuclear localization signal containing nucleo-cytoplasmic shuttling protein. In oredr to investigate the role of HIP1 in HIPPI mediated transcriptional regulation in cell, here we performed microarray experiments using stable HIP1 knocked down HeLa cells (Hip1Si) exogenously expressing Green fluorescent protein tagged HIPPI.
Project description:Nuclear entry of transcription factor HIPPI is mediated by its interacting partner Huntingtin Interacting Protein 1 (HIP1), a nuclear localization signal containing nucleo-cytoplasmic shuttling protein. In oredr to investigate the role of HIP1 in HIPPI mediated transcriptional regulation in cell, here we performed microarray experiments using stable HIP1 knocked down HeLa cells (Hip1Si) exogenously expressing Green fluorescent protein tagged HIPPI. Total RNA extracted from HIP1 knocked down HeLa cells (Hip1Si) transfected with empty GFP vector served as control and Total RNA extracted from Hip1Si cells transfected with GFP-Hippi construct served as test. Biological replicates: 4
Project description:STK38 (aka NDR1) is a Hippo pathway serine/threonine protein kinase with multifarious functions in normal and cancer cells. Using a context-dependent proximity labelling assay, we discovered that STK38 modulates its interaction with more than 250 proteins depending on the context. Upon starvation-induced autophagy, STK38 associates with cytoplasmic proteins while upon ECM detachment it binds to mainly nuclear proteins. This differential subcellular-localization-dependent activity is caused by the XPO1 (Exportin-1, CRM1) dependent nuclear/cytoplasmic shuttling of STK38. STK38 associates with nuclear related partners upon ECM detachment and with cytoplasmic related ones upon autophagy, exhibiting a nuclear/cytoplasmic shuttling under the dependency of XPO1 (Exportin-1, aka CRM1). We further uncovered that the XPO1-mediated export of STK38 is dependent on phosphorylation of XPO1s serin residue 1055 by STK38 itself. In addition to regulating its own nuclear export, STK38 also controls the subcellular distribution of Beclin1, a key regulator of autophagy. Moreover, the regulation of XPO1 by STK38 mediates the nuclear exclusion of YAP1. Collectively, our results reveal that functions of STK38 are linked to the XPO1-mediated subcellular distribution of STK38 and key regulators. These observations show that unrelated cellular functions can be regulated by a same mechanism controlled by a single kinase and demonstrate a novel mechanism of XPO1-dependent cargo export regulation y phosphorylation of XPO1s C-terminal auto-inhibitory domain.
Project description:mRNA level is controlled by factors that mediate both mRNA synthesis and decay, including the 5’ to 3’ exonuclease Xrn1 - a major mRNA synthesis and decay factor. Here we show that nucleocytoplasmic shuttling of several mRNA decay factors plays a key role in determining both mRNA synthesis and decay. Shuttling is regulated by RNA-controlled binding of the karyopherin Kap120 to two nuclear localization sequences (NLSs) in Xrn1, location of one of which is conserved from yeast to human. The decaying RNA binds and masks NLS1, establishing a link between mRNA decay and Xrn1 shuttling. Preventing Xrn1 import, either by deleting KAP120 or mutating the two Xrn1 NLSs, compromise transcription and, unexpectedly, also the cytoplasmic decay, uncovering a cytoplasmic decay pathway that initiates in the nucleus. Most mRNAs are degraded by both the “classical” and the novel pathways, the ratio between them represents a full spectrum. Importantly, Xrn1 shuttling is required for proper adaptation to environmental changes, in particular to ever changing environmental fluctuations.
Project description:RNAseIII ribonucleases act at the heart of RNA silencing pathways by processing precursor RNAs into mature microRNAs and siRNAs. In the fission yeast Schizosaccharomyces pombe, siRNAs are generated by the RNAseIII enzyme Dcr1 and are required for heterochromatin formation. In this study, we have analyzed the subcellular localization of Dcr1 and found that it accumulates in the nucleus and is enriched at the nuclear periphery. Nuclear accumulation of Dcr1 depends on a short motif which constrains nuclear export promoted by the double-stranded RNA binding domain of Dcr1. Absence of this motif renders Dcr1 mainly cytoplasmic and is accompanied by remarkable changes in gene expression and failure to assemble heterochromatin. Our findings suggest that dicer proteins are shuttling proteins and that the steady-state subcellular levels can be shifted towards either compartment. This has implications for the mechanism of RNAi-mediated heterochromatin assembly and the spatial organization of RNA silencing pathways in general. Small RNA libraries from total RNA isolations of wild-type, dcr1Delta and dcr1DeltaC33 cells and subjected to high-throughput sequencing.
Project description:SRSF1, shuttles between the nucleus and cytoplasm affecting post-splicing processes. However, the physiological significance of this remains unclear. Here, we used genome editing to knock-in a nuclear retention signal (NRS) in Srsf1 to create a mouse model harboring a non-shuttling SRSF1 protein. We then assessed whether alblation of shuttling activities of SRSF1 affects its nuclear functions.
Project description:RNAseIII ribonucleases act at the heart of RNA silencing pathways by processing precursor RNAs into mature microRNAs and siRNAs. In the fission yeast Schizosaccharomyces pombe, siRNAs are generated by the RNAseIII enzyme Dcr1 and are required for heterochromatin formation. In this study, we have analyzed the subcellular localization of Dcr1 and found that it accumulates in the nucleus and is enriched at the nuclear periphery. Nuclear accumulation of Dcr1 depends on a short motif which constrains nuclear export promoted by the double-stranded RNA binding domain of Dcr1. Absence of this motif renders Dcr1 mainly cytoplasmic and is accompanied by remarkable changes in gene expression and failure to assemble heterochromatin. Our findings suggest that dicer proteins are shuttling proteins and that the steady-state subcellular levels can be shifted towards either compartment. This has implications for the mechanism of RNAi-mediated heterochromatin assembly and the spatial organization of RNA silencing pathways in general.