Project description:Alternative splicing is fundamental for the expansion of biological complexity, particularly in the vertebrate nervous system. Increasing evidence indicates that developmental stage and tissue-dependent alternative exons often control protein-protein interactions, yet only a minor fraction of these events has been characterized at the protein level. Using affinity purification-mass spectrometry (AP-MS) we show that approximately 60% of analyzed neural-differential exons in proteins previously implicated in transcriptional regulation result in the gain or loss of interaction partners. Focusing on Chtop and Sap30bp, the neural exons in these proteins unexpectedly remodel interactions with partners associated with mRNA processing and trafficking. Sap30bp additionally controls RNA localization by regulating the splicing of <100 nt ‘mini-introns’ that contribute to the nuclear retention of transcripts. These activities of Chtop and Sap30bp are linked to programs of transcriptomic regulation associated with development of the nervous system. AP-MS is thus a powerful approach for elucidating multifaceted functions of proteins imparted by context-dependent alternative exons.
Project description:Alternative splicing is fundamental for the expansion of biological complexity, particularly in the vertebrate nervous system. Increasing evidence indicates that developmental stage and tissue-dependent alternative exons often control protein-protein interactions, yet only a minor fraction of these events has been characterized at the protein level. Using affinity purification-mass spectrometry (AP-MS) we show that approximately 60% of analyzed neural-differential exons in proteins previously implicated in transcriptional regulation result in the gain or loss of interaction partners. Focusing on Chtop and Sap30bp, the neural exons in these proteins unexpectedly remodel interactions with partners associated with mRNA processing and trafficking. Sap30bp additionally controls RNA localization by regulating the splicing of <100 nt ‘mini-introns’ that contribute to the nuclear retention of transcripts. These activities of Chtop and Sap30bp are linked to programs of transcriptomic regulation associated with development of the nervous system. AP-MS is thus a powerful approach for elucidating multifaceted functions of proteins imparted by context-dependent alternative exons.
Project description:Alternative splicing is fundamental for the expansion of biological complexity, particularly in the vertebrate nervous system. Increasing evidence indicates that developmental stage and tissue-dependent alternative exons often control protein-protein interactions, yet only a minor fraction of these events has been characterized at the protein level. Using affinity purification-mass spectrometry (AP-MS) we show that approximately 60% of analyzed neural-differential exons in proteins previously implicated in transcriptional regulation result in the gain or loss of interaction partners. Focusing on Chtop and Sap30bp, the neural exons in these proteins unexpectedly remodel interactions with partners associated with mRNA processing and trafficking. Sap30bp additionally controls RNA localization by regulating the splicing of <100 nt ‘mini-introns’ that contribute to the nuclear retention of transcripts. These activities of Chtop and Sap30bp are linked to programs of transcriptomic regulation associated with development of the nervous system. AP-MS is thus a powerful approach for elucidating multifaceted functions of proteins imparted by context-dependent alternative exons.
Project description:The Fe(II)- and 2-oxoglutarate (2OG)-dependent dioxygenase AlkB from E. coli is a demethylase which repairs alkyl lesions in DNA, as well as RNA, through a direct reversal mechanism. Humans possess nine AlkB homologues (ALKBH1-8 and FTO). ALKBH2 and ALKBH3 display demethylase activities corresponding to that of AlkB, and both ALKBH8 and FTO are RNA modification enzymes. The biochemical functions of the rest of the homologues are still unknown. To increase our knowledge on the functions of ALKBH4 and ALKBH7 we have here performed yeast two-hybrid screens to identify interaction partners of the two proteins. While no high-confidence hits were detected in the case of ALKBH7, several proteins associated with chromatin and/or involved in transcription were found to interact with ALKBH4. For all interaction partners, the regions mediating binding to ALKBH4 comprised domains previously reported to be involved in interaction with DNA or chromatin. Furthermore, some of these partners showed nuclear co-localization with ALKBH4. However, the global gene expression pattern was only marginally altered upon ALKBH4 over-expression, and larger effects were observed in the case of ALKBH7. Although the molecular function of both proteins remains to be revealed, our findings suggest a role for ALKBH4 in regulation of gene expression or chromatin state and support the previous association of ALKBH7 with spermatogenesis. Gene expression profiling of ALKBH4 and ALKBH7 over-expression
Project description:The Fe(II)- and 2-oxoglutarate (2OG)-dependent dioxygenase AlkB from E. coli is a demethylase which repairs alkyl lesions in DNA, as well as RNA, through a direct reversal mechanism. Humans possess nine AlkB homologues (ALKBH1-8 and FTO). ALKBH2 and ALKBH3 display demethylase activities corresponding to that of AlkB, and both ALKBH8 and FTO are RNA modification enzymes. The biochemical functions of the rest of the homologues are still unknown. To increase our knowledge on the functions of ALKBH4 and ALKBH7 we have here performed yeast two-hybrid screens to identify interaction partners of the two proteins. While no high-confidence hits were detected in the case of ALKBH7, several proteins associated with chromatin and/or involved in transcription were found to interact with ALKBH4. For all interaction partners, the regions mediating binding to ALKBH4 comprised domains previously reported to be involved in interaction with DNA or chromatin. Furthermore, some of these partners showed nuclear co-localization with ALKBH4. However, the global gene expression pattern was only marginally altered upon ALKBH4 over-expression, and larger effects were observed in the case of ALKBH7. Although the molecular function of both proteins remains to be revealed, our findings suggest a role for ALKBH4 in regulation of gene expression or chromatin state and support the previous association of ALKBH7 with spermatogenesis. Comparison of DNA methylation patterns in cells over expressing ALKBH4 and ALKBH7
Project description:In malignant B-cell context, application of affinity-purification mass spectrometry (AP-MS) on KLHL6 baits revealed novel physical protein interaction partners outside the established ubiquitination/protein degradation machinery, such as BCR signaling components CD79A and Bank1. As a complementary approach to AP-MS, Kelch-domain adjacent proximity-dependent labeling (BioID2) revealed potential substrates processed by the identified KLHL6-CRLs.
Project description:The Fe(II)- and 2-oxoglutarate (2OG)-dependent dioxygenase AlkB from E. coli is a demethylase which repairs alkyl lesions in DNA, as well as RNA, through a direct reversal mechanism. Humans possess nine AlkB homologues (ALKBH1-8 and FTO). ALKBH2 and ALKBH3 display demethylase activities corresponding to that of AlkB, and both ALKBH8 and FTO are RNA modification enzymes. The biochemical functions of the rest of the homologues are still unknown. To increase our knowledge on the functions of ALKBH4 and ALKBH7 we have here performed yeast two-hybrid screens to identify interaction partners of the two proteins. While no high-confidence hits were detected in the case of ALKBH7, several proteins associated with chromatin and/or involved in transcription were found to interact with ALKBH4. For all interaction partners, the regions mediating binding to ALKBH4 comprised domains previously reported to be involved in interaction with DNA or chromatin. Furthermore, some of these partners showed nuclear co-localization with ALKBH4. However, the global gene expression pattern was only marginally altered upon ALKBH4 over-expression, and larger effects were observed in the case of ALKBH7. Although the molecular function of both proteins remains to be revealed, our findings suggest a role for ALKBH4 in regulation of gene expression or chromatin state and support the previous association of ALKBH7 with spermatogenesis.
Project description:The Fe(II)- and 2-oxoglutarate (2OG)-dependent dioxygenase AlkB from E. coli is a demethylase which repairs alkyl lesions in DNA, as well as RNA, through a direct reversal mechanism. Humans possess nine AlkB homologues (ALKBH1-8 and FTO). ALKBH2 and ALKBH3 display demethylase activities corresponding to that of AlkB, and both ALKBH8 and FTO are RNA modification enzymes. The biochemical functions of the rest of the homologues are still unknown. To increase our knowledge on the functions of ALKBH4 and ALKBH7 we have here performed yeast two-hybrid screens to identify interaction partners of the two proteins. While no high-confidence hits were detected in the case of ALKBH7, several proteins associated with chromatin and/or involved in transcription were found to interact with ALKBH4. For all interaction partners, the regions mediating binding to ALKBH4 comprised domains previously reported to be involved in interaction with DNA or chromatin. Furthermore, some of these partners showed nuclear co-localization with ALKBH4. However, the global gene expression pattern was only marginally altered upon ALKBH4 over-expression, and larger effects were observed in the case of ALKBH7. Although the molecular function of both proteins remains to be revealed, our findings suggest a role for ALKBH4 in regulation of gene expression or chromatin state and support the previous association of ALKBH7 with spermatogenesis.
Project description:DDX39A and DDX56 recombinant proteins were assayed using commercial protein microarrays in order to detect potential interaction partners.
Project description:The upstream Gg-globin cAMP-response element (G-CRE) plays a role in regulating Gg-globin expression through binding of CREB1, cJun and ATF2. In this study we identified the ATF2 DNA-binding partners. ATF2 knockdown resulted in a significant reduction of g-globin expression accompanied by decreased ATF2 binding to the G-CRE. By contrast, stably expressed ATF2 in K562 cells increased g-globin, which was reduced by ATF2 knockdown. Moreover, a similar role for ATF2 on g-globin expression was observed in primary erythroid progenitors. To understand the role of ATF2 in g-globin expression, chromatographically purified G-CRE/ATF2-interacting proteins were subjected to mass spectrometry analysis; binding partners included CREB1, cJun, Brg1, and histone deacetylases among others. Co-immunoprecipitation and chromatin immunoprecipitation assay demonstrated interaction of these proteins with ATF2 in CD34+ cells undergoing erythroid differentiation which was correlated with g-globin expression during development. These results suggest synergism between developmental stage-specific recruitments of the ATF2 protein complex and expression of g-globin during erythropoiesis. Microarray studies in K562 cells support additional roles for ATF2 in hematopoiesis and chromatin remodeling Total RNA was isolated from K562 cells in culture following transfection with scrambled siRNA or ATF2 siRNA following which RNA was isolated and gene expression monitored