Project description:Human LIN28A and B are RNA-binding proteins (RBPs) conserved in animals with important roles during development and stem cell reprogramming. We used Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) in HEK293 cells and identified a largely overlapping set of ~3,000 mRNAs at ~9,500 sites located in the 3M-bM-^@M-^YUTR and CDS. In vitro and in vivo, LIN28 preferentially bound single-stranded RNA containing a uridine-rich element and one or more flanking guanosines, and appeared to be able to disrupt base-pairing to access these elements when embedded in predicted secondary structure. In HEK293 cells, LIN28 protein binding mildly stabilized target mRNAs and increased protein abundance. The top targets were its own mRNAs and those of other RBPs and cell-cycle regulators. Alteration of LIN28 protein levels also negatively regulated the abundance of some, but not all let-7 miRNA family members, indicating sequence-specific binding of let-7 precursors to LIN28 proteins and competition with cytoplasmic miRNA biogenesis factors. LIN28 protein PAR-CLIP
Project description:The goals of this study were to identify LIN28 downstream gene targets in breast cancer cells. We use a subclone of the MCF-7 breast cancer cell line, MCF-7M as our model system. Methods: mRNA-protein complexes (mRNP) lysates were prepared from MCF-7M cells and incubated with Protein-A Sepharose beads (Sigma-Aldrich) and either LIN28 (Abcam) or control normal rabbit serum IgG antibodies. LIN28 interacting mRNAs were identified by whole genome sequencing. Results: Using an optimized data analysis workflow, we mapped approximately 13 million sequence reads for LIN28-IP and CTL- IP (IgG), respectively to the to the human genome (build h19). Conclusions: mRNA were significantly bound by LIN28 if LIN28 RIP had 2.5 fold increase in normalized reads compared to IgG. We found that LIN28 was predominantly bound at coding exons and 3'UTRs, 38% & 45% respectively, in the 843 mRNAs within MCF-7M genome.
Project description:Human LIN28A and B are RNA-binding proteins (RBPs) conserved in animals with important roles during development and stem cell reprogramming. We used Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) in HEK293 cells and identified a largely overlapping set of ~3,000 mRNAs at ~9,500 sites located in the 3’UTR and CDS. In vitro and in vivo, LIN28 preferentially bound single-stranded RNA containing a uridine-rich element and one or more flanking guanosines, and appeared to be able to disrupt base-pairing to access these elements when embedded in predicted secondary structure. In HEK293 cells, LIN28 protein binding mildly stabilized target mRNAs and increased protein abundance. The top targets were its own mRNAs and those of other RBPs and cell-cycle regulators. Alteration of LIN28 protein levels also negatively regulated the abundance of some, but not all let-7 miRNA family members, indicating sequence-specific binding of let-7 precursors to LIN28 proteins and competition with cytoplasmic miRNA biogenesis factors.
Project description:Human LIN28A and B are RNA-binding proteins (RBPs) conserved in animals with important roles during development and stem cell reprogramming. We used Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) in HEK293 cells and identified a largely overlapping set of ~3,000 mRNAs at ~9,500 sites located in the 3’UTR and CDS. In vitro and in vivo, LIN28 preferentially bound single-stranded RNA containing a uridine-rich element and one or more flanking guanosines, and appeared to be able to disrupt base-pairing to access these elements when embedded in predicted secondary structure. In HEK293 cells, LIN28 protein binding mildly stabilized target mRNAs and increased protein abundance. The top targets were its own mRNAs and those of other RBPs and cell-cycle regulators. Alteration of LIN28 protein levels also negatively regulated the abundance of some, but not all let-7 miRNA family members, indicating sequence-specific binding of let-7 precursors to LIN28 proteins and competition with cytoplasmic miRNA biogenesis factors.
Project description:Human LIN28A and B are RNA-binding proteins (RBPs) conserved in animals with important roles during development and stem cell reprogramming. We used Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) in HEK293 cells and identified a largely overlapping set of ~3,000 mRNAs at ~9,500 sites located in the 3M-bM-^@M-^YUTR and CDS. In vitro and in vivo, LIN28 preferentially bound single-stranded RNA containing a uridine-rich element and one or more flanking guanosines, and appeared to be able to disrupt base-pairing to access these elements when embedded in predicted secondary structure. In HEK293 cells, LIN28 protein binding mildly stabilized target mRNAs and increased protein abundance. The top targets were its own mRNAs and those of other RBPs and cell-cycle regulators. Alteration of LIN28 protein levels also negatively regulated the abundance of some, but not all let-7 miRNA family members, indicating sequence-specific binding of let-7 precursors to LIN28 proteins and competition with cytoplasmic miRNA biogenesis factors. To assess whether miRNAs are regulated by LIN28B we analyzed the miRNA levels of LIN28B overexpressing and LIN28B-depleted cells using small RNA cDNA library sequencing. The RBP LIN28B was depleted by siRNAs and the expression levels was compared to mock-transfected HEK293 cells.
Project description:Human LIN28A and B are RNA-binding proteins (RBPs) conserved in animals with important roles during development and stem cell reprogramming. We used Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) in HEK293 cells and identified a largely overlapping set of ~3,000 mRNAs at ~9,500 sites located in the 3M-bM-^@M-^YUTR and CDS. In vitro and in vivo, LIN28 preferentially bound single-stranded RNA containing a uridine-rich element and one or more flanking guanosines, and appeared to be able to disrupt base-pairing to access these elements when embedded in predicted secondary structure. In HEK293 cells, LIN28 protein binding mildly stabilized target mRNAs and increased protein abundance. The top targets were its own mRNAs and those of other RBPs and cell-cycle regulators. Alteration of LIN28 protein levels also negatively regulated the abundance of some, but not all let-7 miRNA family members, indicating sequence-specific binding of let-7 precursors to LIN28 proteins and competition with cytoplasmic miRNA biogenesis factors. To assess whether the transcripts identified by PAR-CLIP are regulated by LIN28B we analyzed the mRNA levels of LIN28B overexpressing and LIN28B-depleted cells using microarrays. Transcripts crosslinked to LIN28B were slightly downregulated upon LIN28B knockdown compared to LIN28B overexpression indicating that LIN28B stabilizes transcripts. The RBP LIN28B was depleted by siRNAs and the expression levels was compared to mock-transfected HEK293 cells The RBP LIN28B was depleted by siRNAs and the expression levels was compared to mock-transfected HEK293 cells