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Long noncoding RNAs (lncRNAs) are increasingly being appreciated as participants in regulation of important cellular processes, including transcription. Because lncRNAs are highly cell type specific, they have the potential to contribute to the unique transcriptional repertoire of diverse cells, but underlying mechanisms are unclear. We studied BGLT3, an erythroid lncRNA encoded downstream of Aγ-globin (HBG1). BGLT3and γ-globin genes are dynamically cotranscribed in erythroid cells in vivo. Deletion of BGLT3using CRISPR/Cas9 editing shows that it specifically contributes to regulation of γ-globin genes. We used reduction or overexpression of the RNA and inhibition of transcription through the locus by CRISPRi to distinguish functions of the transcript vs the underlying sequence. Transcription of the BGLT3locus is critical for looping between the γ-globin genes and BGLT3sequences. In contrast, the BGLT3transcript is dispensable for γ-globin/BGLT3looping but interacts with the mediator complex on chromatin. Manipulation of the BGLT3locus does not compromise γ-globin gene long-range looping interactions with the β-globin locus control region (LCR). These data reveal that BGLT3regulates γ-globin transcription in a developmental stage-specific fashion together with the LCR by serving as a separate means to increase RNA Pol II density at the γ-globin promoters.

For the first time, the effect of air-bridges on the suppression of the unwanted coupled-slotline (CSL) mode on a coplanar waveguide (CPW) is experimentally observed up to 250-GHz bandwidth, based on the picosecond photoconductive sampling technique. The CSL mode is initially originated from the asymmetric pulse generation on the CPW using ultrashort laser pulses and photoconductive switches. We find that more than two crossover air-bridges are needed to remove the unwanted CSL modes. The parasitic capacitance for the crossover air-bridge over the CPW and the parasitic inductance for the ground connecting air-bridge along the CPW are crucial in determining the signal distortion.