nMOWChIP-seq: low-input genome-wide mapping of non-histone targets.

Genome-wide profiling of interactions between genome and various functional proteins is critical for understanding regulatory processes involved in development and diseases. Conventional assays require a large number of cells and high-quality data on tissue samples are scarce. Here we optimized a low-input chromatin immunoprecipitation followed by sequencing (ChIP-seq) technology for profiling RNA polymerase II (Pol II), transcription factor (TF), and enzyme binding at the genome scale. The new approach produces high-quality binding profiles using 1,000-50,000 cells. We used the approach to examine the binding of Pol II and two TFs (EGR1 and MEF2C) in cerebellum and prefrontal cortex of mouse brain and found that their binding profiles are highly reflective of the functional differences between the two brain regions. Our analysis reveals the potential for linking genome-wide TF or Pol II profiles with neuroanatomical origins of brain cells.

A diffusion-based microfluidic device for single-cell RNA-seq.

Microfluidic devices provide a low-input and efficient platform for single-cell RNA-seq (scRNA-seq). Existing microfluidic devices have a complicated multi-chambered structure for handling the multi-step process involved in RNA-seq and dilution between steps is used to negate the inhibitory effects among reagents. This makes the device difficult to fabricate and operate. Here we present microfluidic diffusion-based RNA-seq (MID-RNA-seq) for conducting scRNA-seq with a diffusion-based reagent swapping scheme. This device incorporates cell trapping, lysis, reverse transcription and PCR amplification all in one simple microfluidic device. MID-RNA-seq provides high data quality that is comparable to existing scRNA-seq methods while implementing a simple device design that permits multiplexing. The robustness and scalability of the MID-RNA-seq device will be important for transcriptomic studies of scarce cell samples.