The low-dimensional embedding representation of scATAC data refers to the process of transforming high-dimensional data generated by scATAC-seq into a lower-dimensional space using mathematical dimensionality reduction techniques, facilitating visualization, clustering analysis, and biological interpretation. Due to the typically high dimensionality of scATAC-seq data (with potentially thousands of open chromatin sites per cell), direct analysis of these raw data is not only computationally expensive but also difficult to intuitively grasp the patterns and structures within the data.
Low-dimensional embedding methods such as t-distributed Stochastic Neighbor Embedding (t-SNE), Principal Component Analysis (PCA), Uniform Manifold Approximation and Projection (UMAP), or Locally Linear Embedding (LLE) are employed to mitigate this complexity. These techniques aim to preserve important structures and neighborhood relationships within the data while reducing the dimensionality, allowing the data to be visualized in two or three-dimensional plots for researchers to observe clustering of cell populations, continuous trends, or specific characteristics of cell types.
In the analysis of scATAC-seq data, low-dimensional embedding representations aid in discovering cell subpopulations, deciphering cell differentiation trajectories, and inferring relationships between chromatin states and gene expression regulation. Through this approach, researchers can extract meaningful biological insights from the vast and complex single-cell epigenetic data.