The cell cycle is fundamental for life, enabling organisms to grow, heal, reproduce, and maintain cellular function. In the subcellular resource of the Human Protein Atlas protein imaging and single cell RNAseq analysis have been used to explore cell-to-cell variability and the cell cycle dependent proteome.

The cell cycle is a highly regulated sequence of events through which a cell grows and divides, consisting of four main phases: G1 (cell growth), S (DNA replication), G2 (preparation for mitosis), and M (mitosis and cytokinesis). In response to specific signals cells can also enter a non-dividing resting state, G0. Dysregulation of the cell cycle can lead to uncontrolled proliferation, genomic instability, and cancer, and it is therefore controlled by by a complex network of proteins regulated by transcription, post-translational modifications, and protein degradation.

The cell cycle is the primary source of cell-to-cell variation seen in asynchronous cell cultures. In the subcellular resource in the Human Protein Atlas this protein heterogeneity has been explored at the single cell level leading to the detection of almost 4000 proteins with cell-cell variation and about 400 proteins determined to be cell cycle dependent by their localization to mitotic structures.

Further, the use of single-cell RNA-sequencing data from FUCCI U2OS cells in combination with proteomic imaging has enabled monitoring of protein and RNA expression in individual cells during cell cycle progression. This resulted in the identification of almost 300 proteins correlating with interphase progression.

Learn more about cell cycle dependent proteins and their functional role here