Molecular mechanism of a protein that regulates endoreduplication and cell growth in Arabidopsis

Endoreduplication is an alternative version of the classic cell cycle, during which cells replicate their nuclear DNA without subsequently dividing, thereby increasing their level of ploidy. This process occurs in a variety of cell types and contributes to normal growth and development of plant cells and plant responses to biotic and abiotic stress. However, the underlying mechanism for endoreduplication has remained elusive.

SNW/SKI-INTERACTING PROTEIN (SKIP) functions as a component of the spliceosome and as a co-regulator of the transcription of a number of important cellular signaling molecules involved in the regulation of plant growth and development. However, the role of SKIP in endoreduplication control has not been described so far.

A joint research team led by Prof. Li Yunhai at the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Profs. Song Chunpeng and Guo Siyi from Henan University recently revealed the molecular mechanism of a SNW/SKI INTERACTING PROTEIN in regulating endoreduplication and cell growth in Arabidopsis.

Previously, Prof. Li Yunhai’s team reported that DA3-encoded UBIQUITIN-SPECIFIC PROTEASE 14 (UBP14) interacts with ULTRAVIOLET-B INSENSITIVE4 (UVI4) to regulate endoreduplication and cell and organ growth in Arabidopsis. Then the regulatory cascade for the UBP14/DA3-CDKB1;1-CDKG2/SUD6-mediated control of endoreduplication and cell growth in Arabidopsis was established.

In this study, researchers discovered that another suppressor of the da3-1 (sud3) mutation suppressed the da3-1 phenotype. SUD3 encodes SKIP. Overexpression of SKIP/SUD3 significantly increases ploidy levels, indicating that SKIP/SUD3 is a positive regulator of endoreduplication. SUD3 physically interacts with DA3 and UVI4 in vitro and in vivo. Genetic analyzes support that SUD3 acts downstream of DA3 and UVI4 to control endoreduplication and cell growth.

In summary, this work reveals an important genetic and molecular mechanism by which SKIP/SUD3 associates with UBP14/DA3 and UVI4 to modulate endoreduplication and cell growth in Arabidopsis.

This work entitled “A SNW/SKI-INTERACTING PROTEIN Affects Endoreduplication and Cell Growth in Arabidopsis” was published in plant physiology on September 5, 2022.