The Arabidopsis Transcription Factor AtTCP15 Regulates Endoreduplication by Modulating Expression of Key Cell-cycle Genes

Abstract

Plant cells frequently undergo endoreduplication, a modified cell cycle in which genome is repeatedly replicated without cytokinesis. As the key step to achieve final size and function for cells, endoreduplication is prevalent during plant development. However, mechanisms to control the balance between endoreduplication and mitotic cell division are still poorly understood. Here, we show that the Arabidopsis TCP (CINCINNATA-like TEOSINTE BRANCHED1-CYCLOIDEA-PCF)-family transcription factor gene AtTCP15 is expressed in trichomes, as well as in rapidly dividing and vascular tissues. Expression of AtTCP15SRDX, AtTCP15 fused with a SRDX repressor domain, induces extra endoreduplication in trichomes and cotyledon cells in transgenic Arabidopsis. On the contrary, overexpression of AtTCP15 suppresses endoreduplication in trichomes and other examined cells. Misregulation of AtTCP15 affects the expression of several important genes involved in cell-cycle regulation. AtTCP15 protein binds directly to the promoter regions of CYCA2;3 and RETINOBLASTOMA-RELATED (RBR) genes, which play key roles in endoreduplication. Taken together, AtTCP15 plays an important role in regulating endoreduplication during Arabidopsis development.

TheArabidopsis thalianaTCP transcription factors: A broadening horizon beyond development

“…Given the similar cis-elements bound by both classes of TCP factors, it has been postulated that TCP proteins participate in a diverse spectrum of both antagonistic and synergistic biological interactions. 17,60,70,71 The antagonistic relationship between the 2 classes of TCP factors is known to balance contrasting activities of class I members, which promote cell proliferation in leaves, and class II CIN-TCPs, which act as negative regulators of leaf growth and positive modulators of senescence. 17,60,70,71 So far, TCP proteins have been demonstrated to be involved in a large variety of developmental processes (Table A1).…”

“…17,60,70,71 The antagonistic relationship between the 2 classes of TCP factors is known to balance contrasting activities of class I members, which promote cell proliferation in leaves, and class II CIN-TCPs, which act as negative regulators of leaf growth and positive modulators of senescence. 17,60,70,71 So far, TCP proteins have been demonstrated to be involved in a large variety of developmental processes (Table A1). Several independent studies have shed light on a redundant role in lateral organ organogenesis for 8 CIN-like TCP genes, including miR-JAW-targeted TCP2-4, TCP10 and TCP24 as well as miRJAWresistant TCP5, TCP13 and TCP17.…”

Ubiquitylation activates a peptidase that promotes cleavage and destabilization of its activating E3 ligases and diverse growth regulatory proteins to limit cell proliferation in Arabidopsis

“…Members of the DA1 family also limit cell proliferation (Li et al 2008), and loss-offunction mutations in BB and DA2 interact synergistically with the da1-1 allele of DA1 to increase organ and seed size in Arabidopsis (Li et al 2008;Xia et al 2013), suggesting that one of their growth-limiting activities is mediated by enhancing the growth-repressive activity of DA1 family members. Genetic analyses showed that DA1 reduced the stability of both UBP15 (Du et al 2014), a deubiquitylation enzyme promoting cell proliferation (Liu et al 2008), and TEOSINTE BRANCED 1/CYCLOI-DEA/PCF 14 (TCP14) and TCP15 proteins (Peng et al 2015), which repress endoreduplication by transcriptional control of RETINOBLASTOMA-RELATED1 (RBR1) and CYCLIN A2;3 (CYCA2;3) gene expression (Li et al 2012). …”

The Cotton Transcription Factor TCP14 Functions in Auxin-Mediated Epidermal Cell Differentiation and Elongation

“…This notion is further supported by a recent study of Uberti-Manassero et al (2012), which showed that AtTCP15 regulates the expression of boundary-specific genes, presumably through alteration of auxin homeostasis. Although these studies represent important achievements in understanding the roles of this family of proteins, elucidation of the functions of class I TCP proteins is still limited (Li et al, 2012).…”