Regulation of cellulose synthesis via exocytosis and endocytosis

• Published in: Current opinion in plant biology 2022-10, Vol.69, p.102273-102273, Article 102273
• Main Authors: Zhu, Yu, McFarlane, Heather E.
• Format: Article
• Language: English
• Subjects: Cell wall signaling; Cellulose synthase; Cellulose synthesis; Clathrin; Endocytosis; Exocyst complex; Exocytosis; Plant cell wall; Secretion
• ISSN: 1369-5266; 1879-0356
• DOI: 10.1016/j.pbi.2022.102273

Cellulose is a critical component of plant cell walls. Cellulose is made at the plasma membrane by cellulose synthase (CESA) enzymes organized into large, multi-subunit cellulose synthase complexes (CSCs). Although CESAs are only active at the plasma membrane, fluorescently-tagged CESAs also substantially label the Golgi apparatus and other intracellular compartments, even when cellulose synthesis rates are high. These data imply that CESA activity is regulated by trafficking to the plasma membrane (exocytosis) and removal from the plasma membrane (endocytosis), as well as recycling of endocytosed CESAs back to the plasma membrane. Key molecular components and events of CESA exocytosis and endocytosis have recently been defined, primarily using mutant analysis and live-cell imaging in Arabidopsis thaliana. Here, we integrate these data into a working model of CESA regulation by exocytosis and endocytosis and highlight key outstanding questions. We present the hypothesis that cycling of CESAs between the plasma membrane and the endomembrane system is important for regulating cellulose synthesis and for maintaining a robust population of active CSCs in the plasma membrane. [Display omitted] •Cellulose synthase (CESA) enzymes are active at the plasma membrane where they are regulated by exocytosis and endocytosis.•Key molecular components and events of CESA exocytosis and endocytosis have recently been defined.•It is unclear how CESAs are targeted for endocytosis or why CESAs cycle to and from the plasma membrane.