Transmembrane kinase 1‐mediated auxin signal regulates membrane‐associated clathrin in Arabidopsis roots

• Published in: Journal of integrative plant biology 2023-01, Vol.65 (1), p.82-99
• Main Authors: Wang, Yutong, Yan, Xu, Xu, Mei, Qi, Weiyang, Shi, Chunjie, Li, Xiaohong, Ma, Jiaqi, Tian, Dan, Shou, Jianxin, Wu, Haijun, Pan, Jianwei, Li, Bo, Wang, Chao
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; auxin; Auxins; Cell Membrane - metabolism; Chains; Clathrin; Clathrin - metabolism; Efflux; Endocytosis; Gravitropism; Immunofluorescence; Indoleacetic Acids - metabolism; Kinases; Light chains; Membrane proteins; Membranes; Molecular modelling; PIN2; Plant hormones; Plant Roots - metabolism; Proteins; Seedlings; Skewed distributions; transmembrane kinase1 (TMK1)
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.13366

ABSTRACT Clathrin‐mediated endocytosis (CME) is the major endocytic pathway in eukaryotic cells that directly regulates abundance of plasma membrane proteins. Clathrin triskelia are composed of clathrin heavy chains (CHCs) and light chains (CLCs), and the phytohormone auxin differentially regulates membrane‐associated CLCs and CHCs, modulating the endocytosis and therefore the distribution of auxin efflux transporter PIN‐FORMED2 (PIN2). However, the molecular mechanisms by which auxin regulates clathrin are still poorly understood. Transmembrane kinase (TMKs) family proteins are considered to contribute to auxin signaling and plant development; it remains unclear whether they are involved in PIN transport by CME. We assessed TMKs involvement in the regulation of clathrin by auxin, using genetic, pharmacological, and cytological approaches including live‐cell imaging and immunofluorescence. In tmk1 mutant seedlings, auxin failed to rapidly regulate abundance of both CHC and CLC and to inhibit PIN2 endocytosis, leading to an impaired asymmetric distribution of PIN2 and therefore auxin. Furthermore, TMK3 and TMK4 were shown not to be involved in regulation of clathrin by auxin. In summary, TMK1 is essential for auxin‐regulated clathrin recruitment and CME. TMK1 therefore plays a critical role in the establishment of an asymmetric distribution of PIN2 and an auxin gradient during root gravitropism. Endocytosis of the clathrin‐mediated auxin efflux transporter PIN‐FORMED2 (PIN2) promotes auxin efflux for auxin‐mediated regulation of organogenesis and development. The transmembrane kinase family protein TMK1 mediates auxin regulation of clathrin as well as clathrin‐mediated PIN2 endocytosis, resulting in basipetal auxin transport, thereby influencing plant root gravitropism.