Function and evolution of ‘green’ GSK3/Shaggy-like kinases

Abstract

Glycogen synthase kinase 3 (GSK3) proteins, also known as SHAGGY-like kinases, have many important cell signalling roles in animals, fungi and amoebae. In particular, GSK3s participate in key developmental signalling pathways and also regulate the cytoskeleton. GSK3-encoding genes are also present in all land plants and in algae and protists, raising questions about possible ancestral functions in eukaryotes. Recent studies have revealed that plant GSK3 proteins are actively implicated in hormonal signalling networks during development as well as in biotic and abiotic stress responses. In this review, we outline the mechanisms of Arabidopsis GSK3 action, summarize GSK3 functions in dicot and monocot flowering plants, and speculate on the possible functions of GSK3s in the earliest-evolving land plants.

Plant GSK3 proteins regulate xylem cell differentiation downstream of TDIF–TDR signalling

“…In mammals, there are only two isoforms of GSK3, alpha and beta, which play crucial roles in the various signal transduction pathways 39,40 . On the other hand, Arabidopsis GSK3s are encoded by ten genes 38 , consisting of four subgroups 22 . Of them, SKI and II members redundantly mediate TDIF signalling, as suggested by Y2H, FRET and genetic analyses.…”

Stress-Induced GSK3 Regulates the Redox Stress Response by Phosphorylating Glucose-6-Phosphate Dehydrogenase in Arabidopsis

“…ASKa is a novel component regulating the high salinity response. Plant GSK3s are encoded by a gene family, and different GSK3 proteins have diverse functions (Jonak and Hirt, 2002;Saidi et al, 2012). In addition to ASKa, other GSK3 family members have been implicated in the response of plants to salinity.…”

“…Originally identified in mammals as a cytoplasmic modulator of glycogen metabolism, GSK3 is now recognized as a central regulator of an array of cellular events, including cell fate determination, microtubule function, cell cycle regulation, apoptosis, and inflammatory responses (Cohen and Frame, 2001;Doble and Woodgett, 2003;Jope and Johnson, 2004;Martin et al, 2005). In plants, GSK3/ shaggy-like kinases (GSKs) are encoded by a gene family that directs different physiological responses (Jonak and Hirt, 2002;Saidi et al, 2012). In alfalfa (Medicago sativa), several GSKs have emerged as regulatory components in stress signaling.…”

Structural and Functional Characterization of Arabidopsis GSK3-like Kinase AtSK12

“…Of the ten members of the AtSK family, seven members (AtSK11,12,13,21,22,23, and 31) are known to function in BR signaling (Saidi et al, 2012 (Kim et al, 2009). Consistently, gain-of-func-tion mutants of AtSK12 belonging to subfamily I showed almost normal development of stomatal cell, although they have severe growth defects such as a dwarfism (Fig.…”

“…In Arabidopsis, there are ten GSK3-like kinases. So far, Arabidopsis Shaggy/GSK3-like kinases (AtSK) appear to have diverse functions in the regulation of growth, responses for abiotic and biotic stress, flower and stomatal development (Gudesblat et al, 2012;Jonak and Hirt, 2002;Saidi et al, 2012). Of these, the molecular action of plant GSK3-like kinases was best understood in brassinosteroid (BR) signaling (Choe et al, 2002;He et al, 2002;Kim et al, 2009;Li and Nam, 2002;Peng et al, 2008;Perez-Perez et al, 2002;Rozhon et al, 2010).…”