The MICALs are a Family of F-actin Dismantling Oxidoreductases Conserved from Drosophila to Humans

Heng Wu,Hunkar Gizem Yesilyurt,Jonathan R Terman,Jimok Yoon

doi:10.1038/s41598-017-17943-5

Heng Wu, Hunkar Gizem Yesilyurt + Show 2 more

Open Access

https://doi.org/10.1038/s41598-017-17943-5

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Abstract

Cellular form and function – and thus normal development and physiology – are specified via proteins that control the organization and dynamic properties of the actin cytoskeleton. Using the Drosophila model, we have recently identified an unusual actin regulatory enzyme, Mical, which is directly activated by F-actin to selectively post-translationally oxidize and destabilize filaments – regulating numerous cellular behaviors. Mical proteins are also present in mammals, but their actin regulatory properties, including comparisons among different family members, remain poorly defined. We now find that each human MICAL family member, MICAL-1, MICAL-2, and MICAL-3, directly induces F-actin dismantling and controls F-actin-mediated cellular remodeling. Specifically, each human MICAL selectively associates with F-actin, which directly induces MICALs catalytic activity. We also find that each human MICAL uses an NADPH-dependent Redox activity to post-translationally oxidize actin’s methionine (M) M44/M47 residues, directly dismantling filaments and limiting new polymerization. Genetic experiments also demonstrate that each human MICAL drives F-actin disassembly in vivo, reshaping cells and their membranous extensions. Our results go on to reveal that MsrB/SelR reductase enzymes counteract each MICAL’s effect on F-actin in vitro and in vivo. Collectively, our results therefore define the MICALs as an important phylogenetically-conserved family of catalytically-acting F-actin disassembly factors.

Highlights

(h) MICAL protein family members contains the same core domains as Drosophila (d) Mical including a flavoprotein monooxygenase (FM) domain, a single calponin homology domain, and a single LIM domain
Since hMICAL-2, hMICAL-3 and Drosophila Mical, which have a low basal nicotinamide adenine dinucleotide phosphate (NADPH) consumption rate, increased their effects on F-actin dynamics in a concentration-dependent manner (Fig. 4e, Supplementary Figure 7d11), our results argue that MICAL-1 exhibits such rapid consumption of NADPH in the absence of its F-actin substrate that NADPH becomes limiting in allowing MICAL-1 to modify F-actin
F-actin) NADPH consumption by MICAL-1 is close to 100 times more NADPH consumption per second than hMICAL-2, 60 times more NADPH consumption per second than Drosophila Mical, and over 10 times more NADPH consumption per second than hMICAL-3. [MICALs] = 600 nM, [NADPH] = 200 μM. (b) human MICAL-1 (hM-1) generates substantially more hydrogen peroxide (H2O2) than other MICALs

Summary

Introduction

(h) MICAL protein family members contains the same core domains as Drosophila (d) Mical including a flavoprotein monooxygenase (FM) domain ( called the redox or MO domain), a single calponin homology domain, and a single LIM domain. Differences among the catalytic and F-actin regulatory activities of the MICALs exist, including that MICAL-1, which is the most divergent of the MICALs, has a single naturally-occurring amino acid substitution that allows it to have higher basal enzymatic activity and consume NADPH more robustly in the absence of its F-actin substrate than the other MICALs. Collectively, our results define the MICALs as an important new phylogenetically-conserved family of redox-acting actin filament disassembly factors

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