Interplay of TRIM2 E3 Ubiquitin Ligase and ALIX/ESCRT Complex: Control of Developmental Plasticity During Early Neurogenesis.

Ashwin Lokapally,Herbert Neuhaus,Thomas Hollemann,Juliane Herfurth

doi:10.3390/cells9071734

Abstract

Tripartite motif 2 (TRIM2) drives neurite outgrowth and polarization, is involved in axon specification, and confers neuroprotective functions during rapid ischemia. The mechanisms controlling neuronal cell fate determination and differentiation are fundamental for neural development. Here, we show that in Xenopus, trim2 knockdown affects primary neurogenesis and neural progenitor cell survival. Embryos also suffer from severe craniofacial malformation, a reduction in brain volume, and the loss of motor sensory function. Using a high-throughput LC-MS/MS approach with GST-Trim2 as bait, we pulled down ALG-2 interacting protein X (Alix) from Xenopus embryonic lysates. We demonstrate that the expression of trim2/TRIM2 and alix/ALIX overlap during larval development and on a cellular level in cell culture. Interestingly, trim2 morphants showed a clustering and apoptosis of neural progenitors, which are phenotypic hallmarks that are also observed in Alix KO mice. Therefore, we propose that the interaction of Alix and Trim2 plays a key role in the determination and differentiation of neural progenitors via the modulation of cell proliferation/apoptosis during neurogenesis.

Highlights

Tripartite motif (TRIM) proteins represent a family with more than 80 members in humans.TRIM proteins are characterized by a similar domain structure consisting of a RING-finger domain, one or two zinc finger domains, so-called B boxes, and a coiled-coil domain
A comparison of amino acid sequences revealed that the known domains of Tripartite motif 2 (TRIM2)/Trim2 are fully conserved between mammals and Xenopus
To analyze the spatial expression of trim2 during early neural development, we performed a series of whole-mount in situ hybridizations (Wmish) on Xenopus embryos

Summary

Introduction

Tripartite motif (TRIM) proteins represent a family with more than 80 members in humans.TRIM proteins are characterized by a similar domain structure consisting of a RING-finger domain, one or two zinc finger domains, so-called B boxes, and a coiled-coil domain. Most TRIM family members have been proposed to function as E3 ubiquitin ligases due the presence of their RING-finger domain. The RING-type E3 ligases operate as scaffolds to recruit both ubiquitin coupled E2 and substrate, thereby facilitating ubiquitination [1,2]. Despite their overall similar structural organization, TRIM proteins regulate a wide variety of cellular processes. One such ubiquitin ligase, TRIM2, is expressed in the mouse brain, predominantly within the cytoplasm of hippocampal neurons, where it interacts with motor protein myosin V [3].

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