Controversial Regulation of Gene Expression and Protein Transduction of Aquaporins under Drought and Salinity Stress.

Lucía Yepes-Molina,Gloria Bárzana,Micaela Carvajal

doi:10.3390/plants9121662

Lucía Yepes-Molina, Gloria Bárzana + Show 1 more

Open Access

https://doi.org/10.3390/plants9121662

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Abstract

Enhancement of the passage of water through membranes is one of the main mechanisms via which cells can maintain their homeostasis under stress conditions, and aquaporins are the main participants in this process. However, in the last few years, a number of studies have reported discrepancies between aquaporin messenger RNA (mRNA) expression and the number of aquaporin proteins synthesised in response to abiotic stress. These observations suggest the existence of post-transcriptional mechanisms which regulate plasma membrane intrinsic protein (PIP) trafficking to the plasma membrane. This indicates that the mRNA synthesis of some aquaporins could be modulated by the accumulation of the corresponding encoded protein, in relation to the turnover of the membranes. This aspect is discussed in terms of the results obtained: on the one hand, with isolated vesicles, in which the level of proteins present provides the membranes with important characteristics such as resistance and stability and, on the other, with isolated proteins reconstituted in artificial liposomes as an in vitro method to address the in vivo physiology of the entire plant.

Highlights

Aquaporins are regulated to deal with variations in the amount and availability of water, since they are channels that allow water transport across cell membranes [1]
Aquaporins in plants are placed in seven subfamilies according to their intracellular locations and sequence similarities: (1) plasma membrane intrinsic proteins (PIPs), (2) tonoplast intrinsic proteins (TIPs), (3) nodulin 26-like intrinsic proteins (NIPs), (4) small, basic intrinsic proteins (SIPs), (5) GlpF-like intrinsic proteins (GIPs), (6) hybrid intrinsic proteins (HIPs), and (7) uncategorised X intrinsic protein (XIPs) [22]
In the work carried out by Boursiac et al [23], the amount of protein was analysed 24 h after the treatment commenced, and the results showed a correlation between the messenger RNA (mRNA) levels and the amounts of PIP aquaporins in the plasma membrane (PM), as both decreased

Summary

Introduction

Aquaporins are regulated to deal with variations in the amount and availability of water, since they are channels that allow water transport across cell membranes [1] They are regulated at multiple levels (for instance, during transcription and translation or through post-translational modifications) to modulate the trafficking, gating, or degradation/turnover [2]. Soil salinity and drought affect plant growth and productivity and, are a problem for agriculture [8] These two stresses, in many aspects, can be studied in parallel because both involve a reduction in water uptake and, a net plant water loss; aquaporins are important to the understanding of the response of plants to these stresses [9].

General Features

Discrepancies between the mRNA and Protein Levels of PIP Aquaporins

PIP Trafficking and Turnover under Drought and Salt Stresses

In Vitro Studies to Determine the In Vivo Physiology of Plant Aquaporins

Concluding Remarks