LANCL1 binds abscisic acid and stimulates glucose transport and mitochondrial respiration in muscle cells via the AMPK/PGC-1α/Sirt1 pathway

Abstract

Objective Abscisic acid (ABA) is a plant hormone also present and active in animals. In mammals, ABA regulates blood glucose levels by stimulating insulin-independent glucose uptake and metabolism in adipocytes and myocytes through its receptor LANCL2. The objective of this study was to investigate whether another member of the LANCL protein family, LANCL1, also behaves as an ABA receptor and, if so, which functional effects are mediated by LANCL1. Methods ABA binding to human recombinant LANCL1 was explored by equilibrium-binding experiments with [ 3 H]ABA, circular dichroism, and surface plasmon resonance. Rat L6 myoblasts overexpressing either LANCL1 or LANCL2, or silenced for the expression of both proteins, were used to investigate the basal and ABA-stimulated transport of a fluorescent glucose analog (NBDG) and the signaling pathway downstream of the LANCL proteins using Western blot and qPCR analysis. Finally, glucose tolerance and sensitivity to ABA were compared in LANCL2 −/− and wild-type (WT) siblings. Results Human recombinant LANCL1 binds ABA with a K d between 1 and 10 μM, depending on the assay (i.e., in a concentration range that lies between the low and high-affinity ABA binding sites of LANCL2). In L6 myoblasts, LANCL1 and LANCL2 similarly, i) stimulate both basal and ABA-triggered NBDG uptake (4-fold), ii) activate the transcription and protein expression of the glucose transporters GLUT4 and GLUT1 (4-6-fold) and the signaling proteins AMPK/PGC-1α/Sirt1 (2-fold), iii) stimulate mitochondrial respiration (5-fold) and the expression of the skeletal muscle (SM) uncoupling proteins sarcolipin (3-fold) and UCP3 (12-fold). LANCL2 −/− mice have a reduced glucose tolerance compared to WT. They spontaneously overexpress LANCL1 in the SM and respond to chronic ABA treatment (1 μg/kg body weight/day) with an improved glycemia response to glucose load and an increased SM transcription of GLUT4 and GLUT1 (20-fold) of the AMPK/PGC-1α/Sirt1 pathway and sarcolipin, UCP3, and NAMPT (4- to 6-fold). Conclusions LANCL1 behaves as an ABA receptor with a somewhat lower affinity for ABA than LANCL2 but with overlapping effector functions: stimulating glucose uptake and the expression of muscle glucose transporters and mitochondrial uncoupling and respiration via the AMPK/PGC-1α/Sirt1 pathway. Receptor redundancy may have been advantageous in animal evolution, given the role of the ABA/LANCL system in the insulin-independent stimulation of cell glucose uptake and energy metabolism.

Short Linear Motifs Orchestrate Functioning of Human Proteins during Embryonic Development, Redox Regulation, and Cancer

“…Additionally, glutathione S-transferase LANCL1 is involved in oxidative stress response and is overexpressed in prostate cancer cells [ 40 ]. LANCL1 causes the expression of glucose transporters, as well as mitochondrial uncoupling and respiration via the AMPK/PGC-1α/Sirt1 pathway [ 71 ]. HSPB-associated protein 1 (HSPBAP1) exhibits oxidoreductase activity, and its overexpression has been observed in prostate cancer samples [ 41 ].…”

Relieving Cellular Energy Stress in Aging, Neurodegenerative, and Metabolic Diseases, SIRT1 as a Therapeutic and Promising Node

“…Metabolic stress is characterized by a decrease in the ratio of ATP to AMP/ADP, which activates AMPK, resulting in phosphorylation that activates a series of pathways that up-regulate ATP (Herzig and Shaw, 2018 ; Yan et al, 2018 ). As a sensor for the energy state of cells, researchers found that AMPK can be activated when skeletal muscle energy is exhausted, and directly phosphorylate PGC-1α at threonine-177 and serine-538 (Spinelli et al, 2021 ). Moreover, researchers discovered that AMPK regulates NAD+/NADH ratio and SIRT1 activity in a manner independent of NAMPT shortly after the activation, and this process relies on mitochondrial β-oxidation (Cantó et al, 2009 ).…”

The ABA-LANCL1/2 Hormone-Receptors System Protects H9c2 Cardiomyocytes from Hypoxia-Induced Mitochondrial Injury via an AMPK- and NO-Mediated Mechanism

“…In mammals, ABA is also involved in glycemia homeostasis: plasma ABA increases after an oral glucose load in healthy subjects [ 12 ], and intake of microgram amounts of ABA improves glucose tolerance in rats and in healthy humans undergoing an oral glucose load [ 13 ]. The mechanism through which ABA reduces glycemia occurs via an AMPK/PGC-1α/Sirt1-dependent pathway, which activates transcription and expression of GLUT4 and GLUT1 in the skeletal muscle, resulting in a significant increase in insulin-independent glucose uptake in vitro on isolated cells, ex vivo on isolated skeletal muscle and in vivo in rodents and humans [ 14 , 15 ]. ABA also stimulates oxidative glucose metabolism, increases mitochondrial number and respiration and stimulates the expression of uncoupling proteins, both in the skeletal muscle and in brown adipocytes, leading to increased glucose uptake and consumption by these tissues [ 14 ].…”

“…LANCL1 shares with LANCL2 a sequence identity of approx. 50%, a similar intracellular localization (it is a peripheral membrane protein) and tissue expression pattern [ 15 ]. Interestingly, silencing or genetic ablation of LANCL2 in cells or in mice results in the spontaneous overexpression of LANCL1 [ 15 ].…”

“…50%, a similar intracellular localization (it is a peripheral membrane protein) and tissue expression pattern [ 15 ]. Interestingly, silencing or genetic ablation of LANCL2 in cells or in mice results in the spontaneous overexpression of LANCL1 [ 15 ]. Similarly, silencing of LANCL1 causes a significant increase in the expression of LANCL2 in cells [ 15 ].…”