ADP-ribosylation factors (ARF) GTPases are activated by guanine nucleotide exchange factors (GEFs) to support cellular homeostasis. Key to understanding spatio-temporal regulation of ARF signaling is the mechanism of GEF recruitment to membranes. Small GEFs are recruited through phosphoinositide (PIP) binding by a pleckstrin homology (PH) domain downstream from the catalytic Sec7 domain (Sec7d). The large GEFs lack PH domains, and their recruitment mechanisms are poorly understood. We probed Golgi recruitment of GBF1, a GEF catalyzing ARF activation required for Golgi homeostasis. We show that the homology downstream of Sec7d-1 (HDS1) regulates Golgi recruitment of GBF1. We document that GBF1 binds phosphoinositides, preferentially PI3P, PI4P and PI(4,5)P₂, and that lipid binding requires the HDS1 domain. Mutations within HDS1 that reduce GBF1 binding to specific PIPs in vitro inhibit GBF1 targeting to Golgi membranes in cells. Our data imply that HDS1 and PH domains are functionally analogous in that each uses lipid-based membrane information to regulate GEF recruitment. Lipid-based recruitment of GBF1 extends the paradigm of lipid regulation to small and large GEFs and suggests that lipid-based mechanisms evolved early during GEF diversification. This article has an associated First Person interview with the first author of the paper.

The integrity of the Golgi and trans-Golgi network (TGN) is disrupted by Brefeldin A, which inhibits the GBF1, BIG1 and BIG2 guanine nucleotide exchange factors (GEFs). Using a cellular replacement assay to assess GBF1 functionality without interference from the BIGs, we show that GBF1 alone maintains Golgi architecture, facilitates secretion, activates ARF1, 3, 4 and 5, and recruits ARF effectors to Golgi membranes. Unexpectedly, GBF1 also supports TGN integrity and recruits numerous TGN-localized ARF effectors. The impact of the catalytic Sec7 domain (Sec7d) on GBF1 functionality was assessed by swapping it with the Sec7d from ARNO/cytohesin-2, a plasma membrane GEF reported to activate all ARFs. The resulting chimera (GARG) targets like GBF1, supports Golgi/TGN architecture and facilitates secretion. However, unlike GBF1, GARG activates all ARFs (including ARF6) at the Golgi/TGN and recruits additional ARF effectors to the Golgi/TGN. Our results have general implications: 1) GEF's targeting is independent of Sec7d, but Sec7d influence the GEF substrate specificity and downstream effector events; 2) all ARFs have access to all membranes, but are restricted in their distribution by the localization of their activating GEFs; and 3) effector association with membranes requires the coincidental presence of activated ARFs and specific membrane identifiers.

The endoplasmic reticulum (ER) fulfills essential duties in cell physiology, and impairment of this organelle’s functions is associated with a wide number of metabolic diseases. When ER stress is generated in the adipose tissue, it is observed that the metabolism and energy homeostasis of the adipocytes are altered, leading to obesity-associated metabolic disorders such as type 2 diabetes (T2D). In the present work, we aimed to evaluate the protective effects of Δ9-tetrahydrocannabivarin (THCV, a cannabinoid compound isolated from Cannabis sativa L.) against ER stress in adipose-derived mesenchymal stem cells. Our results show that pre-treatment with THCV prevents the subcellular alteration of cell components such as nuclei, F-actin, or mitochondria distribution, and restores cell migration, cell proliferation and colony-forming capacity upon ER stress. In addition, THCV partially reverts the effects that ER stress induces regarding the activation of apoptosis and the altered anti- and pro-inflammatory cytokine profile. This indicates the protective characteristics of this cannabinoid compound in the adipose tissue. Most importantly, our data demonstrate that THCV decreases the expression of genes involved in the unfolded protein response (UPR) pathway, which were upregulated upon induction of ER stress. Altogether, our study shows that the cannabinoid THCV is a promising compound that counters the harmful effects triggered by ER stress in the adipose tissue. This work paves the way for the development of new therapeutic means based on THCV and its regenerative properties to create a favorable environment for the development of healthy mature adipocyte tissue and to reduce the incidence and clinical outcome of metabolic diseases such as diabetes.

Corneal ulcers, characterized by severe inflammation of the cornea, can lead to serious, debilitating complications and may be vision-threatening for horses. In this study, we aimed to investigate the role of endoplasmic reticulum (ER) stress in corneal stem progenitor cell (CSSC) dysfunction and explore the potential of equine adipose-derived stromal stem cell (ASC)-derived extracellular vesicles (EVs) to improve corneal wound healing. We showed that CSSCs expressed high levels of CD44, CD45, and CD90 surface markers, indicating their stemness. Supplementation of the ER-stress-inducer tunicamycin to CSSCs resulted in reduced proliferative and migratory potential, accumulation of endoplasmic reticulum (ER)-stressed cells in the G0/G1 phase of the cell cycle, increased expression of proinflammatory genes, induced oxidative stress and sustained ER stress, and unfolded protein response (UPR). Importantly, treatment with EVs increased the proliferative activity and number of cells in the G2/Mitosis phase, enhanced migratory ability, suppressed the overexpression of proinflammatory cytokines, and upregulated the anti-inflammatory miRNA-146a-5p, compared to control and/or ER-stressed cells. Additionally, EVs lowered the expression of ER-stress master regulators and effectors (PERK, IRE1, ATF6, and XBP1), increased the number of mitochondria, and reduced the expression of Fis-1 and Parkin, thereby promoting metabolic homeostasis and protecting against apoptosis in equine CSSCs. Our findings demonstrate that MSCs-derived EVs represent an innovative and promising therapeutic strategy for the transfer of bioactive mediators which regulate various cellular and molecular signaling pathways.

Background/Objectives: Magnesium (Mg)-based food supplements contribute to the maintenance of adequate levels of Mg that are essential for overall health and well-being. The aim of this double-blind, randomized, cross-over clinical study was to assess the plasma Mg levels in volunteers following the oral administration of a magnesium-based nutraceutical ingredient, MAGSHAPE^TM microcapsules (Mg-MS), in comparison to other commonly used magnesium sources, including the following: Mg Oxide (MgO), Mg Citrate (Mg-C), and Mg bisglycinate (Mg-BG). Methods: A total of 40 healthy women and men were put on a low-Mg diet for 7 days, and after 8 h of fasting, a blood sample was taken from a digital puncture before (0 h) and 1 h, 4 h, and 6 h after the oral intake of each product. Results: Our results showed that the blood plasma levels of Mg increased significantly at all tested time-points after the oral intake of Mg-MS, while the blood plasma levels of Mg increased significantly only after 1 and 4 h of the oral intake of MgO and Mg-C, respectively. However, no significant increase in Mg levels was observed upon the intake of Mg-BG. Interestingly, the Mg-MS microencapsulation technology was observed to enable a sustained increase in plasma Mg levels over the duration of this study, i.e., 1, 4, and 6 h after oral intake. A direct comparison of the increase in plasma Mg levels over the 6 h period revealed that the Mg-MS microencapsulation technology significantly increased Mg bioavailability compared to the non-microencapsulated MgO. Our study also showed that, compared to the other Mg sources tested, the Mg-MS microencapsulation technology reduced adverse side effects commonly associated with Mg supplementation, specifically with regard to increased intestinal motility and sensations of gastric heaviness following oral administration. Conclusions: Altogether, this clinical study introduced MAGSHAPE^TM microcapsules as a bioavailable and well-tolerated alternative to existing Mg-based ingredients used in food supplements.

Androgenetic alopecia is the most common cause of hair loss for women and men. Current treatments for androgenetic alopecia, such as those based on drugs like Minoxidil, Finasteride, or Dutasteride, have been associated with a variety of side effects, such as irritation, contact dermatitis, scalp pruritus, burning, etc. In this regard, plant extracts have emerged as promising alternatives to available chemical-based treatments for androgenetic alopecia given their efficacy, customer acceptability, and potentially minimized side effects. In this study, we evaluated the efficacy of Kyoh^®, an extract from rocket leaves, as a treatment to improve the signs of androgenetic alopecia. We found that Kyoh^® contained 2.1% total flavonoids, with kaempferol, quercetin, and isorhamnetin diglucosides being the most abundant. Additionally, Kyoh^® showed a stimulating effect on the growth of human dermal follicle papilla cells in laboratory conditions. Most importantly, Kyoh^® enhanced the gene expression of the hair growth-associated growth factors VEGF (Vascular Endothelial Growth Factor) and FGF7 (Fibroblast Growth Factor 7). Specifically, VEGF expression increased by 60.7% after 4 h and 267.3% after 24 h, while FGF7 expression increased by 50.3% after 4 h and 244.3% after 24 h, indicating both a rapid induction of gene expression and a sustained effect lasting at least one day. Moreover, Kyoh^® increased the gene expression of NRF2 (Nuclear factor erythroid 2-related factor 2) by 71.2%, which encodes for a protein participating in the antioxidant response. Overall, our study shows that flavonol-rich rocket extract (Kyoh^®) is a promising treatment for promoting hair growth, demonstrated by its proliferation-promoting effect, potential antioxidant priming, and induction of the expression of growth factors associated with hair growth and health.