In October 1910 a revolution drove out the king of Portugal and established the Portuguese Republic. In 1926 a military coup overthrew the parliamentary system and led to the authoritarian regime of Salazar, but in April 1974 a revolution led by the military restored the parliamentary republic. In this book edited by Richard Herr (Berkeley) and António Costa Pinto (Lisbon), eighteen Portuguese and American authors present essays in celebration of the centennial of the Portuguese Republic. With a review of its course and needs for the future, they offer an assessment of accomplishments of the two periods of the republic, the nature of republican institutions, the role of women in politics and letters, and the republic’s social, economic, religious, and environmental policies. Much thought has gone into analyzing the two revolutions, the challenge of an authoritarian tradition, and the difficulties posed for establishing a workable parliamentary government with a democratic suffrage.

Mutations in the adiponectin receptor 1 gene (AdipoR1) lead to retinitis pigmentosa and are associated with age-related macular degeneration. This study explores the effects of AdipoR1 gene deficiency in mice, revealing a striking decline in ω3 polyunsaturated fatty acids (PUFA), an increase in ω6 fatty acids, and elevated ceramides in the retina. The AdipoR1 deficiency impairs peroxisome proliferator-activated receptor α signaling, which is crucial for FA metabolism, particularly affecting proteins associated with FA transport and oxidation in the retina and retinal pigmented epithelium. Our lipidomic and proteomic analyses indicate changes that could affect membrane composition and viscosity through altered ω3 PUFA transport and synthesis, suggesting a potential influence of AdipoR1 on these properties. Furthermore, we noted a reduction in the Bardet-Biedl syndrome proteins, which are crucial for forming and maintaining photoreceptor outer segments that are PUFA-enriched ciliary structures. Diminution in Bardet-Biedl syndrome-proteins content combined with our electron microscopic observations raises the possibility that AdipoR1 deficiency might impair ciliary function. Treatment with inhibitors of ceramide synthesis led to substantial elevation of ω3 LC-PUFAs, alleviating photoreceptor degeneration and improving retinal function. These results serve as the proof of concept for a ceramide-targeted strategy to treat retinopathies linked to PUFA deficiency, including age-related macular degeneration.

Omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) play critical roles in membrane stability and cell signaling within the retina. ELOVL2 (Elongation of Very Long Chain Fatty Acids-Like 2), an elongase involved in the synthesis of long chain polyunsaturated fatty acids (LC-PUFAs), has recently been implicated in regulating aging in the mammalian retina. In this work, we characterize the expression and function of elovl2 in the retina development in embryonic zebrafish. Whole mount in situ hybridization shows elovl2 is expressed in the Muller glia in embryonic and adult zebrafish. Lipidomics analysis of elovl2 crispants whole embryos at day 2 and eyes at day 7 demonstrated significant changes in lipids composition, especially on the level of lipids containing docosahexaenoic acid (DHA). Histological analysis of zebrafish lacking elovl2 revealed increased retinal thickness compared to controls at day 7 without gross disruptions of the retinal architecture. Finally, elovl2 crispants showed differences in the visual motor reflex light off (VMR-OFF) at day 7 compared to controls. In sum, inactivation of elovl2 in zebrafish embryos caused changes in lipid composition and in visual behavior, further confirming the important role of LC-PUFAs in healthy vision.

FAHFAs are a class of bioactive lipids, which show great promise for treating diabetes and inflammatory diseases. Deciphering the metabolic pathways that regulate endogenous FAHFA levels is critical for developing diagnostic and therapeutic strategies. However, it remains unclear how FAHFAs are metabolized in cells or tissues. Here, we investigate whether FAHFAs can be incorporated into other lipid classes and identify a novel class of endogenous lipids, FAHFA-containing triacylglycerols (FAHFA-TGs), which contain a FAHFA group esterified to the glycerol backbone. Isotope-labeled FAHFAs are incorporated into FAHFA-TGs when added to differentiated adipocytes, which implies the existence of enzymes and metabolic pathways capable of synthesizing these lipids. Induction of lipolysis (i.e., triacylglycerol hydrolysis) in adipocytes is associated with marked increases in nonesterified FAHFA levels, demonstrating that FAHFA-TGs breakdown is a regulator of cellular FAHFA levels. To quantify FAHFA levels in FAHFA-TGs and determine their regioisomeric distributions, we developed a mild alkaline hydrolysis method that liberates FAHFAs from triacylglycerols for easier detection. FAHFA-TG concentrations are greater than 100-fold than that of nonesterified FAHFAs, indicating that FAHFA-TGs are a major reservoir of FAHFAs in cells and tissues. The discovery of FAHFA-TGs reveals a new branch of TG and FAHFA metabolism with potential roles in metabolic health and regulation of inflammation.

Thyroid hormones are vital in metabolism, growth and development¹. Thyroid hormone synthesis is controlled by thyrotropin (TSH), which acts at the thyrotropin receptor (TSHR)². In patients with Graves' disease, autoantibodies that activate the TSHR pathologically increase thyroid hormone activity³. How autoantibodies mimic thyrotropin function remains unclear. Here we determined cryo-electron microscopy structures of active and inactive TSHR. In inactive TSHR, the extracellular domain lies close to the membrane bilayer. Thyrotropin selects an upright orientation of the extracellular domain owing to steric clashes between a conserved hormone glycan and the membrane bilayer. An activating autoantibody from a patient with Graves' disease selects a similar upright orientation of the extracellular domain. Reorientation of the extracellular domain transduces a conformational change in the seven-transmembrane-segment domain via a conserved hinge domain, a tethered peptide agonist and a phospholipid that binds within the seven-transmembrane-segment domain. Rotation of the TSHR extracellular domain relative to the membrane bilayer is sufficient for receptor activation, revealing a shared mechanism for other glycoprotein hormone receptors that may also extend to other G-protein-coupled receptors with large extracellular domains.

Photoreceptors rely on distinct membrane compartments to support their specialized function. Unlike protein localization, identification of critical differences in membrane content has not yet been expanded to lipids, due to the difficulty of isolating domain-specific samples. We have overcome this by using SMA to coimmunopurify membrane proteins and their native lipids from two regions of photoreceptor ROS disks. Each samples copurified lipids were subjected to untargeted lipidomic and fatty acid analysis. Extensive differences between center (rhodopsin) and rim (ABCA4 and PRPH2/ROM1) samples included a lower PC to PE ratio and increased LC- and VLC-PUFAs in the center relative to the rim region, which was enriched in shorter, saturated FAs. The comparatively few differences between the two rim samples likely reflect specific protein-lipid interactions. High-resolution profiling of the ROS disk lipid composition gives new insights into how intricate membrane structure and protein activity are balanced within the ROS, and provides a model for future studies of other complex cellular structures.

Serine, glycine and other nonessential amino acids are critical for tumour progression, and strategies to limit their availability are emerging as potential therapies for cancer^1-3. However, the molecular mechanisms driving this response remain unclear and the effects on lipid metabolism are relatively unexplored. Serine palmitoyltransferase (SPT) catalyses the de novo biosynthesis of sphingolipids but also produces noncanonical 1-deoxysphingolipids when using alanine as a substrate^4,5. Deoxysphingolipids accumulate in the context of mutations in SPTLC1 or SPTLC2^6,7-or in conditions of low serine availability^8,9-to drive neuropathy, and deoxysphinganine has previously been investigated as an anti-cancer agent¹⁰. Here we exploit amino acid metabolism and the promiscuity of SPT to modulate the endogenous synthesis of toxic deoxysphingolipids and slow tumour progression. Anchorage-independent growth reprogrammes a metabolic network involving serine, alanine and pyruvate that drives the endogenous synthesis and accumulation of deoxysphingolipids. Targeting the mitochondrial pyruvate carrier promotes alanine oxidation to mitigate deoxysphingolipid synthesis and improve spheroid growth, similar to phenotypes observed with the direct inhibition of SPT or ceramide synthesis. Restriction of dietary serine and glycine potently induces the accumulation of deoxysphingolipids while decreasing tumour growth in xenograft models in mice. Pharmacological inhibition of SPT rescues xenograft growth in mice fed diets restricted in serine and glycine, and the reduction of circulating serine by inhibition of phosphoglycerate dehydrogenase (PHGDH) leads to the accumulation of deoxysphingolipids and mitigates tumour growth. The promiscuity of SPT therefore links serine and mitochondrial alanine metabolism to membrane lipid diversity, which further sensitizes tumours to metabolic stress.

Compositional oscillations of the gut microbiome are essential for normal peripheral circadian rhythms, both of which are disrupted in diet-induced obesity (DIO). Although time-restricted feeding (TRF) maintains circadian synchrony and protects against DIO, its impact on the dynamics of the cecal gut microbiome is modest. Thus, other regions of the gut, particularly the ileum, the nexus for incretin and bile acid signaling, may play an important role in entraining peripheral circadian rhythms. We demonstrate the effect of diet and feeding rhythms on the ileal microbiome composition and transcriptome in mice. The dynamic rhythms of ileal microbiome composition and transcriptome are dampened in DIO. TRF partially restores diurnal rhythms of the ileal microbiome and transcriptome, increases GLP-1 release, and alters the ileal bile acid pool and farnesoid X receptor (FXR) signaling, which could explain how TRF exerts its metabolic benefits. Finally, we provide a web resource for exploration of ileal microbiome and transcriptome circadian data.

Adiponectin receptor 1 (ADIPOR1) is a lipid and glucose metabolism regulator that possesses intrinsic ceramidase activity. Mutations of the ADIPOR1 gene have been associated with nonsyndromic and syndromic retinitis pigmentosa. Here, we show that the absence of AdipoR1 in mice leads to progressive photoreceptor degeneration, significant reduction of electroretinogram amplitudes, decreased retinoid content in the retina, and reduced cone opsin expression. Single-cell RNA-Seq results indicate that ADIPOR1 encoded the most abundantly expressed ceramidase in mice and one of the 2 most highly expressed ceramidases in the human retina, next to acid ceramidase ASAH1. We discovered an accumulation of ceramides in the AdipoR1-/- retina, likely due to insufficient ceramidase activity for healthy retina function, resulting in photoreceptor death. Combined treatment with desipramine/L-cycloserine (DC) lowered ceramide levels and exerted a protective effect on photoreceptors in AdipoR1-/- mice. Moreover, we observed improvement in cone-mediated retinal function in the DC-treated animals. Lastly, we found that prolonged DC treatment corrected the electrical responses of the primary visual cortex to visual stimuli, approaching near-normal levels for some parameters. These results highlight the importance of ADIPOR1 ceramidase in the retina and show that pharmacological inhibition of ceramide generation can provide a therapeutic strategy for ADIPOR1-related retinopathy.

Oncogenic lesions in pancreatic ductal adenocarcinoma (PDAC) hijack the epigenetic machinery in stromal components to establish a desmoplastic and therapeutic resistant tumor microenvironment (TME). Here we identify Class I histone deacetylases (HDACs) as key epigenetic factors facilitating the induction of pro-desmoplastic and pro-tumorigenic transcriptional programs in pancreatic stromal fibroblasts. Mechanistically, HDAC-mediated changes in chromatin architecture enable the activation of pro-desmoplastic programs directed by serum response factor (SRF) and forkhead box M1 (FOXM1). HDACs also coordinate fibroblast pro-inflammatory programs inducing leukemia inhibitory factor (LIF) expression, supporting paracrine pro-tumorigenic crosstalk. HDAC depletion in cancer-associated fibroblasts (CAFs) and treatment with the HDAC inhibitor entinostat (Ent) in PDAC mouse models reduce stromal activation and curb tumor progression. Notably, HDAC inhibition (HDACi) enriches a lipogenic fibroblast subpopulation, a potential precursor for myofibroblasts in the PDAC stroma. Overall, our study reveals the stromal targeting potential of HDACi, highlighting the utility of this epigenetic modulating approach in PDAC therapeutics.