Antiviral innate immunity represents the first defense against invading viruses and is key to control viral infections, including SARS-CoV-2. Body temperature is an omnipresent variable but was neglected when addressing host defense mechanisms and susceptibility to SARS-CoV-2 infection. Here, we show that increasing temperature in a 1.5°C window, between 36.5 and 38°C, strongly increases the expression of genes in two branches of antiviral immunity, nitric oxide production and type I interferon response. We show that alternative splicing coupled to nonsense-mediated decay decreases STAT2 expression in colder conditions and suggest that increased STAT2 expression at elevated temperature induces the expression of diverse antiviral genes and SARS-CoV-2 restriction factors. This cascade is activated in a remarkably narrow temperature range below febrile temperature, which reflects individual, circadian and age-dependent variation. We suggest that decreased body temperature with aging contributes to reduced expression of antiviral genes in older individuals. Using cell culture and in vivo models, we show that higher body temperature correlates with reduced SARS-CoV-2 replication, which may affect the different vulnerability of children versus seniors toward severe SARS-CoV-2 infection. Altogether, our data connect body temperature and pre-mRNA processing to provide new mechanistic insight into the regulation of antiviral innate immunity.

Alternative splicing (AS) strongly increases proteome diversity and functionality in eukaryotic cells. Protein secretion is a tightly controlled process, especially when it occurs in a tissue-specific and differentiation-dependent manner. While previous work has focussed on transcriptional and post-translational regulatory mechanisms, the impact of AS on the secretory pathway remains largely unexplored. Here, we integrate results from a published screen for modulators of protein transport and RNA-Seq analyses to identify over 200 AS events as secretion regulators. We confirm that splicing events along all stages of the secretory pathway regulate the efficiency of membrane trafficking using morpholino and CRISPR/Cas9 experiments. We furthermore show that these events are highly tissue-specific and mediate an adaptation of the secretory pathway during T-cell activation and adipocyte differentiation. Our data substantially advance the understanding of AS functionality, add a new regulatory layer to a fundamental cell biological process and provide a resource of alternative isoforms that control the secretory pathway.

Recent work has associated point mutations in both zinc fingers (ZnF) of the spliceosome component U2AF35 with malignant transformation. However, surprisingly little is known about the functionality of the U2AF35 ZnF domains in general. Here we have analysed key functionalities of the ZnF domains of mammalian U2AF35 and its paralog U2AF26. Both ZnFs are required for splicing regulation, whereas only ZnF2 controls protein stability and contributes to the interaction with U2AF65. These features are confirmed in a naturally occurring splice variant of U2AF26 lacking ZnF2, that is strongly induced upon activation of primary mouse T cells and localized in the cytoplasm. Using Ribo-Seq in a model T cell line we provide evidence for a role of U2AF26 in activating cytoplasmic steps in gene expression, notably translation. Consistently, an MS2 tethering assay shows that cytoplasmic U2AF26/35 increase translation when localized to the 5ʹUTR of a model mRNA. This regulation is partially dependent on ZnF1 thus providing a connection between a core splicing factor, the ZnF domains and the regulation of translation. Altogether, our work reveals unexpected functions of U2AF26/35 and their ZnF domains, thereby contributing to a better understanding of their role and regulation in mammalian cells.

Alternative splicing (AS) strongly increases proteome diversity and functionality in eukaryotic cells. Protein secretion is a tightly-controlled process, especially in a tissue-specific and differentiation-dependent manner. While previous work has focussed on transcriptional and posttranslational regulatory mechanisms, the impact of AS on the secretory pathway remains largely unexplored. Here we integrate a published screen for modulators of protein transport and RNA-Seq analyses to identify over 200 AS events as secretion regulators. We confirm that splicing events along all stages of the secretory pathway regulate the efficiency of protein transport using Morpholinos and CRISPR/Cas9. We furthermore show that these events are highly tissue-specific and adapt the secretory pathway during T-cell activation and adipocyte differentiation. Our data substantially advance the understanding of AS functionality, add a new regulatory layer to a fundamental cell biological process and provide a resource of alternative isoforms that control the secretory pathway.

No abstract

Oxygenic phototrophs have evolved a remarkable plethora of strategies to react to changes in light intensity and spectral range, which allows them to thrive in a wide range of environmental conditions. Varying light quality and quantity influences the balance between solar energy capture and utilisation in photosynthesis, affecting concomitantly the downstream processes of central carbon and nitrogen metabolism as well as cellular growth and division. Here, we performed a comprehensive analysis of the mechanisms of long-term photoacclimation of an extremophilic red alga Cyanidioschyzon merolae that grows in sulphuric hot springs at high temperatures and low pH. By using spectroscopic, confocal fluorescence microscopy, photosynthetic performance measurements and global transcriptome analyses, we identified several molecular mechanisms underlying the long-term adaptation of this acido-thermophilic red alga to varying light intensity and spectral quality. These include: (1) remodelling of the functional antenna size of both photosystems; (2) rearrangement of the PSB/PSII/PSI microdomains within thylakoids; (3) modulation of the photosynthetic performance parameters, especially at the level of non-photochemical quenching, and (4) transcriptional regulation of photosynthesis and its regulatory components as well as downstream metabolic pathways related to ROS detoxification, cell/organelle division, and central carbon and nitrogen metabolism. Such an intricate network of interplay between light-driven reactions and downstream metabolic pathways provides the necessary basis for maintaining the highest photosynthetic performance under light-limiting conditions.

Perfluorobutanesulfonic acid (PFBS) is a replacement for perfluorooctanesulfonic acid (PFOS) that is increasingly detected in drinking water and human serum. Higher PFBS exposure is associated with risk for preeclampsia, the leading cause of maternal and infant morbidity and mortality in the United States. This study investigated relevant maternal and fetal health outcomes after gestational exposure to PFBS in a New Zealand White rabbit model. Nulliparous female rabbits were supplied drinking water containing 0 mg/L (control), 10mg/L (low) or 100mg/L (high) PFBS. Maternal blood pressure, body weights, liver and kidney weights and histopathology, clinical chemistry panels, and thyroid hormone levels were evaluated. Fetal endpoints evaluated at necropsy included viability, body weights, crown rump length, and liver and kidney histopathology, while placenta endpoints included weight, morphology, histopathology, and full transcriptome RNA sequencing. PFBS-high dose dams exhibited significant changes in blood pressure markers, seen through increased pulse pressure and renal resistive index measures, as well as kidney histopathological changes. Fetuses from these dams showed decreased crown-rump length. Statistical analysis of placental weight via a mixed model statistical approach identified a significant interaction term between PFBS high dose and fetal sex, suggesting a sex-specific effect on placental weight. RNA sequencing identified the dysregulation of angiotensin (AGT) in PFBS high dose placentas. These results suggest that PFBS exposure during gestation leads to adverse maternal outcomes, such as renal injury and hypertension, and fetal outcomes, including decreased growth parameters and adverse placenta function. These outcomes raise concerns about pregnant women’s exposure to PFBS and pregnancy outcomes.

Traditional bacterial fermentation techniques used to manufacture plasmid are time-consuming, expensive, and inherently unstable. The production of sufficient GMP grade material thus imposes a major bottleneck on industrial-scale manufacturing of lentiviral vectors (LVV). Touchlight’s linear doggybone DNA (dbDNATM) is an enzymatically amplified DNA vector produced with exceptional speed through an in vitro dual enzyme process, enabling industrial-scale manufacturing of GMP material in a fraction of the time required for plasmid. We have previously shown that dbDNATM can be used to produce functional LVV; however, obtaining high LVV titres remained a challenge. Here, we aimed to demonstrate that dbDNATM could be optimised for the manufacture of high titre LVV. We found that dbDNATM displayed a unique transfection and expression profile in the context of LVV production, which necessitated the optimisation of DNA input and construct ratios. Furthermore, we demonstrate that efficient 3’ end processing of viral genomic RNA (vgRNA) derived from linear dbDNATM transfer vectors required the addition of a strong 3’ termination signal and downstream spacer sequence to enable efficient vgRNA packaging. Using these improved vector architectures along with optimised transfection conditions, we were able to produce a CAR19h28z LVV with equivalent infectious titres as achieved using plasmid, demonstrating that dbDNATM technology can provide a highly effective solution to the plasmid bottleneck.