Dynamic allostery drives autocrine and paracrine TGF-ß signaling.

TGF-ß, essential for development and immunity, is expressed as a latent complex (L-TGF-ß) non-covalently associated with its prodomain and presented on immune cell surfaces by covalent association with GARP. Binding to integrin αvß8 activates L-TGF-ß1/GARP. The dogma is that mature TGF-ß must physically dissociate from L-TGF-ß1 for signaling to occur. Our previous studies discovered that αvß8-mediated TGF-ß autocrine signaling can occur without TGF-ß1 release from its latent form. Here, we show that mice engineered to express TGF-ß1 that cannot release from L-TGF-ß1 survive without early lethal tissue inflammation, unlike those with TGF-ß1 deficiency. Combining cryogenic electron microscopy with cell-based assays, we reveal a dynamic allosteric mechanism of autocrine TGF-ß1 signaling without release where αvß8 binding redistributes the intrinsic flexibility of L-TGF-ß1 to expose TGF-ß1 to its receptors. Dynamic allostery explains the TGF-ß3 latency/activation mechanism and why TGF-ß3 functions distinctly from TGF-ß1, suggesting that it broadly applies to other flexible cell surface receptor/ligand systems.

Cryo-EM Reveals Integrin-Mediated TGF-ß Activation without Release from Latent TGF-ß.

Integrin αvß8 binds with exquisite specificity to latent transforming growth factor-ß (L-TGF-ß). This binding is essential for activating L-TGF-ß presented by a variety of cell types. Inhibiting αvß8-mediated TGF-ß activation blocks immunosuppressive regulatory T cell differentiation, which is a potential therapeutic strategy in cancer. Using cryo-electron microscopy, structure-guided mutagenesis, and cell-based assays, we reveal the binding interactions between the entire αvß8 ectodomain and its intact natural ligand, L-TGF-ß, as well as two different inhibitory antibody fragments to understand the structural underpinnings of αvß8 binding specificity and TGF-ß activation. Our studies reveal a mechanism of TGF-ß activation where mature TGF-ß signals within the confines of L-TGF-ß and the release and diffusion of TGF-ß are not required. The structural details of this mechanism provide a rational basis for therapeutic strategies to inhibit αvß8-mediated L-TGF-ß activation.

Balancing of mitochondrial translation through METTL8-mediated m3C modification of mitochondrial tRNAs.

Mitochondria contain a specific translation machinery for the synthesis of mitochondria-encoded respiratory chain components. Mitochondrial tRNAs (mt-tRNAs) are also generated from the mitochondrial DNA and, similar to their cytoplasmic counterparts, are post-transcriptionally modified. Here, we find that the RNA methyltransferase METTL8 is a mitochondrial protein that facilitates 3-methyl-cytidine (m3C) methylation at position C32 of the mt-tRNASer(UCN) and mt-tRNAThr. METTL8 knockout cells show a reduction in respiratory chain activity, whereas overexpression increases activity. In pancreatic cancer, METTL8 levels are high, which correlates with lower patient survival and an enhanced respiratory chain activity. Mitochondrial ribosome profiling uncovered mitoribosome stalling on mt-tRNASer(UCN)- and mt-tRNAThr-dependent codons. Further analysis of the respiratory chain complexes using mass spectrometry revealed reduced incorporation of the mitochondrially encoded proteins ND6 and ND1 into complex I. The well-balanced translation of mt-tRNASer(UCN)- and mt-tRNAThr-dependent codons through METTL8-mediated m3C32 methylation might, therefore, facilitate the optimal composition and function of the mitochondrial respiratory chain.

Retapamulin-Assisted Ribosome Profiling Reveals the Alternative Bacterial Proteome.

The use of alternative translation initiation sites enables production of more than one protein from a single gene, thereby expanding the cellular proteome. Although several such examples have been serendipitously found in bacteria, genome-wide mapping of alternative translation start sites has been unattainable. We found that the antibiotic retapamulin specifically arrests initiating ribosomes at start codons of the genes. Retapamulin-enhanced Ribo-seq analysis (Ribo-RET) not only allowed mapping of conventional initiation sites at the beginning of the genes, but strikingly, it also revealed putative internal start sites in a number of Escherichia coli genes. Experiments demonstrated that the internal start codons can be recognized by the ribosomes and direct translation initiation in vitro and in vivo. Proteins, whose synthesis is initiated at internal in-frame and out-of-frame start sites, can be functionally important and contribute to the "alternative" bacterial proteome. The internal start sites may also play regulatory roles in gene expression.

Context-based sensing of orthosomycin antibiotics by the translating ribosome.

Orthosomycin antibiotics inhibit protein synthesis by binding to the large ribosomal subunit in the tRNA accommodation corridor, which is traversed by incoming aminoacyl-tRNAs. Structural and biochemical studies suggested that orthosomycins block accommodation of any aminoacyl-tRNAs in the ribosomal A-site. However, the mode of action of orthosomycins in vivo remained unknown. Here, by carrying out genome-wide analysis of antibiotic action in bacterial cells, we discovered that orthosomycins primarily inhibit the ribosomes engaged in translation of specific amino acid sequences. Our results reveal that the predominant sites of orthosomycin-induced translation arrest are defined by the nature of the incoming aminoacyl-tRNA and likely by the identity of the two C-terminal amino acid residues of the nascent protein. We show that nature exploits this antibiotic-sensing mechanism for directing programmed ribosome stalling within the regulatory open reading frame, which may control expression of an orthosomycin-resistance gene in a variety of bacterial species.

Petroleum jelly: A comprehensive review of its history, uses, and safety.

Petrolatum, also known as petroleum jelly, is a widely used topical agent, with a variety of uses in dermatology. Despite its popularity, many myths surround this ubiquitous dermatologic staple. This review details the history of petrolatum and how it is manufactured as well as how its biologic properties make it a great moisturizer. Additionally, data on its potential for flammability, allergenicity, and comedogenicity are detailed, dispelling misconceptions about petrolatum use around oxygen and as a cause of acne. The uses and benefits of petrolatum in dermatology are wide-ranging-a patch test instrument, a vehicle for medicated ointments, and a wound care essential. Given its ubiquitous presence, it is important for dermatologists to understand the history, safety profile, and myths surrounding this humble skincare staple.

Photopatch testing: Clinical characteristics, test results, and final diagnoses from the North American Contact Dermatitis Group, 2009-2020.

BACKGROUND: Photoallergic contact dermatitis (PACD) is a delayed hypersensitivity reaction to allergens only in the presence of ultraviolet radiation in sunlight. Photopatch testing (PhotoPT) is necessary to confirm the diagnosis of PACD. There are few published studies of PhotoPT in North America. OBJECTIVE: To summarise the results of patients photopatch tested by members of the North American Contact Dermatitis Group (NACDG), 2009-2020. METHODS: Retrospective analysis of patient characteristics and PhotoPT results to 32 allergens on the NACDG Photopatch Test Series. RESULTS: Most of the 454 tested patients were female (70.3%), 21-60 years old (66.7%) and White (66.7%). There were a total of 119 positive photopatch tests. Sunscreen agents comprised 88.2% of those, with benzophenones responsible for over half of them. Final diagnoses included PACD in 17.2%, allergic contact dermatitis (ACD) in 44.5%, polymorphous light eruption (PMLE) in 18.9% and chronic actinic dermatitis (CAD) in 9.0% of patients. CONCLUSIONS: In 454 patients with suspected photosensitivity referred for photopatch testing in North America, approximately one-fifth had PACD. Sunscreen agents, especially benzophenones, were the most common photoallergens. Other common diagnoses included ACD, PMLE and CAD. Photopatch testing is an important tool for differentiating these conditions.

Safety Assessment of Ginkgo biloba-Derived Ingredients as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 10 Ginkgo biloba-derived ingredients, which are most frequently reported to function in cosmetics as skin conditioning agents or antioxidants. The Panel reviewed the available data to determine the safety of these ingredients. Because final product formulations may contain multiple botanicals, each containing the same constituents of concern, formulators are advised to be aware of these constituents and to avoid reaching levels that may be hazardous to consumers. The Panel was concerned about the presence of ginkgolic acid in cosmetics. Industry should use good manufacturing practices to limit impurities. The Panel concluded that 5 Ginkgo biloba leaf-derived ingredients are safe in the present practices of use and concentration described in this safety assessment when formulated to be non-sensitizing; data are insufficient to determine the safety of the remaining 5 ingredients under the intended conditions of use in cosmetic formulations.

Safety Assessment of Alkanoyl Lactyl Lactate Salts as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 10 alkanoyl lactyl lactate salts. These ingredients have the surfactant function in cosmetics in common. The Panel reviewed data relevant to the safety of these ingredients, and concluded that these 10 ingredients are safe in cosmetics in the present practices of use and concentration described in the safety assessment when formulated to be nonirritating and nonsensitizing, which may be based on a quantitative risk assessment (QRA) or other accepted methodologies.

Safety Assessment of Vinylpyrrolidone Polymers as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 30 vinylpyrrolidone polymers as used in cosmetic products; most of these ingredients have the reported cosmetic function of film former in common. The Panel reviewed data relevant to the safety of these ingredients, and determined that 27 vinylpyrrolidone polymers are safe in cosmetics in the present practices of use and concentration described in the safety assessment. The Panel also concluded that the available data are insufficient to make a determination that 3 vinylpyrrolidone polymers (all urethanes) are safe under the intended conditions of use in cosmetic formulations.

Safety Assessment of Polyol Phosphates as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 10 polyol phosphates. Some of the possible functions in cosmetics that are reported for this ingredient group are chelating agents, oral care agents, and skin conditioning agents. The Panel reviewed relevant data relating to the safety of these ingredients under the intended conditions of use in cosmetic formulations, and concluded that Sodium Phytate, Phytic Acid, Phytin, and Trisodium Inositol Triphosphate are safe in cosmetics in the present practices of use and concentration described in the safety assessment. The Panel also concluded that the data are insufficient to determine the safety of the following 6 ingredients as used in cosmetics: Disodium Glucose Phosphate, Manganese Fructose Diphosphate, Sodium Mannose Phosphate, Trisodium Fructose Diphosphate, Xylityl Phosphate, and Zinc Fructose Diphosphate.

Safety Assessment of Methylxanthines as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of three methylxanthines, Caffeine, Theobromine, and Theophylline, as used in cosmetics. All of these ingredients are reported to function as skin-conditioning agents in cosmetic products. The Panel reviewed the data relevant to the safety of these ingredients and concluded that Caffeine, Theobromine, and Theophylline are safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Safety Assessment of Polysilicone-11 as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Polysilicone-11 as used in cosmetic formulations. This ingredient is reported to function as a film former. The Panel considered the available data and concluded that Polysilicone-11 is safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Safety Assessment of Palm-Derived Ingredients as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reviewed the safety of 8 palm tree (Euterpe edulis (juçara) and Euterpe oleracea (açaí))-derived ingredients as used in cosmetic products; these ingredients are reported to function mostly as skin conditioning agents. The Panel reviewed relevant data relating to the safety of these ingredients in cosmetic formulations. Industry should continue to use good manufacturing practices to limit impurities. The Panel concluded that palm tree (açaí and juçara)-derived ingredients are safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Safety Assessment of Capryloyl Salicylic Acid as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) reassessed the safety of Capryloyl Salicylic Acid in cosmetic products; this ingredient is reported to function as a skin conditioning agent. The Panel reviewed relevant data relating to the safety of this ingredient in cosmetic formulations, and concluded that the available data are insufficient to make a determination that Capryloyl Salicylic Acid is safe under the intended conditions of use in cosmetic formulations.

Safety Assessment of Hydroxyethyl Urea as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Hydroxyethyl Urea, which is reported to function as a humectant and a hair and skin conditioning agent. The Panel reviewed the available data to determine the safety of this ingredient. The Panel concluded that Hydroxyethyl Urea is safe in cosmetics in the present practices of use and concentration described in the safety assessment when formulated to be non-irritating.

Safety Assessment of Basic Red 76 as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Basic Red 76, which is reported to function in cosmetics as a hair colorant and hair-conditioning agent. The Panel reviewed the available data to determine the safety of this ingredient. The Panel concluded that Basic Red 76 is safe for use as a hair dye ingredient in the present practices of use and concentration described in the safety assessment.

Safety Assessment of Hops as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Humulus Lupulus (Hops) Extract (reported functions include antimicrobial agent and hair conditioning agent) and Humulus Lupulus (Hops) Oil (reported function is fragrance). The Panel reviewed the relevant data related to these ingredients. Because final product formulations may contain multiple botanicals, each containing the same constituents of concern, formulators are advised to be aware of these constituents and to avoid reaching levels that may be hazardous to consumers. For these ingredients, the Panel was concerned about the presence of 8-prenylnaringenin, ß-myrcene, and quercetin in cosmetics, which could result in estrogenic effects, dermal irritation, and genotoxicity, respectively. Industry should use current good manufacturing practices to limit impurities and constituents of concern. The Panel concluded that Humulus Lupulus (Hops) Extract and Humulus Lupulus (Hops) Oil are safe in cosmetics in the present practices of use and concentration when formulated to be non-sensitizing.

Safety Assessment of Alkyl Sultaines as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 13 alkyl sultaines, which are most frequently reported to function in cosmetics as antistatic agents, surfactants, and skin and hair conditioning agents. The Panel reviewed the available data to determine the safety of these ingredients. The Panel noted gaps in the available safety data for some of the alkyl sultaines in this safety assessment; the available data on some of the ingredients are sufficient, however, and can be read across to support the safety of other members of the group. The Panel concluded that these alkyl sultaines are safe in cosmetics in the present practices of use and concentration described in this safety assessment.

Safety Assessment of Adenosine as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Adenosine, Adenosine Phosphate, Adenosine Triphosphate, Disodium Adenosine Phosphate, and Disodium Adenosine Triphosphate. These ingredients are reported to function in cosmetics as skin-conditioning agents - miscellaneous. The Panel considered the available data and concluded that the five adenosine ingredients reviewed in this report are safe in cosmetics in the present practices of use and concentration described in this safety assessment.