New factors for protein transport identified by a genome-wide CRISPRi screen in mammalian cells

Protein and membrane trafficking pathways are critical for cell and tissue homeostasis. Traditional genetic and biochemical approaches have shed light on basic principles underlying these processes. However, the list of factors required for secretory pathway function remains incomplete, and mechanisms involved in their adaptation poorly understood. Here, we present a powerful strategy based on a pooled genome-wide CRISPRi screen that allowed the identification of new factors involved in protein transport. Two newly identified factors, TTC17 and CCDC157, localized along the secretory pathway and were found to interact with resident proteins of ER-Golgi membranes. In addition, we uncovered that upon TTC17 knockdown, the polarized organization of Golgi cisternae was altered, creating glycosylation defects, and that CCDC157 is an important factor for the fusion of transport carriers to Golgi membranes. In conclusion, our work identified and characterized new actors in the mechanisms of protein transport and secretion, and opens stimulating perspectives for the use of our platform in physiological and pathological contexts.Includes Wellcome Trust, MRC and H202

Vitamine D, ultraviolets et cancer de la peau

Vitamin D, ultraviolets and skin cancer The vitamin D supply is fundamental for the prevention of falls and fractures in aged people, among other effects. UVB triggers vitamin D synthesis in the skin. This relationship has recently gained attention both with the general public and with health care professionals. Some authors suggest a relaxation of UV protection measures, while others even advocate regular sunlight exposure in order to increase cutaneous vitamin D synthesis. However, the UV irradiation responsible for vitamin D synthesis also is a known carcinogen. UV exposure is an insufficient and harmful method to increase vitamin D synthesis. Oral supplementation is the recommended way to prevent and cure vitamin D deficiency