title: Lacritin rescues stressed epithelia via rapid forkhead box O3 (FOXO3)-associated autophagy that restores metabolism.
abstract: Homeostasis is essential for cell survival. However, homeostatic regulation of surface epithelia is poorly understood. The eye surface, lacking the cornified barrier of skin, provides an excellent model. Tears cover the surface of the eye and are deficient in dry eye, the most common eye disease affecting at least 5% of the world's population. Only a tiny fraction of the tear proteome appears to be affected, including lacritin, an epithelium-selective mitogen that promotes basal tearing when topically applied to rabbit eyes. Here we show that homeostasis of cultured corneal epithelia is entirely lacritin-dependent and elucidate the mechanism as a rapid autophagic flux to promptly restore cellular metabolism and mitochondrial fusion in keeping with the short residence time of lacritin on the eye. Accelerated flux appears to be derived from lacritin-stimulated acetylation of FOXO3 as a novel ligand for ATG101 and coupling of stress-acetylated FOXO1 with ATG7 (which remains uncoupled without lacritin) and be sufficient to selectively divert huntingtin mutant Htt103Q aggregates largely without affecting non-aggregated Htt25Q. This is in keeping with stress as a prerequisite for lacritin-stimulated autophagy. Lacritin targets the cell surface proteoglycan syndecan-1 via its C-terminal amino acids Leu(108)-Leu(109)-Phe(112) and is also available in saliva, plasma, and lung lavage. Thus, lacritin may promote epithelial homeostasis widely.
authors: Department of Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA.
authors: Ningning
authors: N
authors: Wang
authors: Keith
authors: K
authors: Zimmerman
authors: Ronald W
authors: RW
authors: Raab
authors: Robert L
authors: RL
authors: McKown
authors: Cindy M L
authors: CM
authors: Hutnik
authors: Venu
authors: V
authors: Talla
authors: Milton F
authors: MF
authors: Tyler
authors: Jae K
authors: JK
authors: Lee
authors: Gordon W
authors: GW
authors: Laurie
mesh_terms: D000595:Amino Acid Sequence; D001343:Autophagy / Q000187:drug effects*; D000071193:Autophagy-Related Protein 7; D000071183:Autophagy-Related Proteins; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D000071058:Huntingtin Protein; D007371:Interferon-gamma / Q000494:pharmacology; D013058:Mass Spectrometry; D055442:Metabolome / Q000187:drug effects*; D008969:Molecular Sequence Data; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000494:pharmacology; D034622:RNA Interference; D011994:Recombinant Proteins / Q000494:pharmacology; D053668:Syndecan-1 / Q000235:genetics / Q000378:metabolism; D013666:Tears / Q000737:chemistry / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D044764:Ubiquitin-Activating Enzymes / Q000235:genetics / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: C543518:ATG101 protein, human; D000071183:Autophagy-Related Proteins; C499517:FOXO3 protein, human; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D006023:Glycoproteins; C086055:HTT protein, human; D000071058:Huntingtin Protein; C431764:LACRT protein, human; D009419:Nerve Tissue Proteins; D010455:Peptides; D011994:Recombinant Proteins; D053668:Syndecan-1; D014409:Tumor Necrosis Factor-alpha; D033921:Vesicular Transport Proteins; D007371:Interferon-gamma; C509349:ATG7 protein, human; D000071193:Autophagy-Related Protein 7; D044764:Ubiquitin-Activating Enzymes
keywords: ATG101; Autophagy; Cell Metabolism; Cornea; Dry Eye; FOXO3; Lacritin; Metabolomics; Proteoglycan; Stress
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