Editing Autophagy (section)

=== Nutrient starvation ===
Autophagy has roles in various cellular functions. One particular example is in yeasts, where the nutrient starvation induces a high level of autophagy. This allows unneeded proteins to be degraded and the amino acids recycled for the synthesis of proteins that are essential for survival.<ref name=Klionsky2002>{{cite journal | vauthors = Reggiori F, Klionsky DJ | title = Autophagy in the eukaryotic cell | journal = Eukaryotic Cell | volume = 1 | issue = 1 | pages = 11–21 | date = February 2002 | pmid = 12455967 | pmc = 118053 | doi = 10.1128/EC.01.1.11-21.2002 }}</ref><ref>{{cite journal | vauthors = Klionsky DJ, Emr SD | title = Autophagy as a regulated pathway of cellular degradation | journal = Science | volume = 290 | issue = 5497 | pages = 1717–21 | date = December 2000 | pmid = 11099404 | pmc = 2732363 | doi = 10.1126/science.290.5497.1717 | bibcode = 2000Sci...290.1717K }}</ref><ref>{{cite journal | vauthors = Levine B, Klionsky DJ | title = Development by self-digestion: molecular mechanisms and biological functions of autophagy | journal = Developmental Cell | volume = 6 | issue = 4 | pages = 463–77 | date = April 2004 | pmid = 15068787 | doi = 10.1016/S1534-5807(04)00099-1 | doi-access = free }}</ref> In higher eukaryotes, autophagy is induced in response to the nutrient depletion that occurs in animals at birth after severing off the trans-placental food supply, as well as that of nutrient starved cultured cells and tissues.<ref name=Kuma2004>{{cite journal | vauthors = Kuma A, Hatano M, Matsui M, Yamamoto A, Nakaya H, Yoshimori T, Ohsumi Y, Tokuhisa T, Mizushima N | display-authors = 6 | title = The role of autophagy during the early neonatal starvation period | journal = Nature | volume = 432 | issue = 7020 | pages = 1032–6 | date = December 2004 | pmid = 15525940 | doi = 10.1038/nature03029 | s2cid = 4424974 | bibcode = 2004Natur.432.1032K }}</ref><ref name=Ohsumi2004>{{cite journal | vauthors = Mizushima N, Yamamoto A, Matsui M, Yoshimori T, Ohsumi Y | title = In vivo analysis of autophagy in response to nutrient starvation using transgenic mice expressing a fluorescent autophagosome marker | journal = Molecular Biology of the Cell | volume = 15 | issue = 3 | pages = 1101–11 | date = March 2004 | pmid = 14699058 | pmc = 363084 | doi = 10.1091/mbc.E03-09-0704 }}</ref> Mutant yeast cells that have a reduced autophagic capability rapidly perish in nutrition-deficient conditions.<ref name=Tsukada93>{{cite journal | vauthors = Tsukada M, Ohsumi Y | title = Isolation and characterization of autophagy-defective mutants of Saccharomyces cerevisiae | journal = FEBS Letters | volume = 333 | issue = 1–2 | pages = 169–74 | date = October 1993 | pmid = 8224160 | doi = 10.1016/0014-5793(93)80398-E | s2cid = 46017791 | doi-access = free | bibcode = 1993FEBSL.333..169T }}</ref> Studies on the ''apg'' mutants suggest that autophagy via autophagic bodies is indispensable for protein degradation in the vacuoles under starvation conditions, and that at least 15 APG genes are involved in autophagy in yeast.<ref name=Tsukada93/> A gene known as ATG7 has been implicated in nutrient-mediated autophagy, as mice studies have shown that starvation-induced autophagy was impaired in ''atg7''-deficient mice.<ref name=Ohsumi2004/>