Horton, M. A. | Search bioRxiv

bioRxiv2026

Distinct effects of Atg3 and Atg10 on Autophagosome Formation in Yeast

Autophagosome formation involves two E2 enzymes: Atg3, which conjugates Atg8 to the lipid phosphatidylethanolamine, and Atg10, which conjugates Atg12 to Atg5. Although both are required for autophagy, it is unclear exactly what roles these pathways play in the process of autophagosome formation. We used baker's yeast expressing mutant versions of both Atg3 and Atg10 that reduce, but do not eliminate, their activity to better understand their effects on Atg8 lipidation, autophagic flux, and the size and number of autophagosomes formed during nitrogen starvation. We found that while Atg3 primarily affects Atg8 lipidation and autophagosome size, Atg10 has less of an effect on Atg8 lipidation and primarily controls autophagosome number. This demonstrates that these two enzymes have distinct mechanistic roles in autophagosome formation, and implies an as-of-yet undiscovered function for the Atg12-Atg5 conjugate.

cell biology↗

bioRxiv2022

Elevated estradiol during a hormone simulated pseudopregnancy decreases sleep and increases hypothalamic activation in female Syrian hamsters

Sleep disruptions are a common occurrence during the peripartum period. While physical and environmental factors associated with pregnancy and newborn care account for some sleep disruptions, there is evidence that peripartum fluctuations in estrogens may independently impact sleep. We therefore used a hormone-simulated pseudopregnancy in female Syrian hamsters to test the hypothesis that pregnancy-like increases in estradiol decrease sleep in the absence of other factors. Adult female Syrian hamsters were ovariectomized and given daily hormone injections that simulate estradiol levels during early pregnancy, late pregnancy, and the postpartum period. Home cage video recordings were captured at seven timepoints and videos were analyzed for actigraphy. During "late pregnancy," total sleep time and sleep efficiency were decreased in hormone-treated animals during the white light period compared to vehicle controls. During both "early pregnancy" and "late pregnancy," locomotion was increased in the white light period for hormone-treated animals; this change continued into the "postpartum period" for animals who continued to receive estradiol treatment, but not for animals who were withdrawn from estradiol. At the conclusion of the experiment, animals were euthanized and cFos expression was quantified in the ventral lateral preoptic area (VLPO) and lateral hypothalamus (LH). Animals who continued to receive high levels of estradiol during the "postpartum" period had significantly more cFos in the VLPO and LH than animals who were withdrawn from hormones or vehicle controls. Together, these data suggest that increased levels of estradiol during pregnancy are associated with sleep suppression which may be mediated by increased activation of hypothalamic nuclei.

neuroscience↗