In the conserved autophagy pathway, autophagosomes (APs) engulf cellular components and deliver them to the lysosome for degradation. Before fusing with the lysosome, APs have to close via an unknown mechanism. We have previously shown that the endocytic Rab5-GTPase regulates AP closure. Therefore, we asked whether ESCRT, which catalyzes scission of vesicles into late endosomes, mediates the topologically similar process of AP sealing. Here, we show that depletion of representative subunits from all ESCRT complexes causes late autophagy defects and accumulation of APs. Focusing on two subunits, we show that Snf7 and the Vps4 ATPase localize to APs and their depletion results in accumulation of open APs. Moreover, Snf7 and Vps4 proteins complement their corresponding mutant defects in vivo and in vitro. Finally, a Rab5-controlled Atg17–Snf7 interaction is important for Snf7 localization to APs. Thus, we unravel a mechanism in which a Rab5-dependent Atg17–Snf7 interaction leads to recruitment of ESCRT to open APs where ESCRT catalyzes AP closure.

Roses are one of the most important cut flowers among ornamental plants. Rose flower longevity is largely dependent on the timing of petal shedding occurrence. To understand the molecular mechanism underlying petal abscission in rose, we performed transcriptome profiling of the petal abscission zone during petal shedding using Illumina technology. We identified a total of 2592 differentially transcribed genes (DTGs) during rose petal shedding. Gene ontology term enrichment and pathway analysis revealed that major biochemical pathways the DTGs were involved in included ethylene biosynthesis, starch degradation, superpathway of cytosolic glycolysis, pyruvate dehydrogenase and TCA cycle, photorespiration and the lactose degradation III pathway. This suggests that alterations in carbon metabolism are an important part of rose petal abscission. Among these DTGs, approximately 150 genes putatively encoding transcription factors were identified in rose abscission zone. These included zinc finger, WRKY, ERF, and Aux/IAA gene families, suggesting that petal abscission involves complex transcriptional reprogramming. Approximately 108 DTGs were related to hormone pathways, of which auxin and ethylene related DTGs were the largest groups including 52 and 41 genes, respectively. These also included 12 DTGs related to gibberellin and 6 DTGs in jasmonic acid pathway. Surprisingly, no DTGs involved in the biosynthesis/signaling of abscisic acid, cytokinin, brassinosteroid, and salicylic acid pathways were detected. Moreover, among DTGs related to auxin, we identified an Aux/IAA gene RhIAA16 that was up-regulated in response to petal shedding. Down-regulation of RhIAA16 by virus-induced gene silencing in rose promoted petal abscission, suggesting that RhIAA16 plays an important role in rose petal abscission.

Autologous fat transplantation (AFT) is a common and important operation in plastic surgery for soft tissue defects and adipose tissue-derived stem cells (ADSCs) are considered as a promising supplement to decrease absorption and subsequent side effects due to the ability of multiple differentiation and production of vascular endothelial growth factor (VEGF). The capacities of ADSCs can be further enhanced by treatment with 17-β estradiol (E2). Therefore, we hypothesized that E2 may promote the potential of ADSCs for AFT. In this study, ADSCs were extracted from three female patients by liposuction. In vitro studies showed that E2 supplementation at an optimal concentration of 10 -8 M resulted in enhanced proliferation, VEGF production, and adipogenic differentiation of human ADSCs, and reduced apoptosis rate in a serum-free environment. In addition, a nude mice model of fat transplantation was utilized to demonstrate the efficacy of ADSC for survival ratio in vivo. These results using the volume of fat tissues after 12 weeks compared original volume, revealed that the addition of E2-treated ADSCs induced a significantly higher tissue survival ratio (76.9 ± 1.9%) when compared with the ADSC-free system (55.5 ± 1.5%). Furthermore, increased capillary formation stained with hematoxylin-eosin (H&E) was observed in ADSCs systems after treatment with E2. Therefore, this study demonstrated E2 could promote the capacities of ADSCs about aspects of adipogenic differentiation, growth factor secretion and apoptosis reduction in vitro, vascularization improvement in vivo, and then enhanced the survival ratio of AFT.

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Background Adipose tissue-derived mesenchymal stem cells (ASCs) improve the regenerative ability and retention of fat grafts for breast reconstruction in cancer patients following mastectomy. However, ASCs have also been shown to promote breast cancer cell growth and metastasis. For the safety of ASC application, we aimed to identify specific markers for the subpopulation of ASCs that enhance the growth of breast cancer. Methods ASCs and bone marrow-derived vascular endothelial progenitor cells (EPCs) were isolated from Balb/c mice. c-Kit-positive (c-Kit+) or c-Kit-negative (c-Kit−) ASCs were cocultured with 4T1 breast cancer cells. Orthotropic murine models of 4T1, EPCs + 4T1, and c-Kit+/-ASCs + 4T1/EPCs were established in Balb/c mice. Results In coculture, c-Kit+ ASCs enhanced the viability and proliferation of 4T1 cells and stimulated c-Kit expression and interleukin-3 (IL-3) release. In mouse models, c-Kit+ASCs + 4T1/EPCs coinjection increased the tumor volume and vessel formation. Moreover, IL-3, stromal cell-derived factor-1, and vascular endothelial growth factor A in the c-Kit+ASCs + 4T1/EPCs coinjection group were higher than those in the 4T1, EPCs + 4T1, and c-Kit−ASCs + 4T1/EPCs groups. Conclusions c-Kit+ ASCs may promote breast cancer growth and angiogenesis by a synergistic effect of c-Kit and IL-3. Our findings suggest that c-Kit+ subpopulations of ASCs should be eliminated in fat grafts for breast reconstruction of cancer patients following mastectomy.

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This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Mitochondria play important roles in energy generation and homeostasis maintenance in eukaryotic cells. The damaged or superfluous mitochondria can be nonselectively or selectively removed through the autophagy/lysosome pathway, which was referred as mitophagy. According to the molecular machinery for degrading mitochondria, the selectively removed mitochondria can occur through macromitophagy or micromitophagy. In this study, we show that the endosomal sorting complex required for transport III (ESCRT‐III) in budding yeast regulates macromitophagy induced by nitrogen starvation, but not by the post‐logarithmic phase growth in lactate medium by monitoring a mitochondrial marker, Om45. Firstly, loss of ESCRT‐III subunit Snf7 or Vps4‐Vta1 complex subunit Vps4, two representative subunits of the ESCRT complex, suppresses the delivery and degradation of Om45‐GFP to vacuoles. Secondly, we show that the mitochondrial marker Om45 and mitophagy receptor Atg32 accumulate on autophagosomes marked with Atg8 (mitophagosomes, MPs) in ESCRT mutants. Moreover, the protease‐protection assay indicates that Snf7 and Vps4 are involved in MP closure. Finally, Snf7 interacts with Atg11, which was detected by two ways, glutathione‐S‐transferase (GST) pulldown and bimolecular fluorescence complementation (BiFC) assay, and this BiFC interaction happens on mitochondrial reticulum. Therefore, we proposed that the ESCRT‐III machinery mediates nitrogen starvation‐induced macromitophagy by the interaction between Snf7 and Atg11 so that Snf7 is recruited to Atg32‐marked MPs by the known Atg11–Atg32 interaction to seal them. These results reveal that the ESCRT‐III complex plays a new role in yeast on macromitophagy.