Biology of the Cell最新文献

Metabolism and mechanics are two key facets of structural and functional processes in cells, such as growth, proliferation, homeostasis and regeneration. Their reciprocal regulation has been increasingly acknowledged in recent years: external physical and mechanical cues entail metabolic changes, which in return regulate cell mechanosensing and mechanotransduction. Since mitochondria are pivotal regulators of metabolism, we review here the reciprocal links between mitochondrial morphodynamics, mechanics and metabolism. Mitochondria are highly dynamic organelles which sense and integrate mechanical, physical and metabolic cues to adapt their morphology, the organization of their network and their metabolic functions. While some of the links between mitochondrial morphodynamics, mechanics and metabolism are already well established, others are still poorly documented and open new fields of research. First, cell metabolism is known to correlate with mitochondrial morphodynamics. For instance, mitochondrial fission, fusion and cristae remodeling allow the cell to fine-tune its energy production through the contribution of mitochondrial oxidative phosphorylation and cytosolic glycolysis. Second, mechanical cues and alterations in mitochondrial mechanical properties reshape and reorganize the mitochondrial network. Mitochondrial membrane tension emerges as a decisive physical property which regulates mitochondrial morphodynamics. However, the converse link hypothesizing a contribution of morphodynamics to mitochondria mechanics and/or mechanosensitivity has not yet been demonstrated. Third, we highlight that mitochondrial mechanics and metabolism are reciprocally regulated, although little is known about the mechanical adaptation of mitochondria in response to metabolic cues. Deciphering the links between mitochondrial morphodynamics, mechanics and metabolism still presents significant technical and conceptual challenges but is crucial both for a better understanding of mechanobiology and for potential novel therapeutic approaches in diseases such as cancer.

Exosomes are emerging intercellular communicators essential for cellular homeostasis during development and differentiation. The dysregulation in exosome-mediated communication alters cellular networking leads to developmental defects and chronic diseases. Exosomes are heterogeneous in nature depending on differences in size, membrane protein abundance, and differential cargo load. In this review, we have highlighted the latest developments in exosome biogenesis pathways, heterogeneity, and selective enrichment of various exosomal cargoes including proteins, nucleic acids, and mitochondrial DNA. Furthermore, the recent developments in the isolation techniques of exosome subpopulations have also been discussed. The comprehensive knowledge of extracellular vesicle (EV) heterogeneity and selective cargo enrichment during specific pathology may provide a clue for disease severity and early prognosis possibilities. The release of specific exosome subtypes is associated with the progression of specific disease type and hence a probable tool for therapeutics and biomarker development.

Background information

Phagocytosis is the mechanism of the internalization of large particles, microorganisms and cellular debris. The complement pathway represents one of the first mechanisms of defense against infection and the complement receptor 3 (CR3), which is highly expressed on macrophages, is a major receptor for many pathogens and debris. Key to dissecting the mechanisms by which CR3-mediated phagocytosis occurs, is understanding how the complex actin binding protein machinery and associated regulators interact with actin during phagocytosis, from triggering of receptor, through to phagosome formation and closure.

Results

Here, we reveal that Dynamin-2 is recruited concomitantly with polymerized actin at the phagocytic cup and during phagosome formation and closure. Inhibition of Dynamin activity leads to stalled phagocytic cups and a decrease in the amount of F-actin at the site of phagocytosis.

Conclusions

Dynamin-2 regulates the assembly of the F-actin phagocytic cup for successful CR3-mediated phagocytosis.

Significance

These results highlight an important role for Dynamin-2 in actin remodeling downstream of integrins.

Background Information

During tumor invasion and metastasis processes, cancer cells are exposed to major compressive and shearing forces, due to their migration through extracellular matrix, dense cell areas, and complex fluids, which may lead to numerous plasma membrane damages. Cancer cells may survive to these mechanical stresses thanks to an efficient membrane repair machinery. Consequently, this machinery may constitute a relevant target to inhibit cancer cell dissemination.

Results

We show here that annexin-A5 (ANXA5) and ANXA6 participate in membrane repair of MDA-MB-231 cells, a highly invasive triple-negative breast cancer cell line. These crucial components of the membrane repair machinery are substantially expressed in breast cancer cells in correlation with their invasive properties. In addition, high expression of ANXA5 and ANXA6 predict poor prognosis in high-grade lung, gastric, and breast cancers. In zebrafish, the genetic inhibition of ANXA5 and ANXA6 leads to drastic reduction of tumor cell dissemination.

Conclusion

We conclude that the inhibition of ANXA5 and ANXA6 prevents membrane repair in cancer cells, which are thus unable to survive to membrane damage during metastasis.

Significance

This result opens a new therapeutic strategy based on targeting membrane repair machinery to inhibit tumor invasion and metastasis.