Vps60 initiates alternative ESCRT-III filaments

The green ESCRTs: Newly defined roles for ESCRT proteins in plants

Endocytosis and endosomal trafficking of plasma membrane proteins for degradation regulate cellular homeostasis and development. As part of these processes, ubiquitinated plasma membrane proteins (cargo) are recognized, clustered, and sorted into intraluminal vesicles of multivesicular endosomes by endosomal sorting complexes required for transport (ESCRT) proteins. At endosomes, ESCRT proteins recognize ubiquitinated cargo and mediate the deformation of the endosomal membrane in a negative geometry, away from the cytosol. ESCRTs are organized in five major complexes that are sequentially recruited to the endosomal membrane where they mediate its vesiculation and cargo sequestration. ESCRTs also participate in other membrane remodeling events and are widely conserved across organisms, both eukaryotes and prokaryotes. Plants contain both conserved and unique ESCRT components and show a general trend toward gene family expansion. Plant endosomes show a wide range of membrane budding patterns with potential implications in cargo sequestration efficiency, plant development, and hormone signaling. Understanding the diversification and specialization of plant ESCRT proteins can provide valuable insights in the mechanisms of ESCRT-mediated membrane bending. In this review, we discuss the endosomal function of ESCRT proteins, their unique features in plants, and the potential connections to the modes of plant endosomal vesiculation.

ESCRTs - a multi-purpose membrane remodeling device encoded in all life forms

The ESCRT (endosomal sorting complexes required for transport) membrane remodeling complex, found across all life forms, exhibits a versatility that transcends evolutionary boundaries. From orchestrating the constriction of micron-wide tubes in cell division to facilitating the budding of 50 nm vesicles in receptor degradation, ESCRTs perform diverse functions in animal cells. However, the basis of this functional diversity remains enigmatic. While extensively studied in eukaryotes, the role of ESCRTs in prokaryotes is only beginning to emerge. This review synthesizes data on ESCRT systems across the tree of life, focusing on microorganisms and drawing parallels to their functions in human cells. This comparative approach highlights the remarkable plasticity of the ESCRT system across functional, structural, and genomic levels in both prokaryotes and eukaryotes. This integrated knowledge supports a model in which the ESCRT system evolved as a multipurpose membrane remodeling tool, adaptable to specific functions within and across organisms. Our review not only underscores the significance of ESCRTs in microorganisms but also paves the way for exciting avenues of research into the intricacies of cellular membrane dynamics, offering valuable insights into the evolution of cellular complexity across diverse organisms and ecosystems.

Proteomic analysis across aged tissues reveals distinct signatures and the crucial involvement of midgut barrier function in the regulation of aging

The process of aging is a natural phenomenon characterized by gradual deterioration in biological functions and systemic homeostasis, which can be modulated by both genetic and environmental factors. Numerous investigations conducted on model organisms, including nematodes, flies, and mice, have elucidated several pivotal aging pathways, such as insulin signaling and AMPK signaling. However, it remains uncertain whether the regulation of the aging process is uniform or diverse across different tissues and whether manipulating the same aging factor can result in consistent outcomes in various tissues. In this study, we utilize the Drosophila organism to investigate tissue-specific proteome signatures during the aging process. Although distinct proteins undergo changes in aged tissues, certain common altered functional networks are constituently identified across different tissues, including the decline of the mitochondrial ribosomal network, autophagic network, and anti-ROS defense networks. Furthermore, downregulation of insulin receptor (InR) in the midguts, muscle, and central nervous system (CNS) of flies leads to a significant extension in fly lifespans. Notably, despite manipulating the same aging gene InR, diverse alterations in proteins are observed across different tissues. Importantly, knockdown of InR in the midguts leads to a distinct proteome compared with other tissues, resulting in enhanced actin nucleation and glutathione metabolism, while attenuating age-related elevation of serine proteases. Consequently, knockdown of InR results in rejuvenation of the integrity of the midgut barrier and augmentation of anti-ROS defense capabilities. Our findings suggest that the barrier function of the midgut plays a pivotal role in defending against aging, underscoring the paramount importance of maintaining optimal gut physiology to effectively delay the aging process. Moreover, when considering age-related changes across various tissues, it is more reasonable to identify functional networks rather than focusing solely on individual proteins.

Interaction between ESCRT-III proteins and the yeast SERINC homolog Tms1

The endosomal sorting complex required for transport (ESCRT)-III is involved in membrane remodeling and abscission during intraluminal vesicle (ILV) formation at endosomes. Our data now suggest that ESCRT-III function could be connected to lipid remodeling of the endosomal membrane. This notion is based on our finding that ESCRT-III proteins bind to the yeast serine incorporator (SERINC) homolog Tms1. Human SERINC3 and SERINC5 are HIV-1 restriction factors and have been shown to act as scramblases, flipping phospholipids between membrane leaflets. Due to the extraordinarily high sequence conservation between Tms1 and human SERINCs, it is likely that Tms1 is also a scramblase. While deletion of TMS1 had only a moderate effect on the sorting of multivesicular body (MVB) cargo proteins, the simultaneous deletion of a component of the Vps55/Vps68 complex led to a strong synergistic phenotype. This pronounced synergism suggests that Tms1 and Vps55/Vps68 perform a parallel function at endosomes. Vps55/Vps68 loosely resembles Tms1 in its overall structure. Thus, it is possible that Vps55/Vps68 is also a scramblase. Since both Vps55 and Tms1 physically interact with ESCRT-III proteins, we propose that the recruitment of a scramblase plays a crucial role in ESCRT-III-dependent membrane remodeling at endosomes.

Incomplete divisions between sister germline cells require Usp8 function

Cytokinetic abscission is the final step of cell division, resulting in two separate daughter cells. While abscission is typically complete across most cell types, germline cells, which produce sexual gametes, do not finish cytokinesis, maintaining connections between sister cells. These connections are essential for sharing cytoplasm as they differentiate into oocyte and sperm. First, we outline the molecular events of cytokinesis during both complete and delayed abscission, highlighting the role of the ESCRT-III proteins. We then focus on recent discoveries that reveal the molecular mechanisms blocking abscission in Drosophila germline cells. The enzyme Usp8 was identified as vital for ensuring incomplete cytokinesis through the regulation of ESCRT-III ubiquitination and localization. Finally, we explore how the processes of incomplete cytokinesis could hold evolutionary importance, suggesting additional studies into choanoflagellates to comprehend the origins of multicellularity.

ESCRT-III: a versatile membrane remodeling machinery and its implications in cellular processes and diseases

The endosomal sorting complexes required for transport (ESCRT) machinery is an evolutionarily conserved cytosolic protein complex that plays a crucial role in membrane remodeling and scission events across eukaryotes. Initially discovered for its function in multivesicular body (MVB) formation, the ESCRT complex has since been implicated in a wide range of membrane-associated processes, including endocytosis, exocytosis, cytokinesis, and autophagy. Recent advances have elucidated the ESCRT assembly pathway and highlighted the distinct functions of the various ESCRT complexes and their associated partners. Among the ESCRT complexes, ESCRT-III stands out as a critical player in membrane remodeling, with its subunits assembled into higher-order multimers capable of bending and severing membranes. This review focuses on the ESCRT-III complex, exploring its diverse functions in cellular processes beyond MVB biogenesis. We delve into the molecular mechanisms underlying ESCRT-III-mediated membrane remodeling and highlight its emerging roles in processes such as viral budding, autophagosome closure, and cytokinetic abscission. We also discuss the implications of ESCRT-III dysregulation in neurodegenerative diseases. The versatile membrane remodeling capabilities of ESCRT-III across diverse cellular processes underscore its importance in maintaining proper cellular function. Furthermore, we highlight the promising potential of ESCRT-III as a therapeutic target for neurodegenerative diseases, offering insights into the treatments of the diseases and the technical applications in related research fields.

Exosome-Mediated Antigen Delivery: Unveiling Novel Strategies in Viral Infection Control and Vaccine Design

Exosomes are small subtypes of extracellular vesicles (EVs) naturally released by different types of cells into their environment. Their physiological roles appear to be multiple, yet many aspects of their biological activities remain to be understood. These vesicles can transport and deliver a variety of cargoes and may serve as unconventional secretory vesicles. Thus, they play a crucial role as important vectors for intercellular communication and the maintenance of homeostasis. Exosome production and content can vary under several stresses or modifications in the cell microenvironment, influencing cellular responses and stimulating immunity. During infectious processes, exosomes are described as double-edged swords, displaying both beneficial and detrimental effects. Owing to their tractability, the analysis of EVs from multiple biofluids has become a booming tool for monitoring various pathologies, from infectious to cancerous origins. In this review, we present an overview of exosome features and discuss their particular and ambiguous functions in infectious contexts. We then focus on their properties as diagnostic or therapeutic tools. In this regard, we explore the capacity of exosomes to vectorize immunogenic viral antigens and their function in mounting adaptive immune responses. As exosomes provide interesting platforms for antigen presentation, we further review the available data on exosome engineering, which enables peptides of interest to be exposed at their surface. In the light of all these data, exosomes are emerging as promising avenues for vaccine strategies.

Research progress of exosomes in the angiogenesis of digestive system tumour

Malignant tumours of the digestive system cover a wide range of diseases that affect the health of people to a large extent. Angiogenesis is indispensable in the development, and metastasis of tumours, mainly in two ways: occupation or formation. Vessels can provide nutrients, oxygen, and growth factors for tumours to encourage growth and metastasis, so cancer progression depends on simultaneous angiogenesis. Recently, exosomes have been proven to participate in the angiogenesis of tumours. They influence angiogenesis by binding to tyrosine kinase receptors (VEGFR)-1, VEGFR-2, and VEGFR-3 with different affinities, regulating Yap-VEGF pathway, Akt pathway or other signaling pathway. Additionally, exosomes are potential therapeutic vectors that can deliver many types of cargoes to different cells. In this review, we summarize the roles of exosomes in the angiogenesis of digestive system tumours and highlight the clinical application prospects, directly used as targers or delivery vehicles, in antiangiogenic therapy.