Organelles in health and diseases

Bioorthogonal Chemistry in Cellular Organelles

While bioorthogonal reactions are routinely employed in living cells and organisms, their application within individual organelles remains limited. In this review, we highlight diverse examples of bioorthogonal reactions used to investigate the roles of biomolecules and biological processes as well as advanced imaging techniques within cellular organelles. These innovations hold great promise for therapeutic interventions in personalized medicine and precision therapies. We also address existing challenges related to the selectivity and trafficking of subcellular dynamics. Organelle-targeted bioorthogonal reactions have the potential to significantly advance our understanding of cellular organization and function, provide new pathways for basic research and clinical applications, and shape the direction of cell biology and medical research.

Small Molecule AIEgens for Illuminating Sub-Cellular Endoplasmic Reticulum, Mitochondria, and Lysosomes

Organelles are the working hubs of the cells. Hence, visualizing these organelles inside the cells is highly important for understanding their roles in pathological states and development of therapeutic strategies. Herein, we report the development of a novel highly substituted oxazoles with modular scaffolds (AIE-ER, AIE-Mito, and AIE-Lyso), which can home into endoplasmic reticulum (ER), mitochondria, and lysosomes inside the cells. These oxazoles showed remarkable aggregation-induced emission (AIE) property in water and in the solid state due to dual intramolecular H-bonding, which was confirmed by pH- and temperature-dependent fluorescence studies followed by molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Confocal laser scanning microscopy studies revealed that AIE-ER, AIE-Mito, and AIE-Lyso efficiently homed into ER, mitochondria and lysosomes, respectively, in the HeLa cervical cancer cells and non-cancerous human retinal pigment epithelial RPE-1 cells within 3 h without showing any toxicity to the cells with high sub-cellular photostability. To the best of our knowledge, this is the first report of highly substituted oxazole-based small molecule AIEgens for organelle imaging. We anticipate these novel AIEgens have promise to image sub-cellular organelles in different diseased states as well as understanding the inter-organelle interactions towards the development of novel therapeutics.

Autonomous metal-organic framework nanorobots for active mitochondria-targeted cancer therapy

Nanorobotic manipulation to access subcellular organelles remains unmet due to the challenge in achieving intracellular controlled propulsion. Intracellular organelles, such as mitochondria, are an emerging therapeutic target with selective targeting and curative efficacy. We report an autonomous nanorobot capable of active mitochondria-targeted drug delivery, prepared by facilely encapsulating mitochondriotropic doxorubicin-triphenylphosphonium (DOX-TPP) inside zeolitic imidazolate framework-67 (ZIF-67) nanoparticles. The catalytic ZIF-67 body can decompose bioavailable hydrogen peroxide overexpressed inside tumor cells to generate effective intracellular mitochondriotropic movement in the presence of TPP cation. This nanorobot-enhanced targeted drug delivery induces mitochondria-mediated apoptosis and mitochondrial dysregulation to improve the in vitro anticancer effect and suppression of cancer cell metastasis, further verified by in vivo evaluations in the subcutaneous tumor model and orthotopic breast tumor model. This nanorobot unlocks a fresh field of nanorobot operation with intracellular organelle access, thereby introducing the next generation of robotic medical devices with organelle-level resolution for precision therapy.

Emerging Landscape of Cell-Penetrating Peptide-Mediated Organelle Restoration and Replacement

Organelles are specialized subunits within a cell membrane that perform specific roles or functions, and their dysfunction can lead to a variety of pathophysiologies including developmental defects, aging, and diseases (cancer, cardiovascular and neurodegenerative diseases). Recent studies have shown that cell-penetrating peptide (CPP)-based pharmacological therapies delivered to organelles or even directly resulting in organelle replacement can restore cell function and improve or prevent disease. In this review, we summarized the current developments in the precise delivery of exogenous cargoes via CPPs at the organelle level, CPP-mediated organelle delivery, and discuss their feasibility as next-generation targeting strategies for the diagnosis and treatment of diseases at the organelle level.

Illuminating Sub-Cellular Organelles by Small Molecule AIEgens

Sub-cellular organelles play a critical role in a myriad biological phenomena. Consequently, organelle structures and functions are invariably highjacked in diverse diseases including metabolic disorders, aging, and cancer. Hence, illuminating organelle dynamics is crucial in understanding the diseased states as well as developing organelle-targeted next generation therapeutics. In this review, we outline the novel small molecules which show remarkable aggregation-induced emission (AIE) properties due to restriction in intramolecular motion (RIM). We outline the examples of small molecules developed to image organelles like mitochondria, endoplasmic reticulum (ER), Golgi, lysosomes, nucleus, cell membrane and lipid droplets. These AIEgens have tremendous potential for next-generation phototherapy.

Intracellular organelles in health and kidney disease

Subcellular organelles consist of smaller substructures called supramolecular assemblies and these in turn consist of macromolecules. Various subcellular organelles have critical functions that consist of genetic disorders of organelle biogenesis and several metabolic disturbances that occur during non-genetic diseases e.g. infection, intoxication and drug treatments. Mitochondrial damage can cause renal dysfunction as ischemic acute renal injury, chronic kidney disease progression. Moreover, mitochondrial dysfunction is an early event in aldosterone-induced podocyte injury and cardiovascular disease due to oxidative stress in chronic kidney disease. Elevated production of reactive oxygen species could be able to activate NLRP3 inflammasome representing new deregulated biological machinery and a novel therapeutic target in hemodialysis patients. Peroxisomes are actively involved in apoptosis and inflammation, innate immunity, aging and in the pathogenesis of age related diseases, such as diabetes mellitus and cancer. Peroxisomal catalase causes alterations of mitochondrial membrane proteins and stimulates generation of mitochondrial reactive oxygen species. High concentrations of hydrogen peroxide exacerbate organelles and cellular aging. The importance of proper peroxisomal function for the biosynthesis of bile acids has been firmly established. Endoplasmic reticulum stress-induced pathological diseases in kidney cause glomerular injury and tubulointerstitial injury. Furthermore, there is a link between oxidative stress and inflammations in pathological states are associated with endoplasmic reticulum stress. Proteinuria and hyperglycemia in diabetic nephropathy may induce endoplasmic reticulum stress in tubular cells of the kidney. Due to the accumulation in the proximal tubule lysosomes, impaired function of these organelles may be an important mechanism leading to proximal tubular toxicity.