Recently, it has been recognized that physical abnormalities (e.g. elevated solid stress, elevated interstitial fluid pressure, increased stiffness) are associated with tumor progression and development. Additionally, these mechanical forces originating from tumor cell environment through mechanotransduction pathways can affect metabolism. On the other hand, mitochondria are well-known as bioenergetic, biosynthetic, and signaling organelles crucial for sensing stress and facilitating cellular adaptation to the environment and physical stimuli. Disruptions in mitochondrial dynamics and function have been found to play a role in the initiation and advancement of cancer. Consequently, it is logical to hypothesize that mitochondria dynamics subjected to physical cues may play a pivotal role in mediating tumorigenesis. Recently mitochondrial biogenesis and turnover, fission and fusion dynamics was linked to mechanotransduction in cancer. However, how cancer cell mechanics and mitochondria functions are connected, still remain poorly understood. Here, we discuss recent studies that link mechanical stimuli exerted by the tumor cell environment and mitochondria dynamics and functions. This interplay between mechanics and mitochondria functions may shed light on how mitochondria regulate tumorigenesis.
- Klíčová slova
- Cancer, Mechanotransduction, Mitochondria, Mitochondrial dynamics, Tumor metabolism,
- Publikační typ
- časopisecké články MeSH
Alpers' syndrome is an early-onset neurodegenerative disorder usually caused by biallelic pathogenic variants in the gene encoding the catalytic subunit of polymerase-gamma (POLG), which is essential for mitochondrial DNA (mtDNA) replication. The disease is progressive, incurable, and inevitably it leads to death from drug-resistant status epilepticus. The neurological features of Alpers' syndrome are intractable epilepsy and developmental regression, with no effective treatment; the underlying mechanisms are still elusive, partially due to lack of good experimental models. Here, we generated the patient derived induced pluripotent stem cells (iPSCs) from one Alpers' patient carrying the compound heterozygous mutations of A467T (c.1399G>A) and P589L (c.1766C>T), and further differentiated them into cortical organoids and neural stem cells (NSCs) for mechanistic studies of neural dysfunction in Alpers' syndrome. Patient cortical organoids exhibited a phenotype that faithfully replicated the molecular changes found in patient postmortem brain tissue, as evidenced by cortical neuronal loss and depletion of mtDNA and complex I (CI). Patient NSCs showed mitochondrial dysfunction leading to ROS overproduction and downregulation of the NADH pathway. More importantly, the NAD+ precursor nicotinamide riboside (NR) significantly ameliorated mitochondrial defects in patient brain organoids. Our findings demonstrate that the iPSC model and brain organoids are good in vitro models of Alpers' disease; this first-in-its-kind stem cell platform for Alpers' syndrome enables therapeutic exploration and has identified NR as a viable drug candidate for Alpers' disease and, potentially, other mitochondrial diseases with similar causes.
- Klíčová slova
- Alpers' disease, NAD+, NR, cortical organoids, induced pluripotent stem cells, mitochondrial function,
- MeSH
- DNA polymeráza gama MeSH
- indukované pluripotentní kmenové buňky * MeSH
- lidé MeSH
- mitochondriální DNA genetika MeSH
- mitochondriální nemoci * MeSH
- mutace MeSH
- NAD genetika MeSH
- niacinamid analogy a deriváty MeSH
- pyridinové sloučeniny * MeSH
- Schilderova difuzní cerebroskleróza * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA polymeráza gama MeSH
- mitochondriální DNA MeSH
- NAD MeSH
- niacinamid MeSH
- nicotinamide-beta-riboside MeSH Prohlížeč
- pyridinové sloučeniny * MeSH
BACKGROUND & AIMS: Lymphedema cholestasis syndrome 1 or Aagenaes syndrome is a condition characterized by neonatal cholestasis, lymphedema, and giant cell hepatitis. The genetic background of this autosomal recessive disease was unknown up to now. METHODS: A total of 26 patients with Aagenaes syndrome and 17 parents were investigated with whole-genome sequencing and/or Sanger sequencing. PCR and western blot analyses were used to assess levels of mRNA and protein, respectively. CRISPR/Cas9 was used to generate the variant in HEK293T cells. Light microscopy, transmission electron microscopy and immunohistochemistry for biliary transport proteins were performed in liver biopsies. RESULTS: One specific variant (c.-98G>T) in the 5'-untranslated region of Unc-45 myosin chaperone A (UNC45A) was identified in all tested patients with Aagenaes syndrome. Nineteen were homozygous for the c.-98G>T variant and seven were compound heterozygous for the variant in the 5'-untranslated region and an exonic loss-of-function variant in UNC45A. Patients with Aagenaes syndrome exhibited lower expression of UNC45A mRNA and protein than controls, and this was reproduced in a CRISPR/Cas9-created cell model. Liver biopsies from the neonatal period demonstrated cholestasis, paucity of bile ducts and pronounced formation of multinucleated giant cells. Immunohistochemistry revealed mislocalization of the hepatobiliary transport proteins BSEP (bile salt export pump) and MRP2 (multidrug resistance-associated protein 2). CONCLUSIONS: c.-98G>T in the 5'-untranslated region of UNC45A is the causative genetic variant in Aagenaes syndrome. IMPACT AND IMPLICATIONS: The genetic background of Aagenaes syndrome, a disease presenting with cholestasis and lymphedema in childhood, was unknown until now. A variant in the 5'-untranslated region of the Unc-45 myosin chaperone A (UNC45A) was identified in all tested patients with Aagenaes syndrome, providing evidence of the genetic background of the disease. Identification of the genetic background provides a tool for diagnosis of patients with Aagenaes syndrome before lymphedema is evident.
- Klíčová slova
- UNC45A, bile acids, cholestasis, genetic, lymphedema, myosin, non-coding, non-coding variant, untranslated region,
- MeSH
- 5' nepřekládaná oblast genetika MeSH
- cholestáza * genetika MeSH
- HEK293 buňky MeSH
- intracelulární signální peptidy a proteiny * genetika MeSH
- lidé MeSH
- lymfedém * diagnóza genetika metabolismus MeSH
- myosiny genetika metabolismus MeSH
- novorozenec MeSH
- transportní proteiny genetika MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- 5' nepřekládaná oblast MeSH
- intracelulární signální peptidy a proteiny * MeSH
- myosiny MeSH
- transportní proteiny MeSH
- UNC45A protein, human MeSH Prohlížeč
Dramatically increased levels of electromagnetic radiation in the environment have raised concerns over the potential health hazards of electromagnetic fields. Various biological effects of magnetic fields have been proposed. Despite decades of intensive research, the molecular mechanisms procuring cellular responses remain largely unknown. The current literature is conflicting with regards to evidence that magnetic fields affect functionality directly at the cellular level. Therefore, a search for potential direct cellular effects of magnetic fields represents a cornerstone that may propose an explanation for potential health hazards associated with magnetic fields. It has been proposed that autofluorescence of HeLa cells is magnetic field sensitive, relying on single-cell imaging kinetic measurements. Here, we investigate the magnetic field sensitivity of an endogenous autofluorescence in HeLa cells. Under the experimental conditions used, magnetic field sensitivity of an endogenous autofluorescence was not observed in HeLa cells. We present a number of arguments indicating why this is the case in the analysis of magnetic field effects based on the imaging of cellular autofluorescence decay. Our work indicates that new methods are required to elucidate the effects of magnetic fields at the cellular level.
- MeSH
- elektromagnetická pole * MeSH
- HeLa buňky MeSH
- lidé MeSH
- magnetické pole * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Liver cell types derived from induced pluripotent stem cells (iPSCs) share the potential to investigate development, toxicity, as well as genetic and infectious disease in ways currently limited by the availability of primary tissue. With the added advantage of patient specificity, which can play a role in all of these areas. Many iPSC differentiation protocols focus on 3 dimensional (3D) or organotypic differentiation, as these offer the advantage of more closely mimicking in vivo systems including; the formation of tissue like architecture and interactions/crosstalk between different cell types. Ultimately such models have the potential to be used clinically and either with or more aptly, in place of animal models. Along with the development of organotypic and micro-tissue models, there will be a need to co-develop imaging technologies to enable their visualization. A variety of liver models termed "organoids" have been reported in the literature ranging from simple spheres or cysts of a single cell type, usually hepatocytes, to those containing multiple cell types combined during the differentiation process such as hepatic stellate cells, endothelial cells, and mesenchymal cells, often leading to an improved hepatic phenotype. These allow specific functions or readouts to be examined such as drug metabolism, protein secretion or an improved phenotype, but because of their relative simplicity they lack the flexibility and general applicability of ex vivo tissue culture. In the liver field these are more often constructed rather than developed together organotypically as seen in other organoid models such as brain, kidney, lung and intestine. Having access to organotypic liver like surrogates containing multiple cell types with in vivo like interactions/architecture, would provide vastly improved models for disease, toxicity and drug development, combining disciplines such as microfluidic chip technology with organoids and ultimately paving the way to new therapies.
- Klíčová slova
- 3D microscopy, liver architecture, liver development, organoids, pluripotent stem cells, stem cell differentiation,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
