scholarly journals Mitochondria and Eye

2021 ◽  
Author(s):  
Lata Singh ◽  
Mithalesh Kumar Singh
Keyword(s):  
Nuclear Dna ◽  
Protein Complexes ◽  
Critical Role ◽  
Mitochondrial Disorders ◽  
Treatment Modalities ◽  
Renal Tubules ◽  
Metabolic Demand ◽  
Mammalian Mitochondria ◽  
Ocular Disorders

Mitochondria are essential subcellular organelles and important key regulators of metabolism. Mammalian mitochondria contain their own DNA (mtDNA). Human mtDNA is remarkably small (16,569 bp) compared to nuclear DNA. Mitochondria promote aerobic respiration, an important part of energy metabolism in eukaryotes, as the site of oxidative phosphorylation (OXPHOS). OXPHOS occurs in the inner membrane of the mitochondrion and involves 5 protein complexes that sequentially undergo reduction-oxygen reactions ultimately producing adenosine triphosphate (ATP). Tissues with high metabolic demand such as lungs, central nervous system, peripheral nerves, heart, adrenal glands, renal tubules and the retina are affected preferentially by this critical role in energy production by mitochondrial disorders. Eye-affected mitochondrial disorders are always primary, but the role of mitochondrial dysfunction is now best understood in acquired chronic progressive ocular diseases. Recent advances in mitochondrial research have improved our understanding of ocular disorders. In this chapter, we will discuss the mitochondria in relation to eye diseases, ocular tumors, pathogenesis, and treatment modalities that will help to improve the outcomes of these conditions.

Targeting mTOR Signaling in Type 2 Diabetes Mellitus and Diabetes Complications

2022 ◽  
Vol 23 ◽  
Author(s):  
Lin Yang ◽  
Zhixin Zhang ◽  
Doudou Wang ◽  
Yu Jiang ◽  
Ying Liu
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Protein Complexes ◽  
Cell Metabolism ◽  
Critical Role ◽  
Mtor Inhibitors ◽  
Mtor Signaling

Abstract: The mechanistic target of rapamycin (mTOR) is a pivotal regulator of cell metabolism and growth. In the form of two different multi-protein complexes, mTORC1 and mTORC2, mTOR integrates cellular energy, nutrient and hormonal signals to regulate cellular metabolic homeostasis. In type 2 diabetes mellitus (T2DM) aberrant mTOR signaling underlies its pathological conditions and end-organ complications. Substantial evidence suggests that two mTOR-mediated signaling schemes, mTORC1-p70S6 kinase 1 (S6K1) and mTORC2-protein kinase B (AKT), play a critical role in insulin sensitivity and that their dysfunction contributes to development of T2DM. This review summaries our current understanding of the role of mTOR signaling in T2DM and its associated complications, as well as the potential use of mTOR inhibitors in treatment of T2DM.

scholarly journals S-Palmitoylation determines TMEM55B-dependent positioning of lysosomes

2021 ◽  
Author(s):  
Sönke Rudnik ◽  
Saskia Heybrock ◽  
Paul Saftig ◽  
Markus Damme
Keyword(s):  
Molecular Motors ◽  
Protein Complexes ◽  
Critical Role ◽  
Adaptor Protein ◽  
Retrograde Transport ◽  
Microtubule Motors ◽  
Lysosomal Sorting ◽  
Sorting Motif ◽  
Spatio Temporal

The spatio-temporal cellular distribution of lysosomes depends on active transport mainly driven by microtubule-motors such as kinesins and dynein. Different protein complexes attach these molecular motors to their vesicular cargo: TMEM55B, as an integral lysosomal membrane protein, is a component of such a complex mediating the retrograde transport of lysosomes by establishing an interaction with the cytosolic scaffold protein JIP4 and dynein/dynactin. Here we show that TMEM55B and its paralog TMEM55A are S-palmitoylated proteins and lipidated at multiple cysteine-residues. Mutation of all cysteines in TMEM55B prevents S-palmitoylation and causes the retention of the mutated protein in the Golgi-apparatus. Consequently, non-palmitoylated TMEM55B is no longer able to modulate lysosomal positioning and the perinuclear clustering of lysosomes. Additional mutagenesis of the dileucine-based lysosomal sorting motif in non-palmitoylated TMEM55B leads to partial missorting to the plasma membrane instead of retention in the Golgi, implicating a direct effect of S-palmitoylation on the adaptor-protein-dependent sorting of TMEM55B. Our data suggest a critical role of S-palmitoylation on the trafficking of TMEM55B and TMEM55B-dependent lysosomal positioning.

scholarly journals Modeling Adipogenesis: Current and Future Perspective

Cells ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 2326 ◽  
Author(s):  
Hisham F. Bahmad ◽  
Reem Daouk ◽  
Joseph Azar ◽  
Jiranuwat Sapudom ◽  
Jeremy C. M. Teo ◽  
...  
Keyword(s):  
Stem Cells ◽  
Adipose Tissue ◽  
Crucial Role ◽  
Critical Role ◽  
Treatment Modalities ◽  
Future Perspective ◽  
Adipose Derived Stem Cells ◽  
Physiological Importance ◽  
And Personalized Medicine

Adipose tissue is contemplated as a dynamic organ that plays key roles in the human body. Adipogenesis is the process by which adipocytes develop from adipose-derived stem cells to form the adipose tissue. Adipose-derived stem cells’ differentiation serves well beyond the simple goal of producing new adipocytes. Indeed, with the current immense biotechnological advances, the most critical role of adipose-derived stem cells remains their tremendous potential in the field of regenerative medicine. This review focuses on examining the physiological importance of adipogenesis, the current approaches that are employed to model this tightly controlled phenomenon, and the crucial role of adipogenesis in elucidating the pathophysiology and potential treatment modalities of human diseases. The future of adipogenesis is centered around its crucial role in regenerative and personalized medicine.

scholarly journals Role of the high-affinity leukotriene B4 receptor signaling in fibrosis after unilateral ureteral obstruction in mice

2018 ◽  
Author(s):  
Mariko Kamata ◽  
Hideki Amano ◽  
Yoshiya Ito ◽  
Tomoe Fujita ◽  
Kanako Hosono ◽  
...  
Keyword(s):  
Growth Factor ◽  
Ureteral Obstruction ◽  
Type I Collagen ◽  
Critical Role ◽  
Unilateral Ureteral Obstruction ◽  
Type I ◽  
Renal Tubules ◽  
Kidney Fibrosis ◽  
High Affinity

AbstractLeukotriene B4 (LTB4) is a lipid mediator that acts as a potent chemoattractant for inflammatory leukocytes. Kidney fibrosis is caused by migrating inflammatory cells and kidney-resident cells. Here, we examined the role of the high-affinity LTB4 receptor BLT1 during development of kidney fibrosis in wild-type (WT) mice and BLT1 knockout (BLT1-/-) mice with unilateral ureteral obstruction (UUO). We found elevated expression of 5-lipoxygenase (5-LOX), which generates LTB4, in the renal tubules of WT and BLT1-/- UUO mice. Accumulation of immunoreactive type I collagen in UUO kidneys of WT mice increased over time; however, the increase was less prominent in BLT1-/- mice. Accumulation of S100A4-positive fibroblasts also increased temporally in WT UUO kidneys, but was again less pronounced in those of BLT1-/- mice. The same was true of mRNA encoding transforming growth factor-β (TGF)-β and fibroblast growth factor (FGF)-2. Finally, accumulation of F4/80-positive macrophages, which secrete TGF-β, also increased temporally in WT UUO and BLT1-/- kidneys, but to a lesser extent in the latter. Following LTB4 stimulation in vitro, macrophages showed increased expression of mRNA encoding TGF-β/FGF-2 and Col1a1, whereas L929 fibroblasts showed increased expression of mRNA encoding α smooth muscle actin (SMA). Bone marrow (BM) transplantation studies revealed that the area positive for type I collagen was significantly smaller in BLT1-/--BM→WT UUO kidneys than in WT-BM→WT kidneys. Thus, LTB4-BLT1 signaling plays a critical role in fibrosis in UUO kidneys by increasing accumulation of macrophages and fibroblasts. Therefore, blocking BLT1 may prevent renal fibrosis.

scholarly journals LncRNA H19 Suppresses Osteosarcomagenesis by Regulating snoRNAs and DNA Repair Protein Complexes

2021 ◽  
Vol 11 ◽  
Author(s):  
An Xu ◽  
Mo-Fan Huang ◽  
Dandan Zhu ◽  
Julian A. Gingold ◽  
Danielle A. Bazer ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Molecular Mechanisms ◽  
Malignant Tumors ◽  
Protein Complexes ◽  
Familial Cancer ◽  
Critical Role ◽  
Childhood And Adolescence ◽  
Cancer Syndrome ◽  
Li Fraumeni Syndrome

Osteosarcoma is one of the most frequent common primary malignant tumors in childhood and adolescence. Long non-coding RNAs (lncRNAs) have been reported to regulate the initiation and progression of tumors. However, the exact molecular mechanisms involving lncRNA in osteosarcomagenesis remain largely unknown. Li-Fraumeni syndrome (LFS) is a familial cancer syndrome caused by germline p53 mutation. We investigated the tumor suppressor function of lncRNA H19 in LFS-associated osteosarcoma. Analyzing H19-induced transcriptome alterations in LFS induced pluripotent stem cell (iPSC)-derived osteoblasts, we unexpectedly discovered a large group of snoRNAs whose expression was significantly affected by H19. We identified SNORA7A among the H19-suppressed snoRNAs. SNORA7A restoration impairs H19-mediated osteogenesis and tumor suppression, indicating an oncogenic role of SNORA7A. TCGA analysis indicated that SNORA7A expression is associated with activation of oncogenic signaling and poor survival in cancer patients. Using an optimized streptavidin-binding RNA aptamer designed from H19 lncRNA, we revealed that H19-tethered protein complexes include proteins critical for DNA damage response and repair, confirming H19's tumor suppressor role. In summary, our findings demonstrate a critical role of H19-modulated SNORA7A expression in LFS-associated osteosarcomas.

scholarly journals The CARD plays a critical role in ASC foci formation and inflammasome signalling

2013 ◽  
Vol 449 (3) ◽  
pp. 613-621 ◽  
Author(s):  
Martina Proell ◽  
Motti Gerlic ◽  
Peter D. Mace ◽  
John C. Reed ◽  
Stefan J. Riedl
Keyword(s):  
Protein Complexes ◽  
Critical Role ◽  
Bimolecular Fluorescence Complementation ◽  
Nucleotide Binding Domain ◽  
Caspase 1 ◽  
Pyrin Domain ◽  
Raw264.7 Cell ◽  
Multimeric Protein ◽  
Mediate Inflammation

The ASC (apoptosis speck-like protein) is a key component of multimeric protein complexes that mediate inflammation and host defence. Comprising a PYD (Pyrin) domain and a CARD (caspase activation and recruitment domain), ASC functions downstream of NLRs (nucleotide-binding domain, leucine-rich repeat-containing receptors) and AIM2 (absent in melanoma 2) through the formation of supramolecular structures termed inflammasomes. However, the mechanism underlying ASC signalling and its dependency on oligomeric arrangements in inflammasome formation remain poorly understood. When expressed in cells, ASC forms discrete foci (called ‘specks’) typically with one speck per cell. We employed a BiFC (bimolecular fluorescence complementation) system to investigate and visualize ASC foci formation in living cells. We demonstrated that the CARD of ASC plays a central role in ASC inflammasome assembly, representing the minimal unit capable of forming foci in conjunction with the caspase 1 CARD. Mutational studies point to multiple surfaces on the ASC CARD and two predominant areas on the caspase 1 CARD mediating the formation of ASC/caspase 1 foci. The lack of foci formation for ASC CARD mutants correlates with a loss of IL-1β (interleukin 1β) processing in response to NLRP (NLR family, PYD domain-containing) 3 or AIM2 agonists in RAW264.7 cell reconstitution assays. Analogously, we show that productive formation of the Salmonella typhimurium-induced NLRC4 (NLR family CARD domain-containing protein 4) inflammasome is dependent on ASC–CARD-mediated platform formation. Thus the results of the present study depict a central role of CARDs in the formation of ASC signalling platforms and provide an important tool for investigation of CARD-dependent networks.

scholarly journals A critical role of VMP1 in lipoprotein secretion

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Hideaki Morishita ◽  
Yan G Zhao ◽  
Norito Tamura ◽  
Taki Nishimura ◽  
Yuki Kanda ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Neutral Lipids ◽  
Protein Complexes ◽  
Transmembrane Protein ◽  
Critical Role ◽  
Visceral Endoderm ◽  
Peripheral Tissues ◽  
Lipoprotein Secretion ◽  
Er Membrane

Lipoproteins are lipid-protein complexes that are primarily generated and secreted from the intestine, liver, and visceral endoderm and delivered to peripheral tissues. Lipoproteins, which are assembled in the endoplasmic reticulum (ER) membrane, are released into the ER lumen for secretion, but its mechanism remains largely unknown. Here, we show that the release of lipoproteins from the ER membrane requires VMP1, an ER transmembrane protein essential for autophagy and certain types of secretion. Loss of vmp1, but not other autophagy-related genes, in zebrafish causes lipoprotein accumulation in the intestine and liver. Vmp1 deficiency in mice also leads to lipid accumulation in the visceral endoderm and intestine. In VMP1-depleted cells, neutral lipids accumulate within lipid bilayers of the ER membrane, thus affecting lipoprotein secretion. These results suggest that VMP1 is important for the release of lipoproteins from the ER membrane to the ER lumen in addition to its previously known functions.

scholarly journals Intraflagellar transport-A deficiency attenuates ADPKD in a renal tubular- and maturation-dependent manner

2020 ◽  
Author(s):  
Wei Wang ◽  
Luciane M. Silva ◽  
Henry H. Wang ◽  
Matthew A. Kavanaugh ◽  
Tana S. Pottorf ◽  
...  
Keyword(s):  
Mouse Models ◽  
Primary Cilia ◽  
Protein Complexes ◽  
Collecting Duct ◽  
Intraflagellar Transport ◽  
Renal Tubules ◽  
Dependent Manner ◽  
Cortical Collecting Duct ◽  
Knock Out

AbstractPrimary cilia are sensory organelles that are built and maintained by intraflagellar transport (IFT) multi-protein complexes. Deletion of certain ciliary genes in Autosomal Dominant Polycystic Kidney Disease (ADPKD) mouse models markedly attenuates PKD severity, indicating that a component of cilia dysfunction may have potential therapeutic value. To broaden the role of ciliary dysfunction, here we investigate the role of global deletion of Ift-A gene, Thm1, in juvenile and adult ADPKD mouse models. In cyst-lining cells of both juvenile and adult ADPKD models, cortical collecting duct cilia lengths and cytoplasmic and nuclear levels of the nutrient sensor, O-linked β-Nacetylglucosamine (O-GlcNAc) were increased. Relative to juvenile Pkd2 conditional knock-out mice, deletion of Thm1 together with Pkd2 both increased and reduced cystogenesis in a tubule-specific manner without altering kidney function, inflammation, cilia lengths, and ERK, STAT3 and OGlcNAc signaling. In contrast, Thm1 deletion in adult ADPKD mouse models markedly attenuated almost all features of PKD, including renal cystogenesis, inflammation, cilia lengths, and ERK, STAT3 and O-GlcNAc signaling. These data suggest that differential factors in the microenvironments between renal tubules and between developing and mature kidneys influence cilia and ADPKD pathobiology. Further, since O-GlcNAcylation directly regulates ciliary homeostasis and the balance between glycolysis and oxidative phosphorylation, we propose that increased O-GlcNAcylation may promote certain key ADPKD pathological processes.

scholarly journals Mitochondrial dysfunction and the role of the non-specialist laboratory

2002 ◽  
Vol 39 (5) ◽  
pp. 456-463 ◽  
Author(s):  
Maggie R Hancock
Keyword(s):  
Mitochondrial Dna ◽  
Oxidative Phosphorylation ◽  
Highly Active Antiretroviral Therapy ◽  
Nuclear Dna ◽  
Nuclear Genome ◽  
Mitochondrial Disorders ◽  
Highly Active ◽  
Clinical Presentations ◽  
Immunodeficiency Virus

Each human cell contains at least 1000 mitochondria, each containing several copies of mitochondrial DNA. This DNA is tiny compared with the nuclear genome, and its structure and products have been fully elucidated. Whilst oxidative phosphorylation depends on the polypeptides encoded by mitochondrial DNA, it also requires a huge number of nuclear DNA products. Inherited deleterious mutations of mitochondrial DNA leading to inefficient oxidative phosphorylation have been described as 'mitochondrial disorders', with a variety of clinical presentations. When similar clinical presentations occur with no discernible mutation of mitochondrial DNA, histological and biochemical evidence is required for diagnosis. The number of these laboratory-proven inherited mitochondrial disorders is growing. It is also becoming clear that mitochondrial DNA defects can be acquired, the most common cause being therapy with highly active antiretroviral therapy (HAART) for human immunodeficiency virus-1 (HIV-1) infection. Whilst definitive diagnosis of inherited or acquired mitochrondrial dysfunction requires access to specialist laboratory techniques, routine laboratories have a role to play in the initial investigation and monitoring of these conditions.

scholarly journals NLRP3 Inflammasome and Its Critical Role in Gynecological Disorders and Obstetrical Complications

2021 ◽  
Vol 11 ◽  
Author(s):  
Xuhui Fang ◽  
Yanshi Wang ◽  
Yu Zhang ◽  
Yelin Li ◽  
Joanne Kwak-kim ◽  
...  
Keyword(s):  
Nlrp3 Inflammasome ◽  
Protein Complexes ◽  
Critical Role ◽  
Obstetrical Complications ◽  
Gynecological Disorders ◽  
Pyrin Domain ◽  
Aspartate Proteinase ◽  
Multimeric Protein ◽  
And Function

Inflammasomes, intracellular, multimeric protein complexes, are assembled when damage signals stimulate nucleotide-binding oligomerization domain receptors (NLRs). Several inflammasomes have been reported, including the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3), NLRP1, NLRP7, ice protease-activating factor (IPAF), absent in melanoma 2 (AIM2) and NLR family CARD domain-containing protein 4 (NLRC4). Among these inflammasomes, the NLRP3 inflammasome is the most well-studied in terms of structure and function. Unlike other inflammasomes that can only be activated by a finite number of pathogenic microorganisms, the NLRP3 inflammasome can be activated by the imbalance of the internal environment and a large number of metabolites. The biochemical function of NLRP3 inflammasome is to activate cysteine-requiring aspartate proteinase-1 (caspase-1), which converts pro-IL-1β and pro-IL-18 into their active forms, namely, IL-1β and IL-18, which are then released into the extracellular space. The well-established, classic role of NLRP3 inflammasome has been implicated in many disorders. In this review, we discuss the current understanding of NLRP3 inflammasome and its critical role in gynecological disorders and obstetrical complications.

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