Novel intracellular functions of apolipoproteins: the ApoO protein family as constituents of the Mitofilin/MINOS complex determines cristae morphology in mitochondria

2014 ◽  
Vol 395 (3) ◽  
pp. 285-296 ◽  
Author(s):  
Sebastian Koob ◽  
Andreas S. Reichert

Abstract Mitochondria exist in a highly dynamic network that is constantly altered by fusion and fission events depending on various factors such as cellular bioenergetic state and cell cycle. Next to this dynamic nature of the organelle, its cristae membrane also undergoes drastic morphological changes upon physiological or pathological alterations. The Mitofilin/mitochondrial inner membrane organizing system (MINOS) complex was recently reported to ensure mitochondrial architecture and crista junction integrity. Several subunits of this complex are linked to a diverse set of neurological human disorders. Recently, two apolipoproteins, ApoO (APOO) and ApoO-like (APOOL) were suggested to represent constituents of the mammalian Mitofilin/MINOS complex. APOOL was shown to bind the mitochondrial phospholipid cardiolipin (CL) and to interact physically with this complex. In this review we highlight the current view on the mammalian Mitofilin/MINOS complex and focus on APOOL and the role of CL in determining cristae morphology. We will discuss possible functions of the Mitofilin/MINOS complex on lipid transport, on assembly of respiratory supercomplexes, on F1FO-ATP synthase organization, on contact site formation, and on trapping CL within the cristae subcompartment.

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 600
Author(s):  
Ruchika Anand ◽  
Andreas S. Reichert ◽  
Arun Kumar Kondadi

Mitochondria are double membrane-enclosed organelles performing important cellular and metabolic functions such as ATP generation, heme biogenesis, apoptosis, ROS production and calcium buffering. The mitochondrial inner membrane (IM) is folded into cristae membranes (CMs) of variable shapes using molecular players including the ‘mitochondrial contact site and cristae organizing system’ (MICOS) complex, the dynamin-like GTPase OPA1, the F1FO ATP synthase and cardiolipin. Aberrant cristae structures are associated with different disorders such as diabetes, neurodegeneration, cancer and hepato-encephalopathy. In this review, we provide an updated view on cristae biogenesis by focusing on novel roles of the MICOS complex in cristae dynamics and shaping of cristae. For over seven decades, cristae were considered as static structures. It was recently shown that cristae constantly undergo rapid dynamic remodeling events. Several studies have re-oriented our perception on the dynamic internal ambience of mitochondrial compartments. In addition, we discuss the recent literature which sheds light on the still poorly understood aspect of cristae biogenesis, focusing on the role of MICOS and its subunits. Overall, we provide an integrated and updated view on the relation between the biogenesis of cristae and the novel aspect of cristae dynamics.


Author(s):  
Jayarami Reddy Medapati ◽  
Deepthi Rapaka ◽  
Veera Raghavulu Bitra ◽  
Santhosh Kumar Ranajit ◽  
Girija Sankar Guntuku ◽  
...  

Abstract Background The endocannabinoid CB1 receptor is known to have protective effects in kidney disease. The aim of the present study is to evaluate the potential agonistic and antagonistic actions and to determine the renoprotective potential of CB1 receptors in diabetic nephropathy. The present work investigates the possible role of CB1 receptors in the pathogenesis of diabetes-induced nephropathy. Streptozotocin (STZ) (55 mg/kg, i.p., once) is administered to uninephrectomised rats for induction of experimental diabetes mellitus. The CB1 agonist (oleamide) and CB1 antagonist (AM6545) treatment were initiated in diabetic rats after 1 week of STZ administration and were given for 24 weeks. Results The progress in diabetic nephropathy is estimated biochemically by measuring serum creatinine (1.28±0.03) (p < 0.005), blood urea nitrogen (67.6± 2.10) (p < 0.001), urinary microprotein (74.62± 3.47) (p < 0.005) and urinary albuminuria (28.31±1.17) (p < 0.0001). Renal inflammation was assessed by estimating serum levels of tumor necrosis factor alpha (75.69±1.51) (p < 0.001) and transforming growth factor beta (8.73±0.31) (p < 0.001). Renal morphological changes were assessed by estimating renal hypertrophy (7.38± 0.26) (p < 0.005) and renal collagen content (10.42± 0.48) (p < 0.001). Conclusions From the above findings, it can be said that diabetes-induced nephropathy may be associated with overexpression of CB1 receptors and blockade of CB1 receptors might be beneficial in ameliorating the diabetes-induced nephropathy. Graphical abstract


2021 ◽  
pp. 112972982110154
Author(s):  
Raffaella Mauro ◽  
Cristina Rocchi ◽  
Francesco Vasuri ◽  
Alessia Pini ◽  
Anna Laura Croci Chiocchini ◽  
...  

Background: Arteriovenous fistula (AVF) for hemodialysis integrates outward remodeling with vessel wall thickening in response to drastic hemodynamic changes. Aim of this study is to determine the role of Ki67, a well-established proliferative marker, related to AVF, and its relationship with time-dependent histological morphologic changes. Materials and methods: All patients were enrolled in 1 year and stratified in two groups: (A) pre-dialysis patients submitted to first AVF and (B) patients submitted to revision of AVF. Morphological changes: neo-angiogenesis (NAG), myointimal thickening (MIT), inflammatory infiltrate (IT), and aneurysmatic fistula degeneration (AD). The time of AVF creation was recorded. A biopsy of native vein in Group A and of arterialized vein in Group B was submitted to histological and immunohistochemical (IHC) analysis. IHC for Ki67 was automatically performed in all specimens. Ki67 immunoreactivity was assessed as the mean number of positive cells on several high-power fields, counted in the hot spots. Results: A total of 138 patients were enrolled, 69 (50.0%) Group A and 69 (50.0%) Group B. No NAG or MIT were found in Group A. Seven (10.1%) Group A veins showed a mild MIT. Analyzing the Group B, a moderate-to-severe MIT was present in 35 (50.7%), IT in 19 (27.5%), NAG in 37 (53.6%); AD was present in 10 (14.5%). All AVF of Group B with the exception of one (1.4%) showed a positivity for Ki67, with a mean of 12.31 ± 13.79 positive cells/hot spot (range 0–65). Ki67-immunoreactive cells had a subendothelial localization in 23 (33.3%) cases, a myointimal localization in SMC in 35 (50.7%) cases. The number of positive cells was significantly correlated with subendothelial localization of Ki67 ( p = 0.001) and with NA ( p = 0.001). Conclusions: Native veins do not contain cycling cells. In contrast, vascular cell proliferation starts immediately after AVF creation and persists independently of the time the fistula is set up. The amount of proliferating cells is significantly associated with MIT and subendothelial localization of Ki67-immunoreactive cells, thus suggesting a role of Ki-67 index in predicting AVF failure.


2019 ◽  
Vol 35 (11) ◽  
pp. 1853-1861 ◽  
Author(s):  
Miriam Zacchia ◽  
Emanuela Marchese ◽  
Elena Martina Trani ◽  
Marianna Caterino ◽  
Giovanna Capolongo ◽  
...  

Abstract The primary cilium (PC) was considered as a vestigial organelle with no significant physiological importance, until the discovery that PC perturbation disturbs several signalling pathways and results in the dysfunction of a variety of organs. Genetic studies have demonstrated that mutations affecting PC proteins or its anchoring structure, the basal body, underlie a class of human disorders (known as ciliopathies) characterized by a constellation of clinical signs. Further investigations have demonstrated that the PC is involved in a broad range of biological processes, in both developing and mature tissues. Kidney disease is a common clinical feature of cilia disorders, supporting the hypothesis of a crucial role of the PC in kidney homoeostasis. Clinical proteomics and metabolomics are an expanding research area. Interestingly, the application of these methodologies to the analysis of urine, a biological sample that can be collected in a non-invasive fashion and possibly in large amounts, makes these studies feasible also in patients. The present article describes the most recent proteomic and metabolomic studies exploring kidney dysfunction in the setting of ciliopathies, showing the potential of these methodologies in the elucidation of disease pathophysiology and in the discovery of biomarkers.


Biomedicines ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 759
Author(s):  
Gaku Yamanaka ◽  
Fuyuko Takata ◽  
Yasufumi Kataoka ◽  
Kanako Kanou ◽  
Shinichiro Morichi ◽  
...  

Pericytes are a component of the blood–brain barrier (BBB) neurovascular unit, in which they play a crucial role in BBB integrity and are also implicated in neuroinflammation. The association between pericytes, BBB dysfunction, and the pathophysiology of epilepsy has been investigated, and links between epilepsy and pericytes have been identified. Here, we review current knowledge about the role of pericytes in epilepsy. Clinical evidence has shown an accumulation of pericytes with altered morphology in the cerebral vascular territories of patients with intractable epilepsy. In vitro, proinflammatory cytokines, including IL-1β, TNFα, and IL-6, cause morphological changes in human-derived pericytes, where IL-6 leads to cell damage. Experimental studies using epileptic animal models have shown that cerebrovascular pericytes undergo redistribution and remodeling, potentially contributing to BBB permeability. These series of pericyte-related modifications are promoted by proinflammatory cytokines, of which the most pronounced alterations are caused by IL-1β, a cytokine involved in the pathogenesis of epilepsy. Furthermore, the pericyte-glial scarring process in leaky capillaries was detected in the hippocampus during seizure progression. In addition, pericytes respond more sensitively to proinflammatory cytokines than microglia and can also activate microglia. Thus, pericytes may function as sensors of the inflammatory response. Finally, both in vitro and in vivo studies have highlighted the potential of pericytes as a therapeutic target for seizure disorders.


2021 ◽  
Vol 142 ◽  
pp. 112051
Author(s):  
Soudeh Ghafouri-Fard ◽  
Tayyebeh Khoshbakht ◽  
Mohammad Taheri ◽  
Mahsa Ghanbari

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Ahmad Maqboul ◽  
Bakheet Elsadek

Background. Models of cancer-induced neuropathy are designed by injecting cancer cells near the peripheral nerves. The interference of tissue-resident immune cells does not allow a direct contact with nerve fibres which affects the tumor microenvironment and the invasion process. Methods. Anaplastic tumor-1 (AT-1) cells were inoculated within the sciatic nerves (SNs) of male Copenhagen rats. Lumbar dorsal root ganglia (DRGs) and the SNs were collected on days 3, 7, 14, and 21. SN tissues were examined for morphological changes and DRG tissues for immunofluorescence, electrophoretic tendency, and mRNA quantification. Hypersensitivities to cold, mechanical, and thermal stimuli were determined. HC-030031, a selective TRPA1 antagonist, was used to treat cold allodynia. Results. Nociception thresholds were identified on day 6. Immunofluorescent micrographs showed overexpression of TRPA1 on days 7 and 14 and of CGRP on day 14 until day 21. Both TRPA1 and CGRP were coexpressed on the same cells. Immunoblots exhibited an increase in TRPA1 expression on day 14. TRPA1 mRNA underwent an increase on day 7 (normalized to 18S). Injection of HC-030031 transiently reversed the cold allodynia. Conclusion. A novel and a promising model of cancer-induced neuropathy was established, and the role of TRPA1 and CGRP in pain transduction was examined.


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