Role of Mitochondrial Stress Protein HSP60 in Diabetes-Induced Neuroinflammation.

Diabetes mellitus is the most common metabolic disorder characterized by hyperglycemia and associated malfunctions of the metabolism of carbohydrates, proteins, and lipids. There is increasing evidence of a relationship between diabetes and vascular dementia. Interestingly, hyperglycemia-linked neuroinflammation in the central nervous system is considered to play a key role during vascular dementia in diabetic patients.

Endothelial TNF-α induction by Hsp60 secreted from THP-1 monocytes exposed to hyperglycaemic conditions.

A non-resolving inflammation of the endothelium is recognised to be an important process leading to atherosclerosis. In diabetes, this process is thought to account for a significant number of cardiovascular disease-associated death and disability. However, the molecular mechanisms by which diabetes contributes to endothelial inflammation remain to be established.

Does Hsp60 Provide a Link between Mitochondrial Stress and Inflammation in Diabetes Mellitus?

The focus of this review is to summarise the known relationships between the expression of heat shock protein 60 (Hsp60) and its association with the pathogenesis of Type 1 and Type 2 diabetes mellitus. Hsp60 is a mitochondrial stress protein that is induced by mitochondrial impairment. It is known to be secreted from a number of cell types and circulating levels have been documented in both Types 1 and 2 diabetes mellitus patients.

Pterocellin A isolated from marine bryozoan Pterocella vesiculosa is cytotoxic to human HeLa cells via mitochondrial apoptotic processes.

Pterocellin A is a novel bioactive alkaloid isolated from the New Zealand marine bryozoan Pterocella vesiculosa. It exhibits potent antitumour activity towards the P388 (murine leukaemia) cell line in vitro and is selectively sensitive towards certain non-small cell lung, melanoma, and breast cancer cell lines, however, the biological mode of action of pterocellin A is unknown. Using the human cervical cancer cell line HeLa, we show that pterocellin A exhibited cytotoxicity against HeLa cells with an IC50 of 886 ng/mL.

Hyperglycaemia and oxidative stress upregulate HSP60 & HSP70 expression in HeLa cells.

Heat Shock Proteins 60 & 70 (HSP60 & HSP70) are intracellular protein that has been shown to be present at elevated levels in systemic circulation in Type 2 Diabetes mellitus (T2DM) patients. Conditions that lead to its secretion, and the mechanism of its translocation from cells, have not yet been defined. The aim of this study was to determine if specific cell stressors associated with T2DM, namely hyperglycaemia and oxidative stress, result in the upregulation of HSP60 in human cells in vitro.

Angiopoietin-like protein 2, a chronic inflammatory mediator, is a new target induced by TGF-β1 through a Smad3-dependent mechanism.

Angiopoietin-like protein 2 (Angptl2) levels are increased by obesity and obesity-related pathological conditions, and it is considered to be an important adipocyte-derived inflammatory mediator. In contrast, the multifunctional cytokine TGF-β1 has been reported to be augmented in obesity of rodents and humans, but inhibits adipocyte differentiation in vitro. Here we demonstrate that TGF-β1 induces expression of the Angptl2 gene through a Smad3-dependent pathway in RAW264.

Metformin induced expression of Hsp60 in human THP-1 monocyte cells.

Metformin is in widespread clinical use for the treatment of diabetes mellitus in patients. It has been shown to inhibit mitochondrial bioenergetic functions by inhibiting complex I of the electron transport chain. The expression of mitochondrial-specific molecular stress protein Hsp60 is a key consequence of mitochondrial impairment.

Detection of Hsp60 in saliva and serum from type 2 diabetic and non-diabetic control subjects.

There is increasing evidence that mitochondrial dysfunction and oxidative stress may be integral to the pathogenesis of type 2 diabetes mellitus. Heat shock protein (Hsp60) is a mitochondrial stress protein known to be induced under conditions of mitochondrial impairment. Although this intracellular protein is normally found in the mitochondrion, several studies have shown that this protein is also present in systemic circulation.

The effect of complement C5a on mitochondrial functions of PC12 cells.

C5a is thought to play a role during complement-activated neuronal apoptotic cell death in the central nervous system. The mechanisms responsible are however not well-understood. As mitochondria play a key role during apoptosis, we investigated mitochondria as a potential target for C5a.

Comparative proteomics of skeletal muscle mitochondria from myostatin-null mice.

Myostatin, a secreted protein, is a negative regulator of skeletal muscle growth. Down-regulating its expression increases skeletal muscle mass that is accompanied by a marked change in the fibre composition from one reliant on mitochondrial oxidative metabolism to glycolysis. A comparative proteomic investigation of this altered metabolism was carried out on mitochondria from the gastrocnemius muscle of myostatin-null mice compared with wild-type.

Identification of new pathogens in the intraocular fluid of patients with uveitis.

Purpose: To determine infectious causes in patients with uveitis of unknown origin by intraocular fluids analysis.

Design: Case-control study.

Methods: Ocular fluids from 139 patients suspected of infectious uveitis, but negative for herpes simplex virus, varicella-zoster virus, cytomegalovirus, and Toxoplasma gondii by polymerase chain reaction and/or antibody analysis in intraocular fluids, were assessed for the presence of 18 viruses and 3 bacteria by real-time polymerase chain reaction (PCR).

Effect of psychological intervention on exercise adherence in type 2 diabetic subjects.

Previous research has pointed to the efficacy of physical activity in individuals suffering from type 2 diabetes mellitus (type 2 DM). However, as with other populations, adherence to exercise programs is often problematic. This study assessed the effectiveness of a combination of exercise and psychological interventions in type 2 diabetics in terms of disease management and exercise adherence.

Expression of chaperonin 60 in the hippocampus of the streptozotocin diabetic rat.

Mitochondrial dysfunction and oxidative stress are implicated in the pathological changes observed in the diabetic central nervous system. In this study, using the streptozotocin-induced diabetic rat model we document for the first time the over-expression of a mitochondrial specific stress protein (chaperonin 60) in the CA1/CA3 regions of the diabetic hippocampus in the absence of neurodegeneration. The increase in expression of chaperonin 60 was not observed in the cohort treated with insulin, suggesting that the observed effect was not due to streptozotocin per se but due to the hyperglycaemic state induced by the diabetic state.

Outer egg coats of the marsupial conceptus: secretion and protein composition.

Little is known of the composition of the outer egg coats. We aimed to quantify secretion during embryonic development, identify precursor secreting cells and investigate protein composition. The study was based on 259 egg coats and 14 reproductive tracts of 104 T.

Upregulation of P-glycoprotein in rat hepatoma rho(o) cells: implications for drug-DNA interactions.

Rat hepatoma cells lacking mitochondrial DNA (rho(o) cells) were used as a model system to examine the possible roles of mitochondrial DNA as a target for the DNA-acting anticancer drug Adriamycin (doxorubicin). The rho(o) cells were 45-fold less sensitive to Adriamycin than the parental rho+ cells containing mitochondrial DNA. Other non-DNA-acting drugs also exhibited similar behaviour, and this was shown to be due to a multidrug resistance (MDR) phenotype in the rho(o) cells.

Selective induction of mitochondrial chaperones in response to loss of the mitochondrial genome.

Molecular chaperones are known to play key roles in the synthesis, transport and folding of nuclear-encoded mitochondrial proteins and of proteins encoded by mitochondrial DNA. Although the regulation of heat-shock genes has been the subject of considerable investigation, regulation of the genes encoding mitochondrial chaperones is not well defined. We have found that stress applied specifically to the mitochondria of mammalian cells is capable of eliciting an organelle-specific, molecular chaperone response.

Role of chaperones in the biogenesis and maintenance of the mitochondrion.

All cells depend on correctly folded proteins for optimal function. A central question in cellular biology is how such folded structures are formed and maintained, a process that is now recognized to rely heavily on a group of proteins called molecular chaperones. Molecular chaperones constitute distinct families of proteins that are ubiquitous and highly conserved from bacteria to humans.

Growth of rho 0 human Namalwa cells lacking oxidative phosphorylation can be sustained by redox compounds potassium ferricyanide or coenzyme Q10 putatively acting through the plasma membrane oxidase.

Pyruvate is conventionally used as a key growth supplement for mammalian rho 0 cells that lack mitochondrial DNA and are thereby devoid of oxidative phosphorylation. We have tested the proposition that cultured rho 0 human cells can be grown using redox compounds other than pyruvate. The results show that potassium ferricyanide and coenzyme Q10 can each be used to replace pyruvate to support the growth of rho 0 Namalwa cells (a lymphoblastoid cell line).

Sheep and other animals with ceroid-lipofuscinoses: their relevance to Batten disease.

Distinct pathological and histopathological changes distinguish the ceroid-lipofuscinoses from other storage diseases of humans and animals. These various disease entities likely reflect a variety of mutations of the same gene, or mutations of different genes associated with metabolism of the same or similar substrates. The disease in sheep most closely resembles the juvenile human disease.

Mitochondrial ATP synthase subunit c storage in the ceroid-lipofuscinoses (Batten disease).

The ceroid-lipofuscinoses (Batten disease) are neurodegenerative inherited lysosomal storage diseases of children and animals. A common finding is the occurrence of fluorescent storage bodies (lipopigment) in cells. These have been isolated from tissues of affected sheep.

Bovine ceroid-lipofuscinosis (Batten's disease): the major component stored is the DCCD-reactive proteolipid, subunit C, of mitochondrial ATP synthase.

The ceroid-lipofuscinoses (Batten's disease) are a group of recessively inherited lysosomal storage diseases of children and animals in which there is intracellular accumulation of a fluorescent lipopigment in a wide variety of cells. Lipopigment bodies isolated from pancreas, liver, kidney and brain tissue from a heifer affected with ceroid-lipofuscinosis contained between 55 and 62% protein. A dominant component comigrated on LDS-PAGE with the major low molecular weight protein stored in ovine ceroid-lipofuscinosis.

The sequence of the major protein stored in ovine ceroid lipofuscinosis is identical with that of the dicyclohexylcarbodiimide-reactive proteolipid of mitochondrial ATP synthase.

The ceroid lipofuscinoses are a group of neurodegenerative lysosomal storage diseases of children and animals that are recessively inherited. In diseased individuals fluorescent storage bodies accumulate in a wide variety of cells, including neurons. Previous studies of these bodies isolated from tissues of affected sheep confirmed that the storage occurs in lysosomes, and showed that the storage body is mostly made of a single protein with an apparent molecular mass of 3500 Da with an N-terminal amino acid sequence that is the same as residues 1-40 of the c-subunit (or dicyclohexylcarbodi-imide-reactive proteolipid) of mitochondrial ATP synthase.

Ovine ceroid-lipofuscinosis is a proteolipid proteinosis.

The pathogenesis of the ceroid-lipofuscinoses, inherited storage diseases of children, was studied in an ovine model. This was shown to have clinical and pathological features most in common with the late infantile and juvenile human forms of the disease. The ability to study sequential changes allowed the retinal lesions to be described as a dystrophy of photoreceptor outer segments which preceded loss of the photoreceptor cells.

Ovine ceroid lipofuscinosis. The major lipopigment protein and the lipid-binding subunit of mitochondrial ATP synthase have the same NH2-terminal sequence.

Previous studies on lipopigment isolated from sheep affected with ceroid lipofuscinosis (Batten's disease) showed that the disease is a lysosomal proteinosis, involving specific storage of peptide(s) that migrate in dodecyl sulfate-polyacrylamide gel electrophoresis with an apparent Mr of 3500. This band is the dominant contributor to the lipopigment mass. When purified total lipopigment proteins were loaded onto a protein sequencer, a dominant sequence was found, identical to the NH2 terminus of the lipid-binding subunit of protein translocating mitochondrial ATP synthase.