Enrichment of NPC1-deficient cells with the lipid LBPA stimulates autophagy, improves lysosomal function, and reduces cholesterol storage.

Niemann-Pick C (NPC) is an autosomal recessive disorder characterized by mutations in the NPC1 or NPC2 genes encoding endolysosomal lipid transport proteins, leading to cholesterol accumulation and autophagy dysfunction. We have previously shown that enrichment of NPC1-deficient cells with the anionic lipid lysobisphosphatidic acid (LBPA; also called bis(monoacylglycerol)phosphate) via treatment with its precursor phosphatidylglycerol (PG) results in a dramatic decrease in cholesterol storage. However, the mechanisms underlying this reduction are unknown.

Intracellular cholesterol trafficking is dependent upon NPC2 interaction with lysobisphosphatidic acid.

Unesterified cholesterol accumulation in the late endosomal/lysosomal (LE/LY) compartment is the cellular hallmark of Niemann-Pick C (NPC) disease, caused by defects in the genes encoding NPC1 or NPC2. We previously reported the dramatic stimulation of NPC2 cholesterol transport rates to and from model membranes by the LE/LY phospholipid lysobisphosphatidic acid (LBPA). It had been previously shown that enrichment of NPC1-deficient cells with LBPA results in cholesterol clearance.

Evaluation of the peroxynitrite decomposition catalyst Fe(III) tetra-mesitylporphyrin octasulfonate on peripheral neuropathy in a mouse model of type 1 diabetes.

Whereas the important role of free radicals in diabetes-associated complications is well established, the contributions of the highly reactive oxidant peroxynitrite have not been properly explored. The present study used a pharmacological approach to evaluate the role of peroxynitrite in peripheral diabetic neuropathy. Control and STZ-diabetic mice were maintained with or without treatment with the potent peroxynitrite decomposition catalyst Fe(III) tetramesitylporphyrin octasulfonate (FeTMPS), at doses of 5 or 10 mg/kg/day in the drinking water for 3 weeks after an initial 3 weeks without treatment.

PARP inhibition or gene deficiency counteracts intraepidermal nerve fiber loss and neuropathic pain in advanced diabetic neuropathy.

Evidence that poly(ADP-ribose) polymerase (PARP) activation plays an important role in diabetic complications is emerging. This study evaluated the role of PARP in rat and mouse models of advanced diabetic neuropathy. The orally active PARP inhibitor 10-(4-methylpiperazin-1-ylmethyl)-2H-7-oxa-1,2-diaza-benzo[de]anthracen-3-one (GPI-15427; formulated as a mesilate salt, 30 mg kg(-1) day(-1) in the drinking water for 10 weeks after the first 2 weeks without treatment) at least partially prevented PARP activation in peripheral nerve and DRG neurons, as well as thermal hypoalgesia, mechanical hyperalgesia, tactile allodynia, exaggerated response to formalin, and, most importantly, intraepidermal nerve fiber degeneration in streptozotocin-diabetic rats.

A peroxynitrite decomposition catalyst counteracts sensory neuropathy in streptozotocin-diabetic mice.

Whereas an important role of free radicals and oxidants in peripheral diabetic neuropathy is well established, the contribution of nitrosative stress and, in particular, of the highly reactive oxidant peroxynitrite, has not been properly explored. Our previous findings implicate peroxynitrite in diabetes-associated motor and sensory nerve conduction deficits and peripheral nerve energy deficiency and poly(ADP-ribose) polymerase activation associated with Type 1 diabetes. In this study the role of nitrosative stress in diabetic sensory neuropathy is evaluated.

High-fat diet induced neuropathy of pre-diabetes and obesity: effects of "healthy" diet and aldose reductase inhibition.

Objective: Subjects with dietary obesity and pre-diabetes have an increased risk for developing both nerve conduction slowing and small sensory fiber neuropathy. Animal models of this type of neuropathy have not been described. This study evaluated neuropathic changes and their amenability to dietary and pharmacological interventions in mice fed a high-fat diet (HFD), a model of pre-diabetes and alimentary obesity.

Nitrosative stress and peripheral diabetic neuropathy in leptin-deficient (ob/ob) mice.

Nitrosative stress contributes to nerve conduction slowing, thermal hypoalgesia, and impaired nitrergic innervation in animal models of Type 1 diabetes. The role for reactive nitrogen species in Type 2 diabetes-associated neuropathy remains unexplored. This study evaluated the role for nitrosative stress in functional and structural neuropathic changes in ob/ob mice, a model of Type 2 diabetes with mild hyperglycemia and obesity.

The leptin-deficient (ob/ob) mouse: a new animal model of peripheral neuropathy of type 2 diabetes and obesity.

Whereas functional, metabolic, neurotrophic, and morphological abnormalities of peripheral diabetic neuropathy (PDN) have been extensively explored in streptozotocin-induced diabetic rats and mice (models of type 1 diabetes), insufficient information is available on manifestations and pathogenetic mechanisms of PDN in type 2 diabetic models. The latter could constitute a problem for clinical trial design because the vast majority of subjects with diabetes have type 2 (non-insulin dependent) diabetes. This study was aimed at characterization of PDN in leptin-deficient (ob/ob) mice, a model of type 2 diabetes with relatively mild hyperglycemia and obesity.

Poly(ADP-ribose) polymerase inhibition alleviates experimental diabetic sensory neuropathy.

Poly(ADP-ribose) polymerase (PARP) activation is emerging as a fundamental mechanism in the pathogenesis of diabetes complications including diabetic neuropathy. This study evaluated the role of PARP in diabetic sensory neuropathy. The experiments were performed in control and streptozotocin-induced diabetic rats treated with or without the PARP inhibitor 1,5-isoquinolinediol (ISO; 3 mg x kg(-1) x day(-1) i.

Oxidative-nitrosative stress and poly(ADP-ribose) polymerase (PARP) activation in experimental diabetic neuropathy: the relation is revisited.

Poly(ADP-ribose) polymerase (PARP) activation, an important factor in the pathogenesis of diabetes complications, is considered a downstream effector of oxidative-nitrosative stress. However, some recent findings suggest that it is not necessarily the case and that PARP activation may precede and contribute to free radical and oxidant-induced injury. This study evaluated the effect of PARP inhibition on oxidative-nitrosative stress in diabetic peripheral nerve, vasa nervorum, aorta, and high glucose-exposed human Schwann cells.

Transient activation of Ras-dependent signalling at the early stages of Herbimycin A induced erythroid differentiation of human K562 cells.

Aim: To study the dynamics of Ras-dependent signalling in the course of Herbimycin A induced erythroid differentiation of human erythroleukemia K562 cells.

Methods: p21Ras functional activity was analyzed by direct measurement of GTP/GDP ratio in anti-p21Ras immunoprecipitates of K562 cells previously incubated with H3(32)PO4. Dynamics of protein tyrosine phosphorylation was studied using Western blotting.

Differential effects of P2Y1 and P2Y12 nucleotide receptors on ERK1/ERK2 and phosphatidylinositol 3-kinase signalling and cell proliferation in serum-deprived and nonstarved glioma C6 cells.

We have previously shown that, in glioma C6 cells, two nucleotide ADP-sensitive receptors coexist: P2Y1, coupled to PLC and responsible for Ca2+ release, and P2Y12, negatively coupled to adenylate cyclase. In the present study, we examined the effects of the stimulation of these two receptors on ERK1/2 and PI3-K activation, and cell proliferation in either serum-deprived or nonstarved C6 cells. In response to ADP and its analogues, in serum-starved cells, both p44 ERK1 and p42 ERK2 were activated in a time-dependent manner, as monitored by Western blot analysis using an antiphospho-p42/p44 MAPK antibody.