The role of protein kinase C isoenzymes in the pathogenesis of human autoimmune diseases.

The physiological role of protein kinase C (PKC) enzymes in the immune system is presented briefly. From earlier publications of others data were collected how the defects of one/two isoenzymes of PKC system suggested their involvement in the pathogenesis of human autoimmune diseases. Our observations on the defects of seven PKC isoenzymes in the peripheral blood mononuclear cells (PBMC) demonstrate that these molecular impairments are not prerequisits of the pathogenesis of systemic lupus erythematosus (SLE), mixed connective tissue disease and Sjögren's syndrome.

Glycogen phosphorylase inhibitor, 2,3-bis[(2E)-3-(4-hydroxyphenyl)prop-2-enamido] butanedioic acid (BF142), improves baseline insulin secretion of MIN6 insulinoma cells.

Type 2 diabetes mellitus (T2DM), one of the most common metabolic diseases, is characterized by insulin resistance and inadequate insulin secretion of β cells. Glycogen phosphorylase (GP) is the key enzyme in glycogen breakdown, and contributes to hepatic glucose production during fasting or during insulin resistance. Pharmacological GP inhibitors are potential glucose lowering agents, which may be used in T2DM therapy.

Glucose-based spiro-oxathiazoles as in vivo anti-hyperglycemic agents through glycogen phosphorylase inhibition.

The design of glycogen phosphorylase (GP) inhibitors targeting the catalytic site of the enzyme is a promising strategy for a better control of hyperglycaemia in the context of type 2 diabetes. Glucopyranosylidene-spiro-heterocycles have been demonstrated as potent GP inhibitors, and more specifically spiro-oxathiazoles. A new synthetic route has now been elaborated through 1,3-dipolar cycloaddition of an aryl nitrile oxide to a glucono-thionolactone affording in one step the spiro-oxathiazole moiety.

A multidisciplinary study of 3-(β-d-glucopyranosyl)-5-substituted-1,2,4-triazole derivatives as glycogen phosphorylase inhibitors: Computation, synthesis, crystallography and kinetics reveal new potent inhibitors.

3-(β-d-Glucopyranosyl)-5-substituted-1,2,4-triazoles have been revealed as an effective scaffold for the development of potent glycogen phosphorylase (GP) inhibitors but with the potency very sensitive to the nature of the alkyl/aryl 5-substituent (Kun et al., Eur. J.

Nanomolar Inhibitors of Glycogen Phosphorylase Based on β-d-Glucosaminyl Heterocycles: A Combined Synthetic, Enzyme Kinetic, and Protein Crystallography Study.

Aryl substituted 1-(β-d-glucosaminyl)-1,2,3-triazoles as well as C-β-d-glucosaminyl 1,2,4-triazoles and imidazoles were synthesized and tested as inhibitors against muscle and liver isoforms of glycogen phosphorylase (GP). While the N-β-d-glucosaminyl 1,2,3-triazoles showed weak or no inhibition, the C-β-d-glucosaminyl derivatives had potent activity, and the best inhibitor was the 2-(β-d-glucosaminyl)-4(5)-(2-naphthyl)-imidazole with a K value of 143 nM against human liver GPa. An X-ray crystallography study of the rabbit muscle GPb inhibitor complexes revealed structural features of the strong binding and offered an explanation for the differences in inhibitory potency between glucosyl and glucosaminyl derivatives and also for the differences between imidazole and 1,2,4-triazole analogues.

Glycogen phosphorylase inhibition improves beta cell function.

Background And Purpose: Glycogen phosphorylase (GP) is the key enzyme for glycogen degradation. GP inhibitors (GPi-s) are glucose lowering agents that cause the accumulation of glucose in the liver as glycogen. Glycogen metabolism has implications in beta cell function.

Synthetic, enzyme kinetic, and protein crystallographic studies of C-β-d-glucopyranosyl pyrroles and imidazoles reveal and explain low nanomolar inhibition of human liver glycogen phosphorylase.

C-β-d-Glucopyranosyl pyrrole derivatives were prepared in the reactions of pyrrole, 2-, and 3-aryl-pyrroles with O-peracetylated β-d-glucopyranosyl trichloroacetimidate, while 2-(β-d-glucopyranosyl) indole was obtained by a cross coupling of O-perbenzylated β-d-glucopyranosyl acetylene with N-tosyl-2-iodoaniline followed by spontaneous ring closure. An improved synthesis of O-perbenzoylated 2-(β-d-glucopyranosyl) imidazoles was achieved by reacting C-glucopyranosyl formimidates with α-aminoketones. The deprotected compounds were assayed with isoforms of glycogen phosphorylase (GP) to show no activity of the pyrroles against rabbit muscle GPb.

C-Glucopyranosyl-1,2,4-triazol-5-ones: synthesis and inhibition of glycogen phosphorylase.

Various C-glucopyranosyl-1,2,4-triazolones were designed as potential inhibitors of glycogen phosphorylase. Syntheses of these compounds were performed with O-perbenzoylated glucose derivatives as precursors. High temperature ring closure of N(1)-carbamoyl-C-β-D-glucopyranosyl formamidrazone gave 3-β-D-glucopyranosyl-1,2,4-triazol-5-one.

PP2B and ERK1/2 regulate hyaluronan synthesis of HT168 and WM35 human melanoma cell lines.

Hyaluronan (HA) is the major glycosaminoglycan component of the extracellular matrix in either normal or malignant tissues and it may affect proliferation, motility and differentiation of various cell types. Three isoforms of plasma membrane-bound hyaluronan synthases (HAS 1, 2 and 3) secrete and simultaneously bind pericellular HA. HAS enzymes are subjects of post-translational protein phosphorylation which is believed to regulate their enzymatic activity.

4(5)-Aryl-2-C-glucopyranosyl-imidazoles as New Nanomolar Glucose Analogue Inhibitors of Glycogen Phosphorylase.

Inhibition of glycogen phosphorylases may lead to pharmacological treatments of diseases in which glycogen metabolism plays an important role: first of all in diabetes, but also in cardiovascular and tumorous disorders. C-(β-d-Glucopyranosyl) isoxazole, pyrazole, thiazole, and imidazole type compounds were synthesized, and the latter showed the strongest inhibition against rabbit muscle glycogen phosphorylase b. Most efficient was 2-(β-d-glucopyranosyl)-4(5)-(2-naphthyl)-imidazole (11b, K i = 31 nM) representing the best nanomolar glucose derived inhibitor of the enzyme.

Glucose-derived spiro-isoxazolines are anti-hyperglycemic agents against type 2 diabetes through glycogen phosphorylase inhibition.

Glycogen phosphorylase (GP) is a target for the treatment of hyperglycaemia in the context of type 2 diabetes. This enzyme is responsible for the depolymerization of glycogen into glucose thereby affecting the levels of glucose in the blood stream. Twelve new d-glucopyranosylidene-spiro-isoxazolines have been prepared from O-peracylated exo-D-glucals by regio- and stereoselective 1,3-dipolar cycloaddition of nitrile oxides generated in situ by treatment of the corresponding oximes with bleach.

Polymodal Transient Receptor Potential Vanilloid (TRPV) Ion Channels in Chondrogenic Cells.

Mature and developing chondrocytes exist in a microenvironment where mechanical load, changes of temperature, osmolarity and acidic pH may influence cellular metabolism. Polymodal Transient Receptor Potential Vanilloid (TRPV) receptors are environmental sensors mediating responses through activation of linked intracellular signalling pathways. In chondrogenic high density cultures established from limb buds of chicken and mouse embryos, we identified TRPV1, TRPV2, TRPV3, TRPV4 and TRPV6 mRNA expression with RT-PCR.

Insulin sensitivity is modified by a glycogen phosphorylase inhibitor: glucopyranosylidene-spiro-thiohydantoin in streptozotocin-induced diabetic rats.

The major role of liver glycogen is to supply glucose to the circulation maintaining the normal blood glucose level. In muscle and liver the accumulation and breakdown of glycogen are regulated by the reciprocal activities of glycogen phosphorylase and glycogen synthase. Glycogen phosphorylase catalyses the key step of glycogen degradation and its activity can be inhibited by glucose and its analogues.

C-(2-Deoxy-d-arabino-hex-1-enopyranosyl)-oxadiazoles: synthesis of possible isomers and their evaluation as glycogen phosphorylase inhibitors.

Synthetic methods were elaborated for d-glucals attached to oxadiazoles by a C-C bond. Introduction of the double bond was effected by either DBU induced elimination of PhCOOH from the O-perbenzoylated glucopyranosyl precursors or Zn/N-methylimidazole mediated reductive elimination from the 1-bromoglucopyranosyl starting compounds. Alternatively, heterocyclizations of 2-deoxy-d-arabino-hex-1-enopyranosyl cyanide were also carried out.

3-Glucosylated 5-amino-1,2,4-oxadiazoles: synthesis and evaluation as glycogen phosphorylase inhibitors.

Glycogen phosporylase (GP) is a promising target for the control of glycaemia. The design of inhibitors binding at the catalytic site has been accomplished through various families of glucose-based derivatives such as oxadiazoles. Further elaboration of the oxadiazole aromatic aglycon moiety is now reported with 3-glucosyl-5-amino-1,2,4-oxadiazoles synthesized by condensation of a C-glucosyl amidoxime with N,N'-dialkylcarbodiimides or Vilsmeier salts.

Synthesis of 4-amidomethyl-1-glucosyl-1,2,3-triazoles and evaluation as glycogen phosphorylase inhibitors.

Glycogen phosphorylase (GP) appears as a key enzyme for the control of hyperglycemia in the context of type 2 diabetes. In order to gain additional data for structure-activity studies of the inhibition of this enzyme, a series of eight GP inhibitor candidates were prepared from peracetylglucopyranosyl azide 1 by click-chemistry. The need for a N-Boc-protected propargylamine was identified in the CuAAC with azide 1 under Meldal's conditions, while Sharpless' conditions were better adapted to the CuAAC of azide 1 with propargyl bromide.

Poly(ADP) ribose polymerase-1 ablation alters eicosanoid and docosanoid signaling and metabolism in a murine model of contact hypersensitivity.

Poly(ADP‑ribose) polymerase (PARP)‑1 is a pro‑inflammatory protein. The inhibition of PARP‑1 reduces the activity of numerous pro‑inflammatory transcription factors, which results in the reduced production of pro‑inflammatory cytokines, chemokines, matrix metalloproteinases and inducible nitric oxide synthase, culminating in reduced inflammation of the skin and other organs. The aim of the present study was to investigate the effects of the deletion of PARP‑1 expression on polyunsaturated fatty acids (PUFA), and PUFA metabolite composition, in mice under control conditions or undergoing an oxazolone (OXA)‑induced contact hypersensitivity reaction (CHS).

Synthesis of C-xylopyranosyl- and xylopyranosylidene-spiro-heterocycles as potential inhibitors of glycogen phosphorylase.

New derivatives of d-xylose with aglycons of the most efficient glucose derived inhibitors of glycogen phosphorylase were synthesized to explore the specificity of the enzyme towards the structure of the sugar part of the molecules. Thus, 2-(β-d-xylopyranosyl)benzimidazole and 3-substituted-5-(β-d-xylopyranosyl)-1,2,4-triazoles were obtained in multistep procedures from O-perbenzoylated β-d-xylopyranosyl cyanide. Cycloadditions of nitrile-oxides and O-peracetylated exo-xylal obtained from the corresponding β-d-xylopyranosyl cyanide furnished xylopyranosylidene-spiro-isoxazoline derivatives.

Glucopyranosylidene-spiro-iminothiazolidinone, a new bicyclic ring system: synthesis, derivatization, and evaluation for inhibition of glycogen phosphorylase by enzyme kinetic and crystallographic methods.

The reaction of thiourea with O-perbenzoylated C-(1-bromo-1-deoxy-β-D-glucopyranosyl)formamide gave the new anomeric spirocycle 1R-1,5-anhydro-D-glucitol-spiro-[1,5]-2-imino-1,3-thiazolidin-4-one. Acylation and sulfonylation with the corresponding acyl chlorides (RCOCl or RSO₂Cl where R=tBu, Ph, 4-Me-C₆H₄, 1- and 2-naphthyl) produced the corresponding 2-acylimino- and 2-sulfonylimino-thiazolidinones, respectively. Alkylation by MeI, allyl-bromide and BnBr produced mixtures of the respective N-alkylimino- and N,N'-dialkyl-imino-thiazolidinones, while reactions with 1,2-dibromoethane and 1,3-dibromopropane furnished spirocyclic 5,6-dihydro-imidazo[2,1-b]thiazolidin-3-one and 6,7-dihydro-5H-thiazolidino[3,2-a]pyrimidin-3-one, respectively.

Ser/Thr-phosphoprotein phosphatases in chondrogenesis: neglected components of a two-player game.

Protein phosphorylation plays a determining role in the regulation of chondrogenesis in vitro. While signalling pathways governed by protein kinases including PKA, PKC, and mitogen-activated protein kinases (MAPK) have been mapped in great details, published data relating to the specific role of phosphoprotein phosphatases (PPs) in differentiating chondroprogenitor cells or in mature chondrocytes is relatively sparse. This review discusses the known functions of Ser/Thr-specific PPs in the molecular signalling pathways of chondrogenesis.

C-Glucopyranosyl-1,2,4-triazoles As New Potent Inhibitors of Glycogen Phosphorylase.

Glycogen phosphorylase inhibitors are considered as potential antidiabetic agents. 3-(β-d-Glucopyranosyl)-5-substituted-1,2,4-triazoles were prepared by acylation of O-perbenzoylated N (1)-tosyl-C-β-d-glucopyranosyl formamidrazone and subsequent removal of the protecting groups. The best inhibitor was 3-(β-d-glucopyranosyl)-5-(2-naphthyl)-1,2,4-triazole (K i = 0.

New synthesis of 3-(β-D-glucopyranosyl)-5-substituted-1,2,4-triazoles, nanomolar inhibitors of glycogen phosphorylase.

O-Perbenzoylated 5-(β-D-glucopyranosyl)tetrazole was reacted with N-benzyl carboximidoyl chlorides to give the corresponding 4-benzyl-3-(β-D-glucopyranosyl)-5-substituted-1,2,4-triazoles. Removal of the O-benzoyl and N-benzyl protecting groups by base catalysed transesterification and catalytic hydrogenation, respectively, furnished a series of 3-(β-D-glucopyranosyl)-5-substituted-1,2,4-triazoles with aliphatic, mono- and bicyclic aromatic, and heterocyclic substituents in the 5-position. Enzyme kinetic studies revealed these compounds to inhibit rabbit muscle glycogen phosphorylase b: best inhibitors were the 5-(4-aminophenyl)- (Ki 0.

Deletion of PARP-2 induces hepatic cholesterol accumulation and decrease in HDL levels.

Poly(ADP-ribose) polymerase-2 (PARP-2) is acknowledged as a DNA repair enzyme. However, recent investigations have attributed unique roles to PARP-2 in metabolic regulation in the liver. We assessed changes in hepatic lipid homeostasis upon the deletion of PARP-2 and found that cholesterol levels were higher in PARP-2(-/-) mice as compared to wild-type littermates.