No abstract

No abstract

Protein kinase C-(PKC ) is a Ca 2؉ -independent PKC isoform that is selectively expressed in T lymphocytes (and muscle), and is thought to play an important role in T cell receptor-induced activation. To gain a better understanding of the function and regulation of PKC , we have employed the yeast two-hybrid system to identify PKC -interacting proteins. We report the isolation and characterization of a cDNA encoding a novel 335-amino acid (37.5-kDa) PKC -interacting protein termed PICOT (for PKC-interacting cousin of thioredoxin). PICOT is expressed in various tissues, including in T cells, where it colocalizes with PKC . PICOT displays an N-terminal thioredoxin homology domain, which is required for the interaction with PKC. Comparison of the unique C-terminal region of PICOT with expressed sequence tag data bases revealed two tandem repeats of a novel domain that is highly conserved from plants to mammals. Transient overexpression of full-length PICOT (but not its N-or C-terminal fragments) in T cells inhibited the activation of c-Jun N-terminal kinase (but not extracellular signal-regulated kinase), and the transcription factors AP-1 or NF-B. These findings suggest that PICOT and its evolutionary conserved homologues may interact with PKC-related kinases in multiple organisms and, second, that it plays a role in regulating the function of the thioredoxin system.Members of the protein kinase C (PKC) 1 family of intracellular serine/threonine kinases play critical roles in the regulation of cellular differentiation and proliferation in many cell types and in response to diverse stimuli, including hormones, neurotransmitters, and growth factors (1-3). The PKC family consists of 11 known mammalian members that are expressed in a wide variety of tissues and cell types. Based on sequence similarities, domain structures, and cofactor requirements, PKC isoenzymes can be grouped into three subfamilies. 1) The Ca 2ϩ -dependent conventional enzymes, consisting of PKC-␣, -␤I, -␤II, and -␥, contain three conserved domains, namely the diacylglycerol/phorbol ester binding C1 domain, which contains two repeats of a cysteine-rich zinc finger, the phospholipid-and calcium-binding C2 domain, and the catalytic C3 and C4 domains.2) The Ca 2ϩ -independent enzymes (PKC-␦, -⑀, -, -and -) are termed novel PKCs. The C2-like N-terminal domain of these enzymes can bind acidic phospholipids but not Ca 2ϩ . 3) A third PKC subfamily, termed atypical PKCs, includes PKCand -/ that possess a single cysteine-rich domain, lacking the ability to bind phospholipids or phorbol esters. PKC activity is regulated by defined cofactors that interact with specific regions of the regulatory domain as well as transphosphorylation by serine/threonine kinases and autophosphorylation. The activation is accompanied by a conformational change that releases the basic pseudosubstrate region from the catalytic cleft of the kinase domain. In addition, interaction with specific proteins, termed receptors for activated PKC, that function as selective scaffolds for a...

ObjectiveTo assess the efficacy and safety of low-dose prednisone chronotherapy using a new modified-release (MR) formulation for the treatment of rheumatoid arthritis (RA).MethodsIn this 12-week, double-blind, placebo-controlled study, patients with active RA (n=350) were randomised 2:1 to receive MR prednisone 5 mg or placebo once daily in the evening in addition to their existing RA disease-modifying antirheumatic drug (DMARD) treatment. The primary end point was the percentage of patients achieving a 20% improvement in RA signs and symptoms according to American College of Rheumatology criteria (ie, an ACR20 response) at week 12. Changes in morning pain, duration of morning stiffness, 28-joint Disease Activity Score and health-related quality of life were also assessed.ResultsMR prednisone plus DMARD treatment produced higher response rates for ACR20 (48% vs 29%, p<0.001) and ACR50 (22% vs 10%, p<0.006) and a greater median relative reduction from baseline in morning stiffness (55% vs 35%, p<0.002) at week 12 than placebo plus DMARD treatment. Significantly greater reductions in severity of RA (Disease Activity Score 28) (p<0.001) and fatigue (Functional Assessment of Chronic Illness Therapy-Fatigue score) (p=0.003) as well as a greater improvement in physical function (36-item Short-Form Health Survey score) (p<0.001) were seen at week 12 for MR prednisone versus placebo. The incidence of adverse events was similar for MR prednisone (43%) and placebo (49%).ConclusionLow-dose MR prednisone added to existing DMARD treatment produced rapid and relevant improvements in RA signs and symptoms.ClinicalTrials.gov, numberNCT00650078

No abstract