Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.16 (calcineurin)
 17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The catalytic subunit of the Ca2+/calmodulin- (CaM) dependent phosphoprotein phosphatase calcineurin (CN) was phosphorylated by an activated form of Ca2+/CaM-dependent protein kinase II (CaM-kinase II) incorporating approximately 1 mol of phosphoryl group/mol of catalytic subunit, in agreement with a value previously reported (Hashimoto et al., 1988). Cyanogen bromide cleavage of radiolabeled CN followed by peptide fractionation using reverse-phase high-performance liquid chromatography yielded a single labeled peptide that contained a phosphoserine residue. Microsequencing of the peptide allowed both the determination of the cleavage cycle that released [32P]phosphoserine and the identity of amino acids adjacent to it. Comparison of this sequence with the sequences of methionyl peptides deduced from the cDNA structure of CN (Kincaid et al., 1988) allowed the phosphorylated serine to be uniquely identified. Interestingly, the phosphoserine exists in the sequence Met-Ala-Arg-Val-Phe-Ser(P)-Val-Leu-Arg-Glu, part of which lies within the putative CaM-binding site. The phosphorylated serine residue was resistant to autocatalytic dephosphorylation, yet the slow rate of hydrolysis could be powerfully stimulated by effectors of CN phosphatase activity. The mechanism of dephosphorylation may be intramolecular since the initial rate was the same at phosphoCN concentrations of 2.5-250 nM.
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PMID:Identification of the site on calcineurin phosphorylated by Ca2+/CaM-dependent kinase II: modification of the CaM-binding domain. 255 15

Calcineurin (CaN) contains an autoinhibitory element (residues 457-482) 43 residues COOH-terminal of the calmodulin-binding domain (Hashimoto, Y., Perrino, B. A., and Soderling, T. R. (1990) J. Biol. Chem. 265, 1924-1927) that regulates the Ca(2+)-dependent activation of its phosphatase activity. Substitution of Arg476 and Arg477 or Asp467 to Ala in the autoinhibitory peptide 457-482 significantly decreased its inhibitory potency. CaN A subunits with these residues mutated to Ala were coexpressed with the Ca(2+)-binding B subunit using the baculovirus/Sf9 cell system. Kinetic analysis showed that although the purified mutants had no activity in the absence of calcium, they were less dependent than the wild-type enzyme on calcium and calmodulin for activity. To determine if additional autoinhibitory motifs were present in the COOH terminus of calcineurin, the A subunit was truncated at residues 457 or 420 and co-expressed with B subunit. The Vmax values of both truncation mutants with or without Ca2+ were increased relative to wild-type calcineurin. The increased Ca(2+)-independent activity of CaN420 relative to CaN457 indicates the presence of additional autoinhibitory element(s) within residues 420-457. CaN420 had similar high Vmax values with or without Ca2+, but the Km value for peptide substrate was increased 5-fold to 125 microM in the absence of Ca2+. The Km values of all the expressed calcineurin species were increased in the absence of Ca2+. The CaN A or CaN A420 subunits alone have low Vmax and high Km (115 microM) values even in the presence of Ca2+. These results indicate that 1) there are several autoinhibitory motifs between the CaM-binding domain and the COOH terminus that are relieved by Ca2+ binding to CaM and the B subunit, 2) Ca2+ binding to the B subunit also regulates enzyme activity by lowering the Km of the catalytic subunit for substrate, 3) binding of the B subunit is required for high Vmax values even after removal of the autoinhibitory domain. These results are consistent with synergistic activation of calcineurin by Ca2+ acting through both CaM and the B subunit.
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PMID:Calcium regulation of calcineurin phosphatase activity by its B subunit and calmodulin. Role of the autoinhibitory domain. 789 54

There has been no reported case of Hashimoto's encephalopathy (HE) ('steroid-responsive encephalopathy associated with autoimmune thyroiditis', 'SREAT'), in the renal transplant recipient population. We describe the case of a 55-year-old female with Type-1 diabetes who presented 2 years posttransplantation in a comatose state that had developed over the preceding 24 h. The patient had received a short, intensive course of rATG induction at the time of transplantation and early steroid withdrawal. After 6 months she had been withdrawn from calcineurin inhibitors and was maintained on mycophenolate mofetil and sirolimus. Systematic workup determined the cause of her coma to be HE. High-dose steroid therapy resulted in complete resolution of the patient's symptoms. The literature regarding the diagnosis, course and treatment of HE is reviewed and the possibility that increased use of steroid-free immunosuppression and intensive lymphocyte depletion regimens may increase the prevalence of de novo autoimmune disease is discussed.
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PMID:Hashimoto's encephalopathy after intensive lymphocyte depletion with rabbit anti-thymocyte globulin in a renal transplant patient. 1809 72

Lichen sclerosus (LS) is a chronic, inflammatory, mucocutaneous disorder of genital and extragenital skin (1). Simultaneous involvement of the oral mucosa is extremely rare, but it may be the only affected area (2). A 55-year-old woman was referred to the Department of Oral Medicine, School of Dental Medicine University of Zagreb due to whitish lesions on the right ventrolateral part of the tongue and buccal mucosa with desquamative gingivitis (Figure 1, a-c). The lesions were asymptomatic but indurated on palpation. Histology was conclusive for oral lichen sclerosus (OLS). The lesions on gingiva were successfully treated with betamethasone ointment, three times a day for two weeks. One year earlier, she had been referred to the Department of Dermatology and Venereology with progressive pruritus and dyspareunia, white patches, obliteration of the labia minora, and stenosis of the introitus (Figure 2). Histology was conclusive for vulvar LS (Figure 3, a and b). She was successfully treated for 5 months with clobetasol propionate 0.05% ointment. The patient was taking levothyroxine to treat hypothyroidism associated with Hashimoto's thyroiditis and was otherwise healthy. Oral LS is clinically characterized by the appearance of white macules, papules, or plaques mostly appearing on labial mucosa but also on buccal, palate mucosa and on the lower lip (2,3). On the genitals, it typically manifests as atrophic white plaques, which may be accompanied by purpura or fissuring (1). While vulvar LS is often associated with pruritus, dyspareunia, and dysuria, OLS is often asymptomatic, although pain, soreness, pruritus, and tightness when opening the mouth can be present (1,2). Oral manifestations of LS, as well as association of anogenital and oral LS, are rarely reported in the literature (4-6). Tomo et al. searched the Medline database for papers reporting oral LS cases with histological diagnosis confirmation from 1957 to 2016 and found only 34 cases of oral LS with histopathologic confirmation of the diagnosis (4). Kakko et al. reported 39 histologically proven cases of OLS (2). Attilli et al. (5) reviewed the clinical and histologic features of 72 cases of LS with oral/genital involvement. They reported that LS was diagnosed with exclusive genital lesions in 45, exclusive lip involvement in 20, and orogenital involvement in only 7 cases (5). Some believe that many cases of clinically diagnosed lichen planus may actually be LS and that isolated oral mucosal LS may not be as rare as is generally thought (2). While vulvar LS can occur at any age with increasing incidence with age, the median age of patients with OLS was 34 years and most of the patients were female (1,2,5). Due to the small number of patients in the literature, treatment recommendations for OLS are not available. In case of symptomatic oral lesions, topical or intralesional corticosteroids are considered to be the first-line treatment (2). First-line treatment for anogenital LS is a potent to very potent topical corticosteroid ointment, and second-line therapies include topical calcineurin inhibitors 1% pimecrolimus and 0.1% and 0.03% tacrolimus (1). For treatment-resistant genital LS, oral retinoids, methotrexate, and possibly local steroid injections for single lesions are mainly applicable for women (1). There is limited evidence for systemic treatments for both conditions. If it is not treated, genital LS is associated with a greater degree of scarring and an elevated risk of progression to squamous cell cancer; however, malignant transformation of OLS has not been reported (1-6). Due to the very rare presentation in the oral cavity, it is important to notice these lesions during a dental exam.
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PMID:Oral and Vulvar Lichen Sclerosus. 3154 67