Kidney Na+,K(+)-ATPase is associated with moesin.

Na+,K(+)-ATPase is a ubiquitous plasmalemmal membrane protein essential for generation and maintenance of transmembrane Na+ and K+ gradients in virtually all animal cell types. Activity and polarized distribution of renal Na+,(+)-ATPase appears to depend on connection of ankyrin to the spectrin-based membrane cytoskeleton as well as on association with actin filaments. In a previous study we showed copurification and codistribution of renal Na+,K(+)-ATPase not only with ankyrin, spectrin and actin, but also with two further peripheral membrane proteins, pasin 1 and pasin 2. In this paper we show by sequence analysis through mass spectrometry as well as by immunoblotting that pasin 2 is identical to moesin, a member of the FERM (protein 4.1, ezrin, radixin, moesin) protein family, all members of which have been shown to serve as cytoskeletal adaptor molecules. Moreover, we show that recombinant full-length moesin as well as its FERM domain bind to Na+,K(+)-ATPase and that this binding can be inhibited by an antibody specific for the ATPase activity-containing cytoplasmic loop (domain 3) of the Na+,K(+)-ATPase alpha-subunit. This loop has been previously shown to be a site essential for ankyrin binding. These observations indicate that moesin might not only serve as direct linker molecule of Na+,K(+)-ATPase to actin filaments but also modify ankyrin binding at domain 3 of Na+,K(+)-ATPase in a way similar to protein 4.1 modifying the binding of ankyrin to the cytoplasmic domain of the erythrocyte anion exchanger (AE1).

[Systemic mastocytosis. Classification, symptoms, therapy]. / Systemische Mastozytose. Klassifikation, Symptome und Therapie.

BACKGROUND: Systemic mastocytoses are a group of diseases, which are characterized by accumulation and unusual growth of mast cells infiltrating two different organs or types of tissue. Two case reports are introduced. CLASSIFICATION: According to the new WHO classification of 2000, mastocytoses are separated into cutaneous and systemic mastocytoses. Systemic mastocytosis is subdivided into an indolent course with good prognosis and four subgroups with poor prognosis (systemic mastocytosis with associated clonal hematologic non-mast-cell disease, aggressive systemic mastocytosis, mast cell leukemia, and mast cell sarcoma). GENETICS: Systemic mastocytoses are clonal disorders of mast cells and their progenitor cells, which may show point mutations of the protooncogene c-kit. This gene codes for the stem cell receptor (CD117). THERAPY: Therapy of systemic mastocytosis depends on patient's symptoms. There is no known cure of the disease. Besides diet and avoidance of skin irritations, symptoms are treated with H(1)- or H(2)-blockers, steroids, leukotriene receptor antagonists, and PUVA therapy. If patients suffer from systemic reactions such as hypotension or syncope, epinephrine solution should be prescribed for emergency use.

Nuclear Pore Protein p62 Autoantibodies in Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease which is classically characterised by a variety of autoantibodies to deoxyribonucleic acid (DNA), ribonucleic acid (RNA), other nuclear and cytoplasmic antigens. Recently several novel autoantibodies against a variety of specific nuclear pore proteins have been described, including the nucleoporin p62. In this paper we evaluate anti-nucleoporin p62 antibodies by western blot analysis in 25 systemic lupus erythematosus patients. Six patients showed antibodies directed against nucleoporin p62. Our data indicate that p62 antibodies could be a useful additional marker in SLE.

Missense mutation in a patient with X-linked dyskeratosis congenita.

We report the case of a 40-year-old male patient with dyskeratosis congenita(DKC). Sequencing of the DKC1 gene revealed an inherited missense mutation in base 1050 (GC), changing methionine to isoleucine. This is the third description of a mutation in codon 350 (exon 11), changing a very well conserved amino acid in the pseudouridine synthase (PUA) domain of dyskerin.

Nucleoporin p62 antibodies in a case of mixed connective tissue disease.

Mixed connective tissue disease is an overlap syndrome characterized by features of different systemic autoimmune diseases and a high titer of U1-snRNP antibodies. We examine here the autoantibodies to nucleoporin p62 in a severe case of mixed connective tissue disease in a young male patient. Thus far, p62 antibodies have mainly been described in cases of primary biliary cirrhosis. We speculate that the presence of p62 antibodies is an indication of a poor prognosis in connective tissue disorders.