CACP, encoding a secreted proteoglycan, is mutated in camptodactyly-arthropathy-coxa vara-pericarditis syndrome.

Altered growth and function of synoviocytes, the intimal cells which line joint cavities and tendon sheaths, occur in a number of skeletal diseases. Hyperplasia of synoviocytes is found in both rheumatoid arthritis and osteoarthritis, despite differences in the underlying aetiologies of the two disorders. We have studied the autosomal recessive disorder camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP; MIM 208250) to identify biological pathways that lead to synoviocyte hyperplasia, the principal pathological feature of this syndrome. Using a positional-candidate approach, we identified mutations in a gene (CACP) encoding a secreted proteoglycan as the cause of CACP. The CACP protein, which has previously been identified as both 'megakaryocyte stimulating factor precursor' and 'superficial zone protein', contains domains that have homology to somatomedin B, heparin-binding proteins, mucins and haemopexins. In addition to expression in joint synovium and cartilage, CACP is expressed in non-skeletal tissues including liver and pericardium. The similarity of CACP sequence to that of other protein families and the expression of CACP in non-skeletal tissues suggest it may have diverse biological activities.

Mutations in the CCN gene family member WISP3 cause progressive pseudorheumatoid dysplasia.

Members of the CCN (for CTGF, cyr61/cef10, nov) gene family encode cysteine-rich secreted proteins with roles in cell growth and differentiation. Cell-specific and tissue-specific differences in the expression and function of different CCN family members suggest they have non-redundant roles. Using a positional-candidate approach, we found that mutations in the CCN family member WISP3 are associated with the autosomal recessive skeletal disorder progressive pseudorheumatoid dysplasia (PPD; MIM 208230). PPD is an autosomal recessive disorder that may be initially misdiagnosed as juvenile rheumatoid arthritis. Its population incidence has been estimated at 1 per million in the United Kingdom, but it is likely to be higher in the Middle East and Gulf States. Affected individuals are asymptomatic in early childhood. Signs and symptoms of disease typically develop between three and eight years of age. Clinically and radiographically, patients experience continued cartilage loss and destructive bone changes as they age, in several instances necessitating joint replacement surgery by the third decade of life. Extraskeletal manifestations have not been reported in PPD. Cartilage appears to be the primary affected tissue, and in one patient, a biopsy of the iliac crest revealed abnormal nests of chondrocytes and loss of normal cell columnar organization in growth zones. We have identified nine different WISP3 mutations in unrelated, affected individuals, indicating that the gene is essential for normal post-natal skeletal growth and cartilage homeostasis.

Abnormal protein translocation as the elusive cause of cystic fibrosis: an hypothesis.

Despite the recent rapid advances in isolation of the abnormal gene responsible for cystic fibrosis, there remains the need to explain the mechanism by which a single gene mutation causes the widespread clinical effects seen in this disease. Careful review of the otherwise unexplained abnormalities of cystic fibrosis from the perspective of cell biology reveals the following common features: (1) all these abnormalities involve proteins which are either (A) inserted into cell membranes in the RER and arrested after partial translocation or (B) inserted into RER membranes and fully translocated to be compartmentalized away from the cytosol in secretory vacuoles, lysosomes or peroxisomes; (2) all the involved proteins have minor abnormalities in their physicochemical properties or activity functions; (3) none of the involved proteins are missing or totally deficient in function; (4) final compartmentalization of the involved proteins is unaffected. These observations have directed our attention to the process by which most proteins are inserted into and translocated across lipid bilayer membranes, namely the signal peptide mechanism. This mechanism, not previously examined in cystic fibrosis, is reviewed in detail. Of the major proteins controlling signal peptide translocation, deficiencies in the function of signal peptidase activity appear most capable of causing the effects seen in cystic fibrosis.

Synthesis of L-idaro-1,4-lactone, an inhibitor of alpha-L-idosiduronase.

L-idaro-1,4-lactone was synthesized by two different, published methods: (1) epimerization of monopotassium D-glucarate by refluxing in aqueous barium hydroxide, and (2) oxidation of L-iditol by heating in dilute nitric acid. The lactone, formed by heat dehydration from aqueous solution at low pH, was purified by paper chromatography, and quantitated by gas-liquid chromatography using inositol as the internal standard. The monolactone inhibited human, seminal-fluid alpha-L-idosiduronase activity, with either phenyl or 4-methylumbelliferyl alpha-L-idosiduronic acid as the substrate, to the same degree as D-glucaro-1,4-lactone inhibits alpha-D-glucosiduronase.

Mucolipidosis type III. Multiple elevated serum and urine enzyme activities.

The clinical characteristics of a 16-year-old white girl with mucolipidosis type III included early growth retardation, severe dysostosis multiplex, restricted joint motion, tight indurated skin, swollen eyelids, late-onset hepatosplenomegaly, umbilical hernia, corneal opacities, and only slightly impaired mental and neurological development. Cultured fibroblasts contained numerous coarse perinuclear retractile inclusions. Biochemical findings indicated the following: (1) normal levels of urinary acid mucopolysaccharides, (2) deficient activities of multiple lysosomal hydrolases in cultured fibroblasts, (3) elevated activity levels of seven serum lysosomal hydrolases, and (4) elevated activity levels of four lysosomal hydrolases in urine.

Separation of dermatan sulfate from heparan sulfate in mucopolysaccharidosis urine by chromatography on Sephadex G-75.

Oligosaccharides of testicular hyaluronidase-degraded dermatan sulfate were separated from undegraded dermatan sulfate by chromatography on Sephadex G-75, but not by chromatography on Sephadex G-25. All but the smallest of these oligosaccharides were recovered in excellent yield following dialysis and precipitation with cetyl pyridinium chloride (CPC). G-75 chromatography of dialyzed, concentrated Hunter urine mucopolysaccharides precipitated with CPC resolved most of the large dermatan sulfate into a void volume related peak which was free of heparan sulfate. Decreasing amounts of dermatan sulfate oligosaccharides were eluted with sephadex-retarded polysaccharides, including small amounts which appeared with otherwise pure heparan sulfate.

In vitro correction of Hurler fibroblasts with bovine testicular hyaluronidase.

Bovine testicular hyaluronidase (endo-beta-N-acetyl hexosaminidase) has a significant corrective effect on cultured Hurler fibroblasts. Nonspecificity of this effect is indicated by its equally strong corrective effect on Hunter fibroblasts. Although all specimens of hyaluronidase also possessed iduronidase activity, a separate corrective effect could be attributed to the endo-N-acetyl hexosaminidase activity of at least one hyaluronidase (Wyeth M-151) for four reasons: (i) its very low content of iduronidase activity; (ii) a decrease in intracellular macromolecular mucopolysaccharides (believed to be largely dermatan sulfate) with a corresponding increase in intracellular and extracellular oligosaccharides; (iii) no measurable increase in iduronidase activity of hyaluronidase-treated cells despite near maximal correction; (iv) direct correlation between Hurler cell correction and hyaluronidase activity when enzymes of different strength were used at less than maximal correction.

The Hurler syndrome: treatment of cultured Hurler fibroblasts with normal human serum.

Prolonged replacement of fetal calf serum by normal human serum for the enrichment of medium during tissue culture of Hurler fibroblasts resulted in increased acid mucopolysaccharides in the cells and in the medium. The predominant intracellular mucopolysaccharide had the characteristics of dermatan sulfate when Hurler cells were treated with either serum. Normal human serum contains a nonspecific coreective factor capable of augmenting the loss of 35SO4-AMPS from Hurler cells, but not from normal cells. Fetal calf serum and Hurler serum have similar corrective factor activity for labeled Hurler cells. The corrective factor activity of all three sera was recovered from reconstituted dialyzed ammonium sulfate precipitates. The corrective factor of normal human serum did not increase degradation of mucopolysaccharide, but increased secretion of macromolecular and large oligosaccharide components. Failure of the corrective factor of normal human serum to effectively decrease the dermatan sulfate content of Hurler cells during prolonged exposure may be a quantitative phenomenon due partly to the brief duration of corrective factor activity and partly to increased synthesis of mucopolysaccharide.

Rubella-virus infection in juvenile rheumatoid arthritis.

Antibody activity against mumps, measles, polio, and rubella viruses was determined in patients with juvenile rheumatoid arthritis (J.R.A.), rubella-vaccine associated arthritis, adult rheumatoid arthritis, other chronic systemic disorders (e.g., systemic lupus and dermatomyositis), and in a matched population of normal, non-rheumatoid (control) children. The antibody levels against mumps, measles, and poliovirus were similar in all patients. Rubella-antibody levels in rheumatoid arthritis and other systemic disorders were similar to those observed in controls. The mean rubella-antibody levels in rubella-vaccine arthritis were 4 times higher than in controls. The IgM and IgG rubella-antibody levels in J.R.A. were found to be 4-6 times higher when compared to titres observed in the controls. Highest antibody levels were seen in younger children with J.R.A. Detection of rubella-virus antigen was attempted by immunofluorescence in the sediment smears of synovial fluid of patients with J.R.A., adult rheumatoid arthritis, and other non-rheumatoid joint diseases. Specific staining for rubella virus antigen was observed in the synovial fluid of 33 percent of patients with J.R.A. No antigen was detected in the synovial fluid from other patients. These observations suggest a possible role of rubella-virus infection in J.R.A.