Molecular Pathogenesis of Type I Congenital Plasminogen Deficiency: Expression of Recombinant Human Mutant Plasminogens in Mammalian Cells

Oxidative stress-associated mitochondrial dysfunction in corticosteroid-treated muscle cells

We analyzed the effects of corticosteroid on mitochondrial membrane potentials (DeltaPsi(m)), generation of reactive oxygen species (ROS), and apoptosis in a human rhabdomyosarcoma cell line, RD, and a dopaminergic neuroblastoma cell line, SH-SY5Y. The cell lines were cultured in the presence or absence of dexamethasone and superoxide dismutase (SOD) for up to 1 week. Dexamethasone treatment increased DeltaPsi(m), ROS generation, and apoptosis in proliferating RD cells. Treatment with SOD attenuated ROS generation and apoptosis, but not DeltaPsi(m). The increase in DeltaPsi(m) seemed to be the primary effect of dexamethasone on proliferating RD cells, which is probably mediated by mitochondrial transcription. In differentiated RD cells, but not differentiated SH-SY5Y cells, dexamethasone treatment showed a delayed effect of interfering with the DeltaPsi(m) and increasing ROS generation and apoptosis. Since these changes disappeared in the presence of SOD, dexamethasone primarily induced ROS generation, resulting in apoptosis. We speculate that this mechanism provides the basis of a pathophysiological model of corticosteroid myopathy.

Recurrent Recalcitrant Gingival Hyperplasia and Plasminogen Deficiency: A Case Report

BACKGROUND

Recurrent gingival hyperplasia due to plasminogen deficiency is a rare condition due to fibrin deposition in the connective tissue. Only eight cases have previously been reported in the English literature, and all cases were diagnosed before the age of 35 years. This paper presents an older patient with recurrent gingival hyperplasia due to plasminogen deficiency (hypoplasminogenemia).

METHODS

A 59-year-old woman presented with recurrent gingival swelling of 6 years' duration. Multiple biopsies performed at various time periods were histologically reported to be gingival hyperplasia with chronic inflammation. Routine hematoxylin and eosin (H & E) staining and direct immunofluorescence were performed.

RESULTS

H & E-stained sections showed subepithelial, eosinophilic, amorphous, acellular deposits. Direct immunofluorescence showed positive staining for fibrin, immunoglobulin (Ig) G, IgA, and IgM. Functional plasminogen and plasminogen activator inhibitor-1 assays were done and found to be deficient. A diagnosis of gingival hyperplasia due to plasminogen deficiency (hypoplasminogenemia) was rendered.

CONCLUSIONS

Recurrent gingival hyperplasia due to plasminogen deficiency (hypoplasminogenemia) is a newly recognized and rare condition. H & E staining, direct immunofluorescence, and assessment of functional plasminogen levels are essential to differentiate this condition from other conditions in which subepithelial, eosinophilic, amorphous materials are deposited.

Disturbed secretion of mutant adiponectin associated with the metabolic syndrome

Adiponectin, an adipocyte-derived protein, consists of collagen-like fibrous and complement C1q-like globular domains, and circulates in human plasma in a multimeric form. The protein exhibits anti-diabetic and anti-atherogenic activities. However, adiponectin plasma concentrations are low in obese subjects, and hypoadiponectinemia is associated with the metabolic syndrome, which is a cluster of insulin resistance, type 2 diabetes mellitus, hypertension, and dyslipidemia. We have recently reported a missense mutation in the adiponectin gene, in which isoleucine at position 164 in the globular domain is substituted with threonine (I164T). Subjects with this mutation showed markedly low level of plasma adiponectin and clinical features of the metabolic syndrome. Here, we examined the molecular characteristics of the mutant protein associated with a genetic cause of hypoadiponectinemia. The current study revealed (1) the mutant protein showed an oligomerization state similar to the wild-type as determined by gel filtration chromatography and, (2) the mutant protein exhibited normal insulin-sensitizing activity, but (3) pulse-chase study showed abnormal secretion of the mutant protein from adipose tissues. Our results suggest that I164T mutation is associated with hypoadiponectinemia through disturbed secretion into plasma, which may contribute to the development of the metabolic syndrome.

A K19E missense mutation in the plasminogen gene is a common cause of familial hypoplasminogenaemia

The prevalence of familial plasminogen deficiency in Scotland has recently been calculated at 2.9/1000. However, little is known of the molecular genetic background and the frequency of plasminogen gene mutations in most cases of inherited plasminogen deficiency. Having previously identified 28 unrelated subjects with familial plasminogen deficiency from a cohort of 9611 blood donors, we have now reviewed 19 of these 28 subjects and screened the plasminogen gene in 15 subjects with hypoplasminogenaemia (plus five relatives) and four subjects with dysplasminogenaemia for mutations and polymorphisms. A missense mutation K19E in the plasminogen gene was found in 13 of the 15 propositi with hypoplasminogenaemia, in one of these in a homozygous manner. In two subjects with hypoplasminogenaemia, two new mutations (P353A and R471X) were identified. These three different mutations, if inherited in a homozygous or compound-heterozygous manner, may be associated with the development of ligneous conjunctivitis. In four subjects with dysplasminogenaemia, three heterozygous mutations (C548G, n = 1; A601T, n = 1; G693R, n = 2) were found. None of the propositi with plasminogen deficiency developed venous thrombosis at any time. In conclusion, the K19E mutation in the plasminogen gene is a common cause of hypoplasminogenaemia in Scotland, with an estimated prevalence of around 0.14%.

Androgens decrease plasma adiponectin, an insulin-sensitizing adipocyte-derived protein

Adiponectin, an adipose-specific secretory protein, exhibits antidiabetic and antiatherogenic properties. In the present study, we examined the effects of sex hormones on the regulation of adiponectin production. Plasma adiponectin concentrations were significantly lower in 442 men (age, 52.6 +/- 11.9 years [mean +/- SD]) than in 137 women (53.2 +/- 12.0 years) but not different between pre- and postmenopausal women. In mice, ovariectomy did not alter plasma adiponectin levels. In contrast, high levels of plasma adiponectin were found in castrated mice. Testosterone treatment reduced plasma adiponectin concentration in both sham-operated and castrated mice. In 3T3-L1 adipocytes, testosterone reduced adiponectin secretion into the culture media, using pulse-chase study. Castration-induced increase in plasma adiponectin was associated with a significant improvement of insulin sensitivity. Our results indicate that androgens decrease plasma adiponectin and that androgen-induced hypoadiponectinemia may be related to the high risks of insulin resistance and atherosclerosis in men.

Compound-Heterozygous Mutations in the Plasminogen Gene Predispose to the Development of Ligneous Conjunctivitis

Homozygous type I plasminogen deficiency has been identified as a cause of ligneous conjunctivitis. In this study, 5 additional patients with ligneous conjunctivitis are examined. Three unrelated patients (1 boy, 1 elderly woman, and 1 man) had plasminogen antigen levels of less than 0.4, less than 0.4, and 2.4 mg/dL, respectively, but had plasminogen functional residual activity of 17%, 18%, and 17%, respectively. These subjects were compound-heterozygotes for different missense mutations in the plasminogen gene: Lys19 → Glu/Arg513 → His, Lys19 → Glu/Arg216 → His, and Lys19 → Glu/Leu128 → Pro, respectively. The other 2 patients, a 14-year-old boy and his 19-year-old sister, who both presented with a severe course of the disease, exhibited plasminogen antigen and functional activity levels below the detection limit (<0.4 mg/dL and <5%, respectively). These subjects were compound-heterozygotes for a deletion mutation (del Lys212) and a splice site mutation in intron Q (Ex17 + 1del-g) in the plasminogen gene. These findings show that certain compound-heterozygous mutations in the plasminogen gene may be associated with ligneous conjunctivitis. Our findings also suggest that the severity of clinical symptoms of ligneous conjunctivitis and its associated complications may depend on the amount of plasminogen functional residual activity.

Homozygous Mutations in the Plasminogen Gene of Two Unrelated Girls With Ligneous Conjunctivitis

Ligneous conjunctivitis is a rare and unusual form of chronic pseudomembranous conjunctivitis that usually starts in early infancy. The disease may be associated with pseudomembranous lesions of other mucous membranes in the mouth, nasopharynx, trachea, and female genital tract. We examined two unrelated Turkish girls both suffering from ligneous conjunctivitis and occlusive hydrocephalus. Both children exhibited a severe plasminogen deficiency. Genomic DNA from both patients as well as from clinically healthy family members were screened for mutations in the plasminogen gene by polymerase chain reaction, single-strand conformation polymorphism (SSCP) analysis, and DNA sequencing. In the first girl with ligneous conjunctivitis a homozygous G → A point mutation was identified in plasminogen exon 7 at position 780 leading to an amino acid exchange (Arg216 → His). Her healthy sister and her healthy parents were heterozygous for this mutation. The second patient revealed a homozygous G → A point mutation in plasminogen exon 15 at position 1924 which leads to a stopcodon (Trp597 → Stop). The healthy parents were shown to be heterozygous for this mutation. In addition, the father's second allele revealed another mutation in the same codon (Trp597 → Cys) (compound heterozygosity). In conclusion, certain homozygous mutations in the plasminogen gene may cause ligneous conjunctivitis.

Homozygous Mutations in the Plasminogen Gene of Two Unrelated Girls With Ligneous Conjunctivitis

Ligneous conjunctivitis is a rare and unusual form of chronic pseudomembranous conjunctivitis that usually starts in early infancy. The disease may be associated with pseudomembranous lesions of other mucous membranes in the mouth, nasopharynx, trachea, and female genital tract. We examined two unrelated Turkish girls both suffering from ligneous conjunctivitis and occlusive hydrocephalus. Both children exhibited a severe plasminogen deficiency. Genomic DNA from both patients as well as from clinically healthy family members were screened for mutations in the plasminogen gene by polymerase chain reaction, single-strand conformation polymorphism (SSCP) analysis, and DNA sequencing. In the first girl with ligneous conjunctivitis a homozygous G → A point mutation was identified in plasminogen exon 7 at position 780 leading to an amino acid exchange (Arg216 → His). Her healthy sister and her healthy parents were heterozygous for this mutation. The second patient revealed a homozygous G → A point mutation in plasminogen exon 15 at position 1924 which leads to a stopcodon (Trp597 → Stop). The healthy parents were shown to be heterozygous for this mutation. In addition, the father's second allele revealed another mutation in the same codon (Trp597 → Cys) (compound heterozygosity). In conclusion, certain homozygous mutations in the plasminogen gene may cause ligneous conjunctivitis.