Skewed X-chromosome inactivation causes intra-familial phenotypic variation of an EBP mutation in a family with X-linked dominant chondrodysplasia punctata

X-linked dominant chondrodysplasia punctata (CDPX2) is a skeletal dysplasia characterized by stippled epiphyses, cataracts, alopecia and skin lesions, including ichthyosis. CDPX2 exhibits a number of perplexing clinical features, such as intra- and inter-familial variation, anticipation, incomplete penetrance and possible gonadal and somatic mosaicism. Recently, mutations in the gene encoding Delta8,Delta7 sterol isomerase/emopamil-binding protein (EBP) have been identified in CDPX2. To better understand the genetics of CDPX2, we examined the entire EBP gene by direct sequencing in four CDPX2 patients. We found EBP mutations in all four patients, including three novel mutations: IVS3+1G>A, Y165C and W82C. Surprisingly, a known mutation (R147H) was identified in a patient and her clinically unaffected mother. Expression analysis revealed the mutant allele was predominantly expressed in the patient, while both alleles were expressed in the mother. Methylation analysis revealed that the wild-type allele was predominantly inactivated in the patient, while the mutated allele was predominantly inactivated in her mother. Thus, differences in expression of the mutated allele caused by skewed X-chromosome inactivation produced the diverse phenotypes within the family. Our findings could explain some of the perplexing features of CDPX2. The possibility that an apparently normal parent is a carrier should be considered when examining seemingly sporadic cases and providing genetic counseling to CDPX2 families.     

Dual effect of AMD3100, a CXCR4 antagonist, on bleomycin-induced lung inflammation

The chemokine receptor CXCR4, which binds the chemokine stromal cell-derived factor 1, has been reported to be involved in the chemotaxis of inflammatory cells. In addition, AMD3100, an antagonist of CXCR4, has been reported to be an attractive drug candidate for therapeutic intervention in several disorders in which CXCR4 is critically involved. However, little is known about the therapeutic value of AMD3100 in the treatment of pulmonary fibrosis. In this study, we examined the effects of AMD3100 on a murine bleomycin-induced pulmonary fibrosis model. Concurrent administration of AMD3100 and bleomycin apparently attenuated bleomycin-induced pulmonary inflammation. In this process, an inhibition of neutrophil recruitment at early stage followed by the decrease of other inflammatory cell recruitment in the lung were observed. In addition, it also inhibited the expression of cytokines, including MCP-1, MIP-2, MIP-1alpha, and TGF-beta. In contrast, when AMD3100 was administered following bleomycin treatment, the bleomycin-induced lung inflammation progressed and resulted in severe pulmonary fibrosis. In this process, an increase of inflammatory cell recruitment, an up-regulation of lung MCP-1 and TGF-beta, and a remarkable activation of p44/42 MAPK in neutrophils were observed. U0126, an inhibitor of p44/42 MAPK, significantly abolished these effects. Thus, AMD3100 has dual effect on bleomycin-induced pulmonary fibrosis. Difference of inflammatory cell recruitment and activation might be associated with the dual effect of AMD3100 on bleomycin-induced pulmonary fibrosis.     

Induced helical conformation of ionic polypeptides by phospholipids solubilized in a nonionic surfactant solution.

Phosphatidylcholine that has been solubilized in hexadecylpoly (oxyethylene) ether can induce a coil-to-helix transformation for poly (L-glutamic acid) in neutral solution. Similarly, solubilized phosphatidylserine promotes a helical conformation of poly (L-lysine) at neutral pH through complex formation. The mixed micelles of a phospholipid and a nonionic surfactant are thermodynamically stable and do not separate on standing. The nonionic surfactant here has no effect on the conformation of the two polypeptides.     

A new form of amyloid protein associated with chronic hemodialysis was identified as beta 2-microglobulin

Amyloid fibrils were isolated from amyloid-laden tissue obtained from a chronic hemodialysis patient with carpal tunnel syndrome. After solubilization in guanidine HCl, a significant amount of the protein was located in a homogeneous low molecular weight fraction. The protein was found to be identical to beta 2-microglobulin, with regard to its molecular weight of 11,000, amino acid composition and 16 amino-terminal amino acids: Ile-Gln-Arg-Thr-Pro-Lys-Ile-Gln-Val-Tyr-Ser-Arg-His-Pro-Ala-Glu-. These results demonstrate that the amyloid associated with chronic hemodialysis contains as major component a new form of amyloid fibril protein that is homologous to beta 2-microglobulin.     

Expression of a carbohydrate signal, sialyl dimeric Le(x) antigen, is associated with metastatic potential of transitional cell carcinoma of the human urinary bladder.

Sialyl dimeric Le(x) antigen was expressed in significant portion of transitional cell carcinoma of the human urinary bladder, but not in the normal uroepithelial tissue. Primary tumors with weak or no expression of the antigen scarcely metastasized to lymph nodes, whereas tumors with high levels of antigen expression metastasized frequently. Metastatic lymph nodes expressed the antigen in most cases. Sialyl dimeric Le(x) antigen was mainly located on 60 and 42 KDa glycoproteins. Since a group of cell adhesion molecules, called LECCAMs, recognize a portion of the antigen, the above results strongly suggest that a LECCAM on the surface of host cells recognizes the carbohydrate structure on the glycoprotein, leading to promotion of metastasis.     

Incorporation of [14C]glucosamine and [14C]leucine into mouse kidney β-glucuronidase induced by gonadotrophin

Male BALB/C mice were injected intraperitoneally with 2.5 i.u. of gonadotrophin. After the injection, increase of β-glucuronidase activity was first observed in the microsomal fraction. By 36h 45–50% of the total homogenate activity was found in the microsomal fraction compared with 20–25% in the control microsomal fraction. From 36 to 80h not only microsomal β-glucuronidase but also lysosomal β-glucuronidase increased progressively. After 69h stimulation with 2.5 i.u. of gonadotrophin, d-[1-¹⁴C]glucosamine or l-[U-¹⁴C]leucine was injected intraperitoneally. After a further 3h the kidneys were homogenized and five particulate fractions were prepared by differential centrifugation. The β-glucuronidase in the microsomal and lysosomal fractions was released respectively by ultrasonication and by freezing and thawing treatment. The enzyme was purified by organic-solvent precipitation and by sucrose-density-gradient centrifugation. The results demonstrated the incorporation of these two labels into the mouse renal β-glucuronidase. The microsomal β-glucuronidase was much more radioactive than the lysosomal enzyme and approx. 80% of the newly synthesized enzyme appeared in microsomes and approx. 20% of that was found in lysosomes at this period. These results suggest that the mouse renal β-glucuronidase is a glycoprotein and that the newly synthesized enzyme is transported from endoplasmic reticulum to lysosomes.