Myotonic dystrophy protein kinase (DMPK) prevents ROS-induced cell death by assembling a hexokinase II-Src complex on the mitochondrial surface.

The biological functions of myotonic dystrophy protein kinase (DMPK), a serine/threonine kinase whose gene mutations cause myotonic dystrophy type 1 (DM1), remain poorly understood. Several DMPK isoforms exist, and the long ones (DMPK-A/B/C/D) are associated with the mitochondria, where they exert unknown activities. We have studied the isoform A of DMPK, which we have found to be prevalently associated to the outer mitochondrial membrane. The kinase activity of mitochondrial DMPK protects cells from oxidative stress and from the ensuing opening of the mitochondrial permeability transition pore (PTP), which would otherwise irreversibly commit cells to death. We observe that DMPK (i) increases the mitochondrial localization of hexokinase II (HK II), (ii) forms a multimeric complex with HK II and with the active form of the tyrosine kinase Src, binding its SH3 domain and (iii) it is tyrosine-phosphorylated by Src. Both interaction among these proteins and tyrosine phosphorylation of DMPK are increased under oxidative stress, and Src inhibition selectively enhances death in DMPK-expressing cells after HK II detachment from the mitochondria. Down-modulation of DMPK abolishes the appearance of muscle markers in in vitro myogenesis, which is rescued by oxidant scavenging. Our data indicate that, together with HK II and Src, mitochondrial DMPK is part of a multimolecular complex endowed with antioxidant and pro-survival properties that could be relevant during the function and differentiation of muscle fibers.

Gluten-dependent diabetes-related and thyroid-related autoantibodies in patients with celiac disease.

Patients with celiac disease are at high risk of having autoimmune disorders. Moreover, untreated patients with celiac disease have been found to have a higher than expected prevalence of organ-specific autoantibodies. In a prospective study of 90 patients with celiac disease, we found that the prevalence of diabetes and thyroid-related serum antibodies was 11.1% and 14.4%, respectively. Like antiendomysium autoantibodies, these organ-specific antibodies seem to be gluten-dependent and tend to disappear during a gluten-free diet.

Usefulness of screening program for celiac disease in autoimmune thyroiditis.

We determined the prevalence of celiac disease in subjects with autoimmune thyroiditis compared with sick and healthy subjects. The screening was performed with IgA-class endomysium antibody, by indirect immunofluorescence using human umbilical cord as the antigenic substrate. Six of the 172 patients with autoimmune thyroiditis were found to be anti-endomysium positive (3.4%) and five of these underwent intestinal biopsy, which showed total villous atrophy. By contrast, 3 (0.75%) of 396 patients with nongastroenterologic malignancies and 10 (0.25%) of 4000 blood donors were found to have celiac disease. The prevalence of autoimmune diseases was significantly higher in patients with both celiac disease and autoimmune thyroiditis than in patients with autoimmune thyroiditis alone (P = 0.01). This study confirms that celiac disease is increased among patients with autoimmune thyroiditis. We suggest that these patients may benefit from screening for celiac disease so as to eliminate symptoms and limit the risk of developing other autoimmune disorders.

Screening for coeliac disease in healthy blood donors at two immuno-transfusion centres in north-east Italy.

BACKGROUND AND AIMS: In the past, the reported prevalence of coeliac disease ranged from 1:1000 to 1:4000, whereas recent studies using serological screening methods have found a significantly higher prevalence. The aim of this study was to investigate the prevalence of coeliac disease in healthy blood donors in a North-eastern region of Italy. SUBJECTS: A total of 4000 healthy blood donors were studied from two immunotransfusion centres. METHODS: Serum IgA-antiendomysium antibodies were detected by indirect immunofluorescence using human umbilical cord vein sections, and positive sera were tested also on monkey oesophagus tissue. Intestinal biopsy was performed in all antiendomysium-positive subjects. RESULTS: Ten out of 4000 sera screened were found to be antiendomysium positive on human umbilical cord vein. All positive patients had flat mucosa on intestinal biopsy. Five subjects had coeliac disease-related clinical features (2 had a history of gastrointestinal symptoms, 1 a family history of IDDM, 1 sideropenic anaemia, and 1 IgA deficiency). One of the ten serum, antiendomysium positive on human umbilical cord vein, was found to be negative when tested on monkey oesophagus. CONCLUSIONS: These data confirm the high prevalence of undiagnosed silent coeliac disease in the healthy adult population. This is the first study where umbilical cord was used for screening coeliac disease in a large population. The human umbilical cord vein indirect immunofluorescence test is more specific for villous atrophy than conventional indirect immunofluorescence test on monkey oesophagus and is a reliable screening test for coeliac disease in an apparently healthy population.

In situ RT-PCR allows the detection of ornithine decarboxylase mRNA in paraffin embedded archival human hyperplastic breast tissues.

Expression of ornithine decarboxylase (ODC) is induced by c-Myc oncoprotein and is required for cell proliferation and tumour growth. We have studied the expression of ODC mRNA by in situ hybridisation and in situ RT-PCR in archival human hyperplastic breast tissues. A very low signal was detected by in situ hybridisation, while the in situ RT-PCR on human breast archival tissues demonstrated an over-expression of ODC mRNA in epithelial cells characterised by some degree of hyperplasia, maintaining the morphology of the archival tissue intact despite the multiple steps of fixation, permeabilization and thermal cycling.

Anti-endomysium antibody on human umbilical cord vein tissue: an inexpensive and sensitive diagnostic tool for the screening of coeliac disease.

UNLABELLED: Anti-endomysium antibody (AEA) was evaluated in 136 subjects by indirect immunofluorescence using both cryosections of monkey oesophagus (MO) and the human umbilical cord vein (HUCV) as substrate. This human tissue gave results comparable to those of MO. In particular, the HUCV sections showed positive results in all 22 newly diagnosed cases of coeliac disease. Compared to the MO sections, the sensitivity, specificity and positive predictive values of HUCV tissue was 100%. CONCLUSION: HUCV tissue can replace MO for AEA detection and can make the screening for coeliac disease easier both in at-risk and in normal populations, with a remarkable saving, both in terms of money and of monkeys.