A 450-kDa human epidermal autoantigen was originally identified as a protein that reacted with the serum from an individual with a subepidermal blistering disease. Molecular cloning of this protein has now shown that it contains 5065 amino acids and has a molecular mass of 552 kDa. As reported previously this protein, which we call epiplakin, belongs to the plakin family, but it has some very unusual features. Epiplakin has 13 domains that are homologous to the B domain in the COOH-terminal region of desmoplakin. The last five of these B domains, together with their associated linker regions, are particularly strongly conserved. However, epiplakin lacks a coiled-coil rod domain and an aminoterminal domain, both of which are found in all other known members of the plakin family. Furthermore, no dimerization motif was found in the sequence. Thus, it is likely that epiplakin exists in vivo as a single-chain structure. Epitope mapping experiments showed that the original patient's serum recognized a sequence unique to epiplakin, which was not found in plectin. Immunofluorescence staining revealed the presence of epiplakin in whole sheets of epidermis and esophagus, in glandular cells of eccrine sweat and parotid glands and in mucous epithelial cells in the stomach and colon.Clarification of the basic structure of desmoplakin has been followed by the identification of many related proteins, such as BPAG1, 1 plectin, envoplakin, and periplakin (1-7). These proteins form a family known as the "plakin family" (8). Almost all members of this family have a common structure, with predicted globular amino-terminal and COOH-terminal domains that are separated by a central rod domain. Some homologous domain structures have been identified in both globular domains of many plakins, while the central domain is rich in heptad repeats and is believed to form a parallel ␣-helical coiled-coil structure with a dimerization partner (9). As suggested by this model, it has been demonstrated that desmoplakin I can form homodimers in vitro (10). Early investigations revealed that the COOH-terminal domains of plakins are involved in binding to intermediate filaments (11)(12)(13). The amino-terminal domains of desmoplakin and of BPAG1 are believed to bind to desmosomes or hemidesmosomes. Furthermore, some splicing variants of plectin and BPAG1 have actinor microtubule-binding domains at their amino termini, and it has been proposed that these domains form cross-links between microfilaments and/or microtubules and intermediate filaments (14 -16). Studies of a few inheritable diseases that appear to involve plectin or desmoplakin and of a BPAG1 null mouse have shown that each plakin plays a critical role in the tissue integrity in specific tissues (5,(17)(18)(19). Moreover, it seems likely that, in many autoimmune blistering diseases, plakins, located in the epidermis, might be target antigens, and these plakins are used for markers of specific diseases (2, 20 -22). However, their pathological roles remain to be clarified. Several years ago ...

Background: NASH is a disease characterized by fat accumulation and chronic inflammation in the liver. Results: Pin1 expression was increased in NASH model mouse livers. Pin1 KO mice were resistant to NASH development. Conclusion: Pin1 plays critical roles in NASH development. Significance: A Pin1 inhibitor might be a novel agent for treating NASH.

Glucose transporter 1 (GLUT1) is widely distributed throughout various tissues and contributes to insulin-independent basal glucose uptake. Using a split-ubiquitin membrane yeast two-hybrid system, we newly identified 4F2 heavy chain (4F2hc) as a membrane protein interacting with GLUT1. Though 4F2hc reportedly forms heterodimeric complexes between amino acid transporters, such as LAT1 and LAT2, and regulates amino acid uptake, we investigated the effects of 4F2hc on GLUT1 expression and the associated glucose uptake. First, FLAG-tagged 4F2hc and hemagglutinin-tagged GLUT1 were overexpressed in human embryonic kidney 293 cells and their association was confirmed by coimmunoprecipitation. The green fluorescent protein-tagged 4F2hc and DsRed-tagged GLUT1 showed significant, but incomplete, colocalization at the plasma membrane. In addition, an endogenous association between GLUT1 and 4F2hc was demonstrated using mouse brain tissue and HeLa cells. Interestingly, overexpression of 4F2hc increased the amount of GLUT1 protein in HeLa and HepG2 cells with increased glucose uptake. In contrast, small interfering RNA (siRNA)-mediated 4F2hc gene suppression markedly reduced GLUT1 protein in both cell types, with reduced glucose uptake. While GLUT1 mRNA levels were not affected by overexpression or gene silencing of 4F2hc, GLUT1 degradation after the addition of cycloheximide was significantly suppressed by 4F2hc overexpression and increased by 4F2hc siRNA treatment. Taken together, these observations indicate that 4F2hc is likely to be involved in GLUT1 stabilization and to contribute to the regulation of not only amino acid but also glucose metabolism.

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Background: Par14 is a parvulin-type peptidyl-prolyl cis/trans isomerase homologous with Pin1, but its functions remain largely unknown. Results: Par14 markedly enhanced insulin signaling by associating with IRS-1, and hepatic overexpression of Par14 normalized hyperglycemia in diabetic mice. Conclusion: Par14 exhibits an insulin-sensitizing effect. Significance: This is the first report showing the roles of Par14 in metabolism and signal transduction.

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We report a case of Churg-Strauss syndrome (CSS) with necrosis of the fingers and toes and liver infarction. A 59-year-old man with asthma suddenly noticed that his fingers and toes felt unusually cold. This condition worsened progressively, and some digits became necrotic within several weeks. Laboratory studies revealed hypereosinophilia and an extremely elevated serum level of IgE. Digital subtraction angiography of the extremities revealed extensive irregular narrowing of small and medium-sized arteries in the extremities. Abdominal computed tomography (CT) revealed an area of low density at the periphery of the right lobe of the liver. Angiography revealed irregular narrowing of small arteries that corresponded to the ischemic area. A nerve conduction study suggested sensory nerve neuropathy. The preceding asthma, acute onset of digital necrosis, liver infarction, neuropathy, and hypereosinophilia strongly suggested a diagnosis of CSS. The patient was treated with 40 mg of prednisolone and 120 micro g of intravenous prostaglandin E1 daily, and all the digits that had turned black and necrotic were amputated. After the amputation, the dose of prednisolone was gradually reduced, and no new lesions appeared on the skin or in the liver. The rare possible complications of CSS, including necrosis of digits and liver infarction, should not be ignored.

Background and Aim: Non-alcoholic steatohepatitis (NASH) is characterized by hepatic steatosis, inflammation, and hepatocellular injury with varying degrees of fibrosis. There are currently no established treatment approaches for NASH other than lifestyle interventions. Periostin, a matricellular protein required for tissue remodeling and fibrosis, plays an important role in hepatic steatosis and fibrosis and could be a potential target for NASH treatment. Advances in molecular biology and biochemical engineering have led to the development of antisense oligonucleotides (ASOs) that can inhibit target genes with no significant toxic effects. Herein, we investigated the therapeutic effects of periostin-targeting ASO (PNASO) in NASH. Methods: C57BL/6J mice were fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) to induce NASH with or without intraperitoneal injection of mouse PNASO. To explore the role of periostin in hepatocellular steatosis, Hc3716 cells, an immortalized human hepatocyte line, were treated with recombinant periostin in vitro. Results: The induced periostin expression in the liver of CDAHFD-fed mice was significantly suppressed by PNASO. The deletion of hepatic periostin by PNASO significantly ameliorated hepatic steatosis while restoring the expression levels of peroxisome proliferator-activated receptor-alpha (PPAR-α) and its target genes. PNASO also inhibited hepatic fibrosis, reflected by the reduction of alpha-smooth muscle actin, collagen type I, and other fibrotic markers. In vitro experiments demonstrated that treatment with recombinant periostin increased cellular lipid accumulation in Hc3716 cells accompanied with the downregulation of PPAR-α. Conclusions: Periostin-targeting ASO is a potential therapeutic approach for the efficient treatment of hepatic steatosis and fibrosis in NASH.