The phospholipid flippase ATP9A is required for the recycling pathway from the endosomes to the plasma membrane

Type IV P-type ATPases (P4-ATPases) are phospholipid flippases that translocate phospholipids from the exoplasmic (or luminal) to the cytoplasmic leaflet of lipid bilayers. In Saccharomyces cerevisiae, P4-ATPases are localized to specific subcellular compartments and play roles in compartment-mediated membrane trafficking; however, roles of mammalian P4-ATPases in membrane trafficking are poorly understood. We previously reported that ATP9A, one of 14 human P4-ATPases, is localized to endosomal compartments and the Golgi complex. In this study, we found that ATP9A is localized to phosphatidylserine (PS)-positive early and recycling endosomes, but not late endosomes, in HeLa cells. Depletion of ATP9A delayed the recycling of transferrin from endosomes to the plasma membrane, although it did not affect the morphology of endosomal structures. Moreover, depletion of ATP9A caused accumulation of glucose transporter 1 in endosomes, probably by inhibiting their recycling. By contrast, depletion of ATP9A affected neither the early/late endosomal transport and degradation of epidermal growth factor (EGF) nor the transport of Shiga toxin B fragment from early/recycling endosomes to the Golgi complex. Therefore ATP9A plays a crucial role in recycling from endosomes to the plasma membrane

Simultaneous Oculomotor and Facial Nerve Palsies in a Patient with Systemic Lupus Erythematosus and Sjögren’s Syndrome

A 70-year-old man with systemic lupus erythematosus (SLE) presented with simultaneous right oculomotor nerve palsy and right facial nerve palsy. Brain magnetic resonance imaging and cerebrospinal fluid analysis revealed no abnormality. Coexistent Sjögren’s syndrome was diagnosed on the basis of anti-SS-A antibody positivity, salivary gland scintigraphy, and histological findings on minor salivary gland biopsy. As there was no obvious cause of multiple cranial neuropathies, we supposed that the palsies were induced by either of the underlying diseases. The patient was treated with a high-dose of prednisolone and intravenous cyclophosphamide, and both palsies recovered almost completely within two weeks

Eltrombopag Improves Refractory Thrombocytopenia in a Patient with Systemic Lupus Erythematosus

A 42-year-old woman with systemic lupus erythematosus (SLE) was admitted to our hospital for evaluation of severe thrombocytopenia. She was treated with steroids, intravenous cyclophosphamide, intravenous immunoglobulin, and plasma exchange, but her thrombocytopenia did not improve. Renal biopsy showed class IV-S(C) + V lupus nephritis, according to the classification of the International Society of Nephrology/Renal Pathology Society. The PA-IgG and serum thrombopoietin (TPO) levels were elevated. Her thrombocytopenia responded to off-label administration of eltrombopag, which was discontinued after 42 months. At 18 months after stopping eltrombopag, the platelet count was 19.3 × 104/μL. Eltrombopag may be a therapeutic option for SLE patients with severe thrombocytopenia refractory to conventional therapy

Lupus nephritis with massive subendothelial deposits in a patient with autoimmune hepatitis-related cirrhosis

A 72-year-old Japanese woman with a history of autoimmune hepatitis-associated liver cirrhosis and portosystemic shunt was admitted to our hospital for evaluation of renal dysfunction, nephrotic range proteinuria, a high titer of anti-double-stranded DNA antibody, and hypocomplementemia. Renal biopsy showed massive subendothelial deposits (wire loop lesions), and class IV-G (A/C) lupus nephritis was diagnosed. Immunosuppressants, such as steroids (including intravenous methylprednisolone pulse therapy) and mycophenolate mofetil, could not prevent renal dysfunction. It was assumed that circulating immune deposits produced in the gastrointestinal tract entered the systemic circulation from the portal vein via the portosystemic shunt without hepatic clearance, resulting in massive subendothelial and mesangial accumulation compared to lupus nephritis patients without a shunt and causing renal injury. Keywords: Lupus nephritis, Systemic lupus erythematosus, Autoimmune hepatitis-associated liver cirrhosis, Portosystemic shunt, Wire loop lesio