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The primary treatment of nasopharyngeal carcinoma (NPC) has been external radiotherapy. Rupture of an internal carotid artery (ICA) pseudoaneurysm is a rare complication of irradiation therapy for a nasopharyngeal carcinoma. A 78 years old man had a history of NPC treated with radiotherapy in 1993. He was admitted to the hospital because of epistaxis. Angiography showed an ICA pseudoaneurysm pointing medially to the nasopharynx. Coil embolization of the ICA was performed, but cerebral infarction occurred. Internal carotid artery (ICA) pseudoaneurysms are an uncommon but potentially lethal condition. Angiography is the mainstay of diagnosis of the aneurysm and planning the embolization of the ICA. We should be more aware of this complication in NPC patients.

An ABC transporter, TAP-Like (TAPL), was dissected into its amino-terminal transmembrane domain and the following core domain. When these domains were transiently expressed as tagged proteins with a His6- or Myc-epitope tag, the amino-terminal ones (Met(1)-Lys(182)) could not associate with each other, or with the full-length transporter (Met(1)-Ala(766)). However, both the core domain (Arg(141)-Ala(766)) and full-length protein mutually interacted. The amino-terminal domain (Met(1)-Arg(141)) as well as the full-length transporter fused with fluorescent protein GFP was sorted to lysosomal membranes upon their stable expression, as visualized by means of fluorescent microscopy, while the core domain (Arg(141)-Ala(766)) was broadly distributed in the intra-cellular membranes. These results suggest that the sorting signal for lysosomes is present within the amino-terminal transmembrane domain (Met(1)-Arg(141)) of the TAPL molecule.

The carboxyl terminus of a human ATP-binding cassette (ABC) transporter, transporter associated with antigen processing (TAP)-like (TAPL), was tagged with green fluorescence protein (GFP), and the resulting fusion protein (TAPL-GFP) was stably expressed in Chinese hamster ovary (CHO)-K1 cells. The GFP signal was co-localized with that of LysoTracker but not that of MitoTracker, as visualized under a microscope. TAPL-GFP was co-sedimented with lysosomal marker cathepsin D on Percoll density gradient centrifugation. These results indicated that TAPL is a lysosomal ABC transporter but not a mitochondrial one. It was not solubilized completely with a non-ionic detergent under ice-cold conditions, and was co-sedimented with flotillin-1 on sucrose density gradient centrifugation. A similar result was obtained with high pH-treatment. Furthermore, treatment with methyl-β-cyclodextrin resulted in an altered distribution of TAPL-GFP. These results suggest that TAPL may be localized to the microdomains (lipid rafts) of lysosomal membranes enriched in cholesterol.