ABSTRACT
The STAM family proteins, STAM1 and STAM2/EAST/Hbp, are phosphotyrosine proteins that contain SH3 domains and ubiquitin-interacting motifs. Their yeast homologue, Hse1, and its binding protein, Vps27, are involved in the vacuolar membrane transport machinery. Here we show that STAM1 and STAM2 are localized to the endosomal membrane. Some of these complexes contain Eps15, an endocytic protein, which accumulates in clumps upon expression of a dominant-negative form of Vps4-A, an AAA-type ATPase, that is required for normal endosome function. These results support the idea that the STAMs are mammalian vacuolar protein sorting (Vps) proteins. We also demonstrate that ligand-mediated epidermal growth factor receptor (EGFR) degradation is partially but not completely impaired in both Hrs(-/-) and STAM1(-/-)STAM2(-/-) mouse embryonic fibroblasts. Furthermore, endosome swelling is seen in both Hrs(-/-) and STAM1(-/-)STAM2(-/-) cells. These results suggest that the STAMs and Hrs play important roles in the mammalian endosomal/vacuolar protein sorting pathway.
Subject(s)
Adaptor Proteins, Signal Transducing , Down-Regulation/physiology , ErbB Receptors/physiology , Phosphoproteins/physiology , Animals , Cell Line , Endosomal Sorting Complexes Required for Transport , Mice , Microscopy, Fluorescence , Phosphoproteins/genetics , Protein TransportABSTRACT
We report a case of chronic active Epstein-Barr (EB) virus infection (CAEBV) associated with skin eruptions mimicking hydroa vacciniforme (HV) in a 4-year-old boy. The patient had repeated episodes of vesiculo-necrotic eruptions on the face, scalp, and bilateral forearms one year before the first visit to our department. General symptoms including fever, hepatosplenomegaly, abnormal liver function, and cervical lymph node swelling were noted three months before the first visit. At the first visit, small, bean-sized, erythemic papules with central necrosis were observed on the face and anterior chest wall. Thumb-sized ulcers with crust were present on the bilateral forearms. Histopathological examination of an erythematous lesion in the submandibular area revealed parakeratosis with a thick crust, mild spongiosis in the epidermis, and a dense infiltration of lymphoid cells into the dermis and perivascular space. Laboratory examination showed EBNA x 40, EBV VCA IgG x 1,280, and EBV DNA (PCR) 8 x 10(4). EBV-encoded small nuclear RNA (EBER) positive cells were detected in the dermis by an in situ hybridization (ISH) method. Large granular lymphocytes (65%) with the NK cell phenotype were found in the peripheral blood. A real time PCR method showed 171,741 copies/ micro g DNA in CD 16 positive cells. Although latent EBV infection-associated eruptions have been documented, detailed skin manifestations in CAEBV are less well known.
Subject(s)
Epstein-Barr Virus Infections/diagnosis , Facial Dermatoses/diagnosis , Hydroa Vacciniforme/diagnosis , Scalp Dermatoses/diagnosis , Child, Preschool , Chronic Disease , DNA, Viral/genetics , Diagnosis, Differential , Epstein-Barr Virus Infections/complications , Epstein-Barr Virus Infections/pathology , Facial Dermatoses/complications , Facial Dermatoses/pathology , Forearm/pathology , Herpesvirus 4, Human/isolation & purification , Humans , Hydroa Vacciniforme/complications , Hydroa Vacciniforme/pathology , In Situ Hybridization , Male , Polymerase Chain Reaction , Scalp Dermatoses/complications , Scalp Dermatoses/pathology , Thorax/pathologyABSTRACT
To clarify the frequency and cause of acute pancreatitis following hematopoietic stem cell transplantation (SCT), we examined retrospectively 57 patients who underwent hematopoietic SCT in our institute from 1984 to 2000. Twelve (21%) of the patients showed an elevated level of serum pancreatic amylase following SCT. However, only 3 patients were clinically diagnosed as having acute pancreatitis. Among these 12 patients, 11 had undergone allogeneic transplantation. Furthermore, patients who had undergone unrelated transplantation (7/16; 44%) tended to show a higher incidence of increased amylase than those who had undergone related transplantation (4/24; 17%). Six patients were at an advanced stage of acute GVHD (grade III or IV) and all showed an elevated level of serum amylase, whereas only four patients showed an elevated serum amylase level among 34 with mild acute GVHD (grade I or II) or without GVHD. Furthermore, five out of 12 patients who showed an increased amylase level were concurrently diagnosed as having viral infection such as cytomegalovirus, adenovirus, or varicella zoster virus. We conclude that pancreatitis following SCT occurs more often than realized, and is mostly subclinical. This is closely associated with severe acute GVHD, and possibly viral infection.
