title: Selective expression of Huntingtin-associated protein 1 in {beta}-cells of the rat pancreatic islets.
abstract: Huntingtin-associated protein-1 (HAP1) was initially identified as a binding partner of huntingtin, the Huntington's disease protein. Based on its preferred distribution among neurons and endocrine cells, HAP1 has been suggested to play roles in vesicular transportation in neurons and hormonal secretion of endocrine cells. Given that HAP1 is selectively expressed in the islets of rat pancreas, in this study, we analyzed the expression pattern of HAP1 in the islets. In rats injected intraperitoneally with streptozotocin, which can selectively destroy beta-cells of the pancreatic islets, the number of HAP1 immunoreactive cells was dramatically decreased and was accompanied by a parallel decrease in the number of insulin-immunoreactive cells. Immunofluorescent double staining of pancreas sections showed that, in rat islets, HAP1 is selectively expressed in the insulin-immunoreactive beta-cells but not in the glucagon-immunoreactive alpha-cells and somatostatin immunoreactive delta-cells. In isolated rat pancreatic islets, approximately 80% of cells expressed both HAP1 and insulin. Expression of HAP1 in the INS-1 rat insulinoma cell line was also demonstrated by immunofluorescent staining. Western blotting further revealed that HAP1 in both the isolated rat pancreatic islets and the INS-1 cells also has two isoforms, HAP1A and HAP1B, which are the same as those in the hypothalamus. These results demonstrated that HAP1 is selectively expressed in beta-cells of rat pancreatic islets, suggesting the involvement of HAP1 in the regulation of cellular trafficking and secretion of insulin.
authors.affiliation: Department of Anatomy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P. R. of China.
authors.forename: Min
authors.initials: M
authors.lastname: Liao
authors.forename: Xingxing
authors.initials: X
authors.lastname: Chen
authors.forename: Jinhong
authors.initials: J
authors.lastname: Han
authors.forename: Shiming
authors.initials: S
authors.lastname: Yang
authors.forename: Ting
authors.initials: T
authors.lastname: Peng
authors.forename: He
authors.initials: H
authors.lastname: Li
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005455:Fluorescent Antibody Technique; D050416:Glucagon-Secreting Cells / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007340:Insulinoma; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D010190:Pancreatic Neoplasms; D020033:Protein Isoforms / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D019864:Somatostatin-Secreting Cells / Q000378:metabolism
chemical_list: C490757:Hap1 protein, rat; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms