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05
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2012
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Guanylin and functional coupling proteins in the hepatobiliary system of rat and guinea pig. |
Guanylin, a bioactive intestinal peptide, is involved in the cystic fibrosis transmembrane conductance (CFTR)-regulated electrolyte/water secretion in various epithelia. In the present work we report on the expression and cellular localization of guanylin and its affiliated signaling and effector proteins, including guanylate cyclase C (Gucy2c), Proteinkinase GII (Pkrg2), CFTR and the solute carrier family 4, anion exchanger, member 2 (Slc4a2) in the hepatobiliary system of rat and guinea pig. Localization studies in the liver and the gallbladder revealed that guanylin is located in the secretory epithelial cells of bile ducts of the liver and of the gallbladder, while Gucy2c, Pkrg2, CFTR, and Slc4a2 are confined exclusively to the apical membrane of the same epithelial cells. Based on these findings, we assume that guanylin is synthesized as an intrinsic peptide in epithelial cells of the hepatobiliary system and released luminally into the hepatic and cystic bile to regulate electrolyte secretion by a paracrine/luminocrine signaling pathway. |
HISTOCHEMISTRY and CELL BIOLOGY |
Schwabe K, Cetin Y. |
Fachzeitschrift |
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04
.
2010
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The AF4.MLL fusion protein is capable of inducing ALL in mice without requirement of MLL.AF4. |
The chromosomal translocation t(4;11)(q21;q23) is the most frequent genetic aberration of the human MLL gene, resulting in high-risk acute lymphoblastic leukemia (ALL). To elucidate the leukemogenic potential of the fusion proteins MLL.AF4 and AF4.MLL, Lin(-)/Sca1(+) purified cells (LSPCs) were retrovirally transduced with either both fusion genes or with MLL.AF4 or AF4.MLL alone. Recipients of AF4.MLL- or double-transduced LSPCs developed pro-B ALL, B/T biphenotypic acute leukemia, or mixed lineage leukemia. Transplantation of MLL.AF4- or mock-transduced LSPCs did not result in disease development during an observation period of 13 months. These findings indicate that the expression of the AF4.MLL fusion protein is capable of inducing acute lymphoblastic leukemia even in the absence of the MLL.AF4 fusion protein. In view of recent findings, these results may imply that t(4;11) leukemia is based on 2 oncoproteins, providing an explanation for the very early onset of disease in humans. |
BLOOD |
Bursen A, Schwabe K, Rüster B, Henschler R, Ruthardt M, Dingermann T, Marschalek R. |
Fachzeitschrift |
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