Transcription factor Creb3l1 regulates the synthesis of prohormone convertase enzyme PC1/3 in endocrine cells

The homeodomain transcription factor NKX2.2 is necessary for neuroendocrine (NE) differentiation in the central nervous system and pancreas. NE tumors derived from the gut are defined by their NE phenotype, which is used for diagnosis and contributes to tumorigenicity. We hypothesized that NKX2.2 is important for NE differentiation in normal and neoplastic gut. NKX2.2 and NE marker expression was investigated in the small intestine of embryonic and adult mice using immunofluorescence (IF). To determine the role of NKX2.2 in NE differentiation of the intestine, the phenotype of Nkx2.2 (−/−) mice was examined by IF and real-time (RT)-PCR. NKX2.2 and NE marker expression in human NE tumors of the gut and normal tissues were evaluated by immunohistochemistry and qRT-PCR. NKX2.2 expression was detected in the intervillus/crypt regions of embryonic and adult mouse intestine. Co-expression of Nkx2.2 with neurogenin3 (NEUROG3) and hormones was observed in the adult intestinal crypt compartment, suggesting NKX2.2 functions in NEUROG3-positive endocrine progenitors and newly differentiated endocrine cells. In the intestine of Nkx2.2 (−/−) mice, we found a dramatic reduction in the number of cells producing numerous hormones, such as serotonin, gastrin, cholecystokinin, somatostatin, glucagon-like peptide 1 (GLP-1), and secretin, but an increase in cells producing ghrelin. NKX2.2 was expressed in most (24 of 29) human NE tumors derived from diverse primary sites. We conclude NKX2.2 functions in immature endocrine cells to control NE differentiation in normal intestine and is expressed in most NE tumors of the gut, and is therefore a novel target of diagnosis for patients with gastrointestinal NE tumors.

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Aquaporin 1 Is Important for Maintaining Secretory Granule Biogenesis in Endocrine Cells

Molecular Endocrinology ◽

10.1210/me.2007-0434 ◽

2008 ◽

Vol 22 (8) ◽

pp. 1924-1934 ◽

Cited By ~ 22

Author(s):

Irina Arnaoutova ◽

Niamh X. Cawley ◽

Nimesh Patel ◽

Taeyoon Kim ◽

Trushar Rathod ◽

...

Keyword(s):

Secretory Granule ◽

Endocrine Cells ◽

Cell Function ◽

Hormone Secretion ◽

Prohormone Convertase ◽

Protein Levels ◽

Prohormone Convertase 1 ◽

Aqp1 Expression ◽

Low Levels ◽

Made In

Abstract Aquaporins (AQPs), a family of water channels expressed in epithelial cells, function to transport water in a bidirectional manner to facilitate transepithelial fluid absorption and secretion. Additionally, AQP1 and AQP5 are found in pancreatic zymogen granules and synaptic vesicles and are involved in vesicle swelling and exocytosis in exocrine cells and neurons. Here, we show AQP1 is in dense-core secretory granule (DCSG) membranes of endocrine tissue: pituitary and adrenal medulla. The need for AQP1 in endocrine cell function was examined by stable transfection of AQP1 antisense RNA into AtT20 cells, a pituitary cell line, to down-regulate AQP1 expression. These AQP1-deficient cells showed more than 60% depletion of DCSGs and significantly decreased DCSG protein levels, including proopiomelanocotin/pro-ATCH and prohormone convertase 1/3, but not non-DCSG proteins. Pulse-chase studies revealed that whereas DCSG protein synthesis was unaffected, approximately 50% of the newly synthesized proopiomelanocortin was degraded within 1 h. Low levels of ACTH were released upon stimulation, indicating that the small number of DCSGs that were made in the presence of the residual AQP1 were functionally competent for exocytosis. Analysis of anterior pituitaries from AQP1 knockout mice showed reduced prohormone convertase 1/3, carboxypeptidase E, and ACTH levels compared to wild-type mice demonstrating that our results observed in AtT20 cells can be extended to the animal model. Thus, AQP1 is important for maintaining DCSG biogenesis and normal levels of hormone secretion in pituitary endocrine cells.

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Expression pattern of IAPP and prohormone convertase 1/3 reveals a distinctive set of endocrine cells in the embryonic pancreas

Mechanisms of Development ◽

10.1016/s0925-4773(02)00118-1 ◽

2002 ◽

Vol 115 (1-2) ◽

pp. 171-176 ◽

Cited By ~ 70

Author(s):

Maria E. Wilson ◽

Julie A. Kalamaras ◽

Michael S. German

Keyword(s):

Expression Pattern ◽

Endocrine Cells ◽

Prohormone Convertase ◽

Embryonic Pancreas ◽

Prohormone Convertase 1

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Transcription Factor Hepatocyte Nuclear Factor 6 Regulates Pancreatic Endocrine Cell Differentiation and Controls Expression of the Proendocrine Gene ngn3

Molecular and Cellular Biology ◽

10.1128/mcb.20.12.4445-4454.2000 ◽

2000 ◽

Vol 20 (12) ◽

pp. 4445-4454 ◽

Cited By ~ 238

Author(s):

Patrick Jacquemin ◽

Serge M. Durviaux ◽

Jan Jensen ◽

Catherine Godfraind ◽

Gerard Gradwohl ◽

...

Keyword(s):

Transcription Factor ◽

Cell Differentiation ◽

Endocrine Cell ◽

Endocrine Cells ◽

Glucose Transporter ◽

Nuclear Factor ◽

Hepatocyte Nuclear Factor ◽

Mouse Development ◽

Endocrine Differentiation ◽

Glucose Transporter 2

ABSTRACT Hepatocyte nuclear factor 6 (HNF-6) is the prototype of a new class of cut homeodomain transcription factors. During mouse development, HNF-6 is expressed in the epithelial cells that are precursors of the exocrine and endocrine pancreatic cells. We have investigated the role of HNF-6 in pancreas differentiation by inactivating its gene in the mouse. In hnf6 −/− embryos, the exocrine pancreas appeared to be normal but endocrine cell differentiation was impaired. The expression of neurogenin 3 (Ngn-3), a transcription factor that is essential for determination of endocrine cell precursors, was almost abolished. Consistent with this, we demonstrated that HNF-6 binds to and stimulates the ngn3 gene promoter. At birth, only a few endocrine cells were found and the islets of Langerhans were missing. Later, the number of endocrine cells increased and islets appeared. However, the architecture of the islets was perturbed, and their β cells were deficient in glucose transporter 2 expression. Adult hnf6 −/− mice were diabetic. Taken together, our data demonstrate that HNF-6 controls pancreatic endocrine differentiation at the precursor stage and identify HNF-6 as the first positive regulator of the proendocrine gene ngn3in the pancreas. They also suggest that HNF-6 is a candidate gene for diabetes mellitus in humans.

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Regulation of human prohormone convertase 2 promoter activity by the transcription factor EGR-1

Biochemical Journal ◽

10.1042/bj3280069 ◽

1997 ◽

Vol 328 (1) ◽

pp. 69-74 ◽

Cited By ~ 22

Author(s):

Erik JANSEN ◽

A. Y. Torik AYOUBI ◽

M. P. Sandra MEULEMANS ◽

Wim J. M. VAN DE VEN

Keyword(s):

Transcription Factor ◽

Promoter Region ◽

Promoter Activity ◽

Secretory Pathway ◽

Tata Box ◽

Proximal Promoter ◽

Prohormone Convertase ◽

Specific Expression ◽

Proximal Promoter Region ◽

Prohormone Convertase 2

Prohormone convertases are involved in the tissue-specific endoproteolytic processing of prohormones and neuropeptide precursors within the secretory pathway. In the present study, we have isolated genomic clones comprising the 5ʹ-terminal region of the human prohormone convertase 2 (PC2) gene and established characteristics of the PC2 promoter region. The proximal promoter region is very G+C-rich and does not contain a canonical TATA box or a CAAT box. Transient expression assays with a set of human PC2 gene fragments containing progressive 5ʹ deletions demonstrate that the proximal promoter region is capable of directing high levels of neuroendocrine-specific expression of reporter gene constructs. In addition, we show that the transcription factor EGR-1 interacts with two distinct elements within the proximal human PC2 promoter region. Transfection experiments also demonstrate that EGR-1 is able to enhance PC2 promoter activity.

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Lipid malabsorption from altered hormonal signaling changes early gut microbial responses

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00135.2018 ◽

2018 ◽

Vol 315 (4) ◽

pp. G580-G591 ◽

Cited By ~ 2

Author(s):

Natalie A. Terry ◽

Lucie V. Ngaba ◽

Benjamin J. Wilkins ◽

Danielle Pi ◽

Nishi Gheewala ◽

...

Keyword(s):

Transcription Factor ◽

Antimicrobial Peptides ◽

Endocrine Cells ◽

Ex Vivo ◽

Paneth Cell ◽

Culture Conditions ◽

Specific Gene ◽

Intestinal Hormones ◽

Sterile Culture ◽

Intestinal Endocrine Cells

Infants with congenital diarrheal disorders caused by enteroendocrine cell dysgenesis, or the loss of intestinal endocrine cells, causes severe malabsorptive diarrhea, though the mechanism is not fully understood. The transcription factor “aristaless-related homeobox” (Arx) is specifically expressed in intestinal endocrine cells. This study seeks to characterize the early malabsorptive phenotype of mice deficient for Arx using cell-type specific gene ablation in Villin-Cre; ArxloxP/Y ( Arxint) mice. In neonatal mice, the loss of intestinal Arx caused the loss of intestinal hormones, such as cholecystokinin, secretin, neurotensin, glucose-dependent insulinotropic peptide, glucagon-like peptide (GLP)-1 and GLP-2 but also upregulation of somatostatin. Arxint mice exhibited steatorrhea with the loss of lipid transport in duodenal enterocytes, upregulation of lysozyme-positive Paneth cells, and a secondary increase in antimicrobial peptides, specifically Reg3β. When the epithelium from Arxint mice was cultured ex vivo into enteroids, however, the Reg3β upregulation was lost under the sterile conditions. Thus, Arx is required for the appropriate lineage allocation of multiple enteroendocrine subtypes. We concluded that altered hormonal signaling caused by Arx deficiency results in lipid malabsorption, premature Paneth cell differentiation, and an inflammatory response, including neutrophilic infiltrates and a microbiota-triggered upregulation of Reg3β. NEW & NOTEWORTHY The enteroendocrine transcription factor aristaless-related homeobox (Arx) plays a key role in lineage specification. Changes in hormonal expression mediated by Arx lead to lipid malabsorption and premature Paneth cell development. Furthermore, global profiling of whole intestine from Arx-deficient mice revealed significant upregulation of antimicrobial peptides. This antimicrobial response in Arx-deficient animals is lost under sterile culture conditions of enteroids.

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