scholarly journals Thyroid Hormone Positively Regulates the Enterocyte Differentiation Marker Intestinal Alkaline Phosphatase Gene via an Atypical Response Element

2004 ◽  
Vol 18 (8) ◽  
pp. 1941-1962 ◽  
Author(s):  
Madhu S. Malo ◽  
Wenying Zhang ◽  
Fuad Alkhoury ◽  
Premraj Pushpakaran ◽  
Mario A. Abedrapo ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Thyroid Hormone ◽  
Intestinal Alkaline Phosphatase ◽  
Response Element ◽  
Differentiation Marker ◽  
Enterocyte Differentiation

Enterocyte differentiation marker intestinal alkaline phosphatase is a target gene of the gut-enriched Krüppel-like factor

2004 ◽  
Vol 286 (1) ◽  
pp. G23-G30 ◽  
Author(s):  
Brian F. Hinnebusch ◽  
Aleem Siddique ◽  
J. Welles Henderson ◽  
Madhu S. Malo ◽  
Wenying Zhang ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Interactions ◽  
Target Gene ◽  
Marker Gene ◽  
Luciferase Reporter ◽  
Intestinal Alkaline Phosphatase ◽  
Human Colon Cancer ◽  
Cis Element ◽  
Differentiation Marker ◽  
Enterocyte Differentiation

We have examined the role that the transcription factor gut-enriched Krüppel-like factor (KLF4 or GKLF) plays in activating the enterocyte differentiation marker gene intestinal alkaline phosphatase (IAP). A yeast one-hybrid screen was used to identify proteins interacting with a previously identified cis-element (IF-III) located within the human IAP gene promoter. DNA-protein interactions were determined by using EMSA. Northern blot analysis was used to study RNA expression in human colon cancer RKO cells engineered to overexpress KLF4. Transient transfections with IAP-luciferase reporter constructs were used to characterize the mechanisms by which KLF4 activates IAP transcription. The yeast one-hybrid screen and EMSA identified KLF4 as binding to IF-III. RKO cells induced to overexpress KLF4 demonstrated a corresponding dose-dependent increase in IAP expression, and EMSA with nuclear extract from these cells confirmed that KLF4 binds to the IF-III element. Transient transfections revealed that KLF4 transactivated the IAP gene largely via a critical segment in the IAP promoter that includes the IF-III cis-element. Mutant KLF4 constructs failed to fully activate IAP. We have identified the enterocyte differentiation marker IAP as a KLF4 target gene. IAP transactivation by KLF4 is likely mediated through a critical region located within the proximal IAP promoter region.

Thyroid hormone positively regulates an enterocyte differentiation marker gene through an atypical response element

2003 ◽  
Vol 124 (4) ◽  
pp. A87
Author(s):  
Madhu S. Malo ◽  
Wenying Zhang ◽  
Mario A. Abedrapo ◽  
Joseph W. Henderson ◽  
Aleem Siddique ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Marker Gene ◽  
Response Element ◽  
Differentiation Marker ◽  
Enterocyte Differentiation

Intestinal alkaline phosphatase gene expression is activated by ZBP-89

2006 ◽  
Vol 290 (4) ◽  
pp. G737-G746 ◽  
Author(s):  
Madhu S. Malo ◽  
Moushumi Mozumder ◽  
Xiao Bo Zhang ◽  
Shaluk Biswas ◽  
Alexander Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alkaline Phosphatase ◽  
Transcription Factor ◽  
Fat Absorption ◽  
Rt Pcr ◽  
Intestinal Alkaline Phosphatase ◽  
Reporter Assays ◽  
Differentiation Marker ◽  
Ht 29 ◽  
Enterocyte Differentiation

Intestinal alkaline phosphatase (IAP) is an enterocyte differentiation marker that functions to limit fat absorption. Zinc finger binding protein-89 (ZBP-89) is a Kruppel-type transcription factor that appears to promote a differentiated phenotype in the intestinal epithelium. The purpose of this study was to investigate the regulation of IAP gene expression by ZBP-89. RT-PCR, quantitative real-time RT-PCR, Western blot analyses, and reporter assays were used to determine the regulation of IAP by ZBP-89 in HT-29 and Caco-2 colon cancer cells. ZBP-89 knockdown was achieved by specific short interfering (si)RNA. EMSA and chromatin immunoprecipitation (ChIP) were performed to examine the binding of ZBP-89 to the IAP promoter. The results of RT-PCR, quantitative real-time PCR, and Western blot analyses showed that ZBP-89 was expressed at low levels in Caco-2 and HT-29 cells, whereas IAP was minimally expressed and absent in these cells, respectively. Transfection with ZBP-89 expression plamid increased IAP mRNA and protein levels in both cell lines, whereas knockdown of endogenous ZBP-89 by siRNA reduced basal levels of IAP gene expression in Caco-2 cells. IAP-luciferase reporter assays, EMSA, and ChIP established that ZBP-89 activated the IAP gene through a response element (ZBP-89 response element: 5′-CCTCCTCCC-3′) located between −1018 and −1010 bp upstream of the AUG start codon. We conclude that ZBP-89 is a direct transcriptional activator of the enterocyte differentiation marker IAP. These findings are consistent with the role that this transcription factor is thought to play as a tumor suppressor and suggests its possible function in the physiology of fat absorption.

Differential regulation of intestinal alkaline phosphatase gene expression by Cdx1 and Cdx2

2005 ◽  
Vol 289 (2) ◽  
pp. G285-G290 ◽  
Author(s):  
Fuad Alkhoury ◽  
Madhu S. Malo ◽  
Moushumi Mozumder ◽  
Golam Mostafa ◽  
Richard A. Hodin
Keyword(s):  
Alkaline Phosphatase ◽  
Transcription Factors ◽  
Mrna Expression ◽  
Marker Gene ◽  
Human Colon ◽  
Luciferase Reporter ◽  
Intestinal Alkaline Phosphatase ◽  
Human Colon Cancer ◽  
Response Element ◽  
Cis Element

We have examined the role that the caudal-related homeobox transcription factors Cdx1 and Cdx2 play in activating the enterocyte differentiation marker gene intestinal alkaline phosphatase ( IAP). Human colon cancer Caco-2 cells were transiently transfected with Cdx1 and/or Cdx2, and semiquantitative RT-PCR was used to study the effects on IAP mRNA expression. Transfections with a variety of IAP-luciferase reporter constructs were used to identify a Cdx response element located within the human IAP gene promoter. Protein-DNA interactions were examined by EMSA. Results showed that Cdx1 markedly induced IAP mRNA expression, whereas Cdx2 did not, and, in fact, inhibited the Cdx1 effects. Functional analysis revealed that Cdx1 transactivates (fourfold, P < 0.05) the IAP promoter through a novel Cdx response element (GTTTAGA) located between −2369 and −2375 upstream of the translational start site. EMSA showed that both Cdx1 and Cdx2 could bind to the cis element, but in cotransfection experiments, Cdx2 inhibited the Cdx1 effects by ∼50%. Thus we have identified a previously unrecognized interaction between two important gut transcription factors, Cdx1 and Cdx2, in the context of IAP gene regulation. Cdx1 activates the IAP gene via a novel cis element, whereas Cdx2 inhibits the Cdx1 effects.

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