We have identified an important adaptive response that occurs in the mammalian gut in the setting of starvation and disease, silencing of the enterocyte differentiation marker gene, intestinal alkaline phosphatase (IAP). Based upon its functions in regard to dietary fat absorption and cellular resistance to toxins (such as LPS) and microbes, the silencing of IAP expression likely has important physiological consequences for the host. As such, the broad aims of this proposal are to delineate the mechanisms that govern IAP gene regulation. Ultimately, we hope to identify therapeutic targets that could be used in the clinical setting to treat patients in the context of starvation and other gut-related conditions. The three specific aims of this proposal represent complementary and distinct approaches to understanding enterocyte differentiation in both normal and pathologic conditions.
Aim#1 is based upon our observation that ectopically expressed IAP leads to a remarkable change in enterocyte phenotype, characterized by resistance to LPS and Salmonella. Accordingly, we will examine three transcription factor pathways that activate IAP expression (KLF4, Cdx1, and ZBP-89). Each of these factors will be expressed within intestinal epithelial cells in vitro in order to determine whether they result in altered host cell function in regard to LPS and Salmonella.
In Aim #2 we will dissect a single transcriptional pathway using a well-established inducible cell culture system. Chromatin Immuno-precipitation (ChIP) will be used to define the precise changes in chromatin structure that occur when an individual transcription factor (KLF4) binds and activates a specific target gene (IAP). We will examine the secondary modifications that occur in the histone proteins in response to KLF4 binding, the role of associated proteins, and also determine those changes that occur as the IAP gene is turned off.
In Aim #3 we will focus on the enterocyte adaptation that occurs in response to diseases and stress. We will use both in vitro and in vivo model systems to examine the molecular mechanisms that govern IAP gene repression in the contexts of starvation and inflammation. Taken together, these studies will have important implications for our understanding of normal intestinal physiology, as well as the gut response to disease states.
| Malo, Madhu S; Moaven, Omeed; Muhammad, Nur et al. (2014) Intestinal alkaline phosphatase promotes gut bacterial growth by reducing the concentration of luminal nucleotide triphosphates. Am J Physiol Gastrointest Liver Physiol 306:G826-38 |
| Alam, Sayeda Nasrin; Yammine, Halim; Moaven, Omeed et al. (2014) Intestinal alkaline phosphatase prevents antibiotic-induced susceptibility to enteric pathogens. Ann Surg 259:715-22 |
| Moss, Angela K; Hamarneh, Sulaiman R; Mohamed, Mussa M Rafat et al. (2013) Intestinal alkaline phosphatase inhibits the proinflammatory nucleotide uridine diphosphate. Am J Physiol Gastrointest Liver Physiol 304:G597-604 |
| Kaliannan, Kanakaraju; Hamarneh, Sulaiman R; Economopoulos, Konstantinos P et al. (2013) Intestinal alkaline phosphatase prevents metabolic syndrome in mice. Proc Natl Acad Sci U S A 110:7003-8 |
| Nucera, Carmelo; Nehs, Matthew A; Nagarkatti, Sushruta S et al. (2011) Targeting BRAFV600E with PLX4720 displays potent antimigratory and anti-invasive activity in preclinical models of human thyroid cancer. Oncologist 16:296-309 |
| Ramasamy, Sundaram; Nguyen, Deanna D; Eston, Michelle A et al. (2011) Intestinal alkaline phosphatase has beneficial effects in mouse models of chronic colitis. Inflamm Bowel Dis 17:532-42 |
| Chen, Kathryn T; Malo, Madhu S; Beasley-Topliffe, Laura Kline et al. (2011) A role for intestinal alkaline phosphatase in the maintenance of local gut immunity. Dig Dis Sci 56:1020-7 |
| Ebrahimi, Farzad; Malo, Madhu S; Alam, Sayeda Nasrin et al. (2011) Local peritoneal irrigation with intestinal alkaline phosphatase is protective against peritonitis in mice. J Gastrointest Surg 15:860-9 |
| Chen, Kathryn T; Malo, Madhu S; Moss, Angela K et al. (2010) Identification of specific targets for the gut mucosal defense factor intestinal alkaline phosphatase. Am J Physiol Gastrointest Liver Physiol 299:G467-75 |
| Malo, M S; Alam, S Nasrin; Mostafa, G et al. (2010) Intestinal alkaline phosphatase preserves the normal homeostasis of gut microbiota. Gut 59:1476-84 |
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