Abstract
Although we stimulate enterocytic proliferation to ameliorate short gut syndrome or mucosal atrophy, less effort has been directed at enterocytic differentiation. Schlafen 3 (Slfn3) is a poorly understood protein induced during IEC-6 enterocytic differentiation. We hypothesized that exogenous manipulation of Slfn3 would regulate enterocytic differentiation in vivo. Adenoviral vector coding for Slfn3 cDNA (Ad-GFP-Slfn3) or silencing RNA for Slfn3 (siSlfn3) was introduced intraluminally into rat intestine. We assessed Slfn3, villin, sucrase-isomaltase (SI), Dpp4, and Glut2 by qRT-PCR, Western blot, and immunohistochemistry. We also studied Slfn3 and these differentiation markers in atrophic defunctionalized jejunal mucosa and the crypt-villus axis of normal jejunum. Ad-GFP-Slfn3 but not Ad-GFP increased Slfn3, villin and Dpp4 expression in human Caco-2 intestinal epithelial cells. Injecting Ad-GFP-Slfn3 into rat jejunum in vivo increased mucosal Slfn3 mRNA three days later vs. intraluminal Ad-GFP. This Slfn3 overexpression was associated with increases in all four differentiation markers. Injecting siSlfn3 into rat jejunum in vivo substantially reduced Slfn3 and all four intestinal mucosal differentiation markers three days later, as well as Dpp4 specific activity. Endogenous Slfn3 was reduced in atrophic mucosa from a blind-end Roux-en-Y anastomosis in parallel with differentiation marker expression together with AKT and p38 signaling. Slfn3 was more highly expressed in the villi than the crypts, paralleling Glut2, SI and Dpp4. Slfn3 is a key intracellular regulator of rat enterocytic differentiation. Understanding how Slfn3 works may identify targets to promote enterocytic differentiation and maintain mucosal function in vivo, facilitating enteral nutrition and improving survival in patients with mucosal atrophy or short gut syndrome.
Highlights
The intestinal lumen is lined by a specialized simple columnar epithelium that performs the primary functions of digestion and water and nutrient absorption and forms a barrier against luminal pathogens [1]
To first validate the function of the Ad-GPF-Schlafen 3 (Slfn3) construct, we investigated whether infection of Ad-GFP-Slfn3 increases Slfn3 mRNA in Caco-2 intestinal epithelial cells
In vivo delivery of Slfn3 by adenoviral vector increases the expression of differentiation markers in rat jejunal mucosa
Summary
The intestinal lumen is lined by a specialized simple columnar epithelium that performs the primary functions of digestion and water and nutrient absorption and forms a barrier against luminal pathogens [1]. Prolonged TPN may be required for patients with short gut syndrome awaiting sufficient intestinal adaptation for completely enteral nutrition [3,4]. This can take up to 3 years, and less fortunate patients will require permanent TPN, with risks of complications and very high cost [5]. Growth hormone may enhance adaptation by promoting enterocytic proliferation, increasing the number of enterocytes available for nutrient absorption and digestion, but its clinical efficacy seems limited [4]. An alternative or complementary approach would be to promote enterocytic differentiation, increasing the potency of individual enterocytes, but little is known about how to promote enterocytic differentiation in vivo
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