Background The Schlafen (Slfn) family proteins are important for regulation of cell growth, cell differentiation and cell cycle progression. We sought to distinguish Slfn family expression in Slfn3 knockout (KO) mice after RNA sequencing analysis of Slfn3KO vs. wildtype (WT) mice revealed varying expressions of Slfn family in ileal mucosa. Methods Quantitative PCR analysis of Slfn members was evaluated in ileal mucosa, thymus and spleen tissue since Slfn family members have roles in differentiating intestinal and immune cells. Results Ileal mucosa of Slfn3KO mice displayed a decrease in Slfn3, 4, 8 and 9 while Slfn1 and 5 increased in mRNA expression vs. WT mice. Thymic tissue had a Slfn9 increase and a Slfn4 decrease while splenic tissue had a Slfn8 and Slfn9 increase in Slfn3KO mice vs. WT mice. These differential expressions of Slfn members could indicate a feedback regulatory mechanism within the Slfn family. Indeed, MATCH™ tool from geneXplain predicted that all Slfn members have regions in their promoters for the Kruppel-like factor-6 transcription factor. In addition, NFAT related factors, ING4, ZNF333 and KLF4 are also predicted to bind in up to 6 of the 8 Slfn promoters. This study further describes a possible autoregulatory mechanism amongst the Slfn family members which could be important in how they regulate the differentiation of various cell types.

Bowel resection accelerates enterocyte proliferation in the remaining gut that may have suboptimal absorptive and digestive capacity because of proliferation-associated decrease in functional differentiation markers. We hypothesized that although Slfn3 is an important regulator of murine enterocytic differentiation, Slfn3 would have less impact on the bowel resection adaptation where accelerated proliferation takes priority over differentiation. We assessed proliferation, cell shedding, and enterocyte differentiation markers of mucosa from resected and postoperative bowel of wild type (WT) and Slfn3 knockout (Slfn3KO) mice. Villus length and crypt depth were increased in WT mice and was even longer in Slfn3KO mice, while female Slfn3KO mice displayed even deeper crypts than both WT sexes after resection. Mitotic marker, Phh3+, and proliferation marker expression of Lgr5, FoxL1, and PDGFRα were increased after resection in male WT but this effect was blunted in male Slfn3KO mice. Cell shedding regulators Villin1 and TNFα were downregulated in female mice and male WT mice only, while Gelsolin and EGFR increased expression in all mice. Slfn3 expression increased after resection in WT mice but differentiation markers sucrase isomaltase, Dpp4, Glut2, and SGLT1 were all decreased. This suggests that enterocytic differentiation effort is incompatible with a rapid proliferation shift in intestinal adaptation. Slfn3 absence potentiates villus length and crypt depth, suggesting that the differentiating stimulus of Slfn3 signaling may restrain mucosal mass increase through regulating Villin1, Gelsolin, EGFR, TNFα, and proliferation markers. Slfn3 may therefore be an important regulator not only of "normal" enterocytic differentiation but also the response to bowel resection.

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