Identi®cation and Characterization of a Novel Rat Triosephosphate Isomerase Gene in Remnant Ileum After Massive Small Bowel Resection YUXUN WANG, MMed, SANDRA TAN, BSc, and SHING-CHUAN HOOI, MBBS, PhD This paper describes the identi®cation and characterization of a novel cDNA encoding a putative protein of 254 amino acids that is highly homologous to triosephosphate isomerase. The cDNA was isolated by subtractive hybridization and was differentially expressed in the remnant rat ileum after massive small bowel resection. The novel triosephosphate isomerase was named rsTPI (resection-induce d TPI) and the putative protein encoded RSTPI. The nucleotide and amino acid sequences of rsTPI and RSTPI were about 60% and 62% homologous to Giardia lamblia TPI and TPI, respectively. Active catalytic sites (Lys 13, His 95, and Glu 167) and the peptide motifs, AYEPVWSIGT and GGASLKPEF found in other triosephosphate isomerases were conserved in RSTPI. rsTPI expression was detected in normal ileum and pancreas by reverse transcription-polyme rase chain reaction. Expression of rsTPI in remnant rat ileum was detectable by northern blot analysis one week after massive small bowel resection. Expression increased signi®cantly by 2.8-fold between one and two weeks after surgery. High levels were maintained for at least one month after surgery. The up-regulation of triosephosphate isomerase expression in the remnant small intestine after massive resection indicates that it may play an important role in the adaptive process. KEY WORDS: differential expression; subtractive hybridization; intestinal adaptation; triosephosphate isomerase; small bowel resection. After massive small bowel resection, the remnant intestine undergoes compensatory morphologic and functional change s (1± 4). A rat model for studying intestinal adaptation has been well established (5). Massive small bowel resection (MSBR) provide s a potent stimulus for growth of the remnant intestine. To compensate for the loss of absorptive surface area, the remnant intestine adapts mainly by the prolifera- tion of intestinal crypt cells. In the process of adap- tation, the remnant gut epithelium becomes markedly hyperplastic and displays increased villus height and crypt depth as well as dilation and lengthening of the intestinal remnant (6). These changes offer an excel- lent model to study mechanisms involve d in growth and differentiation of the intestine (7). Moreover, the absorptive capability per unit length also increases aided by decreased gut motility (8). Although the morphological changes in the adaptive process have been well documented, the molecular mechanisms underlying intestinal adaptation are not well under- stood. Luminal nutrition, pancreatiobiliary secretion, and humoral and luminal growth factors and hor- Manuscript received March 31, 1998; revised manuscript re- ceived July 6, 1998; accepted July 16, 1998. From the Department of Physiology, Faculty of Medicine, Na- tional University of Singapore, 10 Kent Ridge Crescent, Singapore 119260. Address for reprint requests: Dr. Shing-Chuan Hooi, Depart- ment of Physiology, Faculty of Medicine, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260. Digestive Diseases and Sciences, Vol. 44, No. 1 (January 1999), pp. 25±32 25 Digestive Diseases and Sciences, Vol. 44, No. 1 (January 1999) 0163-2116/99/0100-0025$16.00/0 Ñ 1999 Plenum Publishing Corporation