고프롤린식이에 의한 백서 소장에서의 ACE과 DAP-IV 유도의 유전적 조절기전에 대한 연구 = The Genetic Mechanism of Rat Intestinal Angiotensin Converting Enzyme and Dipeptidyl Aminopeptidase IV Induction by High Proline Diet고프롤린식이에 의한 백서 소장에서의 ACE과 DAP-IV 유도의 유전적 조절기전에 대한 연구

다국어 초록 (Multilingual Abstract)

Background/Aims: Angiotensin converting enzyme(ACE) and Dipeptidyl aminopeptidase IV(DAP- IV) are well known brush border rnembrane enzymes which have major role in digestion of prolyl peptide(proline). Even though high proline diet is known to induce the increase of enzymatic activity of ACE and DAP-IV, the genetic mechanism of this phenomenon has not been recognized. Therefore we performed this study to clarify the genetic mechanism of ACE and DAP-IV induction by high proline diet. Methods: Total 20 Wistar rats were divided into four groups with different diets. Control group was fed with normal diet(17% protein), sucrose group was fed with high sucrose diet(68% sucrose, 18% protein), protein group was fed with high protein diet(50% casein), and gelatin group was fed with high proline diet(50% gelatin). After 3 weeks the small intestine was removed and divided into three equal length segments, from which homogenate, btesh border membrane and total RNA were prepared. ACE and DAP-IV enzyme activity were estimated in both small intestine homogenate and brush border membrane. The amounts of ACE mRNA and DAP-IV mRNA were also estimated by Northern analysis of RNA. Results: ACE activity of homgenate: There was significant increase of ACE activity in gelatin group(pC0.01) and protein group(p(0.05) throughout all sites(proximal, middle, distal). ACE activity of brush border membrane: There was significant increase of ACE activity in distal site(p0.01) of gelatin group and in middle(p0.05) and distal site(p0.05) of protein group. DAP-IV activity of homogenate: There was significant increase of DAP-IV activity in middle(p<0.01) and distal(p(0.05) site of gelatin group. DAP-IV activity of brush border membrane: There was significant increase of DAP-IV activity in gelatin group(p(0.01) and protein group(pC0.01) throughout all sites. ACE mRNA amount: Gelatin group showed increase of ACE mRNA in proximal site(p C0.05) and total mean value(p0.05). Protein group also showed increase of ACE rnRNA in proximal(pC0.05)), middle(pa0.05) and total mean value(p0.05). DAP-IV mRNA amount: There was no statistically significant change in gelatin and protein group. Conclusions: 1) High proline diet induced the increase of enzymatic activity of ACE and DAP-IV. 2) Increase of ACE activity was associated with increase of ACE mRNA in small intestine. 3) Increase of DAP-IV activity was not correlated with DAP-IV mRNA. These results suggested that the induction of increased ACE activity by high proline diet is regulated on transcriptional level and the induction of increased DAP-IV activity may be regualted on posttranscriptional level (translational and/or posttranslational level). In conclusion, the induction of increased enzyme activity of brush border membrane by specific diet may be regulated on both transcriptional level and posttranscriptional level. (Korean J Gastroenterol 1996; 28:349 - 361)