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Fat feeding stimulates only one of the two mRNAs encoding rat intestinal membranous and secreted alkaline phosphatase
Abstract:
We have identified two mRNAs in rat intestinal mucosa by Northern blot analysis, using cloned cDNAs encoding human placental alkaline phosphatase (PLAP). Probes from both the NH2- and COOH-terminal ends of the human PLAP coding region identified, in rat intestine (especially duodenum), an mRNA of nearly identical size (3 kb) to that found in human placenta. A smaller mRNA (2.7 kb), detected only with the COOH-terminal probe, was more prevalent in jejunum. Following feeding of triacylglycerols, the prevalence of the 2.7 kb mRNA increased over 2-fold. The tissue distribution and response of the 2.7 kb mRNA to fat feeding corresponds exactly with the known behavior of the secreted alkaline phosphatase.
Insights
Researchers identified two messenger RNA (mRNA) types in rat intestines using human placental alkaline phosphatase (PLAP) probes. A specific 2.7 kb mRNA increased after fat consumption, mirroring secreted alkaline phosphatase activity.
Area of Science:
- Molecular Biology
- Gastroenterology
- Biochemistry
Background:
- Alkaline phosphatase (AP) is crucial in various physiological processes.
- Human placental alkaline phosphatase (PLAP) is a well-characterized isoenzyme.
- Understanding AP gene expression in different tissues is vital for physiological research.
Purpose of the Study:
- To identify and characterize mRNAs encoding alkaline phosphatase in rat intestinal mucosa.
- To investigate the tissue distribution and regulation of these mRNAs.
- To correlate mRNA expression with secreted alkaline phosphatase activity.
Main Methods:
- Northern blot analysis was employed to detect and size mRNAs.
- Cloned cDNAs encoding human placental alkaline phosphatase (PLAP) were used as probes.
- Rat intestinal tissues (duodenum and jejunum) were analyzed before and after triacylglycerol feeding.
Main Results:
- Two distinct mRNA species (3 kb and 2.7 kb) related to PLAP were identified in rat intestine.
- The 3 kb mRNA was found in duodenum, similar to human placenta.
- The 2.7 kb mRNA, prevalent in jejunum, showed a significant increase (over 2-fold) after fat feeding.
Conclusions:
- Rat intestinal mucosa expresses at least two AP-related mRNA transcripts.
- The 2.7 kb mRNA's tissue distribution and response to dietary fat align with secreted alkaline phosphatase.
- This suggests the 2.7 kb mRNA may encode the secreted form of alkaline phosphatase in the rat intestine.