Woong Choi

Molecular Physiology, Biochemistry, and Pharmacology of Alzheimer's Amyloid Precursor Protein (APP)

SUMMARY

COMPLETE NUCLEOTIDE SEQUENCE AND TISSUE-SPECIFIC EXPRESSION OF THE RAT PHENYLETHANOLAMINE N-METHYLTRANSFERASE GENE

Abstract: The rat phenylethanolamine N‐methyltransferase (PNMT) gene was isolated from a genomic library by cross‐hybridization with a bovine PNMT cDNA probe. Complete nucleotide sequence analysis of a genomic clone showed that this gene contained three exons and spanned about 2.8 kb in length. There were the acute‐phase response element, TATA, SP1, and GRE sequences. The physicochemical properties of rat adrenal PNMT were different from those of the brainstem PNMT. However, northern blot and reverse transcription‐polymerase chain reaction analysis showed that the rat PNMT gene may not express the multiple forms of mRNA. These results suggest that the rat PNMT gene might produce a single enzyme protein, whose activity may be differentially modulated by tissue‐specific environment in the central and peripheral systems.

Ultrastructural Changes in Microvessel With Age in the Hippocampus of Senescence-Accelerated Mouse (SAM)-P/10

Microvessels in the hippocampus of aged SAM-P/10 (14 months old) showed the following ultrastructural changes compared with those of young-mature controls (3 months old): (1) the majority of capillaries had lost the smooth contours typical of young cases; (2) the luminal surface of capillaries showed irregularity; (3) the endothelial cytoplasm was thicker; (4) vesicles appeared more frequently in the endothelium; (5) interendothelial tight junctions and basement membranes, however, seemed to show no significant abnormalities; (6) pericytes, especially those of arterioles and venules, contained many enlarged cytoplasmic inclusions with honeycomb-like vacuoles; (7) the area of glial perivascular end feet was greater. These morphological findings raise the possibility of impaired blood-brain barrier function and microhemodynamic disturbances in aged SAM-P/10 hippocampus.Microvessels in the hippocampus of aged SAM-P/10 (14 months old) showed the following ultrastructural changes compared with those of young-mature controls (3 months old): (1) the majority of capillaries had lost the smooth contours typical of young cases; (2) the luminal surface of capillaries showed irregularity; (3) the endothelial cytoplasm was thicker; (4) vesicles appeared more frequently in the endothelium; (5) interendothelial tight junctions and basement membranes, however, seemed to show no significant abnormalities; (6) pericytes, especially those of arterioles and venules, contained many enlarged cytoplasmic inclusions with honeycomb-like vacuoles; (7) the area of glial perivascular end feet was greater. These morphological findings raise the possibility of impaired blood-brain barrier function and microhemodynamic disturbances in aged SAM-P/10 hippocampus.

Expression of Alzheimer's amyloid precursor protein in human lymphocyte

Beta-amyloid precursor protein (betaAPP) has been shown to be involved in cell growth regulation. In spleen, the majority of cells showing betaAPP like immunoreactivity was found in the T cell-dependent zone. In Northern blot, the expression of betaAPP was increased to reach the peak at 72 h after the treatment of phytohemagglutinin (PHA). But, in cytofluorometry, almost all CD4(+) T helper/inducer cells and the majority of CD(8+) T suppressor/cytotoxic cells show betaAPP immunoreactivity which remained constant during the stimulation with PHA. These results suggest that betaAPP is a surface molecule of T lymphocyte and the turnover or release of APP might be increased with the treatment of T cell mitogen.

Age-related changes of mRNA expression of amyloid precursor protein in the brain of senescence-accelerated mouse

APP695 mRNA is only expressed in the brains of SAM. The expression of APP mRNA in SAM P1 mice brains is more marked than that in SAM R1 mice brain. APP mRNA expression was increased with advancing age in all brain regions of SAM P1 mice compared with SAM R1. Especially, the changes of the amount of APP mRNA in the prosencephalon and the mesencephalon are significant at P value of 0.05. We suggest that overexpression of APP mRNA may be related to accelerated aging phenomenon in the SAM brain. This is the first report of age-related increase in the amount of APP mRNA in the SAM brain.

Cloning and analysis of the pseudogene for human epinephrine synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT)

1. This gene completely lacks the intervening sequences. 2. This gene is truncated at the 5 end peptide encoding region by 433 base pairs (bp). 3. The 502 bp of this gene containing poly(A) signal are completely identical to the 3 half of mRNA encoding region of functional gene. 4. This gene has a poly(A) tail and is flanked by direct repeat of 6 bp. 5. Here we report for the first time the complete sequence of a human pseudogene for phenylethanolamine N-methyltransferase and this is the first report of cloning of pseudogene for catecholamine biosynthetic enzymes.