Regional distribution of human trypsinogen 4 in human brain at mRNA and protein level.

Gene PRSS3 on chromosome 9 of the human genome encodes, due to alternative splicing, both mesotrypsinogen and trypsinogen 4. Mesotrypsinogen has long been known as a minor component of trypsinogens expressed in human pancreas, while the mRNA for trypsinogen 4 has recently been identified in brain and other human tissues. We measured the amount of trypsinogen 4 mRNA and the quantity of the protein as well in 17 selected areas of the human brain. Our data suggest that human trypsinogen 4 is widely but unevenly distributed in the human brain. By immunohistochemistry, here we show that this protease is localized in neurons and glial cells, predominantly in astrocytes. In addition to cellular immunoreactivity, human trypsinogen 4 immunopositive dots were detected in the extracellular matrix, supporting the view that human trypsinogen 4 might be released from the cells under special conditions.