Abstract
Previously we have shown that trypsin, a protein typically involved in digestion, is released from gills of both fresh and saltwater fishes into surrounding water under stress or injury. We have also shown that each species produces trypsin with different specific activities. In this report, using zebrafish as a model, we identified that trypsin induces an aversive response in zebrafish larvae and adult zebrafish. Since Protease-Activated Receptor 2 (PAR2) responds to trypsin, we tested whether the aversive response is dependent on the activation of PAR2 located on the zebrafish skin cells. Zebrafish larvae treated separately with neomycin and zinc sulfate also showed aversive response indicating neuromast, and olfactory cells are not involved in this aversion. Cultured keratinocytes from zebrafish showed a response to trypsin. Zebrafish larvae subjected to knockdown of par2a also exhibited reduced escape response. Similarly, par2a-deficient mutant larvae displayed no response to trypsin. Since it has been shown that stress activates PAR2 and sends signals to the brain as shown by the increased c-fos expression, we tested c-fos expression in adult zebrafish brains after trypsin treatment of adults and found enhanced c-fos expression by qRT-PCR. Taken together, our results show that the trypsin activates PAR2 on keratinocytes signaling the brain, and this pathway of trypsin-induced escape response will provide a unique communication mechanism in zebrafish. Furthermore, since PAR2 activation also occurs in pain/pruritus sensing, this model might be useful in elucidating components of signaling pathways in pain/pruritus.
Highlights
Trypsin is a digestive enzyme that is a serine protease and released as a zymogen from the pancreas into the duodenum and activated by enterokinase in the small intestines [1]
Since Protease-Activated Receptor 2 (PAR2) activation results in pain/itch sensing and trypsin activates PAR2, trypsin could cause itch or pain-like mechanisms
To determine whether trypsin would induce the fish to produce more trypsin, we placed a single zebrafish in the E3 medium (E3M) and exposed it to zebrafish trypsin
Summary
Trypsin is a digestive enzyme that is a serine protease and released as a zymogen from the pancreas into the duodenum and activated by enterokinase in the small intestines [1]. After 30 minutes, the same fish was placed in another cup of 15 ml of E3M containing 5 μl of 20 μM bovine trypsin. Zebrafish aversion to trypsin tank filled with 2.5 L of E3M for the adult fish trypsin repelling experiment.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
