βγ-CAT, a non-lens betagamma-crystallin and trefoil factor complex, is found to induce calcium-dependent platelet apoptosis, suggested the research team headed by ZHANG Yun from Kunming Institute of Zoology, Chinese Academy of Sciences (KIZ, CAS).

βγ-CAT dots the skin secretions of mammals, whose mechanism and function, however, remain unknown to scientists. The research team of KIZ blazed a trail in this regard by successfully capturing βγ-CAT from frog Bombina maxima skin secretions.

In order to explore the effect of βγ-CAT on platelets, washed platelets were incubated with various concentrations of βγ-CAT for 30 minutes. Results showed that βγ-CAT induced several apoptosis events in human platelets, including caspase-3 activation, phosphatidylserine (PS) exposure, depolarisation of mitochondrial inner transmembrane potential (ΔΨm), cytochrome c release and strong expression of pro-apoptotic Bax and Bak proteins. Besides, the βγ-CAT-induced PS exposure and ΔΨm depolarisation in platelets are Ca2+-dependent. However, βγ-CAT did not significantly induce platelet activation as detected by P-selectin surface expression, GPIIb/IIIa activation and platelet aggregation. It is, therefore, concluded that βγ-CAT can induce Ca2+-dependent platelet apoptosis but does not cause platelet activation.

These findings illustrate novel application of βγ-CAT in the treatment of inflammation, tumor as well as mucosal repair. The related paper has been published in the journal of Thrombosis and Haemostasis.