Studies On Biological Regulation Function Of Non-receptor Tyrosine Kinase C-Abl For Apoptosis-inducing Factor AIF

The non-receptor tyrosine kinase c-Abl in mammalian is the homeotic gene of v-abl which is proto-oncogene of Abelson in murine leukemia virus; it belongs to the family members of the Abl, and can be widely expressed in mammalian cells. It can shuttle between nucleus and cytoplasm via its nuclear export signal(NES) and nuclear localization sequence (NLS) structure domain, and could be located in different sub-cellular structures. The functions of c-Abl in cytoplasm are mainly inhibiting apoptosis, promoting cell proliferation and inducing cell transformation and the formation of tumor. The c-Abl in nucleu is activated in response to a series of physiological and drug stimulation, and is closely related to apoptosis.AIF (Apoptosis-inducing factor) is conservative flavoprotein of mitochondrial which is encoded by 16 exons. The N terminal of AIF protein contains mitochondrial localization sequence MLS, while C terminal contains oxidoreductase domain which is namely bonding domain of FAD and NAD that contains two nuclear localization sequences NLS. AIF protein carries out shuttling between the mitochondria and the nucleus, which relies on the mitochondrial localization sequence (MLS) and nuclear localization sequence (NLS). Under normal physiological conditions, AIF exists between inside and outside mitochondrial membrane, and carries out oxidoreductase function via its FAD binding of N terminal and redox activity, and also plays an important role in maintaining the normal existence of mitochondria. Under the stimulation of apoptosis signal, AIF hydrolyses out 50 amino acids on N terminal, which are released from the mitochondria into the nucleus; and this would lead to chromatin condensation, and induce cells to carry out apoptosis which is not dependent on "caspase" pathway.c-Abl and AIF can get access to the cell nucleus through the NLS, being concerned with different physiological functions in cells. In this study, the interaction of these two proteins in the cell was detected using immunoblotting and Duolink. c-Abl could phosphorylate AIF in cells, and this reveals that AIF may be a potential kinase substrate of c-Abl. c-Abl and AIF together participate in the physiological activity of cells probably through the interaction between the two, and it was further confirmed through ROS stimulation that interaction between the two exactly exist. By immunofluorescence, this study further discovers that with the inhibition of activity of c-Abl kinase by STI571, apoptosis inducing factor AIF protein conglomerates, and is released from the mitochondria. Under the condition that c-Abl kinase activity is inhibited, the activity of mitochondria in the cells is also affected. The results from Western blotting show that c-Abl kinase whose activity is inhibited, could not induce cells to apoptosis, but could promote the apoptosis induced by STS.The change of Apoptosis inducing factor AIF and mitochondrial in the cells under the condition that c-Abl is inhibited was found by this study for the first time. And this article also has confirmed that the interaction between c-Abl and AIF is that c-Abl affects the activity of mitochondria via impacting the activity of AIF. This study provides a new basis for the further exploration of the effect of Abl tyrosine kinase family on apoptosis inducing factor AIF.