Reaserch On The Rac-related Proteins Ced-10 And Rac-2 Involved In Forgetting Of C.elegans

It is well known that forgetting often brings us a lot of troubles in our daily life,for example,forgetting an acquaintance's name when we met in the street,or leaving home without the key.However,the researchers also suggest that forgetting can a lso play positive roles in animals' survival.Animals can eliminate outdated or unrelated memories,which are essential to adapt to the changing environments.In the earlier days,the researches on learning and memory usually do their investigation using the model of the hippocampus in mammals,but its anatomical and functional complexity makes it hard to understand.As a common biological model having a simpler nervous system,Caenorhabditis elegans attracts much attention because it represents a variety of neurological behaviors,including learning and memory.Using this model,it has been revealed that JNK-1 and musashi protein are involved in regulation of forgetting in C.elegans.In this paper we first select some genes related with synaptic plasticity and detect if they are involved in forgetting in C.elegans.We further explore the roles of Rac/PAK/Cofilin pathway in forgetting via RNAi,qPCR,microinjection and Western blot experiments.Additionally,we also reveal the relationship between rac-2 and jnk-1 in forgetting regulation.The main results are as follows:1.Forgetting is regulated via rac related genes ced-10 and rac-2 in C.elegans.Using the model of diacetyl(DA)associated learning,we compared the chemotaxis index toward DA between those worms without(naive)or with(conditioned)preincubation with DA.We found that ced-10 and rac-2 mutants showed longer memory retention after 2 hours than the wild type.These results suggest that ced-10 and rac-2 are involved in the regulation of forgetting in C.elegans.2.Forgetting is not regulated via Rac/PAK/Cofilin pathway.After RNAi silencing of unc-60 which encodes two issue-specific isoforms of actin depolymerizing factor(ADF)/cofilin,the worms showed similar chemotaxis index with WT.Similar results was obtained on pak-1 which function on the upstream of unc-60.We assume that forgetting is not regulated via Rac/PAK/Cofilin pathway in C.elegans.3.The JNK-1 signal pathway is involved in forgetting in C.elegans.We detected the phosphorylation level of JNK-1 of worms without(naive)or with(conditioned)preincubation with DA or after 2 hours via Western blot.It was found that the phosphorylation level of JNK-1 changed during the process of forgetting.We suspect that the JNK-1 signal pathway is involved in the short time memory and forgetting process.4.Rac-related protein Rac-2 can mediate forgetting via JNK-1.We analyzed the relative expression level of jnk-1 by RT-PCR and found that it declined in rac-2 mutant but not ced-10 mutant.We further constructed Pjnk-1::GFP fusion plasmid and transformed it into N2 and rac-2 mutant by microinjection.The fluorescence intensities of the head were compared between N2 and rac-2 mutant.The fluorescence intensities in rac-2 mutant declined compared with wild type.At last we found protein expression of ?-JNK-1 was lower in rac-2 mutant via Western blot.These results suggested rac-2 may regulate forgetting in C.elegans via down-regulating the expression level of ?-JNK-1.The innovations of our investigation are concluded as follows:1.It is firstly reported that forgetting is regulated via ced-10 and rac-2 in C.elegans.2.It is firstly revealed that rac-2 may regulate forgetting in C.elegans via down-regulating the expression level of ?-JNK-1.