The Role Of NTR In Resistance To Heat Shock In C.elegans

Neurotensin(NT)is a 13 amino acid peptide that's isolated from the hypothalamus of bovine and mainly located in the brain/central nervous system and in the intestine.The effect of NT is mediated through the three known receptors NTR1,NTR2,and NTR3.The NT-NTR interaction plays an important role in physiological and pathological processes.In mammals,NTR1 plays an important role in processes such as cognition,sleep arousal,food intake,body weight changes,and hypothermia;the NTR2 is involved in inducing analgesia,hypothermia and other pain related parameters whereas NTR3 helps cellular migration viz,receptor internalization and participating in the growth promoting act.In addition,NTR1/3 also participates in the regulation of fat absorption.In this study,we examined the effect of nmur-3 and npr-32,which are homologous to mammalian NTR,on the physiological function of C.elegans under different environmental conditions.First,we examined the changes in fat content and lifespan of the nmur-3(VC1974)and npr-32(RB1938)mutants and found that the NTR mutations did not affect the fat content and lifespan of the C.elegans.Secondly,we examined the role of NTR in C.elegans' s innate immunity and found that the NTR mutation does not affect the infection of the nematode against the pathogenic bacteria P.aeruginosa.Finally,we examined the effect of NTR on the survival of nematodes under high salt and heat shock condition.It was found that under these two stress conditions,the survival rate of the C.elegans nmur-3(VC1974)mutant was significantly reduced,while the survival rate of the npr-32(RB1938)mutant was not affected.Therefore,nmur-3was screened out and participates in the resistance of the C.elegans to adversity.Further studies revealed that under heat shock condition,the mutation of nmur-3(VC1974)did not affect the nuclear entry of the anti-adversity transcription factor DAF-16 and the expression of the heat shock protein HSP16.2.However,mutations in nmur-3(VC1974)result in decreasing phosphorylation of protein kinase AMPK under heat shock condition.Therefore,we examined the survival rate of the aak-2 mutant strain,aak-2,which encodes the regulatory subunit of AMPK in C.elegans.Under the heat shockcondition,we found that the aak-2 mutation resulted in a decrease in the survival rate of the C.elegans.As AMPK phosphorylation levels decrease,we suspect that AMPK may be involved in the regulation of autophagy.Further investigations revealed that under heat shock condition,nmur-3 and aak-2 is silenced by RNA interference,autophagy is inhibited in seam cells.In order to further verify autophagy is involved in the heat shock response,the autophagy-associated gene bec-1 was used to detect the survival rate of C.elegans under heat shock condition,and the heat shock response corresponding to autophagy involved in this process was determined.The above results suggest that NTR regulates autophagy by mediating phosphorylation of AMPK and helps nematodes respond to heat shock.Our study provides a new way for a better understanding of the mechanism of resistance to NTR in C.elegans,this study gives us a better understanding of the mechanisms of resistance to organisms.