Mechanism Of The Interaction Between HIF-1α And PVHL:the Signaling Pathway Of Improvement In Aerobic Capacity By Hypoxic Training

Objective: Altitude or hypoxic training(hereinafter referred as hypoxic training)is the use of "hypoxia" and training load dual stimulation to cause physiological adaptation of the body,thereby improving the body’s aerobic capacity.Hypoxia-inducible factor-1(HIF-1)acts as a key regulator of cellular response to hypoxia,and its molecular driving effect plays an important role in hypoxic training.The von Hippel–Lindau tumor suppressor protein(pVHL)inhibits the function of HIF-1 by regulating the degradation of hydroxylated HIF-1α during normoxia.In hypoxic environment or hypoxic training,the hydroxylation probability of HIF-1α is inhibited,so that the functionally active HIF-1 protein is formed in the cells.Thereby the body’ can be response to hypoxia,which is also the biological mechanism of hypoxic training.Although the mechanism by which pVHL degrades HIF-1α is clear,its dynamics and other thermodynamic information remain to be determined.Most of the studies use Molecular Dynamics simulation(MDs)to analyze the dynamics of pVHL and HIF-1α complex with different pVHL mutants,and they provide scientific guidance for the treatment of cancer and ischemic diseases.However,there is lack of a study to explore the dynamics of HIF-1 and pVHL under normoxia and hypoxia with a sports training perspective at present.Therefore,this study utilizes MDs to explore the HIF-1α and pVHL complexes under both normoxia and hypoxia.The aim is to explore the structural characteristics of the complex,and analyze the interaction between HIF-1α and pVHL.The expectation is to make suggestions for the hypoxic training at the molecular level.Methods: Using literature review method to access relevant literature to define related concepts,expound relevant research foundation,and understand the relevant research status at home and abroad.Utilizing MDs method to explore the structural stability and interaction of HIF-1α and pVHL complexes.All MDs are simulated using the Gromacs 4.5.3 software package and the Amber99SB-ILDNP force field.Results:(1)The RMSD value of HIF-1α/pVHL complex is lower when Pro564 is hydroxylated,while the RMSD value of HIF-1α/pVHL complex is relatively larger in Pro564 status.Comparing the structural flexibility,the overall RMSF value of the complex was large at hypoxia,and the RMSF value of the complex is reduced during normoxia,and the RMSF value of the α-domain(V155-P192)of pVHL was significantly reduced.(2)When Pro564 was hydroxylated,the RMSF value of α-domain(V155-P192),which far away from the HIF-1α site at pVHL,is significantly reduced.And this is known as allosteric effect.The allosteric path in this study is starting from Hyp564 of HIF-1α,and going via the pVHL protein β-domains S111,I109,R107,T100,L101,V84,A122 and T124,finally reaching to the amino acid S168 of the α-domain of pVHL protein.And then the effect spread to the entire α-domain.(3)The Hyp564 forms two strong hydrogen bonds with pVHL in normoxia,but these two hydrogen bonds do not exist in hypoxia.And the hydrogen bond strength between HIF-1α and pVHL is enhanced due to the hydroxylation of Pro564 in normoxia.Moreover,due to the formation and strengthening of hydrogen bonds,thecontact area between HIF-1α and pVHL is also increased during normoxia.And these changes were mainly due to the contribution of Hyp564 and its surrounding amino acids.(4)By evaluating the binding free energy between HIF-1α and pVHL,it was found that the binding affinity of HIF-1α and pVHL is weaker in hypoxia than that of normal oxygen.The difference value is 9.88 kcal/mol.And finally this result is consistent with the experimental observations.Conclusion: Hydroxylation of Pro564 to Hyp564 is a key factor of HIF-1α binding to pVHL during normoxia.The binding of HIF-1α to pVHL may be directly caused by hydrogen bonding.And the fomation of hydrogen bonding results in a promotion of contact area,binding free energy,and overall structural stability.Binding of HIF-1αto pVHL allosterically leads to an increase in the α-domain rigidity of pVHL,which may further affects the formation and function of E3 ubiquitin ligase.