The Study Of Interaction And Regulation Between REGγ And Its Substrates

An important function of protein degradation within animal and bacterial cells is to remove proteins with highly abnormal structures as might arise by mutation or errors in biosynthesis.REGy as an improtant proteasome activator,can bind and activate the 20S proteasome to promote proteasome-dependent degradation of some important regulatory proteins.It’s shown that the substrates of REGy such as SRC-3, cyclin-dependent kinase inhibitor p21,p19,p16,smurfl and smurf2 can be degraded in a ubiquitin- and ATP-independent method.Furthermore,20S proteasome has been shown to degrade oxidative damaged proteins,but the mechanism is still nuclear.Oxidative stress always reflects an imbalance between the oxidant factors and antioxidant factors in biological system,and it tends to oxidative damage by oxidant function.Oxidation protein is significantly increased during periods of oxidative stress and may become a threat to cell survival.20S proteasome system can selectively recognize and degrade mildly oxidative damaged proteins in intracellular,and to minimize the cytotoxicity of these oxidation proteins.But the 26S proteasome system is quitely sensitive to oxidative stress,it’s not effective to remove the oxidation proteins.It’s suggested that p21 can be degraded in the 20S proteasome by the mildly oxidative stress,but the mechanism need to be further searched.In this study,we mainly investigated the interaction between REGy and the target protein p21 within the oxidative stress in vivo.Oxidative stress can be caused by oxidant factors,such as hydrogen perioxide(H2O2) and phenylhydrazine. And it’s initially confirmed that the degradation of the intracellular oxidation protein p21 is much more rapid than that not be stimulated with oxidative stress, but the regulation mechanism about REGy affacting the turnover of oxidation protein p21 is unclear and we will go to further study.In addition, it’s known that there are three primary hemoglobin variants in normal human red blood cells,HbA(over 95%),HbF(less 1%),HbA2(1.5-3.5%),all of variants are comprise of two similar types of globin chains and then combine to form the tetramer. The subunit component of HbA,HbF and HbA2 are α2β2,α2γ2,α2δ2,respectively.Hemoglobin as an important iron-containing oxygen-transport protein in red blood cells,is attracted more and more concern about the degradation and its biological function.It has been studied that there is a pathway for the degradation of the oxidative-damaged hemoglobin which does not required ATP-or ubiquitin in 20S proteasome system.In my study mainly investigated the mechanism of hemoglobinδ(HBD) degradation.We found the HBD was the potential target protein of REGy by the Mass Spectrometry technology, and both of them maybe intract with each other. And then,we constracted the HBD plasmid and confirmed that HBD can be degraded by REGy in HeLa cell. It’s interesting that the expression of hemoglobin in REGγ-/-mouse is much higher than in REGywt mouse.It’s also shown that REGycan regulate the hemoglobin turnover. Although the regulatory mechanism of the hemoglobin is not distinct due to the specificity itself, it can provide some scientific basis for the abnormal hemoglobin diseases in red blood cell.