This proposal focuses on a previously unappreciated and potentially powerful role that inadequate nutrition can have to modify the expression and function of heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1). HnRNP-E1 binds a multitude of RNA with common c/s-elements including those within the genome of human papillomavirus (HPV) that are involved in the synthesis of HPV viral capsid proteins. Our overarching hypothesis is that intracellular homocysteine which accumulates in folate deficiency derivatizes hnRNP-E1 by a post-translational specific modification that transforms homocysteine-derivatized hnRNP-E1 into a high-affinity RNA-binding protein which up-regulates itself and modulates the expression of a host of other proteins at the post-transcriptional level by regulating their mRNA. We will study the covalent modification of hnRNP-E1 protein by conventional analytical methods and the mechanism of translational auto-regulation of hnRNP-E1 in cervical cancer xenografts propagated in folate- deficient mice by methods recently established in our laboratory. We will also use homocysteine-derivatized hnRNP-E1 as a hook to fish out, amplify, characterize, and catalog as yet undiscovered RNA with common RNA c/s-elements that are likely to be regulated in folate-deficient cells. In addition, we will investigate the mechanism whereby homocysteine-derivatized hnRNP-E1 can quench the generation of HPV viral capsid proteins in pre-malignant HPV-infected keratinocytes that are propagated under conditions of low folate. This is significant because perturbation of the incorporation of both the major (L1) and minor (L2) viral capsid proteins into HPV viral particles can profoundly affect both the infectivity of HPV, and may also eventually influence the potential for HPV to eventually transform infected cells into cancer. These studies can uncover new insight into mechanism(s) by which a common nutritional deficiency can profoundly induce an epigenetic posttranslational change of a key multifunctional RNA-binding protein that can, in turn, influence the post-transcriptional regulation and expression of many other critical proteins involved in cell proliferation, differentiation and apoptosis. And if indeed nutrition can influence the capacity to generate authentic infectious HPV viral particles, this could open the field for future studies to investigate the role of nutrition in modulation of HPV-infectivity and malignant transformation of HPV-infected cells.
|Tang, Ying-Sheng; Khan, Rehana A; Xiao, Suhong et al. (2017) Evidence Favoring a Positive Feedback Loop for Physiologic Auto Upregulation of hnRNP-E1 during Prolonged Folate Deficiency in Human Placental Cells. J Nutr 147:482-498|
|Xiao, Suhong; Tang, Ying-Sheng; Khan, Rehana A et al. (2012) Influence of physiologic folate deficiency on human papillomavirus type 16 (HPV16)-harboring human keratinocytes in vitro and in vivo. J Biol Chem 287:12559-77|
|Tang, Ying-Sheng; Khan, Rehana A; Zhang, Yonghua et al. (2011) Incrimination of heterogeneous nuclear ribonucleoprotein E1 (hnRNP-E1) as a candidate sensor of physiological folate deficiency. J Biol Chem 286:39100-15|