ABSTRACT
Despite an increasing knowledge of dandruff and seborrheic dermatitis (D/SD), the pathophysiological understanding is still incomplete but suggests a role of Malassezia yeasts in triggering inflammatory and hyper-proliferative epidermal responses. The objective of this report is to review published literature from in vivo studies of D/SD populations to provide a more complete description of overall scalp health. New biomolecular capabilities establish a depth of pathophysiological understanding not previously achievable with traditional means of investigation. Biomarkers representing inflammation, hyper-proliferation and barrier function are all perturbed by the D/SD condition and robustly respond to therapeutic resolution. These biomarkers can be sampled noninvasively, enabling their use in routine clinical evaluations as either surrogate endpoints or complementary ones to classical signs/symptoms to broaden the etiological learning.
Subject(s)
Dermatitis, Seborrheic/physiopathology , Dermatomycoses/physiopathology , Pityriasis/physiopathology , Scalp Dermatoses/physiopathology , Scalp/physiopathology , Biomarkers/metabolism , Dermatitis, Seborrheic/metabolism , Dermatitis, Seborrheic/pathology , Dermatomycoses/metabolism , Dermatomycoses/microbiology , Dermatomycoses/pathology , Humans , Malassezia/pathogenicity , Pityriasis/metabolism , Pityriasis/pathology , Predictive Value of Tests , Prognosis , Scalp/metabolism , Scalp/microbiology , Scalp/pathology , Scalp Dermatoses/metabolism , Scalp Dermatoses/microbiology , Scalp Dermatoses/pathologyABSTRACT
In the life-cycle of picornaviruses, the synthesis of the viral polyprotein is initiated cap-independently at the internal ribosome entry site (IRES) far downstream from the 5' end of the viral plus-strand RNA. The cis-acting IRES RNA elements serve as binding sites for translation initiation factors that guide the ribosomes to an internal site of the viral RNA. In this study, we show that the eukaryotic translation initiation factor eIF4G interacts directly with the IRES of foot-and-mouth disease virus (FMDV). eIF4G binds mainly to the large Y-shaped stem-loop 4 RNA structure in the 3' region of the FMDV IRES element, whereas stem-loop 5 contributes only slightly to eIF4G binding. Two subdomains of stem-loop 4 are absolutely essential for eIF4G binding, whereas another subdomain contributes to a lesser extent to binding of eIF4G. At the functional level, the translational activity of stem-loop 4 subdomain mutants correlates with the efficiency of binding of eIF4G in the UV cross-link assay. This indicates that the interaction of eIF4G with the IRES is crucial for the initiation of FMDV translation. A model for the interaction of initiation factors with the IRES element is discussed.
