dsRNA Sensing Induces Loss of Cell Identity.

How cell and tissue identity persist despite constant cell turnover is an important biologic question with cell therapy implications. Although many mechanisms exist, we investigated the controls for site-specific gene expression in skin, given its diverse structures and functions. For example, the transcriptome of in vivo palmoplantar (i.e., volar) epidermis is globally unique, including Keratin 9 (KRT9). Although volar fibroblasts have the capacity to induce KRT9 in nonvolar keratinocytes, we show here that volar keratinocytes continue to express KRT9 in in vitro solo cultures. Despite this, KRT9 expression is lost with volar keratinocyte passaging, despite stable hypomethylation of its promoter. Coincident with KRT9 loss is a gain of the primitive keratin 7 and a signature of dsRNA sensing, including the double-stranded RNA (dsRNA) receptor DExD/H-Box Helicase 58 (DDX58/RIG-I). Exogenous dsRNA inhibits KRT9 expression in early passage volar keratinocytes or in vivo footpads of wild-type mice. Loss of DDX58 in passaged volar keratinocytes rescues KRT9 and inhibits KRT7 expression. Additionally, DDX58-null mice are resistant to the ability of dsRNA to inhibit KRT9 expression. These results show that the sensing of dsRNA is critical for loss of cell-specific gene expression; our results have important implications for how dsRNA sensing is important outside of immune pathways.

Ductal plate in hepatoblasts in human fetal livers: I. ductal plate-like structures with cytokeratins 7 and 19 are occasionally seen within human fetal hepatoblasts.

The author has studied the organogenesis of human intrahepatic bile duct in fetal livers. The developmental studies of the liver have focused mainly on the development of intrahepatic bile ducts including the ductal plate (DP). The DP is a single or double layered structures composed of small cuboidal cells and located in the interface between the hepatoblasts and portal mesenchyme. Herein, the author discovered the DP within the parenchymal hepatocytes. The DP-like structures within the hepatoblasts were found in 17 human fetal livers out of the 32 human fetal livers. The gestational ages of the 17 fetal livers were as follows: 7, 8, 9, 10 (n=2), 11, 12, 13, 14 (n=2), 15, 16, 17, 18, 19, 21, and 23 weeks. The presence of intraparenchymal DP-like structures were mainly found in the fetus of early gestational ages. Morphologically, the DP-like structures within the hepatoblasts were composed of small cuboidal epithelial cells with normal chromatin patterns. The cytoplasm was scant and relatively basophilic. The nuclei were small and round, and had no nucleoli. These cells formed the DP-like structures. The DP-like structures frequently formed cords, tubules, and duplicating patterns. These DP-like structures were scattered and the remaining hepatoblasts are normal hepatoblasts. The density of these DP-structures was low (one or two per 5 low power fields), but varied from case to case and area to area in the same case. The overall appearances were very similar to the true DP. Comparative observations of HE and CK immunostaining were performed. The DP-like structures within the hepatoblasts were positive for biliary-type CK7 and CK19. They were also positive for CK8 and CK18 that are expressed in both hepatocyte and biliary lineages. The true DP was positive for biliary-type CK7 and CK19. They were also positive for CK8 and CK18. Thus, the intraparenchymal DP-like structures were the same as the true DP located in the interface. Thus, the author discovered the intraparenchymal DP in the human fetal livers. This discovery should be confirmed by other researchers. If it is true, many studies of the functions of these intraparenchymal DPs are need.

Apolipoprotein A-IV as a novel gene associated with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder, affecting 6-10% of women of reproductive age. The etiology remains poorly understood. To investigate the differentially expressed proteins from PCOS patients versus healthy women, the protein expression in follicular fluid was analyzed using two-dimensional electrophoresis (2-DE). Since follicular fluid contains a number of secretory proteins required for oocyte fertilization and follicle maturation, it is possible that follicular fluid can be used as a provisional source for identifying pivotal proteins associated with PCOS. In this study, six overexpressed proteins [kininogen 1, cytokeratin 9, antithrombin, fibrinogen γ-chain, apolipoprotein A-IV (apoA-IV) precursor and α-1-B-glycoprotein (A1BG)] in follicular fluids from PCOS patients were identified with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) and nano LC-MS/MS. Western blot analysis confirmed that the protein expression levels of apoA-IV precursor and A1BG were increased in follicular fluid from PCOS patients compared with those from normal controls. The analysis of protein expression for other proteins revealed individual variation. These results facilitate the understanding of the molecular mechanisms of PCOS and provide candidate biomarkers for the development of diagnostic and therapeutic tools.