Joo-Heon Yoon

Drosophila Microbiome Modulates Host Developmental and Metabolic Homeostasis via Insulin Signaling

Successful development of fruit flies depends on a gut bacterium that interacts with its host’s insulin-signaling pathway. The symbiotic microbiota profoundly affect many aspects of host physiology; however, the molecular mechanisms underlying host-microbe cross-talk are largely unknown. Here, we show that the pyrroloquinoline quinone–dependent alcohol dehydrogenase (PQQ-ADH) activity of a commensal bacterium, Acetobacter pomorum, modulates insulin/insulin-like growth factor signaling (IIS) in Drosophila to regulate host homeostatic programs controlling developmental rate, body size, energy metabolism, and intestinal stem cell activity. Germ-free animals monoassociated with PQQ-ADH mutant bacteria displayed severe deregulation of developmental and metabolic homeostasis. Importantly, these defects were reversed by enhancing host IIS or by supplementing the diet with acetic acid, the metabolic product of PQQ-ADH.

Interleukin-1β and Tumor Necrosis Factor-α Induce MUC5AC Overexpression through a Mechanism Involving ERK/p38 Mitogen-activated Protein Kinases-MSK1-CREB Activation in Human Airway Epithelial Cells

Mucin hypersecretion is commonly observed in many inflammatory diseases of the respiratory tract. MUC5AC is generally recognized to be a major airway mucin because MUC5AC is highly expressed in the goblet cells of human airway epithelium. Moreover, it is regulated by various inflammatory cytokines. However, the mechanisms by which the interleukin (IL)-1β and tumor necrosis factor (TNF)-α induce MUC5AC gene expression in normal nasal epithelial cells, and the signal molecules involved, especially in the downstream signaling of mitogen-activated protein (MAP) kinases, remain unclear. Here we show that pharmacologic or genetic inhibition of either ERK or p38 MAP kinase pathway abolished IL-1β- and TNF-α-induced MUC5AC gene expression in normal human nasal epithelial cells. Our results also indicate that the activation of mitogen- and stress-activated protein kinase 1 (MSK1) and cAMP-response element-binding protein and cAMP-response element signaling cascades via ERK and p38 MAP kinases are crucial aspects of the intracellular mechanisms that mediate MUC5AC gene expression. Taken together, these studies give additional insights into the molecular mechanism of IL-1β- and TNF-α-induced MUC5AC gene expression and enhance our understanding on mucin hypersecretion during inflammation.

Molecular Targets of Dietary Polyphenols with Anti-inflammatory Properties

There is persuasive epidemiological and experimental evidence that dietary polyphenols have anti-inflammatory activity. Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) have long been used to combat inflammation. Recently, cyclooxygenase (COX) inhibitors have been developed and recommended for treatment of rheumatoid arthritis (RA) and osteoarthritis (OA). However, two COX inhibitors have been withdrawn from the market due to unexpected side effects. Because conventional therapeutic and surgical approaches have not been able to fully control the incidence and outcome of many inflammatory diseases, there is an urgent need to find safer compounds and to develop mechanism-based approaches for the management of these diseases. Polyphenols are found in many dietary plant products, including fruits, vegetables, beverages, herbs, and spices. Several of these compounds have been found to inhibit the inflammation process as well as tumorigenesis in experimental animals; they can also exhibit potent biological properties. In addition, epidemiological studies have indicated that populations who consume foods rich in specific polyphenols have lower incidences of inflammatory disease. This paper provides an overview of the research approaches that can be used to unravel the biology and health effects of polyphenols. Polyphenols have diverse biological effects, however, this review will focus on some of the pivotal molecular targets that directly affect the inflammation process.

Dynamic modulation of ANO1/TMEM16A HCO3− permeability by Ca2+/calmodulin

Anoctamin 1 (ANO1)/transmembrane protein 16A (TMEM16A) is a calcium-activated anion channel that may play a role in HCO3− secretion in epithelial cells. Here, we report that the anion selectivity of ANO1 is dynamically regulated by the Ca2+/calmodulin complex. Whole-cell current measurements in HEK 293T cells indicated that ANO1 becomes highly permeable to HCO3− at high [Ca2+]i. Interestingly, this result was not observed in excised patches, indicating the involvement of cytosolic factors in this process. Further studies revealed that the direct association between ANO1 and calmodulin at high [Ca2+]i is responsible for changes in anion permeability. Calmodulin physically interacted with ANO1 in a [Ca2+]i-dependent manner, and addition of recombinant calmodulin to the cytosolic side of excised patches reversibly increased PHCO3/PCl. In addition, the high [Ca2+]i-induced increase in HCO3− permeability was reproduced in mouse submandibular gland acinar cells, in which ANO1 plays a critical role in fluid secretion. These results indicate that the HCO3− permeability of ANO1 can be dynamically modulated and that ANO1 may play an important role in cellular HCO3− transport, especially in transepithelial HCO3− secretion.

Kaempferol and quercetin, components of Ginkgo biloba extract (EGb 761), induce caspase‐3‐dependent apoptosis in oral cavity cancer cells

EGb 761, extracted from Ginkgo biloba leaves, has been proven to induce caspase‐3‐dependent apoptosis in oral cavity cancer cells. Since EGb 761 is a composition of various components, it is important to identify which components are responsible for its anticancer effects to reduce the total dosage and to avoid toxicity. Therefore, the study aimed to determine the effective compounds of EGb 761 that induce apoptosis in oral cavity cancer cells and to identify whether caspase‐3 was involved in apoptosis of oral cancer cells by EGb 761 components. The results of cell proliferation assays on oral cavity cancer cells showed that kaempferol and quercetin significantly inhibited cellular proliferation at a concentration of 40 µM. Flow cytometry showed that the antiproliferative effects of each component were due to increased apoptosis. Kaempferol and quercetin induced apoptosis in various oral cancer cell lines (SCC‐1483, SCC‐25 and SCC‐QLL1) and showed cleavage of poly (ADP‐ribose) polymerase (PARP). Caspase‐3 activity assay revealed that induction of apoptosis by kaempferol and quercetin was caspase‐3‐dependent. In conclusion, the results suggest that kaempferol and quercetin, two components of EGb 761, effectively induce caspase‐3‐dependent apoptosis of oral cavity cancer cells and can be considered as possible anti‐oral cavity cancer agents. Copyright

Secretory Differentiation of Serially Passaged Normal Human Nasal Epithelial Cells by Retinoic Acid: Expression of Mucin and Lysozyme:

The purpose of this study was to subculture normal human nasal epithelial (NHNE) cells without compromising their ability to differentiate into secretory and ciliated cells and to study the effect of retinoic acid on mucous and serous secretions in passaged cells and to compare the expression of mucin and lysozyme in cultured cells with those in in vivo nasal epithelium. The subcultured cells were tested after every passage for secretory differentiation in air-liquid interface cultures. The cultured NHNE cells secreted mucin and lysozyme. The cells became squamous and mucin secretion decreased when retinoic acid was deleted from the culture media. Cells from passage 1 through passage 2 remained able to differentiate into mucous or squamous cells. Mucin gene 4 (MUC4), MUC5AC, MUC7, MUC8, and lysozyme messenger RNAs were expressed in passage 2 NHNE cells. In conclusion, passage 2 NHNE cell cultures retain features of normal epithelium and are suitable for many studies of upper airway cell biology.

The Homeobox Gene Caudal Regulates Constitutive Local Expression of Antimicrobial Peptide Genes in Drosophila Epithelia

ABSTRACT In Drosophila melanogaster, although the NF-κB transcription factors play a pivotal role in the inducible expression of innate immune genes, such as antimicrobial peptide genes, the exact regulatory mechanism of the tissue-specific constitutive expression of these genes in barrier epithelia is largely unknown. Here, we show that the Drosophila homeobox gene product Caudal functions as the innate immune transcription modulator that is responsible for the constitutive local expression of antimicrobial peptides cecropin and drosomycin in a tissue-specific manner. These results suggest that certain epithelial tissues have evolved a unique constitutive innate immune strategy by recruiting a developmental “master control” gene.

Effects of TNF-a and IL-1 ß on Mucin, Lysozyme, IL-6 and IL-8 in passage-2 Normal Human Nasal Epithelial Cells

Little is known about the regulatory effects of cytokines on various nasal secretions in normal human nasal epithelial cells. The aim of this study was to examine whether TNF-alpha, IL-1beta or their combination can increase the secretion of mucin as an indicator of mucous secretion, the secretion of lysozyme as an indicator of serous secretion and the secretion of IL-6 and IL-8 as important cytokines. In addition, we wanted to examine their message levels in normal human nasal epithelium. On day 12 of culture, passage-2 normal human nasal epithelial cells were treated with 10 ng/ml TNF-alpha, 10 ng/ml IL-1beta and combinations of both. Twenty-four hours later, the apical secretions were collected. A mixture of TNF-alpha and IL-1beta synergistically increased secretion of mucin, IL-6 and IL-8, but did not increase secretion of lysozyme. A combination of TNF-alpha and IL-1beta showed a questionable increase of MUC2 mRNA levels. TNF-alpha, IL-1beta and a combination of both all significantly increased MUC8 mRNA levels. Neither TNF-alpha, IL-1beta nor a combination of both increased MUC5AC, MUC5B and lysozyme mRNA levels. IL-1beta alone or a combination of TNF-alpha and IL-1beta comparably increased IL-6 and IL-8 mRNA levels slightly. In conclusion, a mixture of inflammatory mediators can synergistically increase secretion of mucin, IL-6 and IL-8 in human nasal epithelium. Accordingly, nasal secretions may be under the control of an inflammatory mediator network.

Surgical anatomy of the anterior ethmoidal canal in ethmoid roof

Objectives/Hypothesis This study was undertaken to examine three main relationships. First, the distance and angle from the anterior ethmoidal canal to the limen nasi and the sill were measured. Second, the location of the anterior ethmoidal canal was examined in relation to the lamellas and the skull base. Third, the existence of bony defects in the canal and the course of the canal through the anterior cranial fossa were studied.

Surgical Anatomy of the Natural Ostium of the Sphenoid Sinus

Objectives This study was undertaken to measure the distance and the angle between the anterior part of nasal cavity and the natural ostium of the sphenoid sinus. The anatomical location of the natural ostium according to the direction of surgeons operating view toward the anterior wall of the sphenoid sinus was also analyzed.