ABSTRACT
The objective is to provide a comprehensive overview of the rapidly developing field of the current state of research on in vivo use of hypochlorous acid (HOCl) to aid infection prevention and control, including naso-pharyngeal, alveolar, topical, and systemic HOCl applications. Also, examples are provided of dedicated applications in COVID-19. A brief background of HOCl's biological and chemical specifics and its physiological role in the innate immune system is provided to understand the effect of in vivo applications in the context of the body's own physiological defense mechanisms.
ABSTRACT
In human gastric cancer cells the human histidine decarboxylase gene is regulated by gastrin through two overlapping cis-acting elements known as gastrin response elements 1&2 (GAS-RE1, GAS-RE2) [J. Biol. Chem. 274 (1999) 20961]. Here, we report the identification and characterization of a third element GAS-RE3 that was localized to a region +28 to +48 downstream of the transcriptional start site (+1). Gastrin stimulation induced a rapid increase in binding to the element of a novel nuclear factor named gastrin response element-binding protein 3 (GAS-REBP3). Block mutations in the GAS-RE3 sequence (+38GTGCG(+42) to +38TAAGT(+42)) led to reduced promoter activity and decreased binding in EMSA. UV cross-linking studies and Southwestern blot analysis with wildtype and mutant GAS-RE3 showed that GAS-REBP3 was a approximately 110kDa protein. Thus, gastrin-mediated regulation of HDC gene expression appears to be mediated by a complex cis-acting element, which binds at least three distinct nuclear factors.
Subject(s)
Gastrins/genetics , Histidine Decarboxylase/genetics , Promoter Regions, Genetic , Response Elements , Base Sequence , Binding Sites , Blotting, Southern , Blotting, Western , Cross-Linking Reagents/pharmacology , Gastrins/metabolism , Genes, Reporter , Humans , Molecular Sequence Data , Mutation , Oligonucleotides/genetics , Protein Binding , Transfection , Ultraviolet RaysABSTRACT
Trefoil factor 2 (TFF2)/spasmolytic polypeptide (SP) is a highly stable peptide which is abundantly expressed and secreted by mucous cells of the stomach and which functions in gastric cytoprotection. Previous studies from our group have shown that TFF2 is an immediate early gene capable of regulating its own expression through activation of the TFF2 promoter. We therefore aimed to investigate the cis-acting elements mediating this response in AGS cells transfected with TFF2 promoter-reporter gene constructs, using a TFF2-expression system resembling physiologic paracrine conditions. TFF2 peptide expression was achieved through stable transfection of AGS cells with a TFF2-expression construct. Stimulation of transiently transfected cells with this TFF2-containing conditioned media resulted in a significant increase in TFF2 promoter activity. Promoter stimulation was blocked by an anti-TFF2 antibody, indicating that it was mediated specifically by TFF2. Deletion analysis of the TFF2 promoter led to the identification of a specific response element located between -191 and -174 upstream of the transcriptional initiation site. This region of the promoter, which was designated SPRE (for spasmolytic polypeptide response element), was sufficient to confer responsiveness in a heterologous promoter system. Mutational analysis and electrophoretic mobility shift assays (EMSA) showed that a GAG motif was responsible for mediating promoter activation in response to TFF2 stimulation. Since auto- and cross-induction of TFF2 promoter is likely to be a means of rapid amplification of TFF2 expression in the critical first minutes following mucosal injury, these results should lead to insight into the molecular events initiating epithelial restitution and healing.
