Year: 2021
Type: conference-abstract
Abstract: Rationale The gain-of-function MUC5B promoter variant rs35705950 is the strongest risk factor for the development of idiopathic pulmonary fibrosis (IPF). MUC5B overexpression is observed with one or two copies of the MUC5B promoter variant. Spliced XBP1 is necessary and sufficient for MUC5B expression; overexpression of MUC5B will lead to increased endoplasmic reticulum (ER) protein load and may disrupt ER homeostasis. MUC5B/Muc5b overexpression is associated with ER stress in IPF and in mice overexpressing Muc5b and/or mice challenged with bleomycin. Objective Determine the cell-intrinsic effect of the MUC5B expression on ER stress, and the consequences of ER stress on differentiation and fibroproliferation in airway epithelia. Method Primary airway epithelia cells from unaffected control donors with or without MUC5B promoter variant were cultured at air-liquid interface (ALI) for 14 days. MUC5B expression was measured by dot blot, and tunicamycin and KIRA8 were used to induce and inhibit ER stress. We also activated MUC5B expression in HBEC-3KT cell line by CRISPRa/dCas9 technology. Result On ALI day 14, primary airway epithelia cells from unaffected control donors with MUC5B promoter variant secreted more MUC5B protein compared to non-variant donors. KIRA8 diminished spliced XBP1 expression in primary airway epithelia cells with tunicamycin-induced ER stress. HBEC-3KT cells edited by CRISPR/dCas9 MUC5B activation system expressed higher MUC5B mRNA in submerged culture (p<0.0001) and on ALI day 21 (p<0.0001). Discussion Our preliminary findings showed primary airway epithelia cells with MUC5B promoter variant and CRISPR/dCas9 MUC5B activation system edited HBEC-3KT cell line express higher concentrations of MUC5B. Moreover, the concentration of MUC5B is directly related to expression of spliced XBP1, a marker of ER stress. Further research is needed to evaluate the relative contribution of the MUC5B overexpression to pathologic ER stress and to quantify its downstream consequences.
Institution: University of Colorado Anschutz
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W4251793763