Mathur Srinivasan Kannan
205 Veterinary Science, 1971 Commonwealth Avenue, University of Minnesota, St. Paul, MN 55108, USA
Abstract:
CD38 is a cell surface protein with multiple enzyme activities and receptor functions expressed in a variety of mammalian cells. In human airway smooth muscle (HASM) cells, CD38 plays a role in cellular Ca2+ dynamics. In vivo studies in mice have shown that CD38 plays a role in the development of airway hyperresponsiveness (AHR) following exposure to allergens or cytokines such as TNF-alpha or IL-13. We previously reported that TNF-alpha induces CD38 expression in HASM cells through transcriptional activation and by stabilizing CD38 mRNA. The 3' untranslated region (3'UTR) of CD38 mRNA carries targets for several microRNAs including microRNA 140-3p (miR140-3p). Expression of miR140-3p is down regulated in HASM cells exposed TNF-alpha and the down regulation is greater in cells isolated from asthmatic donors. We hypothesized that the miR140-3p plays a role in TNF-alpha-induced CD38 expression in HASM cells. Methods: Primary HASM cells were transiently transfected with miR140 mimic oligonucleotides or miR140 antagomirs, followed by exposure to vehicle or human recombinant TNF-alpha (10 ng/ml) for 24 hrs. miR 140 expression and CD38 mRNA expression were determined by qRT-PCR. HEK293 cells were co-transfected with a Luc-CD38 3'UTR construct and miR140 mimic oligonucleotides (5-25 nM) and luciferase activity was determined 24 hrs after transfection. Results: The HASM cells transfected with miR140 mimic showed a significant attenuation of TNF-alpha-induced CD38 mRNA expression, compared to the control oligonucleotide-transfected cells. HASM cells transfected with miR140 antagomirs showed increased TNF-alpha-induced CD38 mRNA levels compared to the control oligonucleotide-transfected cells. HEK293 cells transfected with miR140 mimic (10 and 25 nM) showed decreased luciferase activity compared to the cells transfected with control oligonucleotides. Conclusions: TNF-alpha-induced CD38 expression is regulated by miR140-3p in HASM cells through direct interaction with the 3'UTR of CD38 mRNA. The findings suggest novel regulatory mechanisms involved in CD38 expression in HASM cells and reveal potential therapeutic targets in airway disorders such as asthma.
Supported by grants from the National Institutes of Health.
