Detection of differential fetal and adult expression of chloride intracellular channel 4 (CLIC4) protein by analysis of a green fluorescent protein knock-in mouse line

Abstract

BackgroundChloride Intracellular Channel 4 (CLIC4) is one of seven members in the closely related CLIC protein family. CLIC4 is involved in multiple cellular processes including apoptosis, cellular differentiation, inflammation and endothelial tubulogenesis. Despite over a decade of research, no comprehensive in situ expression analysis of CLIC4 in a living organism has been reported. In order to fulfill this goal, we generated a knock-in mouse to express Green Fluorescent Protein (GFP) from the CLIC4 locus, thus substituting the GFP coding region for CLIC4. We used GFP protein expression to eliminate cross reaction with other CLIC family members.ResultsWe analyzed CLIC4 expression during embryonic development and adult organs. During mid and late gestation, CLIC4 expression is modulated particularly in fetal brain, heart, thymus, liver and kidney as well as in developing brown adipose tissue and stratifying epidermis. In the adult mouse, CLIC4 is highly expressed globally in vascular endothelial cells as well as in liver, lung alveolar septae, pancreatic acini, spermatogonia, renal proximal tubules, cardiomyocytes and thymic epithelial cells. Neural expression included axonal tracks, olfactory bulb, Purkinje cell layer and dentate gyrus. Renal CLIC4 expression was most pronounced in proximal tubules, although altered renal function was not detected in the absence of CLIC4. Myeloid cells and B cells of the spleen are rich in CLIC4 expression as are CD4 and CD8 positive T cells.ConclusionsIn a comprehensive study detailing CLIC4 expression in situ in a mouse model that excludes cross reaction with other family members, we were able to document previously unreported expression for CLIC4 in developing fetus, particularly the brain. In addition, compartmentalized expression of CLIC4 in specific adult tissues and cells provides a focus to explore potential functions of this protein not addressed previously.

Head and neck squamous cancer progression is marked by CLIC4 attenuation in tumor epithelium and reciprocal stromal upregulation of miR-142-3p, a novel post-transcriptional regulator of CLIC4

“…This is supported by known roles of CLIC4 in supporting myofibroblast differentiation [11] and in endothelial cell proliferation and angiogenesis [4,5]. CLIC4 was notably absent from tumor-infiltrating T cells of all subtypes, despite prior documented expression in T cells [108]. Therefore, T cells, which are known to express miR-142-3p, may represent a cellular context in which miR-142-3p represses CLIC4 to promote intrinsic phenotypic changes.…”

Integrative proteomic and microRNA analysis of the priming phase during rat liver regeneration

“…CLIC4, DAP1, PDCD6, FKBP1A and ABCD1, the predicted targets of miR-183, were down-regulated at 2 h and 6 h after PH. Chloride Intracellular Channel 4 (CLIC4) is involved in multiple cellular processes including apoptosis, cellular differentiation, inflammation and endothelial tubulogenesis (Padmakumar et al, 2014). Programmed cell death 6 (PDCD6) as a pro-apoptotic protein, suppressed vascular endothelial growth factor (VEGF)-induced proliferation, invasion, and angiogenesis (Rho et al, 2012).…”

Chloride intracellular channel 4 is required for maturation of the cerebral collateral circulation

“…Endogenous CLIC4 expression patterns in the developing and adult mouse have only recently been described after the development of a knockin Clic4 green fluorescent protein mouse model (29). A midgestation, CLIC4 is expressed widely throughout the embryo and is particularly strong in the brain.…”

“…This observation suggests that CLIC4 is constitutively present in blood vessels but is actively reduced in parenchymal cells. Confirmation of this assumption is currently hindered by absence of specific antibodies (29). Such a decline in CLIC4 expression in parenchymal cells in the vicinity of newly formed collaterals may serve as a paracrine signal that initiates mural cell recruitment and/or differentiation.…”