miR-193 expression differentiates telocytes from other stromal cells

Abstract

Telocytes (TCs) are a particular type of interstitial (stromal) cells defined by very long, moniliform telopodes. Their tissue location, between blood vessels and other cells such as cardiomyocytes (CMC) and neurons, suggests a role in intercellular signalling. In order to define a microRNA (miR) signature in cardiac TCs, we have found that miR-193 is differentially expressed between TCs and other interstitial cells. Because miR-193 regulates c-kit, our data support the previous finding that TCs express c-kit in certain circumstances. In addition, the miRs which are specific to CMC and other muscle cells (e.g. miR-133a, miR-208a) are absent in TCs. Overall the data reinforce the view that TCs are a particular type of interstitial (mesenchymal) cells.

fig 1

Laser microdissection of Giemsa-stained TCs in (A) and control cells (C) in (B) cultivated on membrane dishes. Insets show the corresponding areas after microdissection and correspond to areas enclosed in red discontinuous lines. 20× objective.

fig 2

Expression levels of miRs specifically up-regulated in CMC (A) or in both cultured cardiac interstitial cells and NIH3T3 fibroblasts (B). The relative expression was determined by real-time PCR. RNU43 snoRNA and U6 snRNA were used as normalizing controls. The error bars are mean + S.D. (n = 3) and the data are representative for two replicate experiments. CMCs: cardiomyocytes; CCCs: cultured cardiac cells; NIH3T3: fibroblasts.

fig 3

miR detection in laser microdissected cells. The results represent real-time PCR data were U6 snRNA is the internal control. (A) miR-1, miR-133 and miR-208a are not detected; the interstitial cell specific miRs miR-21, miR-22, miR-29b and miR-199a-5p are present in both fibroblast-like cells and TCs. In case of miR-29b, because the expression level is reduced the data variation from one experiment to another is high. (B) miR-193 is not expressed in TCs, whereas it is present in control cells. The error bars are mean + S.D. (A, n = 2; B, n = 3) and the data are representative for two replicate experiments. CTR: control fibroblast-like cells; TC: telocyte.