Thyroid hormone-regulated expression of nuclear lamins correlates with dedifferentiation of intestinal epithelial cells during Xenopus laevis metamorphosis

Abstract

In the Xenopus laevis intestine during metamorphosis, which is triggered by thyroid hormone (TH), the adult epithelium develops and replaces the larval one undergoing apoptosis. We have previously shown that progenitor/stem cells of the adult epithelium originate from some differentiated larval epithelial cells. To investigate molecular mechanisms underlying larval epithelial dedifferentiation into the adult progenitor/stem cells, we here focused on nuclear lamin A (LA) and lamin LIII (LIII), whose expression is generally known to be correlated with the state of cell differentiation. We analyzed the spatiotemporal expression of LA and LIII during X. laevis intestinal remodeling by reverse transcription PCR, Western blotting, and immunohistochemistry. At the onset of natural metamorphosis, when the adult epithelial progenitor cells appear as small islets, the expression of LA is down-regulated, but that of LIII is up-regulated only in the islets. Then, as the adult progenitor cells differentiate, the expression of LA is up-regulated, whereas that of LIII is down-regulated in the adult cells. As multiple intestinal folds form, adult epithelial cells positive for LIII become restricted only to the troughs of the folds. In addition, we have shown that TH up- or down-regulates the expression of these lamins in the premetamorphic intestine as during natural metamorphosis. These results indicate that TH-regulated expression of LA and LIII closely correlates with dedifferentiation of the epithelial cells in the X. laevis intestine, suggesting the involvement of the lamins in the process of dedifferentiation during amphibian metamorphosis.

Chromatin tethering to the nuclear envelope by nuclear actin filaments: a novel role of the actin cytoskeleton in theXenopusblastula

“…After treatment with 0.1% Triton X-100 in PBS for 1 min at room temperature, coverslips were washed three times in PBS and blocked in 2% BSA-PBS solution. Coverslips were then incubated with anti-Xenopus lamin L3 (LL3) antibody (1:500 dilution; Hasebe et al 2011), followed by incubation with Alexa 488-conjugated secondary antibody (1:1000 dilution; Invitrogen) and DY-590-phalloidin (2 units/ml, Dyomics GmbH). Coverslips were washed in PBS, treated with Hoechst 33342 (2 µg/ml) and mounted on glass slides with a mounting reagent (SlowFade Gold, Molecular Probes).…”

Apoptosis in amphibian development

“…Since some years, studies concerning the role of extra-cellular matrix have been published, showing its importance on metamorphosis [87,[90][91][92][93]. The expressions of MT1-MMP and GelA genes were studied in intestine and tail of X. laevis during metamorphosis [92].…”

Chromatin tethering to the nuclear envelope by nuclear actin filaments: a novel role of the actin cytoskeleton in the Xenopus blastula

“…After treatment with 0.1% Triton X-100 in PBS for 1 min at room temperature, coverslips were washed three times in PBS and blocked in 2% BSA-PBS solution. Coverslips were then incubated with anti-Xenopus lamin L3 (LL3) antibody (1 : 500 dilution; Hasebe et al 2011), followed by incubation with Alexa 488-conjugated secondary antibody (1 : 1000 dilution; Invitrogen, Carlsbad, CA, USA) and DY-590-phalloidin (2 units/mL, Dyomics GmbH). Coverslips were washed in PBS, treated with Hoechst 33342 (2 lg/mL) and mounted on glass slides with a mounting reagent (SlowFade Gold; Molecular Probes, Eugene, OR, USA).…”