LncRNA Dio3os regulates neighboring gene Dio3 and impacts osteogenesis in trans

Consumptive hypothyroidism, a rare pediatric disorder, arises from aberrant Dio3 expression, which inactivates thyroid hormones and disrupts skeletal development. This study investigates the regulatory role of the long non-coding RNA Dio3os, which activates Dio3 in cis and suppresses osteoblast differentiation in trans. We focused on mouse Dio3os variant 203 and human variants 203 and 205. Chromatin accessibility and histone modification analyses revealed higher chromatin openness and active histone H3 modifications at the Dio3os promoter and exons 2-3, followed by increased RUNX2 binding with reduced histone H3 modifications during maturation. Dio3os expression is enhanced by HDAC1/2, HIF1, and thyroid hormones, but repressed by BMP2, TGF{beta}, Runx2, and Brg1. Overexpression of Dio3os upregulated Dio3 while downregulating osteogenic markers. CRISPR-mediated deletion of Dio3os exons or premature intronic polyadenylation suppressed Dio3 and restored osteogenic gene expression. RNA-seq and ATAC-seq confirmed enhanced thyroid hormone-responsive osteoblast gene activity in Dio3os-CRISPR-knockout cells. These findings reveal Dio3os as a key regulator of thyroid hormone metabolism and bone formation, presenting a novel target for treating skeletal abnormalities in early childhood hypothyroidism. SynopsisDuring hypothyroidism, long non-coding RNA (lncRNA) Dio3os activates neighboring Dio3 and inhibits non-neighboring OB-specific genes. O_LIIn bone cells, the long non-coding RNA (lncRNA) Dio3os recruits the NuRD complex to the Dio3 gene promoter, activating its transcription through an unidentified deacetylation mechanism. C_LIO_LIDio3os teams with NuRD, reverse T3 (rT3), and TR1 bind together at the promoters thyroid-responsive element (TRE), replacing T3 to repress osteoblast gene transcription. C_LIO_LIThese findings enhance our understanding of how hypothyroidism affects bone phenotypes. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/647401v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@8e8328org.highwire.dtl.DTLVardef@44c4b7org.highwire.dtl.DTLVardef@cecb8aorg.highwire.dtl.DTLVardef@950ae2_HPS_FORMAT_FIGEXP M_FIG C_FIG