The transcription factor Znf219 regulates chondrocyte differentiation by assembling a transcription factory with Sox9

Abstract

SummarySox9 is an essential transcription factor for chondrogenesis by regulating the expression of chondrogenic genes. However, its regulatory mechanism is not fully understood. To address this, we attempted to identify the transcriptional partners of Sox9 by screening the cDNA library of the chondrogenic cell line ATDC5 using the collagen 21 (Col21) gene promoter fused to a luciferase reporter gene. One of the positive clones encoded the Znf219 gene. Whole mount in situ hybridization experiments indicated that Znf219 mRNA was specifically expressed in the developing limb buds where Col21 and Sox9 were strongly expressed. Znf219 markedly enhanced the transcriptional activity of Sox9 on the Col2a1 gene promoter. In addition, Znf219 is physically associated with Sox9 and is colocalized with Sox9 in the nucleus. We also found that overexpression of Znf219 profoundly increased Sox9-induced mRNA expression of Col2a1, aggrecan and Col11a2. Consistently, knockdown of Znf219 decreased the Sox9-induced mRNA expression of these genes. Furthermore, a dominant-negative mutant Znf219 inhibited Bmp2-induced chondrocyte differentiation. Our results suggest that Znf219 plays an important role in the regulation of chondrocyte differentiation as a transcriptional partner of Sox9.

The transcription factor Foxc1 is necessary for Ihh–Gli2-regulated endochondral ossification

“…Thus, the identification and characterization of novel transcription factors involved in these processes will contribute to a better understanding of endochondral ossification. Numerous attempts have been made to identify these and we previously identified several transcription factors using a high-throughput assay system [21][22][23][24] and Solexa deep-sequencing technology 25 . However, the transcriptional networks of endochondral ossification are still not fully elucidated.…”

Arid5b facilitates chondrogenesis by recruiting the histone demethylase Phf2 to Sox9-regulated genes

“…18), which links Sox9-mediated transcription with RNA processing during chondrogenesis, and Znf219 (ref. 19) are members of the Sox9-assembled transcriptional complex.…”

Regulation of transcriptional network system during bone and cartilage development

“…SOX9 has been also identified as a transcription factor that specifically binds to the Col2a1 gene [64]. These findings indicate that SOX9 is an essential transcription factor that initiates endochondral ossification by upregulating early chondrogenic genes including Col2a1, Col11a2, and aggrecan [64,65]. Sox5 and Sox6, known to be Sox9 target genes [63], are required for chondrocyte differentiation, because Sox5/Sox6 double knockout mice exhibit pronounced cartilage formation defects (Fig.…”

“…A high-throughput biological assay using the Col2a1 luciferase reporter gene revealed that p54 nrb , ARID5A, and ZNF219 form a transcriptional complex with SOX9 during chondrocyte differentiation (Fig. 3) [65,[70][71][72]. Gene profiling by microarray and RNA-Seq experiments have showed that WWP2 and ARID5B are also required for the SOX9-regulated chondrogenesis (Fig.…”