Adamts4 coordinates the transcriptomic profile of primary rat costal chondrocytes.

Chondrocytes play a pivotal role in cartilage tissue engineering. ADAMTS4 gene encodes aggrecanase-1, which is known to affect chondrocyte biology by regulating aggrecan degradation. However, the molecular mechanism by which ADAMTS4 regulates chondrocyte phenotype remains unclear. To comprehensively investigate Adamts4-regulated genes in primary rat costal chondrocytes, we conducted siRNA-mediated Adamts4 knockdown alongside RNA sequencing (RNA-seq), co-immunoprecipitation coupled with mass spectrometry (CO-IP/MS), and enhanced RNA immunoprecipitation sequencing (iRIP-seq). Our results demonstrated that Adamts4 knockdown did not affect chondrocyte apoptosis. However, Adamts4 silencing markedly changed the expression levels of numerous genes linked to cell differentiation and cell cycle progression. CO-IP/MS experiments showed that Adamts4 extensively interacted with RNA-binding proteins (RBPs) in rat chondrocytes. iRIP-seq data suggested that Adamts4 bound to a large number of transcripts, especially those with AU-rich motifs at coding regions. Most interestingly, we found three genes Hmox1, Acan, and Col2a1, which were deregulated upon Adamts4 silencing and enriched in the Adamts4 RIP samples. Altogether, these results indicate that Adamts4 knockdown remarkably modulates the transcriptomic profile of rat chondrocytes. Interactions with RBPs or target mRNAs might contribute to Adamts4-mediated alterations in gene expression. These findings warrant further investigation of the crucial target genes of ADAMTS4 in the regulation of human chondrocyte behaviors.