Distinct expression pattern of periostin splice variants in chondrocytes and ligament progenitor cells

Abstract

Periostin (<i>POSTN</i>), a secretory matricellular matrix protein, plays a multitude of biologic functions. Various splice variants of <i>POSTN</i> have been described; however, their expression pattern and functional implications are not completely understood. This study was undertaken to decipher the differential expression pattern of <i>POSTN</i> and its splice variants in various tissues and cell types. We show that <i>POSTN</i> was more highly expressed in anterior cruciate ligament (ACL) remnants compared with articular cartilage at the cellular and tissue level. Isoforms 1 and 8 were highly expressed only in articular chondrocytes, suggesting their splice-specific regulation in chondrocytes. To discern the role of total <i>POSTN</i> and full-length human POSTN isoform 1 (<i>hPOSTN-001</i>), we stably transfected human chondrosarcoma 1 (hCh-1) cell line with <i>hPOSTN-001</i> using a pcDNA3.1-hPOSTN-001 construct. RNA-sequencing analysis of hCh-1 cells identified differentially expressed genes with a known role in chondrocyte function and osteoarthritis. Similar expression of a subset of candidate genes was revealed in ACL progenitor cells and chondrocytes as well as in ACL progenitor cells in which <i>POSTN</i> activity was altered by overexpression and by small interfering RNA gene knockdown. Cells expressing total <i>POSTN</i>, not isoform 1, exhibited increased cell adhesion potential. These findings suggest an important role for <i>POSTN</i> in the knee.-Cai, L., Brophy, R. H., Tycksen, E. D., Duan, X., Nunley, R. M., Rai, M. F. Distinct expression pattern of periostin splice variants in chondrocytes and ligament progenitor cells.