Developmental Expression Profile of the CXCL12γ Isoform: Insights Into its Tissue‐Specific Role

The CXCL12γ chemokine arises by alternative splicing from Cxcl12, an highly conserved gene that plays pivotal, non‐redundant roles during development. The interaction of the highly cationic carboxy‐terminal (C‐ter) domain of CXCL12γ with glycosaminoglycans (GAG) critically determines the biological properties of this chemokine. Indeed, CXCL12γ isoform displays sustained in vivo recruitment of leukocytes and endothelial progenitor cells as compared to other CXCL12 isoforms. Despite the important, specific roles of CXCL12γ in vivo, the current knowledge about its distribution in embryo and adult tissues is scarce. In this study, we have characterized by both RT‐PCR and immunohistochemistry the expression profile and tissue distribution of CXCL12γ, which showed a distinct mRNA expression pattern during organogenesis that correlates with the specific expression of the CXCL12 γ protein in several tissues and cell types during development. Our results support the biological relevance of CXCL12 γ in vivo, and shed light on the specific roles that this novel isoform could play in muscle development and vascularization as well as on the regulation of essential homeostatic functions during the embryonic development. Anat Rec, 292:891–901, 2009. © 2009 Wiley‐Liss, Inc.