Recombinant Human CXCL12 (SDF-1beta) (carrier-free)

CXCL12beta is constitutively expressed by stromal cells. SDF-1alpha (89 amino acids) and SDF-1beta (93 amino acids) are derived from the CXCL12 gene by alternative splicing. They have identical amino acid sequences, differing only by the addition of four amino acids at the carboxy-terminus of the beta form. CXCL12alpha and beta are ubiquitously expressed, and it has been suggested that their activity is regulated through differential proteolytic processing. Proteases present in serum process CXCL12alpha initially at the carboxy-terminus (through carboxypeptidase N) and subsubsequently at the amino-terminus (through CD26); while CXCL12beta is only processed at the animo-terminus. These proteolytic processes affect the chemokine's properties to bind to heparin and cells, and stimulate proliferation and chemotaxis. CXCL12alpha is inactivated by other enzymes such as metalloproteinases, serine proteases, and leukocyte elastase. CXCL12/CXCR4 pair plays a key role in maintaining proliferation and survival of bone marrow stem cell subpopulations under stress conditions. Also, CXCL12 is highly expressed in bone marrow stromal stem cells and regulates growth and survival. CXCL12 promotes survival by inducing anti-apoptotic proteins and decreasing apoptotic proteins, and increasing transcription of cell survival genes. Data suggests that CXCL12beta mediates cells' survival by enhancing autophagy in bone marrow mesenchymal stem cells.