Assignment¹ of suppressor of cytokine signalling-2 <i>(SOCS2)</i> to porcine chromosome 5 with radiation hybrids

SOCS (suppressor of cytokine signalling) proteins, also known as SSI (stat-induced stat-inhibitor) proteins, are negative regulators of cytokine-induced signal transduction. Cytokines regulate cellular behaviour by interacting with receptors on the plasma membrane of target cells and activating intracellular signal transduction cascades such as the JAK-STAT pathway (Krebs and Hilton, 2000.) Metcalf et al. (2000) generated mice unable to express Socs2, to examine the function of the gene in vivo. Socs2–/– mice grew significantly larger than their wildtype littermates (Metcalf et al., 2000). Characteristics of deregulated growth hormone and insulin-like growth factor-1 (IGF-1) signalling were observed in the Socs2–/– mice, indicating that SOCS2 may have an essential negative regulatory role in the growth hormone/IGF-1 pathway (Metcalf et al., 2000). Greenhalgh et al. (2003) provided compelling evidence that the gigantism displayed in the Socs2–/– phenotype is a result of negative regulation of growth hormone (GH) signalling by creating Socs2–/– mice that were also deficient in endogenous growth hormone production due to a point mutation in the GH-releasing hormone receptor. These Socs2–/–Ghrhrlit/lit mice displayed almost double the response to exogenous growth hormone administration as Socs2+/+Ghrhrlit/lit mice. Genome sequences show that SOCS2 maps to human chromosome 12q (GenBank accession number NM003877) and mouse chromosome 10 (GenBank accession number NM007706). SOCS2 has not previously been mapped in the pig, and this is the first step in further investigation into the gene’s action in a large production animal. Materials and methods