Evidence for stanniocalcin and a related receptor in annelids

The stanniocalcin family of proteins

“…Sodium transport by the skin is mediated by cAMP, although the ligands involved have yet to be identified (Milde et al, 2001). However, leeches also require calcium and actively accumulate it across the skin at rates similar to those reported in freshwater fish (Tanega et al, 2004). The rate of Ca 21 uptake also varies in magnitude, indicating that the process is regulated, and the evidence suggests that one of these regulators could be STC-related.…”

“…The rate of Ca 21 uptake also varies in magnitude, indicating that the process is regulated, and the evidence suggests that one of these regulators could be STC-related. Binding studies have revealed saturable, high-affinity STC receptors on leech microsomal membranes (Tanega et al, 2004), many of which are in the skin (Wagner, unpublished). Furthermore, injections of fish STC are capable of doubling the rates of calcium uptake in leeches, proving that the process is regulated.…”

“…Furthermore, injections of fish STC are capable of doubling the rates of calcium uptake in leeches, proving that the process is regulated. Leech tissue extracts also inhibit GCAT in fish and contain at least two STCimmunoreactive proteins, one of which is heavily glycosylated (Tanega et al, 2004). One source of ligand resides in the skin.…”

“…Sited at regular intervals throughout the outer epidermal layer is a cell type distinguishable only by its low affinity for histological dyes and low glycoprotein content. However, these cells are highly crossreactive to fish STC-1 antiserum and contain a related transcript (Tanega et al, 2004). Moreover, the direct contacts of these STC1cells with adjacent STC receptor-bearing skin cells (Wagner, unpublished) make them the most likely source of the ligand governing calcium uptake by the skin.…”

“…The vacuoles are depleted by food deprivation, suggesting that as in mammals they form a strategic energy reserve (Bradbury,'56). Unlike mammalian adipocytes, however, leech adipose cells are also protein factories and contain a highly developed network of rough endoplasmic reticulum (Bradbury and Meek, '58;Tanega et al, 2004). One of the protein products is STC-related, as adipose cells are also highly crossreactive to fish STC-1 antiserum and also contain a related transcript.…”