Table 1.
CTRP | Tissue distribution | Regulation | Signaling specificity |
Sites of action | Physiological function | Reference |
---|---|---|---|---|---|---|
CTRP1 | Primarily adipose tissue and placenta | Decreased expression and circulating levels in DIO mice; increased expression in adiponectin KO mice | AMPK 44/42-MAPK | Skeletal muscle | Promotes glucose uptake and skeletal muscle fat oxidation; decrease fat mass and enhances insulin sensitivity in transgenicmice fed a high-fat diet | 29, 36, 48 |
CTRP2 | Primarily adipose tissue; lower levels in lung, liver, testis, uterus | Increased expression in the adipose tissue of ob/ob mice | AMPK | Skeletal muscle ? | Promotes fatty acid oxidation in cultured C2C12 myotubes | 36 |
CTRP3 | Adipose tissue, kidney, testis, uterus, bone | Decreased expression and circulating levels in DIO mice; increased expression in overnight fasted mice | AKT | Liver | Suppresses hepatic gluconeogenic gene expression and glucose output; ameliorates diet-induced hepatic steatosis by inhibiting liver triglyceride synthesis | 36, 49 99, 109, 112–116 |
p44/42-MAPK p38-MAPK | Endothelial cells | Inceases migration and proliferation of endothelial cells in vitro | ||||
AKT | Heart | Increases survival and decreases infarct size following myocardial infarction | ||||
? | Monocytes, adipocytes and colonic fibroblasts | Decreases LPS-induced inflammatory response | ||||
CTRP5 | Adipose tissue, eye, testis skeletal muscle, brain spleen, uterus | Circulating levels of CTRP5 are increased in db/db and ob/ob mice, and OLETF rats | AMPK | Skeletal muscle ? | Inreases glucose uptake and fatty acid oxidation in mitochondriadepleted myotubes in vitro | 29, 36, 84, 117–123 |
Eye | S163R mutation results in late-onset retinal maculardegeneration in humans | |||||
CTRP6 | Primarily placenta; much lower levels in spleen, lung, testis, prostate, uterus, adipose tissue | Increased expression in the adipose tissue of ob/ob mice; rosiglitazone treament decrease expression in the adipose tissue | ? | ? | ? | 29, 36 |
CTRP7 | Primarily adipose tissue and lung | ? | ? | ? | ? | 29, 36 |
CTRP9 | Primarily adipose tissue | Decreased circulating levels in DIO mice; Increased expression and circulating levels in fasted/re-fed mice | AMPK | Skeletal muscle | Promotes fat oxidation | 47, 124, 130–133, |
AMPK/eNOS | Endothelial cells | Vasorelaxation | ||||
AMPK | Heart | Improved cardiac function following ischemia/reperfusion injury | ||||
p44/42-MAPK PKA | Vascular smooth muscle cells | Increased migration and cell proliferation; reduces neointima formation | ||||
CTRP11 | Primarily adipose tissue and testis; lower levels in brain and kidney | Increased expression in the adipose tissue of fasted/re-fed mice | p44/42-MAPK | Pre-adipocytes | Inhibit adipogenesis | 52 |
CTRP12 | Primarily adipose tissue in humans; primarily testis, adipose, kidney, spleen, uterus in mice | Decreased expression and circulating levels in ob/ob and DIO mice | AKT | Adipose tissue | Promotes glucose uptake in adipocytes | 50, 54,75, 141 |
AKT | Liver | Suppresses hepatic gluconeogenic gene expression and glucose output | ||||
? | Pancreatic β-cells ? | Enhances insulin secretion inlean but not DIO mice; increases glucose-induced insulin secretion in INS-1 cells | ||||
? | Adipose tissue | Suppresses adipose tissue inflammation | ||||
CTRP13 | Primarily adipose, brain, and kidney | Increased expression in the adipose tissue of ob/ob ice and in adipocytes treated with rosiglitazone | AMPK | Adipocytes, myotubes, and hepatocytes | Promotes glucose uptake in cultured adipocytes, myotubes, and hepatocytes | 51, 142 |
AMPK | Liver ? | Suppressed gluconeogenic gene expression and glucose production in cultured H4IIEhepatocytes | ||||
? | Liver ? | Decreased palmitate-induced insulin resistance in cultured hepatocytes by suppressing JNK signaling | ||||
? | Hypothalamus | Suppressed food intake in mice by inhibiting orexigenic neuropeptide (NPY) expression | ||||
Myonectin (CTRP15) | Primarily skeletal muscle | Decreased expression and circulating levels in fasted mice and strikingly induced in fasted/re-fed mice | ? | Adipose tissue and liver | Promotes lipid uptake by increasing the expression of molecules (FATP, FABP) involved in fatty acid uptake | 53 |