(İstanbul Kültür Üniversitesi, 2009) Çoker, Ajda; Arman, Ahmet
Growth hormone (GH), is expressed from anterior
pituitary gland as a 191 amino acid long
polypeptide hormone, has essential role on
postnatal growth. In addition to longitudinal
growth, GH has various effects on carbohydrate,
lipid, protein and mineral metabolisms. GH is
expressed from GH-N gene which is located
within the GH gene cluster consisting three
chorionic somatomammotropin (CS) and GH-V
genes on chromosome 17q22-24. Secretion of GH
is under control of hypothalamic hormones;
somatostatin (SRIF) and growth hormone
releasing hormone (GHRH). GH shows it’s
biological activities by binding to growth
hormone receptor (GHR). After dimerization of
GHR, JAK2 is associated with GHR and activated,
and JAK2 phosphorylates itself, GHR, signal
transducer and activator of transcription (STAT)
and intracellular proteins. Activated STAT dimers
enter into nucleus, bind to promoter of the target genes such as Spi and activate transcription.
Also, RAS/MAPK and PKC signal transduction
pathways are known to take role in GH signaling.
GH signaling is negatively controlled by SHP via
the reduction of intracellular Ca++ levels and also
suppressors of cytokine signaling (SOC) with
dephosphorilation of JAK2.
