title: Expression of growth hormone receptor isoform exon-3-excluding and exon-3-retaining messenger RNAs in peripheral lymphocytes from normal and acromegalic subjects.
abstract: OBJECTIVE
  To determine the expression of two isoforms of the growth hormone (GH) receptor (GHR), which differ by the presence (GHR3+) or absence (GHR3-) of exon 3, and their correlation with circulating GH and insulin-like growth factor I (IGF-I) in normal subjects and in acromegalic patients.
  
  
  METHODS
  The expression of GHR isoforms was determined by reverse-transcriptase polymerase chain reaction in lymphocytes from 12 normal subjects and from 11 patients with acromegaly. The levels of GHR mRNA were normalized to those of beta-actin, and ratios were calculated to assess the relative levels of expression.
  
  
  RESULTS
  All samples showed expression of both GHR isoforms, but the expression of GHR3+ and GHR3- was similar in acromegalic patients (6.0+/-1.7 vs. 8.3+/-2.0%, mean +/- SE). In contrast, in healthy subjects, GHR3- was the predominant isoform (11.8+/-3.0 vs. 5.1+/-0.68%; p<0.05), and the levels of expression of GHR3- correlated significantly with IGF-I.
  
  
  CONCLUSIONS
  These data demonstrate coexpression of both GHR isoforms under normal and pathological conditions; however, GHR3- is the predominant form in normal subjects and shows a negative correlation with IGF-I levels.
authors.affiliation: Endocrine Research Unit, National Medical Center, Instituto Mexicano del Seguro Social, México, DF, México.
authors.forename: Raquel
authors.initials: R
authors.lastname: Ochoa
authors.forename: Arturo
authors.initials: A
authors.lastname: Zárate
authors.forename: Marco A
authors.initials: MA
authors.lastname: Cerbón
authors.forename: Mauricio
authors.initials: M
authors.lastname: Salcedo
authors.forename: Ricardo
authors.initials: R
authors.lastname: López
authors.forename: Rosa E
authors.initials: RE
authors.lastname: Galván
authors.forename: Marcelino
authors.initials: M
authors.lastname: Hernández
mesh_terms: D000172:Acromegaly / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D001483:Base Sequence; D005091:Exons; D005260:Female; D005786:Gene Expression Regulation; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000097:blood; D011986:Receptors, Somatotropin / Q000097:blood* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D020033:Protein Isoforms; D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone