PARATHYROID-HORMONE RELATED PEPTIDE GENE-EXPRESSION IN HUMAN FETAL AND ADULT HEART

Objective: The aim was to investigate the expression of parathyroid hormone related peptide (PTHrP) gene in the human fetal and adult heart. Methods: Molecular biological techniques were employed as well as immunocytochemistry and western blot analysis using rabbit polyclonal anti-PTHrP(1-34) and anti-PTHrP (56-86) on normal human fetal and adult heart tissues. Northern blot analysis of both normal human fetal and adult heart total RNA, using a human full length cDNA probe, and polymerase chain reaction analysis of normal human fetal and adult heart cDNAs with exon specific oligonucleotides were carried out. Results: Positive staining was detected with both anti-PTHrP(1-34) and anti-PTHrP(56-86) in fetal heart at 12 weeks of gestation. In both fetal and adult hearts, multiple putative PTHrP proteins were observed with apparent molecular mass of 14-125 kDa. Multiple hybridising PTHrP mRNA isoforms (1.4, 2.1, 3.2, and 4.5 kb) were detected in both fetal and adult heart total RNAs. The fetal and adult heart cDNAs amplified from the cDNA libraries showed the presence of the 5' non-coding exon II and coding exons III-IV but not the 5' non-coding exon Ic. Conclusions: PTHrP is expressed in normal human fetal and adult hearts suggesting that it has a function as an endogenous modulator of the cardiovascular system.