Expression of alternatively spliced isoforms of the parathyroid hormone (PTH)/PTH-related peptide receptor messenger RNA in human kidney and bone cells

Mol Endocrinol. 1996 Sep;10(9):1066-76. doi: 10.1210/mend.10.9.8885241.


Using a PCR-based strategy, two variants of the PTH/PTH-related peptide (PTH-rp) receptor mRNA were identified in human kidney, SaOS-2 human osteoblast cells, and rat bone that are produced by alternative splicing of exons coding for the N-terminal portion of the receptor. In the S-N3-E2 isoform, the exon coding the signal peptide (S) is spliced to an alternative 3'-acceptor site, producing a product respecting the reading frame, but in which the E1 exon is replaced by 12 amino acids derived from the N3 intron. In the S-E2 isoform, in which the E1 exon is deleted by cassette exclusion, the reading frame is changed, but a truncated receptor may be produced by reinitiation of translation at an overlapping stop/start codon. After transfection of COS and Chinese hamster ovary cells with the originally described S-E1-E2 isoform and the two splice variants, active transcription of PTH/PTH-rp receptor mRNA was detected by RT-PCR in all cases. Cell lines transfected with the S-E1-E2 and S-N3-E2 isoforms displayed a 15- to 25-fold and 2- to 3-fold increase, respectively, in cAMP content after stimulation with 2.4 x 10(-7) M human PTH(1-34), whereas cells transfected with the S-E2 isoform did not respond. PTH elicited an increase in intracellular calcium only in cells transfected with the S-E1-E2 isoform. Studies evaluating the surface expression of receptors using anti-human PTH/PTH-rp receptor antibodies and the ability of transfected cells to bind [125I]PTH-rp indicated that the low or absent responses to PTH stimulation resulted, at least in part, from low surface expression of the S-N3-E2 and S-E2 isoforms. These studies support the conclusion that exon E1 is extremely important in promoting surface expression of the PTH/PTH-rp receptor but indicate that isoforms lacking this exon can retain the ability to recognize PTH. The possible intracellular expression of these splice variants, which account for 15-20% of total PTH/PTH-rp receptor mRNA, needs to be evaluated.

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Bone and Bones / metabolism*
  • CHO Cells / metabolism
  • COS Cells / metabolism
  • Calcium / metabolism
  • Cell Membrane / metabolism
  • Cloning, Molecular
  • Cricetinae
  • Cyclic AMP / metabolism
  • DNA Primers
  • DNA, Complementary / chemistry
  • Humans
  • Iodine Radioisotopes
  • Kidney / metabolism*
  • Molecular Sequence Data
  • Parathyroid Hormone / metabolism
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Polymerase Chain Reaction / methods
  • RNA, Messenger / genetics
  • Rabbits
  • Rats
  • Receptor, Parathyroid Hormone, Type 1
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism
  • Receptors, Parathyroid Hormone / genetics*
  • Receptors, Parathyroid Hormone / immunology
  • Receptors, Parathyroid Hormone / metabolism*
  • Sequence Analysis, DNA
  • Transfection


  • DNA Primers
  • DNA, Complementary
  • Iodine Radioisotopes
  • Parathyroid Hormone
  • Peptide Fragments
  • RNA, Messenger
  • Receptor, Parathyroid Hormone, Type 1
  • Receptors, Cell Surface
  • Receptors, Parathyroid Hormone
  • Cyclic AMP
  • Calcium