title: Selective coexpression of insulin receptor-related receptor (IRR) and TRK in NGF-sensitive neurons.
abstract: The insulin receptor-related receptor (IRR) has recently been identified as a member of the insulin receptor tyrosine kinase family; however, its endogenous ligand and biological function are still unknown. In contrast to the very widespread pattern of expression of the homologous insulin and IGF-I receptors, IRR demonstrates a very restricted cellular distribution. Using in situ hybridization and immunohistochemistry, we now show that the expression of this receptor is selectively concentrated in a subset of neurons where its appearance is closely associated with that of the NGF receptor TRK. IRR and TRK demonstrate synchronized patterns of coexpression in neural crest-derived sensory and sympathetic neurons and in non-neural crest basal forebrain and striatal neurons. Both appear early in the embryonic development of dorsal root and trigeminal neurons and somewhat later, near the time of birth, in sympathetic neurons. Expression of both IRR and TRK appears perinatally in basal forebrain neurons, reaching maximal levels about postnatal day 20. This association is highly selective, since TRK mRNA is not detected anywhere in the developing nervous system in the absence of coordinate IRR expression, and the same is true for IRR expression with respect to TRK. In the adult rat, the majority of TRK-positive sensory neurons still express IRR mRNA, and coexpression in sympathetic and forebrain neurons continues without evidence of diminution. These findings are consistent with a functional linkage of the IRR and TRK receptors in NGF-sensitive neurons.
authors.affiliation: Developmental Endocrinology Branch, NICHD, NIH, Bethesda, Maryland 20892.
authors.forename: R R
authors.initials: RR
authors.lastname: Reinhardt
authors.forename: E
authors.initials: E
authors.lastname: Chin
authors.forename: B
authors.initials: B
authors.lastname: Zhang
authors.forename: R A
authors.initials: RA
authors.lastname: Roth
authors.forename: C A
authors.initials: CA
authors.lastname: Bondy
mesh_terms: D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D017403:In Situ Hybridization; D009414:Nerve Growth Factors / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D015347:RNA Probes; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism*; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism*
chemical_list: D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; D015347:RNA Probes; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D020917:Receptor, trkA; C066542:insulin receptor-related receptor