RESUMO
This study describes the distribution of parathyroid hormone-related protein (PTHrP) antigen and its mRNA in seven species of cartilaginous fish from six elasmobranch families. Antigen was detected using antibodies to synthetic human PTHrP and the mRNA with a riboprobe to human PTHrP gene sequence. The distribution pattern of PTHrP in the cartilaginous fish studied, reflected that observed in mammals but PTHrP further occurs in some sites unique to cartilaginous fish. Of particular note was the demonstration of PTHrP in the shark skeleton, which although considered not to contain bone, may form by a process similar to that forming the early stages of mammalian endochondral bone. The distribution of PTHrP in the elasmobranch skeleton resembled the distribution of PTHrP in the developing mammalian skeleton. Differences in the staining pattern between antisera to N-terminal PTHrP and mid-molecule PTHrP in the brain and pituitary suggested that the PTHrP molecule might be post-translationally processed in these tissues. The successful use of antibodies and a probe to human PTHrP in tissues from the early vertebrates examined in this study suggests that the PTHrP molecule is conserved from elasmobranchs to humans.
Assuntos
Elasmobrânquios/metabolismo , Biossíntese de Proteínas , Animais , Anticorpos Monoclonais , Antígenos/análise , Humanos , Imuno-Histoquímica/métodos , Hibridização In Situ/métodos , Proteína Relacionada ao Hormônio Paratireóideo , Proteínas/genética , Proteínas/imunologia , Sondas RNA , RNA Mensageiro/análise , Distribuição TecidualRESUMO
Parathyroid hormone-related protein (PTHrP) is a hypercalcemic factor in mammals. The PTHrP antigen has been localized in both bony and cartilaginous fish tissues. Sites of localization included gills, skin and kidney, organs involved in osmoregulation. Physiological and localization experiments were carried out in elasmobranchs to dissect PTHrP's possible role in osmoregulation. The effects of alterations in the external environment on PTHrP in sharks were examined by keeping juvenile animals under conditions of increased temperature or decreased salinity. There were no alterations in the PTHrP levels in either the circulation or tissues. Significant correlations between plasma PTHrP, electrolyte and urea levels were seen in the pretreatment samples. The localization of PTHrP by immunohistochemistry and in situ hybridization revealed conserved sites of distribution from elasmobranchs to mammals, including skin, kidney, muscle and skeleton.
Assuntos
Elasmobrânquios/sangue , Elasmobrânquios/metabolismo , Proteínas/metabolismo , Sais/metabolismo , Água do Mar , Animais , Encéfalo/metabolismo , Elasmobrânquios/genética , Eletrólitos/metabolismo , Brânquias/metabolismo , Imuno-Histoquímica , Hibridização In Situ , Rim/metabolismo , Fígado/metabolismo , Músculo Esquelético/metabolismo , Proteína Relacionada ao Hormônio Paratireóideo , Hipófise/metabolismo , Proteínas/genética , RNA Mensageiro/análise , RNA Mensageiro/genética , Radioimunoensaio , Glândula de Sal/metabolismo , Pele/metabolismo , Coluna Vertebral/metabolismo , TemperaturaRESUMO
Tissues from a range of fish were examined for the presence of parathyroid hormone-related protein (PTHrP) to investigate PTHrP protein distribution and PTHrP gene expression in jawless fish, cartilaginous fish, and bony fish. Immunoreactive PTHrP was localized using antisera to N-terminal and mid-molecule regions of human PTHrP and PTHrP gene expression examined using a digoxigenin labeled riboprobe to a conserved region of the mammalian PTHrP gene. In all of the fish studied, PTHrP protein and messenger RNA (mRNA) were localized to the skin, kidney, and skeletal muscle, following the pattern seen in higher vertebrates. Additional sites of localization for both protein and mRNA included gill, nerve cord, and pituitary, as well as developing dermal denticles and rectal gland in the elasmobranch species. The sites of PTHrP distribution indicate that PTHrP may have roles in ionoregulation as well as growth and differentiation in fish, as has been suggested in higher vertebrates. The results imply that the distribution of PTHrP is widespread in fish and that there is homology between the PTHrP molecules found in humans and fish. The conservation of localization and possible similarity of the PTHrP molecules between tetrapods and fish suggests that PTHrP has a number of fundamental roles in vertebrates. J. Exp. Zool. 284:541-548, 1999.
Assuntos
Peixes/metabolismo , Hormônio Paratireóideo/metabolismo , Proteínas/metabolismo , Animais , Expressão Gênica , Humanos , Técnicas Imunoenzimáticas , Hibridização In Situ , Hormônio Paratireóideo/genética , Proteína Relacionada ao Hormônio Paratireóideo , Proteínas/genética , RNA Mensageiro/metabolismo , Especificidade da Espécie , Distribuição TecidualRESUMO
1. Parathyroid hormone-related protein (PTHrP) is an important mediator of humoral hypercalcaemia of malignancy in humans. Normal human subjects have very low levels of PTHrP in their circulation. 2. Parathyroid hormone-related protein has recently been demonstrated in high levels in the circulation and tissues of the sea bream and the dogfish, leading to the hypothesis that PTHrP may be a 'classical' hormone in fish. 3. Immunohistochemistry and in situ hybridization were performed to investigate the evolutionary history of PTHrP. Tissues were examined from a number of lower vertebrates, including lungfish, lamprey and several species of bony and cartilaginous fish. Parathyroid hormone-related protein was localized to the skin and to kidney tubules in all animals studied. In the developing lungfish, PTHrP was observed in the notochord, developing brain and skeletal muscle layers. These results suggest that PTHrP is of ancient origin and has a basic and fundamental function in vertebrates.