Unique form and osmoregulatory function of a neurohypophysial hormone in a urochordate.

The cyclic nonapeptides, oxytocin and vasopressin, are neurohypophysial hormones that regulate many significant physiological processes related especially to reproduction and osmoregulation. In this study, we characterized an oxytocin-related peptide cDNA from a urochordate, Styela plicata, thought to be a sister group to vertebrates. Sequence analysis of the deduced precursor polypeptide revealed that the precursor is composed of three segments: a signal peptide, an oxytocin-like sequence flanked by a Gly C-terminal amidation signal and a Lys-Arg dibasic processing site, and a neurophysin domain, similar to other oxytocin/vasopressin family precursors. However, unlike other members of this family, the tunicate oxytocin-like peptide (CYISDCPNSRFWST-NH2) is a tetradecapeptide. We termed this peptide Styela oxytocin-related peptide (SOP). Furthermore, analyses of mass spectrometry, in situ hybridization, and immunohistochemistry demonstrated production of mature SOP in the cerebral ganglion. To elucidate the physiological action of SOP, we kept the tunicate for 2 d under the three different concentrations of seawater, 60, 100, and 130%, and measured the expression levels of SOP mRNA in the cerebral ganglion. The greatest expression of SOP mRNA was observed in the 60% seawater. In 60% seawater, but not in 100 or 130%, the tunicate mostly closed the atrial and branchial siphons. Therefore, we investigated the contractile effects of SOP on the siphons in vitro. SOP caused contractions in both siphons in a dose-dependent manner. Taken together, these results suggest that SOP acts to prevent the influx of a low concentration of seawater into the body and thus play an important role in osmoregulation.

Molecular analysis of PROP1, PIT1, HESX1, LHX3, and LHX4 shows high frequency of PROP1 mutations in patients with familial forms of combined pituitary hormone deficiency.

UNLABELLED: Combined Pituitary Hormone Deficiency (CPHD) is a prevalent disease in Neuroendocrinology services. The genetic form of CPHD may originate from mutations in pituitary transcription factor (PTF) genes and the pituitary image in these cases may give a clue of what PTF is most probably mutated: defects in LHX4 are usually associated with ectopic posterior pituitary (EPP); defects in LHX3, PIT1, and PROP1, with normally placed posterior pituitary (NPPP); HESX1 mutations are associated with both. OBJECTIVE: To identify mutations in PTF genes in patients with idiopathic hypopituitarism followed in our service, based on the presence or absence of EPP on sellar MRI. METHODS: Forty patients with idiopathic hypopituitarism (36 families, 9 consanguineous), followed in the Neuroendocrinology Outpatient Clinic of UNIFESP, Brazil, were submitted to sequencing analyses of PTF genes as follows: LHX3, HESX1, PIT1, and PROP1 were sequenced in patients with NPPP (26/40) and HESX1 and LHX4 in patients with EPP (14/40). RESULTS: We identified only PROP1 mutations in 9 out of 26 patients with CPHD and NPPP (35%). Since eight of them came from 4 consanguineous families, the prevalence of PROP1 mutations was higher when only consanguineous families were considered (44%, 4/9). At the end of the study, we decided to sequence PROP1 in patients with EPP, just to confirm that they were not candidates for PROP1 mutations. No patients with EPP had PROP1 or other PTF mutations. CONCLUSIONS: Patients with idiopathic CPHD and NPPP, born from consanguineous parents, are the strong candidates for PROP1 mutations. Other developmental gene(s) may be involved in the genesis of idiopathic hypopituitarism associated with EPP.

Molecular analysis of PROP1, PIT1, HESX1, LHX3, and LHX4 shows high frequency of PROP1 mutations in patients with familial forms of combined pituitary hormone deficiency

Combined Pituitary Hormone Deficiency (CPHD) is a prevalent disease in Neuroendocrinology services. The genetic form of CPHD may originate from mutations in pituitary transcription factor (PTF) genes and the pituitary image in these cases may give a clue of what PTF is most probably mutated: defects in LHX4 are usually associated with ectopic posterior pituitary (EPP); defects in LHX3, PIT1, and PROP1, with normally placed posterior pituitary (NPPP); HESX1 mutations are associated with both. OBJECTIVE: To identify mutations in PTF genes in patients with idiopathic hypopituitarism followed in our service, based on the presence or absence of EPP on sellar MRI. METHODS: Forty patients with idiopathic hypopituitarism (36 families, 9 consanguineous), followed in the Neuroendocrinology Outpatient Clinic of UNIFESP, Brazil, were submitted to sequencing analyses of PTF genes as follows: LHX3, HESX1, PIT1, and PROP1 were sequenced in patients with NPPP (26/40) and HESX1 and LHX4 in patients with EPP (14/40). RESULTS: We identified only PROP1 mutations in 9 out of 26 patients with CPHD and NPPP (35 percent). Since eight of them came from 4 consanguineous families, the prevalence of PROP1 mutations was higher when only consanguineous families were considered (44 percent, 4/9). At the end of the study, we decided to sequence PROP1 in patients with EPP, just to confirm that they were not candidates for PROP1 mutations. No patients with EPP had PROP1 or other PTF mutations. CONCLUSIONS: Patients with idiopathic CPHD and NPPP, born from consanguineous parents, are the strong candidates for PROP1 mutations. Other developmental gene(s) may be involved in the genesis of idiopathic hypopituitarism associated with EPP.

Deficiência Combinada de Hormônios Hipofisários (DCHH) é uma doença prevalente em todos os serviços de Neuroendocrinologia. A DCHH de origem genética pode resultar de mutações nos genes de fatores de transcrição hipofisários (FTH), e a ressonância magnética (RM) de sela desses pacientes pode indicar qual FTH tem maior probabilidade de estar mutado: mutações no LHX4 estão geralmente associadas a neuro-hipófise ectópica (NHE); mutações no LHX3, PIT1 e PROP1, a neuro-hipófise tópica (NHT); mutações no HESX1 podem estar associadas a NHE e NHT. OBJETIVO: Identificar mutações nos FTH em pacientes acompanhados em nosso serviço, portadores de hipopituitarismo idiopático, selecionando os genes a serem estudados de acordo com a presença ou ausência de NHE à RM sela. MÉTODOS: Os genes dos FTH foram seqüenciados em 40 pacientes com hipopituitarismo idiopático (36 famílias, 9 consangüíneas), acompanhados na unidade de Neuroendocrinologia da UNIFESP, SP, Brasil: LHX3, HESX1, PIT1 e PROP1 foram seqüenciados nos pacientes com NHT (26/40) e HESX1 e LHX4, nos pacientes com NHE (14/40). RESULTADOS: Somente mutações PROP1 foram identificadas em 9 de 26 pacientes (35 por cento) com NHT, 8 deles provenientes de 4 famílias consangüíneas (4/9, 44 por cento). Uma vez que mutações no PROP1 foram tão freqüentes, decidimos, ao final do estudo, seqüenciá-lo também nos pacientes com NHE. Nenhum paciente com NHE apresentou mutações no PROP1 ou em outro FTH. CONCLUSÃO: Mutações no gene PROP1 foram encontradas em 22,5 por cento (9/40) de todos os pacientes, em 35 por cento (9/26) dos pacientes com NHT e em 44 por cento (4/9) se considerarmos somente as famílias consangüíneas. Portanto, pacientes com DCHH idiopática e NHT, provenientes de famílias de pais consangüíneos, são os melhores candidatos a mutações PROP1.

Prolactin-releasing activity of neurohypophysial hormones: structure-function relationship.

Oxytocin (OT) and arginine vasopressin (AVP) have been reported to release PRL both in vivo and in vitro. The objectives of this study were 1) to compare the potencies of the PRL-releasing activities of OT and TRH using cultured anterior pituitary (AP) cells, and 2) to assess the PRL-releasing activity of naturally occurring neurohypophysial hormones and selected analogs. AP cells were incubated with peptides for 15 min, and medium PRL concentrations were determined by enzyme-linked immunosorbent assay. OT at 25, 100, and 400 nM increased PRL release by 110%, 175%, and 270%, respectively; higher concentrations (1600 and 6400 nM) did not cause a further increase in PRL release. TRH was 5-10 times more potent than OT on a molar basis. GH3 cells, a somatommamotroph tumor cell line, did not respond to OT and related compounds, but showed a similar responsiveness to TRH as AP cells. Twelve neurohypophysial peptides and selected analogs were incubated with AP cells, and their relative PRL-releasing activities were compared. OT and arginine vasotocin (AVT) showed the highest PRL-releasing activity. T4-G7-oxytocin, mesotocin, isotocin, lysine vasotocin, and AVP showed a moderate PRL-releasing activity, whereas, lysine vasopressin, desmopressin, tocinoic acid, pressinoic acid, and oxytocin free acid showed very low or no PRL-releasing activity. Coincubation of OT, AVT, or AVP with a specific OT receptor antagonist abolished their PRL-releasing activity. We conclude that 1) OT and related peptides are capable of stimulating PRL release in vitro, but their potencies are significantly lower than that of TRH; 2) unlike primary AP cells, GH3 cells are unresponsive to OT and related peptides; 3) AVT and AVP probably stimulate PRL release by acting via an OT receptor; and 4) the amino acid residues in positions 3 and 8 in the peptide chain and an amidated C-terminus are critical for the PRL-releasing activity of the neurohypophysial peptides.