Identification and sequence analysis of prolactin receptor and its differential expression profile at various developmental stages in striped hamsters

Prolactin (PRL) plays critical roles in regulation of biological functions with the binding of specific prolactin receptor (PRLR). Revealing the expression patterns of PRLR at different developmental stages is beneficial to better understand the role of PRL and its mechanism of action in striped hamsters. In this study, the cDNA sequence of PRLR (2866-base-pairs) was harvested from the pituitary of mature female striped hamsters (Cricetulus barabensis) that contains an 834-base-pair 5′-untranslated region (1-834 bp), a 1848-base-pair open reading frame (835-2682 bp), and a 184-base-pair 3′-untranslated region (2683-2866). The 1848-base-pair open reading frame encodes a mature prolactin-binding protein of 592 amino acids. In the mature PRLR, two prolactin-binding motifs, 12 cysteines, and five potential Asn-linked glycosylation sites were detected. Our results showed that the PRLR mRNA quantity in the hypothalamus, pituitary, ovaries, or testis was developmental-stage-dependent, with the highest level at sub-adult stage and the lowest level at old stage. We also found that PRLR mRNAs were highest in pituitary, medium level in hypothalamus, and lowest in ovaries or testis. PRLR mRNAs were significantly higher in males than in females, except in the hypothalamus and pituitary from 7-week-old striped hamsters. Moreover, the PRLR mRNAs in the hypothalamus, pituitary, and ovaries or testis were positively correlated with the expression levels of GnRH in the hypothalamus. These results indicated that the PRLR has conserved domain in striped hamster, but also possesses specific character. PRLR has multiple biological functions including positively regulating reproduction in the striped hamster.

Structurally conserved C-RFa revealed prolactin releasing activity in vitro and gene expression changes in pituitary of seasonally acclimatized carp

Here we show the cloning and characterization of a novel homolog of prepro C-RFa cDNA from Cyprinus carpió. The deduced preprohormone precursor of 115 amino acids leads to a mature bioactive peptide of 20 amino acids with identical sequence to other teleost C-RFa. Modeling of the mature C-RFa peptide highlighted significant similarity to homologous human PrRP20, specifically the conserved amphipathic system defined by the C-terminal alpha-helix. Clearly, the synthetic C-RFa peptide stimulated prolactin release from primary cultured fish pituitary cells. For the first time, significant variation was shown in C-RFa mRNA and protein levels in the hypothalamus and pituitary between summer- and winter-acclimatized carp. Furthermore, C-RFa protein distribution in carp central nervous tissue was visualized by immunodetection in fibers and cells in hypothalamus, olfactory tract, cerebellum and pituitary stalk. In conclusion, we demonstrated the structure conservation of C-RFa in teleosts and mammals and immunopositive cells and fibers for C-RFa in brain areas. Finally, the increase of C-RFa expression suggests the participation of this hypothalamic factor in the mechanism of modulation in PRL expression in carp.

Hiperprolactinemia en niños y adolescentes, conceptos e interrogantes actuales / Hyperprolactinemia in children and adolescents, current questions and concepts

La hiperprolactinemia constituye la alteración endocrina más común del eje hipotálamo-hipofisario, aunque su prevalencia en la población infantojuvenil no está aún claramente definida. Además de la Prolactina (PRL) nativa (23Kda), se han descripto numerosas variantes moleculares (PRL glicosilada, fosforilada, sulfatada, deaminada, BIG PRL, BIG BIG PRL, etc.), algunas de ellas con menor o ausente actividad biológica. El recién nacido presenta inmadurez fisiológica del eje prolactínico, alcanzando niveles de hasta 800 ng/mL en las primeras horas de vida. Posteriormente, cualquier proceso que interrumpa la secreción de dopamina, interfiera con su liberación hacia los vasos portales hipofisarios o bloquee los receptores dopaminérgicos de las células lactotróficas, puede causar hiperprolactinemia. La patología tumoral constituye el diagnóstico de mayor relevancia. Los prolactinomas poco frecuentes tienen, por su presentación clínica en niños y adolescentes, algunas características destacables. De acuerdo a nuestra experiencia, el retraso puberal puede observarse en aproximadamente el 50 % de las pacientes de sexo femenino y en más del 25 % de los varones. La mayor prevalencia de macroadenomas en varones coincide con los hallazgos en adultos y no dependería de un mayor retraso en el diagnóstico. En pacientes con hiperprolactinemia asintomática debe evaluarse la presencia de proporciones alteradas de isoformas de PRL. La cromatografía en columna con sephadex G100, la precipitación con suspensión de proteína A o con PEG y la ultracentrifugación constituyen los métodos más frecuentemente empleados para la detección de las distintas isoformas de PRL. En nuestra experiencia la B PRL constituyó el 6,6 - 32,6 % de la PRL total y la BB PRL constituyó el 40 y el 72 % de la misma en este grupo de pacientes. Por su efectividad y tolerancia, los agonistas dopaminérgicos constituyen la terapia inicial de elección en pacientes en edad pediátrica. La bromocriptina y la cabergolina han sido empleadas y con resultados similares a los de los pacientes adultos. La adquisición de nuevos conceptos y la mejor comprensión de la fisiología y la fisiopatología de los estados hiperprolactinémicos en niños y adolescentes, han modificado las alternativas diagnósticas y terapéuticas

Hyperprolactinemia is the most common endocrine alteration of the pituitary-hypothalamic axis, although its prevalence in the pediatric and adolescent population is not clearly defined yet. Apart from native (23Kda) Prolactin (PRL), many molecular variants (glycosylated, phosphorilated, sulphated, deaminated PRL, BIG PRL, BIG BIG PRL, etc) have been described, some of them with less or no biological activity. Newborns have physiological immaturity of the prolactin axis, attaining levels of as much as 800 ng/mL during the first hours after birth. Subsequently, any process that discontinues dopamine secretion, interferes with its secretion to the pituitary portal vessels or blocks dopaminergic receptors of lactotrophic cells, may cause hyperprolactinemia. Tumor disease is the major diagnosis. Prolactinomas, though rare, have some noticeable features, given their clinical presentation in children and adolescents. Based on our experience, pubertal delay occurs in approximately 50 % of females and in over 25 % of males. The larger prevalence of macroadenomas in males is consistent with findings in adults and would not be related to a later diagnosis. In patients with asymptomatic hyperprolactinemia, the presence of altered proportions of PRL isoforms should be evaluated. G100 Sephadex column chromatography, precipitation with a protein A suspension or PEG and ultracentrifugation, are the most common methods for detection of PRL isoforms. In our experience, B PRL accounted for 6.6 - 32.6 % of total PRL and BB PRL accounted for 40 to 72 % of total PRL in this group of patients. Because of their effectiveness and tolerance, dopaminergic agonists are the initial therapy of choice in pediatric age patients. Bromocriptine and cabergoline have been used with similar results to those obtained in adults. The new concepts gained and the better insight into the physiology and pathophysiology of hyperprolactinemic conditions in children and adolescents have brought about a change in diagnostic and therapeutic alternatives

Microarray for Genes Associated with Signal Transduction in Diabetic OLETF Keratocytes

PURPOSE: The purpose of this study was to identify differences in signal transduction gene expression between normal and diabetic keratocytes stimulated with interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha). METHODS: Normal and diabetic keratocytes were primarily cultured and treated with 20 ng/ml IL-1alpha and TNF-alpha for 6 h. cDNA was hybridized to an oligonucleotide microarray. Genes identified by the microarray were further evaluated by real-time PCR. RESULTS: Diabetic keratocytes over-expressed components of the MAPK and Notch pathways, and under-expressed components of the insulin, calcium, and TGF-beta pathways. Cytokine treated diabetic keratocytes differentially expressed components of the TGF-beta and MAPK pathways. After IL-1alpha and TNF-alpha treatment, nine genes were under-expressed, falling in the insulin, TGF-beta, and Toll-like receptor pathways. Real-time PCR showed a significant decrease in the IL-6 and TGF-beta2 genes and a significant increase in the Ppm1a gene. CONCLUSIONS: There were some differences in gene expression between normal and diabetic keratocytes related to signal transduction pathways, such as the insulin, MAPK, calcium, and TGF-beta pathways. In addition, IL-1alpha and TNF-alpha stimulating the insulin, TGF-beta, and Toll-like receptor signaling pathways may have different effects in diabetic keratocytes.

La prolactina en el sistema inmunológico: aspectos de síntesis y efectos biológicos / Prolactin in the immune system: synthesis and biological effects

Prolactin (PRL) Is a 23 κDa protein hormone that is produced and secreted by the pituitary lactotrophs. Although PRL was initially regarded as an exclusive pituitary hormone, many nonpituitary tissues were later found to contain and produce this hormone. The most established extrapituitary sites that produce PRL are the decidua, the immune system, brain and endometrium. In the immune system, PRL acts as a cytokine where it plays an important role in human immune responses, including in autoimmune diseases. Here, we will discuss the regulation of PRL gene expression in human lymphocytes and review the functions of PRL made by the immune cells, including its involvement in autoimmunity.

La prolactina es una hormona que fue considerada durante mucho tiempo de origen exclusivamente hipofisario, y cuya función más importante era la promoción de la lactancia. Sin embargo, la prolactina no sólo se sintetiza en diversos sitios del organismo, sino que también participa en una amplia variedad de procesos biológicos. Dentro de los sitios de síntesis extrahipofisarios de esta hormona se encuentran diversas células del sistema inmunológico. A este nivel, la prolactina actúa afectando desde la proliferación celular hasta el estado inmune del individuo. En esta revisión presentamos algunos aspectos relativos a la prolactina de origen linfocitario tales como su síntesis, su participación en el sistema inmunológico y su relación con estados de autoinmunidad.