Discordance of prolactin gene transcription, mRNA storage, and hormone release in individual mammotropes

Abstract

The mammotrope has traditionally been a favored model for studies of hormonal gene expression, biosynthesis, and release. However, the primary site(s) at which these processes are coordinated and integrated remains to be established. Because there is considerable indirect evidence to suggest that the rate of prolactin (PRL) secretion is dictated, in large part, at the level of transcription, the relative contribution of other putative regulatory foci has received less attention. The purpose of the present study was to test the primacy of transcriptional regulation at the single-cell level. To this end, we quantified within individual mammotropes the relationship between PRL gene transcription, mRNA storage, and hormone release. This was accomplished by the combined application of "real-time" measurement of gene expression, in situ hybridization cytochemistry, and reverse hemolytic plaque assay, respectively. Our results demonstrate a quantitative dissociation among these variables, suggesting that control mechanisms besides transcription play a primary role in integrating and coordinating flow through the PRL secretory pathway.

Dynamic Changes in Spontaneous Intracellular Free Calcium Oscillations and Their Relationship to Prolactin Gene Expression in Single, Primary Mammotropes

“…In this scenario, a particular series of [Ca 2ϩ ] i oscillations would act over the short term to evoke hormone release and over the long term to induce gene expression required for replenishment of hormonal stores. Our recent observation on the dissociation between PRL gene transcription, mRNA storage, and hormone release within the same mammotropes is entirely consistent with this possibility (25).…”

Adiponectin limits differentiation and trophoblast invasion in human endometrial cells

“…This lack of correspondence between RNA and protein levels is not surprising and has been already described (Salari et al 2012, Beileke et al 2015. One study specifically evidenced the mismatch between the prolactin mRNA expression and hormone release (Castaño et al 1997). Thirdly, we demonstrated that adiponectin downregulates IGFBP-1 and connexin-43 mRNA expression levels.…”

The expression and regulation of matrix metalloproteinase-3 is critically modulated by Porphyromonas gingivalis lipopolysaccharide with heterogeneous lipid A structures in human gingival fibroblasts

“…Moreover, it was noted that both P. gingivalis LPS 1435/1449 and E. coli LPS significantly upregulated the expression of MMP-2 mRNA but not its protein as compared to the controls. A number of factors may account for this finding, such as the stability of mRNA, its processing and splicing patterns, half-life of the target protein and post-translational modifications [43,44]. Therefore, in the present study increase in MMP-2 mRNA expression level may not be necessarily reflected at its protein level.…”

“…Based upon the current findings, further study may be warranted to explore the association of different isoforms of P. gingivalis LPS with periodontal conditions in periodontal patients and the possible effect of periodontal treatment on the expression of these LPS isoforms by P. gingivalis . In addition, the discrepancy observed in TIMP-1 mRNA and protein expression following the stimulation of both P. gingivalis LPS 1435/1449 and E. coli LPS in HGFs could be due to the complex regulation of transcription and translation [43,44]. …”