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Regulation of retinoid receptors by retinoic acid and axonal contact in Schwann cells.

Latasa MJ, Cosgaya JM - PLoS ONE (2011)

Bottom Line: As retinoic acid (RA) and other retinoids have a profound effect as regulators of the myelination program, we sought to investigate how their nuclear receptors levels were regulated in this cell type.The upregulation by axonal contact mimickers and the transcriptional downregulation by RA were dependent on de novo protein synthesis and did not involve changes in mRNA stability.All together, our results show that retinoid receptors are regulated in a complex manner in Schwann cells, suggesting that they could have a prominent role as regulators of Schwann cell physiology.

View Article: PubMed Central - PubMed

Affiliation: Department of Endocrine and Nervous System Physiopathology, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.

ABSTRACT

Background: Schwann cells (SCs) are the cell type responsible for the formation of the myelin sheath in the peripheral nervous system (PNS). As retinoic acid (RA) and other retinoids have a profound effect as regulators of the myelination program, we sought to investigate how their nuclear receptors levels were regulated in this cell type.

Methodology/principal findings: In the present study, by using Schwann cells primary cultures from neonatal Wistar rat pups, as well as myelinating cocultures of Schwann cells with embryonic rat dorsal root ganglion sensory neurons, we have found that sustained expression of RXR-γ depends on the continuous presence of a labile activator, while axonal contact mimickers produced an increase in RXR-γ mRNA and protein levels, increment that could be prevented by RA. The upregulation by axonal contact mimickers and the transcriptional downregulation by RA were dependent on de novo protein synthesis and did not involve changes in mRNA stability. On the other hand, RAR-β mRNA levels were only slightly modulated by axonal contact mimickers, while RA produced a strong transcriptional upregulation that was independent of de novo protein synthesis without changes in mRNA stability.

Conclusions/significance: All together, our results show that retinoid receptors are regulated in a complex manner in Schwann cells, suggesting that they could have a prominent role as regulators of Schwann cell physiology.

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Related in: MedlinePlus

Transcriptional regulation of RAR-β and RXR-γ by RA.(A) The levels of newly synthesized hnRNA for RAR-β and RXR-γ were determined by RT-Q-PCR in myelinating cocultures treated with 1 µM RA for the indicated times. All values are shown as the mean ± SD relative to their respective controls. (B) Newly synthesized RAR-β and RXR-γ hnRNA was determined in isolated SCs treated or not with 1 µM RA for 48 hours. All values are shown as the mean ± SD relative to their respective controls. (C) SCs were treated with 1 µM RA in combination or not with the axonal mimickers forskolin and BPE for 24 hours in the presence or absence of 10 µg/ml of the protein synthesis inhibitor cycloheximide (CHX), and RAR-β and RXR-γ mRNA levels were determined by Q-RT-PCR. All values are shown as the mean ± SEM relative to their respective controls in the absence of cycloheximide and retinoic acid. (D) Isolated SCs were pretreated or not with 1 µM RA for 24 hours and the stability of RAR-β and RXR-γ mRNA was determined by incubating the cells with 10 µg/ml actinomycin D for varying times in the continuous presence or not of the retinoid. All values are shown as the mean ± SD relative to their respective time zero. RA-treated cells presented RAR-β mRNA levels 59 times higher than control cells, while RXR-γ levels were only 40% of those from control cultures.
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pone-0017023-g008: Transcriptional regulation of RAR-β and RXR-γ by RA.(A) The levels of newly synthesized hnRNA for RAR-β and RXR-γ were determined by RT-Q-PCR in myelinating cocultures treated with 1 µM RA for the indicated times. All values are shown as the mean ± SD relative to their respective controls. (B) Newly synthesized RAR-β and RXR-γ hnRNA was determined in isolated SCs treated or not with 1 µM RA for 48 hours. All values are shown as the mean ± SD relative to their respective controls. (C) SCs were treated with 1 µM RA in combination or not with the axonal mimickers forskolin and BPE for 24 hours in the presence or absence of 10 µg/ml of the protein synthesis inhibitor cycloheximide (CHX), and RAR-β and RXR-γ mRNA levels were determined by Q-RT-PCR. All values are shown as the mean ± SEM relative to their respective controls in the absence of cycloheximide and retinoic acid. (D) Isolated SCs were pretreated or not with 1 µM RA for 24 hours and the stability of RAR-β and RXR-γ mRNA was determined by incubating the cells with 10 µg/ml actinomycin D for varying times in the continuous presence or not of the retinoid. All values are shown as the mean ± SD relative to their respective time zero. RA-treated cells presented RAR-β mRNA levels 59 times higher than control cells, while RXR-γ levels were only 40% of those from control cultures.

Mentions: Retinoic acid produced a strong increase in RAR-β hnRNA levels already at day 1 of treatment, an increment that was maintained, although at a lower level, for the two-weeks time point analyzed (Fig. 8A). Conversely, RXR-γ hnRNA levels were already reduced after 1-day treatment with the retinoid, reduction that was maintained and even exacerbated during the whole time period analyzed. Similarly, in isolated SCs, treatment with the hormone for 48 h produced an increase in RAR-β hnRNA, whilst down-regulating RXR-γ hnRNA levels (Fig. 8B).


Regulation of retinoid receptors by retinoic acid and axonal contact in Schwann cells.

Latasa MJ, Cosgaya JM - PLoS ONE (2011)

Transcriptional regulation of RAR-β and RXR-γ by RA.(A) The levels of newly synthesized hnRNA for RAR-β and RXR-γ were determined by RT-Q-PCR in myelinating cocultures treated with 1 µM RA for the indicated times. All values are shown as the mean ± SD relative to their respective controls. (B) Newly synthesized RAR-β and RXR-γ hnRNA was determined in isolated SCs treated or not with 1 µM RA for 48 hours. All values are shown as the mean ± SD relative to their respective controls. (C) SCs were treated with 1 µM RA in combination or not with the axonal mimickers forskolin and BPE for 24 hours in the presence or absence of 10 µg/ml of the protein synthesis inhibitor cycloheximide (CHX), and RAR-β and RXR-γ mRNA levels were determined by Q-RT-PCR. All values are shown as the mean ± SEM relative to their respective controls in the absence of cycloheximide and retinoic acid. (D) Isolated SCs were pretreated or not with 1 µM RA for 24 hours and the stability of RAR-β and RXR-γ mRNA was determined by incubating the cells with 10 µg/ml actinomycin D for varying times in the continuous presence or not of the retinoid. All values are shown as the mean ± SD relative to their respective time zero. RA-treated cells presented RAR-β mRNA levels 59 times higher than control cells, while RXR-γ levels were only 40% of those from control cultures.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3046125&req=5

pone-0017023-g008: Transcriptional regulation of RAR-β and RXR-γ by RA.(A) The levels of newly synthesized hnRNA for RAR-β and RXR-γ were determined by RT-Q-PCR in myelinating cocultures treated with 1 µM RA for the indicated times. All values are shown as the mean ± SD relative to their respective controls. (B) Newly synthesized RAR-β and RXR-γ hnRNA was determined in isolated SCs treated or not with 1 µM RA for 48 hours. All values are shown as the mean ± SD relative to their respective controls. (C) SCs were treated with 1 µM RA in combination or not with the axonal mimickers forskolin and BPE for 24 hours in the presence or absence of 10 µg/ml of the protein synthesis inhibitor cycloheximide (CHX), and RAR-β and RXR-γ mRNA levels were determined by Q-RT-PCR. All values are shown as the mean ± SEM relative to their respective controls in the absence of cycloheximide and retinoic acid. (D) Isolated SCs were pretreated or not with 1 µM RA for 24 hours and the stability of RAR-β and RXR-γ mRNA was determined by incubating the cells with 10 µg/ml actinomycin D for varying times in the continuous presence or not of the retinoid. All values are shown as the mean ± SD relative to their respective time zero. RA-treated cells presented RAR-β mRNA levels 59 times higher than control cells, while RXR-γ levels were only 40% of those from control cultures.
Mentions: Retinoic acid produced a strong increase in RAR-β hnRNA levels already at day 1 of treatment, an increment that was maintained, although at a lower level, for the two-weeks time point analyzed (Fig. 8A). Conversely, RXR-γ hnRNA levels were already reduced after 1-day treatment with the retinoid, reduction that was maintained and even exacerbated during the whole time period analyzed. Similarly, in isolated SCs, treatment with the hormone for 48 h produced an increase in RAR-β hnRNA, whilst down-regulating RXR-γ hnRNA levels (Fig. 8B).

Bottom Line: As retinoic acid (RA) and other retinoids have a profound effect as regulators of the myelination program, we sought to investigate how their nuclear receptors levels were regulated in this cell type.The upregulation by axonal contact mimickers and the transcriptional downregulation by RA were dependent on de novo protein synthesis and did not involve changes in mRNA stability.All together, our results show that retinoid receptors are regulated in a complex manner in Schwann cells, suggesting that they could have a prominent role as regulators of Schwann cell physiology.

View Article: PubMed Central - PubMed

Affiliation: Department of Endocrine and Nervous System Physiopathology, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.

ABSTRACT

Background: Schwann cells (SCs) are the cell type responsible for the formation of the myelin sheath in the peripheral nervous system (PNS). As retinoic acid (RA) and other retinoids have a profound effect as regulators of the myelination program, we sought to investigate how their nuclear receptors levels were regulated in this cell type.

Methodology/principal findings: In the present study, by using Schwann cells primary cultures from neonatal Wistar rat pups, as well as myelinating cocultures of Schwann cells with embryonic rat dorsal root ganglion sensory neurons, we have found that sustained expression of RXR-γ depends on the continuous presence of a labile activator, while axonal contact mimickers produced an increase in RXR-γ mRNA and protein levels, increment that could be prevented by RA. The upregulation by axonal contact mimickers and the transcriptional downregulation by RA were dependent on de novo protein synthesis and did not involve changes in mRNA stability. On the other hand, RAR-β mRNA levels were only slightly modulated by axonal contact mimickers, while RA produced a strong transcriptional upregulation that was independent of de novo protein synthesis without changes in mRNA stability.

Conclusions/significance: All together, our results show that retinoid receptors are regulated in a complex manner in Schwann cells, suggesting that they could have a prominent role as regulators of Schwann cell physiology.

Show MeSH
Related in: MedlinePlus