Accumulation of Protoporphyrin-IX in Rat Leydig Cells Following Induction by 5-Aminolevulinic Acid and Tramadol

BackgroundUnder appropriate culture conditions, undifferentiated embryonic stem (ES) cells can undergo multiple self-renewal cycles without loss of pluripotency suggesting they must be equipped with specific defense mechanisms to ensure sufficient genetic stability during self-renewal expansion. The ATP binding cassette transporter ABCG2 is expressed in a wide variety of somatic and embryonic stem cells. However, whether it plays an important role in stem cell maintenance remains to be defined.Methodology/Principal FindingsHere we provide evidence to show that an increase in the level of ABCG2 was observed accompanied by ES colony expansion and then were followed by decreases in the level of protoporphyrin IX (PPIX) indicating that ABCG2 plays a role in maintaining porphyrin homoeostasis. RNA-interference mediated inhibition of ABCG2 as well as functional blockage of ABCG2 transporter with fumitremorgin C (FTC), a specific and potent inhibitor of ABCG2, not only elevated the cellular level of PPIX, but also arrest the cell cycle and reduced expression of the pluripotent gene Nanog. Overexpression of ABCG2 in ES cells was able to counteract the increase of endogenous PPIX induced by treatment with 5-Aminolevulinic acid suggesting ABCG2 played a direct role in removal of PPIX from ES cells. We also found that excess PPIX in ES cells led to elevated levels of reactive oxygen species which in turn triggered DNA damage signals as indicated by increased levels of γH2AX and phosphorylated p53. The increased level of p53 reduced Nanog expression because RNA- interference mediated inhibition of p53 was able to prevent the downregulation of Nanog induced by FTC treatment.Conclusions/SignificanceThe present work demonstrated that ABCG2 protects ES cells from PPIX accumulation during colony expansion, and that p53 and γH2AX acts as a downstream checkpoint of ABCG2-dependent defense machinery in order to maintain the self-renewal of ES cells.

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“…ALA is a known precursor of PPIX [20], [28], [29], which indeed induced accumulation of PPIX in ES cells (Fig. 5D).…”

Section: Resultsmentioning

confidence: 83%

Porphyrin Homeostasis Maintained by ABCG2 Regulates Self-Renewal of Embryonic Stem Cells

Susanto

Lin

Chen³

et al. 2008

PLoS ONE

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“…Tramadol is a safe and well‐tolerated centrally acting, narcotic‐like analgesic indicated for the management of moderate to moderately severe pain in adults and is available in both short‐ and long‐acting formulations. It has been suggested that in rat Leydig cells (R 2 C), exogenous ALA and tramadol induced protoporphyrin accumulation could possibly help to diminish pain after ALA‐PDT treatment and allow for the use of lower concentrations of ALA during therapy .…”

Section: Introductionmentioning

confidence: 99%

Two‐step irradiance schedule versus single‐dose tramadol sustained‐release tablets for pain control during topical 5‐aminolevulinic acid‐photodynamic therapy of condyloma acuminatum in Chinese patients: A randomized comparative study

et al. 2014

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Accumulation of Protoporphyrin-IX in Rat Leydig Cells Following Induction by 5-Aminolevulinic Acid and Tramadol

Abstract: The results suggested that in R(2)C cells, exogenous ALA and tramadol induced protoporphyrin accumulation. This information is useful for two reasons. First, it may help to diminish pain after ALA-PDT treatment; and second, it allows the use of lower concentrations of ALA during therapy.

Cited by 2 publications

References 15 publications

Porphyrin Homeostasis Maintained by ABCG2 Regulates Self-Renewal of Embryonic Stem Cells

Porphyrin Homeostasis Maintained by ABCG2 Regulates Self-Renewal of Embryonic Stem Cells

Two‐step irradiance schedule versus single‐dose tramadol sustained‐release tablets for pain control during topical 5‐aminolevulinic acid‐photodynamic therapy of condyloma acuminatum in Chinese patients: A randomized comparative study

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