Phthalate esters influence FGF-2 translocation in Py1a rat osteoblasts

Area of Science:

• Endocrinology
• Cell Biology
• Toxicology

Background:

• Endocrine disrupting chemicals (EDCs) pose risks to cellular functions.
• Fibroblast growth factor-2 (FGF-2) plays a crucial role in cellular processes.
• Osteoblastic cells are key in bone metabolism and response to stimuli.

Purpose of the Study:

• To investigate the effects of butyl benzyl phthalate (BBP) and dibutyl phthalate (DBP) on FGF-2 translocation in Py1a rat osteoblastic cells.
• To elucidate the dose- and time-dependent mechanisms of EDC-induced changes in FGF-2 localization.
• To assess the impact of these phthalates on FGF receptor 2 (FGFR-2) and collagen fiber assembly.

Main Methods:

• Exposure of Py1a rat osteoblastic cells to varying concentrations and durations of BBP and DBP.
• Confocal laser scanning microscopy (CLSM) to visualize FGF-2 localization.
• Assessment of Concanavalin A (Con A) binding to evaluate collagen fiber assembly.

Main Results:

• BBP and DBP induced a dose- and time-dependent, reversible translocation of cytoplasmic FGF-2 into the nucleus.
• Observed FGF-2 accumulation near the nuclear envelope, followed by nuclear entry, and eventual re-establishment of basal binding.
• Phthalates did not affect FGFR-2 but decreased Con A binding, suggesting potential inhibition of collagen fiber assembly. No cumulative effects were noted.

Conclusions:

• BBP and DBP are potent modulators of FGF-2 nuclear translocation in osteoblastic cells.
• The observed effects on FGF-2 are reversible and dependent on concentration and exposure time.
• Phthalate exposure may interfere with collagen synthesis, impacting osteoblast function.