Cytoplasmic and Nuclear STAT3 in GH-Stimulated Fibroblasts of Children with Idiopathic Short Stature

Abstract

Background: STAT5, which plays an important role in GH signal transduction, has been studied extensively in children with growth retardation, but there is scarce information regarding STAT3. Aim: We determined total and phosphorylated STAT3 after GH stimulation in fibroblasts from children with idiopathic short stature (ISS) and control children with normal stature. Subjects and Methods: We studied 15 prepubertal children (age 7.6 ± 0.4 years) with short stature (height –2.8 ± 0.2 SDS), decreased growth velocity (<p10), a GH response of >10 ng/ml to the clonidine stimulation test and decreased serum IGF-I concentrations (<–1 SDS), and 19 control children with normal stature (age 6.7 ± 0.3 years). We determined the levels of total and phosphorylated STAT3 in the cytoplasmic and nuclear fractions of fibroblast cultures obtained from a skin biopsy, stimulated with GH (200 ng/ml) for 15–60 min. Results: We observed a reduction in nuclear pSTAT3 levels and a lower nuclear/cytoplasmic STAT3 phosphorylated ratio in 3 patients from the study group compared to the control children. Conclusion: These results suggest that some children with ISS may exhibit a reduction in the nuclear content of their phosphorylated STAT3.