Down syndrome fibroblasts are hyperresponsive to beta-adrenergic stimulation.

Abstract

The hormonal response ofhuman skin fibroblasts after exposure to P-adrenergic agonists, prostaglandin El (PGEI), and cholera toxin was monitored by intracellular cyclic AMP accumulation. Down syndrome (DS; trisomy 21) cells had an approximately 10-fold greater response to fi-adrenergic agonists than did either normal diploid skin fibroblasts or other aneusomic fibroblast strains (trisomy 13, 18, and 22). The altered response in DS fibroblasts was specific for P-adrenergic agonists, because treatment of DS or control cells with PGE1 or cholera toxin resulted in the same degree of cyclic AMP accumulation. Experiments with 3-isobutyl-1-methylxanthine, a cyclic nucleotide phosphodiesterase inhibitor, indicated that the increased response of DS fibroblasts was not primarily a function of altered cyclic AMP degradation. Monosomy 21 cells responded less than normal diploid fibroblasts to stimulation by the 13-adrenergic agonist isoproterenol. These findings suggest that genetic information on chro- (9). In addition to these membrane alterations, major differences exist in the catecholamine metabolism of DS patients. Dopamine /3-hydroxylase activity, which catalyzes the production ofnorepinephrine, is decreased in DS plasma (10) and catechol O-methyltransferase activity is increased (11). Such membrane and metabolic changes could contribute to the well-known sensitivity of DS individuals to certain drugs (12).The alterations in cell growth, membrane function, and catecholamine metabolism suggest that the cellular response to hormones could be perturbed in DS. To test this possibility, we examined the ,B-adrenergic, prostaglandin E1 (PGE1), and cholera toxin response ofnormal human diploid fibroblasts, trisomy 21 fibroblasts, monosomy 21 fibroblasts, and a variety of other human aneusomic fibroblast strains. The experimental results indicate that chromosome 21 influences the ,B-adrenergic responsiveness of human fibroblasts. MATERIALS AND METHODS DS skin fibroblasts purchased from the Human Genetic MutantCell Repository (Camden, NJ) were cell strain numbers GM 2067 and GM 2504. In addition, DS cell strains from Meloy Laboratories (ML 1199, ML 1252, and ML 2475) were also used in these studies. Normal diploid human skin fibroblasts (NSF) and non-DS aneusomic (NDA) strains (trisomy 13, 18, and 22) were initiated and cytologically verified by the cytogenetic laboratories at the University of Minnesota. Monosomy 21 skin fibroblast strains were from the Human Genetic Mutant Cell Repository (GM 230) and Meloy Laboratories (ML 468 and ML 2287). 3H-Labeled cyclic AMP (cAMP) was purchased from New England Nuclear. PGE, was the gift ofJohn Pike, Upjohn.3-Isobutyl-l-methylxanthine (iBuMeX), an inhibitor of cyclic nucleotide phosphodiesterase, was purchased from Sigma.The fibroblast cultures were maintained on Dulbecco's modified Eagle's medium supplemented with 15% fetal calf serum in a 37°C incubator with 5% CO2. For testing, cells were plated at approximately 1.2 x 105 cells per 60-mm plate (Falcon or Nunc) and were exa...

The β2-adrenergic receptor activates pro-migratory and pro-proliferative pathways in dermal fibroblasts via divergent mechanisms

“…Interestingly, ␤2-ARs are the only class of ␤-AR expressed on the three major cell types of human skin: keratinocytes (Steinkraus et al, 1996) dermal fibroblasts (McSwigan et al, 1981) and melanocytes (Gillbro et al, 2004). Keratinocytes also have the capacity to synthesize the catecholamines epinephrine and nor-epinephrine, both ligands for adrenergic receptors (Schallreuter, 1997;Schallreuter et al, 1995).…”

“…␤2-ARs are the only class of ␤-AR expressed on the three major cell types of human skin: keratinocytes (Steinkraus et al, 1996) dermal fibroblasts (McSwigan et al, 1981) and melanocytes (Gillbro et al, 2004). Emerging studies from our laboratory point to a role of the ␤2-adrenergic signaling pathway in wound healing.…”

β-Adrenergic Hyperresponsiveness in Compensated Hypothyroidism Associated with Down Syndrome

“…The response in these cells was~3-to 10-fold greater than in normal diploid fibroblasts and other aneusomic fibroblast strains. This exaggerated response was specific, because treatment of DS and control cells with PGE1 or CTx resulted in the same degree of cAMP accumulation (21). In a subsequent study, an enhanced physiologic response to catecholamine hormones was found in cultured DS-derived fibroblasts and platelets (22), a response that was specific to the adrenergic agonists.…”

“…However, we cannot rule out other defects in the signal-transduction pathway, such as increased activity of phosphodiesterase, which was neutralized in our study by the specific inhibitor 3-isobutyl-1-methylxanthine. We further evaluated an alternative hypothesis, that alteration in the response to adrenergic stimulation, previously reported in fibroblasts (21,22) and platelets (22) from patients with DS, is causally related to the hyperthyrotropinemia in DS. Hyperresponsiveness to ␤-adrenergic agonists in human skin fibroblasts that were obtained from patients with DS was reported by McSwigan et al (21) in 1981.…”

“…We further evaluated an alternative hypothesis, that alteration in the response to adrenergic stimulation, previously reported in fibroblasts (21,22) and platelets (22) from patients with DS, is causally related to the hyperthyrotropinemia in DS. Hyperresponsiveness to ␤-adrenergic agonists in human skin fibroblasts that were obtained from patients with DS was reported by McSwigan et al (21) in 1981. The response in these cells was~3-to 10-fold greater than in normal diploid fibroblasts and other aneusomic fibroblast strains.…”