Corticosteroid-induced abnormality in fetal mice and H-2 haplotype: evidence of a cytoplasmic effect

H-2 gene complex and corticosteroid responsiveness: evidence that the corticosteroid hormone signal transduction pathway in the adult mouse lung is not associated with haplotype-specific responses to corticosteroids

Differential responsiveness to corticosteroids (CORT) has been shown to be related to HLA haplotype. A strong association between the mouse homolog to the human HLA complex, the H-2 complex, and intrauterine responses to CORT have also been demonstrated; haplotype differences alter CORT-induced susceptibility to cleft palate and temporal differences in lung maturation. Since variation in the glucocorticoid receptor (GR) is associated with tissue specific responses to CORT, we hypothesize that haplotype-specific CORT responsiveness may be regulated by H-2 associated modification of GR expression and/or function. Given that H-2 congenic mice are genetically identical except at the H-2 complex on mouse chromosome 17 and the GR structural gene is encoded on chromosome 18, the GR gene is identical in these mice. However, any step in the GR signal transduction pathway may be regulated by gene(s) at or near the H-2 complex and result in haplotype-specific differences in CORT responsiveness. We have investigated differences in qualitative and quantitative characteristics of the adult B10 (H-2b) and B10.A (H-2a) pulmonary GR by Scatchard analysis, immunochemical and biochemical assays. No differences in the GR binding parameters (BMAX and Kd), receptor form and level, or ligand-GR complex binding to glucocorticoid response element (GR-GRE) were detected, leading us to conclude that H-2 associated factors do not regulate the relative intrauterine responses to CORT by modulating the adult GR.(ABSTRACT TRUNCATED AT 250 WORDS)

Mouse major histocompatibility complex and lung development: haplotype variation, H-2 immunolocalization, and progressive maturation

The association of the mouse major histocompatibility complex (H-2), lung maturation, and corticosteroid responsiveness has recently been demonstrated in congenic B10 (H-2b) and B10.A (H-2a) mice (Hu et al.: American Journal of Medical Genetics 35:126-131, 1990). We have investigated additional haplotypes [B10.BR (H-2k) and B10.D2 (H-2d)] to confirm that there is a strong association between H-2 haplotype variation and the degree of pulmonary maturation. Lungs of B10.D2, B10.BR, B10, and B10.A congenic mice achieve haplotypic specific maturation: B10.D2 lungs greater than B10 lungs = B10.BR lung greater than B10.A lungs. It appears that the expression of these developmental potentials is under corticosteroid regulation. Further, to test the hypothesis that H-2 antigens would be expressed earlier in embryonic lungs with the H-2b (B10) or H-2k (B10.BR) haplotype than with the H-2a (B10.A) haplotype, we investigated the spatiotemporal patterns of H-2 antigen localization in B10, B10.BR, and B10.A congenic mouse strains with and without corticosteroid treatment. The spatial patterns of H-2 antigen localization was similar in the B10, B10.BR, and B10.A mouse lungs; however, these patterns appeared earlier in both untreated and treated B10 and B10.BR mice as compared with untreated B10.A mice, suggesting an H-2 haplotype associated rate of pulmonary maturation. Following corticosteroid treatment, all congenic strains had a temporally comparable spatial distribution of H-2 antigens. Our results provide preliminary evidence suggesting that both a lung "developmental gene(s)" and a "glucocorticoid responsiveness gene(s)" are most likely outside the K-D subregions of the H-2 complex. A model of the H-2 regulation of lung maturation and corticosteroid responsiveness is discussed.

Mouse major histocompatibility complex (H-2) and fetal lung development: implications for human pulmonary maturation

Using C57/10Sn (B10, H-2b) and B10.A/SgSn (B10.A,H-2a) congenic mice, we measured 1) the level of endogenous pulmonary corticosterone during mouse development; 2) the degree of lung morphological maturation on gestation day 17, with or without corticosteroid treatment; and 3) the maternal influence on normal lung development and fetal response to corticosteroids. The results of our study indicate that there was a progressive increase in the level of endogenous hormone with time in fetal B10 (H-2b) and B10.A (H-2a) mice; throughout mid- to late gestation, the detectable amount of hormone was almost identical in lungs of both strains. Evaluating the degree of lung maturation by morphometry, B10.A mouse lungs were found to be less mature than B10 mouse lungs. Following corticosteroid treatment on day 12 of gestation, H-2a lungs were equal to or more mature than H-2b lungs. We also compared heterozygous mouse lungs from reciprocal crosses (B10.B10.A, b/a and B10.A.B10, a/b). Mice with a maternally derived H-2a haplotype had less mature lungs than those with a maternally derived H-2b haplotype, suggesting a maternal effect. When exogenous hormone was administered, all heterozygous mouse lungs increased in maturity regardless of the origin of the H-2a haplotype. The treated a/b or b/a lungs were more mature than homozygous b/b and less mature than homozygous a/a lungs. We conclude that progressive lung maturation is associated with a gene(s) at or near the H-2 complex, as is the ability to respond to corticosteroids.

Modification of the cell surface expression of histocompatibility antigens induced by the neurotoxin 2,5 hexanedione

Class I histocompatibility antigens (HLA) are expressed on the surface of almost all nucleated mammalian cells; the expression of this surface antigenic molecule may be changed or abrogated by several factors. In this paper, a modification in HLA expression in a human carcinoma cell line following exposure to the neurotoxicant 2,5 hexanedione is reported. This compound is known to produce a wide spectrum of subcellular pathological events; in this study, we describe an effect on the surface and cytoplasmic distribution of both light and heavy subunits of HLA antigens, demonstrated by immunocytochemical and immunoelectron microscopy techniques. Human carcinoma cells, which under normal growing conditions express the HLA, abrogate the surface expression of this glycoprotein after exposure to 2,5 hexanedione and an intracytoplasmic accumulation seems to occur. Several possibilities are discussed, such as an effect of the toxicant on the transport of the nascent glycoprotein.