Globin gene expression in erythroid human fetal liver cells.

We measured steady-state levels of the human globin mRNAs in liver samples from several mid-gestational fetuses. RNA from the epsilon, gamma, beta, zeta, theta, and alpha globin genes were present in fetal liver samples isolated from 10-25-wk embryos. The abundance of all human globin mRNAs declined in older fetuses, presumably because of a gradual reduction in the proportion of erythroid precursors in the liver as development proceeds. The gamma:beta globin mRNA ratio in 10-18-wk fetal erythroblasts was 6-7:1, and in adult erythroid bone marrow the ratio was 0.02:1. In fetal liver samples, the relative abundance of epsilon transcripts was less than 1% that of gamma, and zeta transcripts less than 5% that of alpha. Embryonic transcripts declined in abundance during late fetal development and were not detected in newborn liver or adult erythroid bone marrow. theta globin mRNA also represented a minor species (less than 1% that of alpha) in fetal liver samples, but in contrast to the embryonic mRNAs, was most abundant in adult marrow samples obtained from patients with erythroid hyperplasia. These results support the hypothesis that globin protein levels are regulated by the relative amounts of each globin mRNA at various stages of erythropoietic development.

Educational innovations in clinical pharmacogenomics.

Genetic and genomic discovery is revolutionizing medicine at an extraordinary pace, leading to a better understanding of disease and improved treatments for patients. This advanced pace of discovery presents an urgency to expand medical school curricula to include genetic and genomic testing (including pharmacogenomics), and integration of genomic medicine into clinical practice. Consequently, organizations and healthcare authorities have charged medical schools with training future physicians to be competent in their knowledge of genomic implementation.

A human protein containing a "cold shock" domain binds specifically to H-DNA upstream from the human gamma-globin genes.

We previously determined that a region between positions -228 and -189 upstream from the human gamma-globin genes can form an intramolecular triplex (H-DNA) in supercoiled plasmids. To identify proteins that might interact with this DNA structure, we performed expression cloning using an adult bone marrow cDNA library and the single-stranded region of the H-DNA structure as a probe. We cloned molecules very similar to two previously identified cDNAs, dbpA and dbpB. The dbpB-like protein (called BP-8 in this study) interacts specifically (KD approximately 4 nM) with two homopyrimidine "half-sites" in the single-stranded gamma-228 to -189 probe, but binds to double-stranded DNA containing the same sequence with 100-fold less affinity. We have also shown that supercoiled plasmids containing the gamma-228 to -189 region contain a high affinity binding site for BP-8 that is stabilized by factors that stabilize H-DNA; two HPFH point mutations (-202 C-->G or C-->T) that destabilize the secondary DNA structure abolish the high affinity binding site. Collectively, these data show that dbpB/BP-8 binds specifically to homopyrimidine half-sites in single-stranded DNA, and that it also binds to H-DNA structures that contain homopyrimidine tracts in the single-stranded and triple-stranded regions.