That’s where blood came in to the picture. During his postdoc at Caltech with Henry Borsook, a pioneer in protein synthesis studies, Lingrel had worked extensively with reticulocytes (immature red blood cells), which were an ideal model system: As hemoglobin factories, all they basically do is churn out globin chains all day long.
By that same token, Lingrel figured reticulocytes should contain a vast amount of α and β globin mRNAs. To isolate these mRNAs, he thought that using an Escherichia coli cell-free translating system, similar to that employed by Marshall Nirenberg to crack the genetic code, would be a reasonable approach; Lingrel would add different fractions of total mouse reticulocyte RNA to extracts of E. coli translation machinery and see which ones produced globins.
Of course, his initial attempts didn’t bear fruit, and he jokes, “It was not the most ideal way to discover that there are significant differences between bacterial and eukaryotic protein synthesis.”
However, when he changed his approach and used a cell-free translation system from rabbit reticulocytes, he achieved success and identified a 9 S RNA that resulted in the synthesis of both α and β globin. In doing this, he identified and translated the first mammalian messenger RNA.
Jerry Lingrel recently has discovered a role for Na,K-ATPase in the brain, as highlighted by this in situ mRNA hybridization analysis of the ion transporter’s α1 and α2 isoforms in developing mouse brains; A and B show sections through the hippocampus, with the star highlighting robust expression for α1 but not α2 in the choroid plexus, whereas the arrow highlights the more intense α2 presence in the ependymal lining. C and D show sections through the cortex, with the arrow highlighting the strong expression of α2 in the pia mater. Moseley, A. E. et al, J. Biol. Chem. (2003) 278, 5317–5324.
No Tension Here
Over the next few years, Lingrel and his lab would further characterize globin mRNA, uncovering many of the key features we know about these transcripts, including their 5’ CAP structure and 3’ poly-A tail as well as the fact that mature mRNAs in the cytoplasm arose from larger precursor RNA molecules in the nucleus. Through his approach, which he shared with many colleagues, globin synthesis became the model in which to study mRNA structure and translation.
As the 1970s progressed, Lingrel continued his work with globins. Having made complementary DNA to his isolated mRNA, he was able to identify and clone globin genes from a variety of mammalian cells and study both the changes in globin expression during development and the evolution of the globin gene family.