Scientists at the Carl R. Woese Institute for Genomic Biology have embarked on an unprecedented study. They’re trying to understand the evolutionary origins of Secretoglobins, a large family of proteins with some really weird biological functions. Their research demonstrates their hypothesis that Secretoglobins are highly conserved across a diverse variety of animal phyla. Unexpectedly, these proteins are not limited to mammals.
The study, led by Christina Laukaitis and Robert C. Karn, utilized bioinformatic approaches. They examined the SCGB genes in a variety of animal genomes, which encode the known Secretoglobins. The results suggest that Secretoglobins likely originated during the Carboniferous roughly 320 million years ago. They developed in early amniotes long before the dinosaurs walked the Earth.
Secretoglobins provide an excellent example of the scientific puzzle posed by the vast majority of known genes. Laukaitis, a clinical associate professor at the Carle Illinois College of Medicine, emphasized that the quest for understanding these proteins is vital for both evolutionary biology and potential medical applications.
The Search for SCGB Genes
This work that Laukaitis and Karn did was to look for SCGB genes outside of mammals. Using more than just mammalian representatives, their goal was to expand the knowledge of these genes in non-mammalian species using a wide bioinformatics survey.
Laukaitis stated, “No one has looked beyond mammals, so the basic question we’re asking is whether we can find SCGBs in non-mammals. This was a bioinformatics survey of all the available genomes of different groups of organisms to figure out who has the different members of this secretoglobin family.” This novel strategy navigated some unexpected challenges and opened doors to deepen their understanding of Secretoglobins’ evolutionary history.
She unveiled through the study that Secretoglobins, mascarading as pheromone binding proteins, are found in turtles, crocodilians, lizards and birds. This remarkable finding emphasizes the important function of SCGB genes in vertebrate evolution. It forces us to reevaluate how these genes work in a wide range of species. Karn noted that “Secretoglobins seem to be an amniote invention,” highlighting their significance in the evolutionary history of terrestrial and semiaquatic tetrapods.
Implications for Understanding Functions
This study highlights the immunological functional roles of Secretoglobins. Both of these roles are new, unexplored territory, rendering this exploration doubly important. Karn remarked, “A first principle of biology is the question of structure versus function.” Though researchers have determined the structures of SCGBs, their exact roles remain just out of reach.
Laukaitis added, “None of these are basic functions, but rather what they do in the right circumstances.” The promise that these poorly understood proteins hold only deepens excitement about their possible use in medical applications. Karn expressed hope that understanding SCGBs could lead to insights into important medical issues: “A lot of these SCGBs could be valuable for medical issues. Since nobody knows what these small cytokine-like proteins do, they might very well be involved in something we need to know about.”
One hypothesized idea from the study was confirmed. It appears some SCGBs are involved in inter-animal communication. Karn continued that one subset of SCGBs, Androgen Binding Proteins (ABPs), are different among mammals. These proteins are extremely abundant specifically in VIP facial glands. He elaborated: “That group of SCGBs is called Androgen Binding Proteins, or ABPs, and they are only found in mammals. That’s what we’ve seen so far in our studies with mice—in just the glands of the face and neck. This indicates a potential identity recognition role in the rodent social interaction.
Future Directions for Research
Determining the evolutionary origins of Secretoglobins provides a strong foundation. This foundational base will enable subsequent exploratory studies to identify convergent function among the SCGB protein family. The researchers hope that by identifying SCGB genes across various organisms, they can bridge gaps in knowledge regarding their roles.
Karn underscored the importance of cross-species comparisons: “If we want to understand ourselves, we have to understand what we share and don’t share with other organisms.” Such an approach would allow them, they hope, to uncover unifying themes in how proteins perform their diverse functions—commonalities that have survived millions of years of evolutionary chaos.
The eagerness fueling this scholarship is just as evident, particularly as the clock ticks down on the number of specialists committed to learning more about Secretoglobins. Karn noted, “The group of evolutionary biologists and geneticists that ran the meeting 25 years ago essentially have all retired, so we’re hoping that more people will get interested in this area.”
