Front-loading with teneurins

So why did I bring up the teneurins? Let’s consider the abstract of a paper that was published a few weeks ago [1]:

Teneurins are type II transmembrane proteins expressed during pattern formation and neurogenesis with an intracellular domain that can be transported to the nucleus and an extracellular domain that can be shed into the extracellular milieu.

In other words, we have a protein that connect the nucleus to the environment outside the cell.

In Drosophila melanogaster, Caenorhabditis elegans and mouse the knockdown or knockout of teneurin expression can lead to abnormal patterning, defasciculation and abnormal pathfinding of neurites, and the disruption of basement membranes.

In other words, this is protein that plays an important role in the formation of brains and nerves. The fact that is carries out the same basic functions in worms, insects, and animals strongly suggests its role in nervous system is quite ancient and may have coincided with the emergence of the nervous system itself. So when did the tenurins arise?

Teneurins

According to Wikipedia,

Teneurins are transmembrane proteins. The name refers to “ten-a” (from “tenascin-like protein, accessory”) and “neurons”, the primary site of teneurin expression.

Teneurins are highly conserved between Drosophila, C. elegans and vertebrates. In each species they are expressed by a subset of neurons as well as at sites of pattern formation and morphogenesis. In Drosophila, a teneurin known as ten-m or Odz is a pair-rule gene, and its expression is required for normal development. The knockdown of teneurin (ten-1) expression in C. elegans with RNAi leads to abnormal neuronal pathfinding and abnormal development of the gonads.

And according to this article,

Teneurins are a unique family of transmembrane proteins conserved from C. elegans and D. melanogaster to mammals. In vertebrates there are four paralogs (teneurin-1 to -4), all of which are expressed prominently in the developing central nervous system.

So why mention these proteins?