Translational Inhibition of α-Neurexin 2

Abstract

Neurexins are extensively investigated presynaptic cell-adhesion molecules which play important roles in transmitting signals and processing information at synapses that connect neurons into a vast network of cellular communications. Synaptic transmission of information is a fast and dynamic process which relies on rapid and tight regulation of synaptic protein expression. However, the mechanism underlying those regulation is still not fully understood. Therefore, we explore how the expression of NRXN2α, one of encoding genes for neurexins, is regulated at the translational level. NRXN2α transcript has a long and conserved 5′-untranslated region (5′UtR) suggestive of the rapid regulation of protein expression at the translational level. We first demonstrate that the 5′UTR has negative effects on the expression of the NRXN2α and find a critical subregion responsible for the major inhibitory function. Then we identify a particular secondary structure of G-quadruplex in the 5′UTR. Moreover, we find that the synergistic roles of G-quadruplex and upstream AUGs are responsible for most of NRXN2α-5′UTR inhibitory effects. In conclusion, we uncovered 5′ UTR of neurexin2 potentially inhibits neurexin2 translation by multiple mechanisms. In addition, this study underscores the importance of direct protein quantitation in experiments rather than using mRNA as an indirect estimate of protein expression.

Development of ultra-low-input nanoRibo-seq enables quantification of translational control, revealing broad uORF translation by subtype-specific neurons

“…Previous work found that multiple conserved, short uORFs within the Nrxn2α 5'UTR cooperatively inhibit translation in vitro (Figure 7-figure supplement 4A) [52]. Interestingly, we find that a longer Nrxn2α uORF using a non-canonical CUG start codon is also translated in developing CPN (Figure 7-figure supplement 4A).…”

“…Interestingly, we find that a longer Nrxn2α uORF using a non-canonical CUG start codon is also translated in developing CPN (Figure 7-figure supplement 4A). While the uORFs identified in the previous study[52] are too short to be directly called by RiboCode, plotting P-site density across these uORFs reveals a bias toward in-frame P-sites across all three uORFs, especially uORF2.…”

“…The identification of multiple uORFs in Nrxn1α, β, Nrxn2α, and Nrxn3α 5' UTRs, along with previous molecular dissection of short uORFs with canonical start codons in Nrxn2α [52], suggests that uORFs might be translational regulators neurexin. Taken…”

“…The identification of multiple uORFs in Nrxn1α, β, Nrxn2α, and Nrxn3α 5’ UTRs, along with previous molecular dissection of short uORFs with canonical start codons in Nrxn2α[52], suggests that uORFs might be translational regulators neurexin. Taken together, our results identifying uORF translation by developing CPN suggest that, during early postnatal CPN development and circuit formation, many genes with translated uORFs function as regulators of axon guidance, cell adhesion, and synapse selection/formation, including multiple examples of semaphorins, neuroligins, and neurexin.…”

“…A) P-site density plots and number of P-sites in each frame for the predicted CUG uORF (top) identified in this study, and for the three short AUG ORFs identified by Ding et al 2020 [52] (uORFs1-3, bottom). Of note, the reference Nrxn2 transcript sequence contains a 5’ extension not analyzed in Ding et al, which contains a possible alternate start codon in-frame with uORF1.…”