Characterization of CkIIα-i1 -a putative ortholog of intellectual disability candidate gene ZBTB11

Abstract

Intellectual Disability (ID) is a heterogenic neurodevelopmental disorder seen in different spectrums in affected individuals. Resulting problems in the diagnosis of ID and limitations in its treatment constitutes a great emotional and financial burden to society. Therefore, identification of ID-causative genes and their functional characterization are important for the improvement of the current conditions. Two pathogenic variants of one of the ID-candidate genes ZBTB11 was identified and its early characterization was performed. In addition, knockdown of CkIIα-i1, a Drosophila ortholog of ZBTB11 showed deficiency in learning and memory center of Drosophila. The main aim of this study is the further investigate CkIIα-i1 and ZBTB11 in Drosophila in the pursuit of identifying their orthology. Since both CkIIα-i1 and ZBTB11 were understudied genes, transgenic and KO fly lines were generated and utilized in this study. In parallel, the expression of CkIIα-i1 was characterized in mushroom bodies (MB) and clock cells, which are learning- and circadian rhythm- related brain compartments, respectively. In addition, the role of CkIIα-i1 in MB development was analyzed by performing morphological analyses of the MB in CkIIα-i1 knockdown flies. For loss-of-function analysis, two RNA interference lines for the knockdown of CkIIα-i1 were utilized. Furthermore, two CkIIα-i1 KO lines were generated using CRISPR/Cas and used for morphological analysis. Both knockdown and KO of CkIIα-i1 resulted in shrinkage in the α lobe of the MB, with higher frequencies in KO lines. In contrast, the over-expression of CkIIα-i1 using the Gal4/UAS system did not result in any changes in MB morphology. Results of morphological analyses indicated that CkIIα-i1 could have a role in axonal guidance of α lobe axons. In order to investigate orthology between CkIIα-i1 and ZBTB11, wt and two identified variant ZBTB11 constructs were transgenically expressed in Drosophila and their expression was validated in the fly brain.