Fatich Mechmet, Alba Sabaté San José, Snaevar Sigurdsson, Ingvi Gautason, Eiríkur Steingrímsson and Petur Henry Petersen
Introduction. Microphthalmia-associated transcription factor (MITF) is a master transcription factor in melanocytes, crucial for their development and function. It also plays a role in other cell types and in the CNS, Mitf is expressed in projection neurons (PNs), mitral and tufted (M/T) cells, of olfactory bulb (OB), the primary site for odor processing in the brain. Mitf was reported as a direct regulator of intrinsic homeostatic plasticity through the regulation of a potassium channel subunit Kcnd3. However, its role and function in neurons have yet to be fully understood. Methods. Gene expression analysis. Results. Here, we identified several putative MITF target genes in PNs through global gene expression analysis (RNA-seq), single molecule fluorescent in situ hybridization (smFISH), and bioinformatic tools. The focus was placed on genes that showed reduced expression in the absence of Mitf due to the anticipation that genes regulated by Mitf would show reduced expression, while those inhibited by MITF would demonstrate increased expression. Selected genes were tested with smFISH. Genes were evaluated in two groups: those likely to suppress neuronal activity and genes specifically expressed in middle tufted cells (mTCs), a subcluster of tufted cells (TCs). The smFISH analysis validated the reduced expression of these genes and the absence of marker genes of mTCs in the OB of Mitf mutant (Mitf mi-vga9/mi-vga9). Conclusions. Our findings suggest that Mitf plays an important role in the development, operation, and viability of PNs, especially in connection with mTCs and their function.
