A major challenge in studying the genetic basis of autism is that many genes are associated with the disorder, but each only accounts for a fraction of the cases. To develop treatments that will help a wide range of autistic subjects, we must identify and understand those genes that are commonly dysregulated. To this end, our group looked at shared genome-wide expression changes across two groups of autistic patients with known genetic causes vs. healthy controls. Janus kinase and microtubule-interacting protein 1, JAKMIP1, was one of the top hits from this screen and was validated in a separate group of autistic patients with unknown causes. JAKMIP1 is an important autism-candidate gene for three reasons. First, it is expressed predominantly in neurons. Secondly, JAKMIP1 regulates the expression and possible transport of GABA receptors and GABAergic systems are known to be abnormal in the autisms. Lastly, JAKMIP1 is downstream of genes that monogenetically cause autism. An important aspect of JAKMIP1 is that is contains four brain-specific isoforms, A, B, C and D, that are conserved between mouse and human and have distinct functional domains. My project aims to understand how irregular Jakmip1 isoform levels could disrupt conserved developmental processes, contributing to autism pathology.
Aim 1 A will determine which isoforms are expressed at the protein and transcript level during development and throughout adulthood. I will collect protein and mRNA from the cortex and cerebellum, two brain regions affected in autism, throughout development and will determine expression changes using western blotting and quantitative real time PCR.
Aim 1 B will elucidate the distribution of Jakmip1's isoforms in the developing and adult brain and in which neuronal subtypes these isoforms are located by using immunohistochemistry and isoform-specific antibodies.
Aim 2 A will ascertain the transcriptome-wide impact of silencing Jakmip1's isoforms in differentiated mouse neural progenitors using shRNA and microarray technology. Lastly, Aim 2B will assess neurite morphological changes and perturbations in the population make-up of dendritically-localized mRNA resulting from decreasing Jakmip1 isoform expression in differentiated mouse neural progenitors pre and post stimulation. I will carry out Aim 2B by employing a recent technique (Poon et al. 2006) to isolate and separate dendritic, axonal, and glial processes from the cell body. This study will shed light on the mechanism by which aberrant JAKMIP1 levels could result in autism and may further implicate JAKMIP1 as an autism-susceptibility gene. These discoveries will aid in pre-symptomatic diagnosis and early behavioral intervention for autistic children as well as the design of pharmaceuticals.