PICK1 expression in the Drosophila central nervous system primarily occurs in the neuroendocrine system

Abstract

The protein interacting with C kinase 1 (PICK1) protein was first identified as a novel binding partner for protein kinase C. PICK1 contains a membrane-binding BAR domain and a PDZ domain interacting with many synaptic proteins, including the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunit GluR2 and the dopamine transporter. PICK1 is strongly implicated in GluR2 trafficking and synaptic plasticity. In mammals, PICK1 has been characterized extensively in cell culture studies. To study PICK1 in an intact system, we characterized PICK1 expression immunohistochemically in the adult and larval Drosophila central nervous system. PICK1 was found in cell bodies in the subesophageal ganglion, the antennal lobe, the protocerebrum, and the neuroendocrine center pars intercerebralis. The cell types that express PICK1 were identified using GAL4 enhancer trap lines. The PICK1-expressing cells form a subpopulation of neurons. PICK1 immunoreactivity was neither detected in glutamatergic nor in dopaminergic neurons. Also, we observed PICK1 expression in only a few GABAergic neurons, located in the antennal lobe. In contrast, we detected robust PICK1 immunolabeling of peptidergic neurons in the neuroendocrine system, which express the transcription factor DIMM and the amidating enzyme peptidylglycine-alpha-hydroxylating monooxygenase (PHM). The PICK1-positive cells include neurosecretory cells that produce the insulin-like peptide dILP2. PICK1 expression in insulin-producing cells also occurs in mammals, as it was also observed in a rat insulinoma cell line derived from pancreatic beta-cells. At the subcellular level, PICK1 was found in the perinuclear zone but surprisingly not in synaptic domains. We conclude that PICK1 may serve an important role in the neuroendocrine system both in insects and vertebrates.

Involvement of the drosophila taurine/aspartate transporter dEAAT2 in selective olfactory and gustatory perceptions

“…The antibody is specific for detection of Repo protein because the antibody detects no antigen in repo-null mutant flies (Spokony and Restifo, 2009). The distribution of nuclei labeled with anti-Repo presently obtained corresponds to the reported glial pattern (Jansen et al, 2009;Spokony and Restifo, 2009). 3.…”

Genome-wide features of neuroendocrine regulation in Drosophila by the basic helix-loop-helix transcription factor DIMMED

“…Secondly, their level of expression exceeded 0.983129 FPKM (Fragments per kilobase of transcript per million mapped reads), which is the level of expression in c929 + cells of the gene Pick1 . Pick1 levels were chosen as a threshold because they displayed the lowest level of expression for any gene known to be enriched in c929 /DIMM + neurons (49). Comparison of the two groups of transcripts reveals an overlap of 337 isoforms, which translates finally into 212 distinct DIMM target genes (Figure 6B and Supplementary Tables S4 and S5).…”

“…We applied a threshold to the data according to absolute gene expression by searching for genes expressed at low levels, that are nevertheless known to be enriched in c929 -GFP+ cells. The Pick1 gene (49) displayed a transcriptional isoform expressed at 0.98 FPKMs in the c929 -GFP+ sample, and 0.26 FPKMs in the c929 -GFP− sample. It was the lowest expression level we could identify among genes previously identified by independent criteria to be ‘ c929 -cell-enriched’.…”

Regulation of neuromuscular junction organization by Rab2 and its effector ICA69 in Drosophila

“…PICK1 was not detectable at the NMJ synapses in Drosophila (Jansen et al, 2009). As our data conclusively demonstrates strong postsynaptic localization of ICA69, we next investigated whether RNAi-mediated knockdown of its binding partner PICK1 in muscle affects iGluR targeting at the NMJ.…”