Objective:

Our objective is to determine if Progranulin (PGRN) RNA variants are produced in neuronal tissues in response to inflammatory stimuli, potentially contributing to the pathology associated with Alzheimer's Disease (AD).  

Background:

PGRN is an immune regulatory protein that is linked to the development of neurodegenerative diseases such as AD. Aberrant PGRN production or mutation disrupts lysosomal function and leads to neurodegeneration. PGRN has 13 known exons, and the GRN gene has been shown to be differentially expressed. 

Design/Methods:

HMC3 human microglial and SW13 adenocarcinoma cells were selected because these cell lines have shown differential expression of PGRN depending on the polarization of the cells. A431 epidermoid carcinoma cell lines were used as a control for SW13 cells. The cells were cultured in the presence of either pro-inflammatory or anti-inflammatory cytokines, with no cytokine addition as a control. After incubation, mRNA was isolated from the cells, converted to cDNA using reverse transcriptase, and then PCR was performed utilizing multiple combinations of specific primers aimed at targeting the 13 exons. PCR product was analyzed using gel electrophoresis to determine if each amplicon produced was smaller, larger, or expected size based on the canonical gene sequence, which may provide evidence of splice variants.  

Results:

Our results suggest that there are some truncations and variable expression of PGRN mRNA transcripts in both HMC3 and SW13 cell lines with respect to inflammatory stimuli.  

Conclusions:

The GRN gene has been shown to be differentially expressed in cancer cell lines, which may be context dependent. We conclude that there is preliminary evidence to suggest that differential expression may also be occurring in neuronal cells in the context of inflammation. Future research will focus on isolating and sequencing the mRNA variants to determine if specific exon splicing is important to PGRN gene expression and whether differential expression correlates to pathology in AD.