Insights into the Influence of Specific Splicing Events on the Structural Organization of LRRK2.

Dimitrios Vlachakis,Nikolaos Labrou,John Hardy,Daniah Trabzuni,Patrick Lewis,Costas Iliopoulos,Hardy Rideout

doi:10.3390/ijms19092784

Abstract

Leucine-rich repeat kinase 2 (LRRK2) is a large protein of unclear function. Rare mutations in the LRRK2 gene cause familial Parkinson’s disease (PD) and inflammatory bowel disease. Genome-wide association studies (GWAS) have revealed significant association of the abovementioned diseases at the LRRK2 locus. Cell and systems biology research has led to potential roles that LRRK2 may have in PD pathogenesis, especially the kinase domain (KIN). Previous human expression studies showed evidence of mRNA expression and splicing patterns that may contribute to our understanding of the function of LRRK2. In this work, we investigate and identified significant regional differences in LRRK2 expression at the mRNA level, including a number of splicing events in the Ras of complex protein (Roc) and C-terminal of Roc domain (COR) of LRRK2, in the substantia nigra (SN) and occipital cortex (OCTX). Our findings indicate that the predominant form of LRRK2 mRNA is full length, with shorter isoforms present at a lower copy number. Our molecular modelling study suggests that splicing events in the ROC/COR domains will have major consequences on the enzymatic function and dimer formation of LRRK2. The implications of these are highly relevant to the broader effort to understand the biology and physiological functions of LRRK2, and to better characterize the role(s) of LRRK2 in the underlying mechanism leading to PD.

Highlights

Non-synonymous coding mutations in the leucine-rich repeat kinase 2 (LRRK2) gene on chromosome 12p12 were identified as a cause of autosomal dominant Parkinson’s disease (PD) in 2004 [1,2]
We report evidence supporting the existence of multiple LRRK2 splice variants (removal of exons 32–33 [Ras of complex proteins (ROC)-C-terminal of ROC (COR)], exons 42–43 [kinase (KIN)] and exons 48–50 [WD40]) within multiple brain regions, and model the projected structural implications of LRRK2 splice variants on the resulting protein
The evidence presented here supports the central hypothesis of our study, that multiple splice isoforms of LRRK2 are present in the human brain at different ratios

Summary

Introduction

Non-synonymous coding mutations in the leucine-rich repeat kinase 2 (LRRK2) gene on chromosome 12p12 were identified as a cause of autosomal dominant Parkinson’s disease (PD) in 2004 [1,2]. The complex domain architecture of LRRK2, shared with its paralog LRRK1, provides membership in two distinct protein families: The ROCO family, and the receptor-interacting protein (RIP) kinase family [3]. There are 4 members of this family, LRRK1, LRRK2, death associated protein kinase 1 (DAPK1), and malignant fibrous histiocytoma-amplified sequence 1 (MFHAS1, known as MASL1) [4]. The human RIP kinase family has seven known members, distinguished by common and functionally overlapping interacting partners and signalling pathways, linked to the plasma membrane “death receptors” and the NF-κB network [5]. Additional genetic studies, most notably genome-wide association studies (GWAS) have revealed the association of variants at the LRRK2 locus with inflammatory bowel disease, Leprosy and PD [6,7,8,9,10]

Methods

Results

Conclusion