Dynamic and redundant regulation of LRRK2 and LRRK1 expression.
BACKGROUND
Mutations within the leucine-rich repeat kinase 2 (LRRK2) gene account for a significant proportion of autosomal-dominant and some late-onset sporadic Parkinson's disease. Elucidation of LRRK2 protein function in health and disease provides an opportunity for deciphering molecular pathways important in neurodegeneration. In mammals, LRRK1 and LRRK2 protein comprise a unique family encoding a GTPase domain that controls intrinsic kinase activity. The expression profiles of the murine LRRK proteins have not been fully described and insufficiently characterized antibodies have produced conflicting results in the literature.


RESULTS
Herein, we comprehensively evaluate twenty-one commercially available antibodies to the LRRK2 protein using mouse LRRK2 and human LRRK2 expression vectors, wild-type and LRRK2-null mouse brain lysates and human brain lysates. Eleven antibodies detect over-expressed human LRRK2 while four antibodies detect endogenous human LRRK2. In contrast, two antibodies recognize over-expressed mouse LRRK2 and one antibody detected endogenous mouse LRRK2. LRRK2 protein resides in both soluble and detergent soluble protein fractions. LRRK2 and the related LRRK1 genes encode low levels of expressed mRNA species corresponding to low levels of protein both during development and in adulthood with largely redundant expression profiles.


CONCLUSIONS
Despite previously published results, commercially available antibodies generally fail to recognize endogenous mouse LRRK2 protein; however, several antibodies retain the ability to detect over-expressed mouse LRRK2 protein. Over half of the commercially available antibodies tested detect over-expressed human LRRK2 protein and some have sufficient specificity to detect endogenous LRRK2 in human brain. The mammalian LRRK proteins are developmentally regulated in several tissues and coordinated expression suggest possible redundancy in the function between LRRK1 and LRRK2.
Institute for Cell Engineering and Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, USA. saskia.biskup@arcor.de
Saskia
S
Biskup
Darren J
DJ
Moore
Alexis
A
Rea
Bettina
B
Lorenz-Deperieux
Candice E
CE
Coombes
Valina L
VL
Dawson
Ted M
TM
Dawson
Andrew B
AB
West
D000818:Animals; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016716:PC12 Cells; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D013702:Temporal Lobe / Q000196:embryology / Q000378:metabolism
D012333:RNA, Messenger; C510751:LRRK1 protein, human; C495280:LRRK2 protein, human; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; C585046:Lrrk1 protein, mouse; D017346:Protein Serine-Threonine Kinases