Biology subjects

Boddu, R.

Publications and source records attributed to Boddu, R..

3 recordsLinked to original sources

bioRxiv2024

Single molecule array measures of LRRK2 kinase activity in serum link Parkinson's disease severity to peripheral inflammation

BackgroundLRRK2-targeting therapeutics that inhibit LRRK2 kinase activity have advanced to clinical trials in idiopathic Parkinsons disease (iPD). LRRK2 phosphorylates Rab10 on endolysosomes in phagocytic cells to promote some types of immunological responses. The identification of factors that regulate LRRK2-mediated Rab10 phosphorylation in iPD, and whether phosphorylated-Rab10 levels change in different disease states, or with disease progression, may provide insights into the role of Rab10 phosphorylation in iPD and help guide therapeutic strategies targeting this pathway. MethodsCapitalizing on past work demonstrating LRRK2 and phosphorylated-Rab10 interact on vesicles that can shed into biofluids, we developed and validated a high-throughput single-molecule array assay to measure extracellular pT73-Rab10. Ratios of pT73-Rab10 to total Rab10 measured in biobanked serum samples were compared between informative groups of transgenic mice, rats, and a deeply phenotyped cohort of iPD cases and controls. Multivariable and weighted correlation network analyses were used to identify genetic, transcriptomic, clinical, and demographic variables that predict the extracellular pT73-Rab10 to total Rab10 ratio. ResultspT73-Rab10 is absent in serum from Lrrk2 knockout mice but elevated by LRRK2 and VPS35 mutations, as well as SNCA expression. Bone-marrow transplantation experiments in mice show that serum pT73-Rab10 levels derive primarily from circulating immune cells. The extracellular ratio of pT73-Rab10 to total Rab10 is dynamic, increasing with inflammation and rapidly decreasing with LRRK2 kinase inhibition. The ratio of pT73-Rab10 to total Rab10 is elevated in iPD patients with greater motor dysfunction, irrespective of disease duration, age, sex, or the usage of PD-related or anti-inflammatory medications. pT73-Rab10 to total Rab10 ratios are associated with neutrophil activation, antigenic responses, and the suppression of platelet activation. ConclusionsThe extracellular ratio of pT73-Rab10 to total Rab10 in serum is a novel pharmacodynamic biomarker for LRRK2-linked innate immune activation associated with disease severity in iPD. We propose that those iPD patients with higher serum pT73-Rab10 levels may benefit from LRRK2-targeting therapeutics to mitigate associated deleterious immunological responses.

neuroscience↗

bioRxiv2021

Nonsense-associated alternative splicing as a putative reno-protective mechanism in Pkhd1cyli/Pkhd1cyli mutant mice

Autosomal recessive polycystic kidney disease (ARPKD) is a hereditary hepato-renal fibrocystic disorder and a significant genetic cause of childhood morbidity and mortality. Mutations in the Polycystic Kidney and Hepatic Disease 1 (PKHD1) gene cause all typical forms of ARPKD. Several mouse strains carrying diverse genetically engineered disruptions in the orthologous Pkhd1 gene have been generated. The current study describes a novel spontaneous mouse recessive mutation causing a cystic liver phenotype resembling the hepato-biliary disease characteristic of human ARPKD. Here we describe mapping of the cystic liver mutation to the Pkhd1 interval on Chromosome 1 and identification of a frameshift mutation within Pkhd1 exon 48 predicted to result in premature translation termination. Mice homozygous for the new mutation, symbollzed Pkhd1cyli, lack renal pathology, consistent with previously generated Pkhd1 mouse mutants that fail to recapitulate human kidney disease. We have identified a profile of alternatively spliced Pkhd1 renal transcripts that are distinct in normal versus mutant mice. The Pkhd1 transcript profile in mutant kidneys is consistent with predicted outcomes of nonsense-associated alternative splicing (NAS) and nonsense mediated decay (NMD). Overall levels of Pkhd1 transcripts in mutant mouse kidneys were reduced compared to kidneys of normal mice, and Pkhd1 encoded protein in mutant kidneys was undetectable by immunoblotting. We suggest that in Pkhd1cyli/Pkhd1cyli (cyli) mice, mutation-promoted Pkhd1 alternative splicing in the kidney yields transcripts encoding low-abundance protein isoforms lacking exon 48 encoded amino acid sequences that are sufficiently functional so as to attenuate expression of a renal cystic disease phenotype.

genetics↗

bioRxiv2020

Pathologic α-Synuclein Species Activate LRRK2 in Pro-Inflammatory Monocyte and Macrophage Responses

Missense mutations in the LRRK2 gene that lead to LRRK2 kinase hyperactivity can cause Parkinsons disease (PD). The link between LRRK2 and -synuclein aggregation in PD remains enigmatic. Numerous reports suggest critical LRRK2 functions in microglial responses. Herein, we find that LRRK2-positive immune cells in the brain represent CD68-positive pro-inflammatory, monocyte-derived macrophages, distinct from microglia. Rod -synuclein fibrils stimulate LRRK2 kinase activity in monocyte-derived macrophages, and LRRK2 mutations lead to enhanced recruitment of classical monocytes into the midbrain in response to -synuclein. LRRK2 kinase inhibition blocks -synuclein fibril induction of LRRK2 protein in both human and murine macrophages, with human cells demonstrating much higher LRRK2 levels and kinase activity than equivalent murine cells. Further, interferon-{gamma} strongly induces LRRK2 kinase activity in primary human macrophages in comparison to weak effects observed in murine cells. These results highlight peripheral immune responses in LRRK2-linked paradigms that further connect two central proteins in PD.

neuroscience↗