Biology subjects

Kerksiek, A.

Publications and source records attributed to Kerksiek, A..

3 recordsLinked to original sources

bioRxiv2026

The COPI coatomer influences LDL receptor activity, hepatic lipid storage, and apoB secretion

BackgroundDecreased hepatic removal of low density lipoproteins (LDL) and increased apolipoprotein B (apoB) production cause hypercholesterolemia, a major causal risk factor of atherosclerotic cardiovascular disease (ASCVD). By a genome-wide siRNA screen, we previously identified subunits of the Coat protein I (COPI) complex to limit LDL uptake into Huh-7 hepatocarcinoma cells. MethodsThese findings were validated by targeted in vitro experiments as well as genetic association studies in humans and three mouse models with mutated or disrupted COPI genes. ResultsSilencing of COPA, COPB1, COPB2, ARCN1, COPG1, and COPZ1 in Huh-7 cells resulted in decreased uptake of LDL and aberrant glycosylation and altered cell surface abundance of the LDL receptor (LDLR) as well as increased apoB secretion and cellular lipid storage. Single nucleotide polymorphisms of ARCN1 were associated with lower ARCN1 expression and higher levels of LDL-cholesterol (LDL-C). Rare variants of COPA and COPG1 were enriched among patients with LDL-C > 5 mmol/L. Patients and mice carrying other rare immunopathogenic missense variants of COPA and COPG1 did not present with elevated plasma levels of LDL-C, while hepatic knockdown of murine Copg1 increased the concentrations of non-HDL-cholesterol in plasma and triglycerides in the liver. ConclusionsThe COPI coatomer regulates LDLR activity and apoB secretion as well as lipid content of liver cells. Loss of function of some variants of COPI genes are associated with higher LDL-C levels.

cell biology↗

bioRxiv2024

Reducing CETP activity prevents memory decline in an Alzheimer's disease mouse model

Epidemiological studies have shown that lower activity of the cholesteryl ester transfer protein (CETP) correlates with reduced Alzheimers disease (AD) risk. While small molecule CETP inhibitors like evacetrapib have previously been assessed for cardiovascular diseases, their involvement in AD has not been investigated. Here, we establish CETP as a novel pharmacological target for AD treatment. Using CETP transgenic mice crossed to a mouse model of amyloidosis and administering evacetrapib, we provide evidence that CETP inhibition maintained memory independent of classic AD markers, increased hippocampal cholesterol, altered plasma lipoproteins, and changed transcription of genes linked to brain barriers. Using proteomic data of cerebrospinal fluid from cognitively unimpaired individuals at risk for AD (the PREVENT-AD cohort), we confirm that our mouse model reflects physiological changes in pre-symptomatic human subjects. We propose the repurposing of CETP inhibitors as an effective therapeutic strategy to delay or prevent cognitive impairment in AD.

neuroscience↗

bioRxiv2019

Atxn2-CAG100-KnockIn mouse spinal cord shows progressive TDP43 pathology associated with cholesterol biosynthesis suppression

Large polyglutamine expansions in Ataxin-2 (ATXN2) cause multi-system nervous atrophy in Spinocerebellar Ataxia type 2 (SCA2). Intermediate size expansions carry a risk for selective motor neuron degeneration, known as Amyotrophic Lateral Sclerosis (ALS). Conversely, the depletion of ATXN2 prevents disease progression in ALS. Although ATXN2 interacts directly with RNA, and in ALS pathogenesis there is a crucial role of RNA toxicity, the affected functional pathways remain ill defined. Here, we examined an authentic SCA2 mouse model with Atxn2-CAG100-KnockIn for a first definition of molecular mechanisms in spinal cord pathology. Neurophysiology of lower limbs detected sensory neuropathy rather than motor denervation. Triple immunofluorescence demonstrated cytosolic ATXN2 aggregates sequestrating TDP43 and TIA1 from the nucleus. In immunoblots, this was accompanied by elevated CASP3, RIPK1 and PQBP1 abundance. RT-qPCR showed increase of Grn, Tlr7 and Rnaset2 mRNA versus Eif5a2, Dcp2, Uhmk1 and Kif5a decrease. These SCA2 findings overlap well with known ALS features. Similar to other ataxias and dystonias, decreased mRNA levels for Unc80, Tacr1, Gnal, Ano3, Kcna2, Elovl5 and Cdr1 contrasted with Gpnmb increase. Preterminal stage tissue showed strongly activated microglia containing ATXN2 aggregates, with parallel astrogliosis. Global transcriptome profiles from stages of incipient motor deficit versus preterminal age identified molecules with progressive downregulation, where a cluster of cholesterol biosynthesis enzymes including Dhcr24, Msmo1, Idi1 and Hmgcs1 was prominent. Gas chromatography demonstrated a massive loss of crucial cholesterol precursor metabolites. Overall, the ATXN2 protein aggregation process affects diverse subcellular compartments, in particular stress granules, endoplasmic reticulum and receptor tyrosine kinase signaling. These findings identify new targets and potential biomarkers for neuroprotective therapies.

neuroscience↗