Gomez-Gutierrez, R. | bioRxiv Science

bioRxiv2026

Reduced LACTB expression in myeloid cells is associated with elevated succinylcarnitine levels and reduced Alzheimers disease risk.

BackgroundLactamase {beta} (LACTB) is a serine {beta}-lactamase-like mitochondrial enzyme associated with cancer progression, obesity, and lipid metabolism. LACTB is located in an Alzheimers Disease (AD) risk locus and has been associated with AD in a proteomic study. MethodsWe performed Mendelian Randomization (MR) analysis to estimate the association between LACTB expression, succinylcarnitine levels, and AD risk. We generated LACTB knock-down (KD) THP1 macrophages, LACTB knock-out (KO) iPSC-derived microglia and LACTB enzymatically-dead (ED) mice. The impact of LACTB loss-of-function in myeloid cells was characterized via transcriptomics, metabolomics, lipidomics, and functional assays. Finally, human LACTB KO microglia precursors were xenotransplanted into the brains of mice with amyloid pathology to assess in vivo interactions with amyloid plaques. ResultsMR analyses revealed that lower LACTB expression in myeloid cells may lead to reduced AD risk and higher levels of succinylcarnitine, a metabolite associated with AD risk. We identified LACTB as a primary enzyme responsible for succinylcarnitine hydrolysis. Transcriptional and functional studies showed that loss of LACTB enhances OXPHOS, and reduces protein synthesis and triglycerides. LACTB expression was upregulated following interferon or TNF stimulation, and its loss modified efferocytosis- related functions under inflammatory conditions. In vivo, xenotransplanted human LACTB KO microglia exhibited enhanced association with amyloid plaques. ConclusionsOur findings define a previously unrecognized axis linking LACTB and succinylcarnitine to myeloid cell function and AD susceptibility. Given the druggability of LACTB and the potential for succinylcarnitine to serve as a translational biomarker, this enzyme represents a promising therapeutic target for modulation of neuroinflammation in AD.

neuroscience↗

bioRxiv2023

TMEM106B coding variant is protective and deletion detrimental in a mouse model of tauopathy

TMEM106B is a risk modifier for a growing list of age-associated dementias including Alzheimers and frontotemporal dementia, yet its function remains elusive. Two key questions that emerge from past work are whether the conservative T185S coding variant found in the minor haplotype contributes to protection, and whether the presence of TMEM106B is helpful or harmful in the context of disease. Here we address both issues while extending the testbed for study of TMEM106B from models of TDP to tauopathy. We show that TMEM106B deletion accelerates cognitive decline, hindlimb paralysis, neuropathology, and neurodegeneration. TMEM106B deletion also increases transcriptional overlap with human AD, making it a better model of disease than tau alone. In contrast, the coding variant protects against tau-associated cognitive decline, neurodegeneration, and paralysis without affecting tau pathology. Our findings show that the coding variant contributes to neuroprotection and suggest that TMEM106B is a critical safeguard against tau aggregation.

neuroscience↗