Biology subjects

Tsingas, M.

Publications and source records attributed to Tsingas, M..

3 recordsLinked to original sources

bioRxiv2025

Lactate metabolic coupling between the endplates and nucleus pulposus via MCT1 is essential for intervertebral disc health

During skeletal growth, there is an increased secretion of lactate by glycolytic nucleus pulposus (NP) cells of the intervertebral disc. To investigate the role of this anion, we generated annulus fibrosus (AF) and endplate (EP) specific Mct1cKO (Slc16a1Col2CreERT2) mice. Histological and spatial transcriptomic studies indicated significant disc degeneration in Mct1cKO, characterized by NP cell loss and delayed EP maturation. Metabolic assays showed that while AF and EP cells were glycolytic, EP chondrocytes readily metabolized lactate. In EP cells, lactate promoted protein, and H3K18 lactylation, implying epigenetic programming. These findings suggest that NP-derived lactate promotes EP cartilage transdifferentiation into the subchondral bone, and in its absence, continued glucose consumption by the persistent EP cartilage reduces glucose availability to the NP and AF likely contributing to tissue degeneration. This study provides the first in vivo evidence that metabolic coupling between NP and EP cells is essential for disc growth and health.

cell biology↗

bioRxiv2024

SIRT6 loss causes intervertebral disc degeneration in mice by promoting senescence and SASP status

Intervertebral disc degeneration is a major risk factor contributing to chronic low back and neck pain. While the etiological factors for disc degeneration vary, age is still one of the most important risk factors. Recent studies have shown the promising role of SIRT6 in mammalian aging and skeletal tissue health, however its role in the intervertebral disc health remains unexplored. We investigated the contribution of SIRT6 to disc health by studying the age-dependent spinal phenotype of mice with conditional deletion of Sirt6 in the disc (AcanCreERT2; Sirt6fl/fl). Histological studies showed a degenerative phenotype in knockout mice compared to Sirt6fl/fl control mice at 12 months which became pronounced at 24 months. RNA-Seq analysis of NP and AF tissues, quantitative histone analysis, and in vitro multiomics employing RNA-seq with ATAC-seq revealed that SIRT6-loss resulted in changes in acetylation and methylation status of specific Histone 3 lysine residues, thereby affecting DNA accessibility and transcriptomic landscape. A decrease in autophagy and an increase in DNA damage were also noted in Sirt6-deficient cells. Further mechanistic insights revealed that loss of SIRT6 increased senescence and SASP burden in the disc characterized by increased p21, {gamma}H2AX, IL-6, and TGF-{beta} abundance. Taken together our study highlights the contribution of SIRT6 in modulating DNA damage, autophagy and cell senescence, and its importance in maintaining disc health during aging thereby underscoring it as a potential therapeutic target to treat intervertebral disc degeneration.

molecular biology↗

bioRxiv2023

Increased HIF-2α Activity in the Nucleus Pulposus Causes Intervertebral Disc Degeneration in the Aging Mouse Spine

Hypoxia-inducible factors (HIFs) are essential to the homeostasis of hypoxic tissues. Although HIF-2, is expressed in nucleus pulposus (NP) cells, consequences of elevated HIF-2 activity on disc health remains unknown. We expressed HIF-2 with proline to alanine substitutions (P405A;P531A) in the Oxygen-dependent degradation domain (HIF-2dPA) in the NP tissue using an inducible, nucleus pulposus-specific K19CreERT allele to study HIF-2 function in the adult intervertebral disc. Expression of HIF-2 in NP impacted disc morphology, as evident from small but significantly higher scores of degeneration in NP of 24-month-old K19CreERT; HIF-2dPA (K19-dPA) mice. Noteworthy, comparisons of grades within each genotype between 14 months and 24 months indicated that HIF-2 overexpression contributed to more pronounced changes than aging alone. The annulus fibrosus (AF) compartment in the 14-month-old K19-dPA mice exhibited lower collagen turnover and Fourier transform-infrared (FTIR) spectroscopic imaging analyses showed changes in the biochemical composition of the 14-and 24-month-old K19-dPA mice. Moreover, there were changes in aggrecan, chondroitin sulfate, and COMP abundance without alterations in NP phenotypic marker CA3, suggesting the overexpression of HIF-2 had some impact on matrix composition but not the cell phenotype. Mechanistically, the global transcriptomic analysis showed enrichment of differentially expressed genes in themes closely related to NP cell function such as cilia, SLIT/ROBO pathway, and HIF/Hypoxia signaling at both 14- and 24-months. Together, these findings underscore the role of HIF-2 in the pathogenesis of disc degeneration in the aged spine.

cell biology↗