Biology subjects

Donahue, H.

Publications and source records attributed to Donahue, H..

5 recordsLinked to original sources

bioRxiv2026

PNPLA3I148M is a novel regulator of bone mass independent of MASLD

Metabolic-dysfunction associated steatotic liver disease (MASLD) is the most common chronic liver disease. Fracture risk is increased among people with MASLD, however, the genetic contribution to risk is undetermined. PNPLA3I148M is a common SNP which accounts for most MASLD heritability and increases MASLD morbidity and mortality. However, PNPLA3I148M impact on bone is unexplored. To bridge this gap, we used a validated murine model of MASLD (DIAMOND mice) which received human PNPLA3 transgenes via adeno-associated vector serotype 8 (AAV8) and assessed bone morphology, cellularity, and transcriptomics. PNPLA3I148M was expressed in bone and associated with bone loss, decreased bone formation, increased bone resorption, and increased bone marrow adiposity. PNPLA3I148M reprogrammed the transcriptome in bone, enriching expression of pathways associated with fatty acid metabolism and hampering bone turnover. Notably, these findings occurred in the absence of MASLD. These findings suggest PNPLA3I148M possesses an intrinsic deleterious skeletal role.

physiology↗

bioRxiv2024

Sexual dimorphism of MASLD-driven bone loss

Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) is highly prevalent with major risk of progression to Metabolic Dysfunction-Associated Steatohepatitis (MASH) and Hepatocellular Carcinoma (HCC). Recently, osteoporosis and bone fracture have emerged as sexually-dimorphic comorbidities of MASLD yet the mechanisms of this bone loss are unknown. Herein, we address these knowledge gaps using DIAMOND mice which develop MASLD, MASH, and HCC via Western diet exposure. We examined the skeletal phenotype of male DIAMOND mice after 16, 36, and 48 weeks of exposure to Western or control diet. At 16 weeks, male DIAMOND mice with MASLD lose trabecular bone but retain mechanical bone integrity. At 48 weeks, males lose cortical bone and mechanical integrity, indicating severe skeletal weakening. Female DIAMOND mice were protected from cortical and trabecular MASLD-associated bone loss and skeletal fragility at all timepoints. Using NicheNet, a publicly available database of hepatic mRNA expression in DIAMOND mice, and a PTH-induced model of bone loss, we suggest Ctgf, Rarres2, Anxa2, Fgf21, and Mmp13 are liver-secreted ligands inducing bone resorption. This study is the first preclinical investigation of bone loss in MASLD, and the first to suggest the role of Ctgf, Rarrest2, Anxa2, Fgf21, and Mmp13 as drivers of this pathology.

physiology↗

bioRxiv2023

Hindlimb Unloading Induces Bone Microarchitectural and Transcriptomic Changes in Murine Long Bones in an Age-Dependent Manner

Age and disuse-related bone loss both result in decreases in bone mineral density, cortical thickness, and trabecular thickness and connectivity. Disuse induces physiological changes in bone like those seen with aging. Bone microarchitecture and biomechanical properties were compared between 6- and 22-month-old C57BL/6J male control mice and 6-month-old mice that were hindlimb unloaded (HLU) for 3 weeks. Epiphyseal trabecular bone was the compartment most affected by HLU and demonstrated an intermediate bone phenotype between age-matched controls and aged controls. RNA extracted from whole-bone marrow-flushed tibiae was sequenced and analyzed. Differential gene expression analysis additionally included 4-month-old male mice unloaded for 3 weeks compared to age-matched controls. Gene ontology analysis demonstrated that there were age-dependent differences in differentially expressed genes. Genes related to downregulation of cellular processes were most affected in 4-month-old mice after disuse whereas those related to mitochondrial function were most affected in 6- month-old mice. Cell-cycle transition was downregulated with aging. A publicly available dataset (GSE169292) from 3-month female C57BL/6N mice unloaded for 7 days was included in ingenuity pathway analysis with the other datasets. IPA was used to identify the leading canonical pathways and upstream regulators in each HLU age group. IPA identified "Senescence Pathway" as the second leading canonical pathway enriched in mice exposed to HLU. HLU induced activation of the senescence pathway in 3- month and 4-month-old mice but inhibited it in 6-month-old mice. In conclusion, we demonstrate that hindlimb unloading and aging initiate similar changes in bone microarchitecture and gene expression. However, aging is responsible for more significant transcriptome and tissue-level changes compared to hindlimb unloading. HighlightsO_LIEpiphyseal trabecular bone is most susceptible to hindlimb unloading. C_LIO_LIHindlimb unloaded limbs resemble an intermediate phenotype between age-matched and aged controls. C_LIO_LIHindlimb unloading induces gene expression changes that are age dependent and may lead to inflammation and/or mitochondrial dysfunction depending on context. C_LIO_LIYounger mice (3-4 months) activate the senescence pathway upon hindlimb unloading, whereas skeletally mature (6 months) mice inhibit it. C_LI

bioengineering↗

bioRxiv2020

Muscle Atrophy: Different Strains of Mice Respond Differently to Single Limb Immobilization

To examine whether genetic variability plays a role in muscle adaption to its mechanical environment, we examined hind limb immobilization in five different strains of mice: CAST/EiJ, NOD/ShiLtJ, NZO/HILtJ, 129S1/SvImJ and A/J. Mice had one limb immobilized by a cast for three weeks. The response to immobilization was dependent on the strain of mice examined. A/J mice lost the most body weight following immobilization and displayed a significant decrease in physical activity. None of the other strains displayed a significant decrease in activity. Food consumption was significantly increased in NOD/ShiLtJ mice. All other strains had non-significant changes in food consumption. Muscle mass/body weight was decreased by immobilization, to varying degrees, in all strains except 1291/SvImJ. Casting decreased absolute muscle mass in both quadriceps and gastrocnemius in NOD/ShiltJ and NZO/HILtJ mice, two strains that can develop diabetes, but not in the other strains. Three weeks of immobilization caused a significant increase in quadriceps levels of atrogenes in CAST/EiJ mice but not in other strains. Immobilization caused a significant increase in quadriceps and gastrocnemius levels of Myh4 in CAST/EiJ mice but not in any other strain. A similar trend was observed for Myh7 in gastrocnemius muscle. Immobilization resulted in a decrease the p-p70S6K1/total p706SK1 ratio in quadriceps of NOD/ShiLtJ mice and the gastrocnemius of A/J mice, but not in other strains. Immobilization did not affect the p-4EBP1/total 4EBP1 ratio in quadriceps of any of the strains examined. However, the p-4EBP1/total 4EBP1 ratio in gastrocnemius was greater in immobilized, relative to control, limbs in CAST/EiJ mice. Muscle mass normalized to body weight in both gastrocnemius and quadriceps displayed the greatest degree of heritability. These results reveal remarkable variability in responsiveness to immobilization across five different genetic strains of mice.

physiology↗

bioRxiv2020

Mechanical Loading Recovers Bone but not Muscle Lost During Unloading

Space travel and prolonged bed rest are examples of mechanical unloading that induce significant muscle and bone loss. To explore interactions between skeletal bone and muscle during reloading, we hypothesized that acute external mechanical loading of bone in combination with re-ambulation facilitates proportional recovery of bone and muscle lost during hind limb suspension (HLS) unloading. Adult male C57Bl/6J mice were assigned to a HLS or time-matched ground control (GC) group. After 2-weeks of HLS, separate groups of mice were studied at day 14 (no re-ambulation), day 28 (14 days re-ambulation) and day 56 (42 days re-ambulation); throughout the re-ambulation period, one limb received mechanical loading and the contralateral limb served as an internal control. HLS induced loss of trabecular bone volume (BV/TV; -51%{+/-}2%) and muscle weight (-15%{+/-}2%) compared to GC at day 14. At day 28, the left tibia (re-ambulation only) of HLS mice had recovered 20% of BV/TV lost during HLS, while the right tibia (re-ambulation and acute external mechanical loading) recovered to GC values of BV/TV ([~]100% recovery). At day 56, the right tibia continued to recover bone for some outcomes (trabecular BV/TV, trabecular thickness), while the left limb did not. Cortical bone displayed a delayed response to HLS, with a 10% greater decrease in BV/TV at day 28 compared to day 14. In contrast to bone, acute external mechanical loading during the re-ambulation period did not significantly increase muscle mass or protein synthesis in the gastrocnemius, compared to re-ambulation alone.

physiology↗