Tomioka, I. | bioRxiv Science

bioRxiv2025

Establishment of a second-generation transgenic marmoset model of polyglutamine disease recapitulating neurological symptoms and pathology

Neurodegenerative diseases, including polyglutamine diseases, remain a major clinical challenge, partly because of limited animal models that recapitulate human disease. Here, we describe a second-generation transgenic marmoset model of spinocerebellar ataxia 3 (SCA3), a polyglutamine disease, which stably expresses expanded CAG repeats in ATXN3. All five offspring of the founder marmoset harbored the transgene with reduced transgene integration sites and without repeat instability or genetic mosaicism, offering improved construct validity. Three of the five marmosets developed progressive motor impairments that segregated into two distinct phenotypes: early onset with rapid progression and late onset with mild progression, accompanied by corresponding patterns in body weight gain and grip strength. Pathological analysis revealed cerebellar Purkinje cell loss, spinal cord neurodegeneration, and widespread intranuclear inclusions. The severity of motor phenotypes correlated with transgene expression levels in disease-relevant brain regions, including the cerebellum, spinal cord, and striatum. By overcoming the common translational limitations of rodent systems, our second-generation model offers a powerful platform for investigating disease mechanisms and testing potential therapeutic interventions. Our results advance the utility of transgenic marmosets as clinically relevant models of neurodegenerative diseases. Summary StatementSecond-generation transgenic marmoset models of spinocerebellar ataxia 3 replicated the progressive motor deficits and neuropathology of the founder marmoset, providing a powerful platform for studying disease mechanisms and developing therapies.

neuroscience↗

bioRxiv2023

Genistein enhances NAD+ biosynthesis by binding to Prohibitin 1 and upregulating nicotinamide phosphoribosyltransferase in adipocytes

Decreased NAD+ levels in adipocytes cause adipose-tissue dysfunction, leading to systemic glucose and lipid metabolism failure. Therefore, developing small molecules and nutraceuticals that can increase NAD+ levels in adipocytes is necessary. Genistein, a nutraceutical derived from soybeans, has various physiological activities and improves glucose and lipid metabolism. In this study, we aimed to unravel the effects of genistein on the intracellular NAD+ levels in adipocytes and the underlying molecular mechanisms. We showed that genistein enhanced NAD+ biosynthesis by increasing the expression of nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in NAD+ biosynthesis. A pull-down assay using genistein-immobilized beads identified prohibitin 1 (PHB1) as a target protein of genistein. The knockdown of PHB1 suppressed the genistein-induced increase in NAMPT expression and NAD+ levels in adipocytes. Genistein-bound PHB1 contributed to the stabilization of the transcription factor CCAAT/enhancer-binding protein {beta} through activation of extracellular signal-regulated kinase, resulting in increased NAMPT expression at the transcriptional level. Genistein induced dephosphorylation of peroxisome proliferator-activated receptor at serine 273 and increased the insulin-sensitizing adipokine, adiponectin, in adipocytes, whereas the knockdown of NAMPT and PHB1 abolished these genistein-mediated effects. Our results proved the potential efficacy of nutraceuticals in promoting NAD+ levels and restoring metabolic function in adipocytes. Furthermore, we identified PHB1, localized to the plasma membrane, as a candidate target protein for increased expression of NAMPT in adipocytes. Overall, these findings will assist in developing NAD+ boosting strategies to alleviate the metabolic dysfunctions in adipose tissues. Significance StatementIncreasing NAD+ levels is an important preventive strategy for maintaining metabolic function. Here, we showed that genistein, a nutraceutical, which increases NAD+ levels in adipocytes, increased NAD+ biosynthesis by upregulating nicotinamide phosphoribosyltransferase (NAMPT), a rate-limiting enzyme in the NAD+ biosynthesis pathway. Our findings also showed that genistein increased NAMPT expression by binding to prohibitin 1 in the plasma membrane. Genistein-induced increase in NAD+ levels promoted adiponectin expression, an insulin-sensitizing adipokine, in adipocytes. This study provides evidence that nutraceuticals, such as genistein, are effective in enhancing NAD+ biosynthesis in adipocytes and that PHB1 is a candidate target protein for increased expression of NAMPT to maintain metabolic functions in adipose tissues.

biochemistry↗