miR-93 is significantly upregulated in livers of human patients with MASLD and diet-induced obese mice
To investigate the involvement of miRNAs in lipid metabolism during MASLD progression, we conducted a comprehensive regulatory network analysis comparing patients with MASLD and healthy controls. Among the downregulated genes associated with the gene ontology (GO) term “Regulation of Lipid Metabolic Process” in MASLD patient samples, our analysis focused on the enrichment of miRNA target genes. Of the top-ranked miRNA families sorted by enrichment false discovery rates (FDR), we identified miR-16 and miR-17 families as prominent candidates for further exploration (Fig. 1a). Of particular interest, miR-93, a member of the miR-17 family, was significantly upregulated in the livers of patients with MASLD compared to healthy controls (Fig. 1b).
In wild-type (WT) mice, miR-93 was predominantly expressed in the liver at markedly higher levels compared to other metabolic tissues (Extended Data Fig. 1a). In assessing the clinical relevance of miR-93, in situ hybridization analysis of MASLD livers revealed a striking increase in miR-93 expression compared to healthy controls (Fig. 1c). Furthermore, hepatic miR-93 expression positively correlated with key clinical parameters of MASLD, including body mass index (BMI), aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels, and the NAFLD activity score (NAS) (Fig. 1d).
We observed consistent upregulation of miR-93 across publicly available transcriptome datasets, including human MASLD specimens (GSE48452 and GSE135251) and murine models of MASLD (GSE13840, GSE144721, and GSE55593) (Fig. 1e). Moreover, human datasets (GSE48452) validated positive correlations between miR-93 expression and clinical metrics, such as BMI and NAS (Extended Data Fig. 1b). In diet-induced obese mouse models, miR-93 expression was significantly elevated in the fatty livers of mice fed a high-fat–high-fructose (HFHFr) diet, Lepob/ob mice, and Gubra-Amylin NASH (GAN) diet-fed mice relative to normal chow diet (NCD)-fed WT controls (Fig. 1f-h). Similarly, miR-93 expression was markedly increased in oleic/palmitic acid (OA/PA)-treated hepatocytes (Fig. 1i). Collectively, these data indicate a robust correlation between miR-93 expression and MASLD, highlighting miR-93 as a potential key regulator contributing to MASLD pathogenesis.
miR-93 modulates hepatic steatosis in vivo
To define the role of miR-93 in MASLD, we generated miR-93 knockout (KO) mice via the CRISPR/Cas9 system and compared them to WT mice fed an NCD or HFHFr diet for 16 weeks. In HFHFr diet-fed WT mice, hepatic miR-93 was significantly upregulated (Fig. 2a). Unlike NCD conditions, HFHFr diet-fed miR-93 KO mice showed reduced body weight relative to WT controls (Fig. 2b,c), attributed to lower fat mass and higher lean mass (Fig. 2d,e). Histological analysis revealed decreased liver weight and hepatic steatosis in HFHFr diet-fed miR-93 KO mice (Fig. 2f-h). miR-93 KO mice demonstrated enhanced glucose tolerance, improved insulin sensitivity (Fig. 2i-m), and reduced levels of triglycerides (TG), cholesterol, AST, and ALT (Fig. 2n-q).
Protective effects from diet-induced obesity were similarly observed in a miR-93 KO model of MASLD using the GAN diet. In the GAN diet model of MASLD, miR-93 KO mice showed significant reductions in body and liver weight (Extended Data Fig. 2a-d). Histological analysis, including hematoxylin and eosin (H&E) and Oil Red O staining, confirmed reduced hepatic lipid accumulation and a lower NAS (Extended Data Fig. 2e,f). Metabolic indices were also significantly improved in miR-93 KO mice fed the GAN diet (Extended Data Fig. 2g-j), further supporting the notion that miR-93 deficiency alleviates MASLD progression.
To examine whether miR-93 upregulation drives MASLD, we overexpressed miR-93 via an adenovirus-associated vector (AAV-miR-93) in mice fed either NCD or HFHFr diet. Hepatic miR-93 overexpression in HFHFr diet-fed mice increased body weight and fat mass and decreased lean mass (Extended Data Fig. 3a-d). These mice also showed higher liver weight gain, hepatic steatosis, and NAS (Extended Data Fig. 3e-g) along with impaired glucose tolerance and insulin sensitivity (Extended Data Fig. 3h-l), and elevated TG, cholesterol, AST, and ALT (Extended Data Fig. 3m-p). Thus, miR-93 deficiency mitigates hepatic steatosis and metabolic dysfunction, whereas miR-93 overexpression exacerbates these pathologies.
miR-93 deficiency attenuates hepatic inflammation and fibrosis in MASH
To investigate the role of miR-93 in MASLD to MASH progression, characterized by advanced hepatic steatosis, liver injury, inflammation, and fibrosis, we subjected miR-93 KO mice and WT controls to a 24-week HFHFr diet (MASH diet). This extended feeding regimen stimulates the advanced pathological stages observed in human MASH, including an increased risk of cirrhosis, liver failure, and HCC.20 MASH diet-fed miR-93 KO mice exhibited significantly lower body weight, liver-to-body weight ratio, and fat mass, accompanied by higher lean mass than WT controls (Fig. 3a-e). Histological examination revealed a notable reduction in hepatic steatosis and fibrosis in MASH diet-fed miR-93 KO mice, indicating diminished liver damage (Fig. 3f-h). Correspondingly, MASH diet-fed miR-93 KO mice demonstrated lower levels of hepatic TG, cholesterol, AST, and ALT levels than WT mice on the same diet (Fig. 3i-l). Gene expression analysis further supported these findings, showing significant downregulation of hepatic inflammation-related genes, such as Tnf, Ccl2, Il6, and Il1b, and fibrosis markers, including Acta2, Col1a1, Fn, and Vim, in MASH diet-fed miR-93 KO mice (Fig. 3m). These results highlight miR-93 as a critical regulator of the transition from MASLD to MASH, revealing its role in driving liver inflammation, fibrosis, and steatosis.
miR-93 modulates cholesterol and lipid metabolism in the liver
To further explore the mechanistic role of miR-93 in MASLD progression, we performed RNA sequencing (RNA-seq) on liver samples from HFHFr diet-fed miR-93 KO and WT mice. miR-93 deficiency significantly changed gene expression compared to WT, with 420 genes upregulated and 442 genes downregulated, using an adjusted p-value threshold of < 0.01 and a fold change > 2 (Fig. 4a). GO enrichment analysis of the differentially expressed genes (DEGs) revealed enhanced expression of genes involved in the fatty acid metabolism and FAO in miR-93 KO livers (Fig. 4b), and significant downregulation of steroid metabolism– and cholesterol biosynthesis-related genes (Fig. 4c).
To verify the RNA-seq findings, we examined the expression of key genes involved in FAO and sterol biosynthesis. In HFHFr diet-fed miR-93 KO mice, we observed significant upregulation of Ppara, a master regulator of FAO, along with its target genes, Cpt1a, Acox1, Ppargc1a, and Tfam. In contrast, crucial cholesterol and fatty acid biosynthesis genes, including Srebf1, Srebf2 and their targets Hmgcr, Sqle, Fasn, and Scd1, were markedly downregulated in miR-93 KO livers (Fig. 4d). Similar effects were observed in GAN diet-fed miR-93 KO mice, which showed increased FAO and reduced sterol metabolism in the liver (Extended Data Fig. 2k,l).
To further explore the crucial role of miR-93 in hepatic lipid metabolism and its contribution to MASLD from RNA-Seq analysis, we isolated primary hepatocytes from WT and miR-93 KO mice. Under OA/PA treatment, miR-93 expression was significantly upregulated in WT hepatocytes, whereas miR-93 deficiency substantially reduced intracellular lipid accumulation (Fig. 4e,f). This reduction was accompanied by markedly lower levels of TG and cholesterol in OA/PA-treated miR-93 KO hepatocytes (Fig. 4g,h). Gene expression analysis of miR-93 KO hepatocytes revealed significant upregulation of lipid catabolism-related genes (Fig. 4i). In contrast, expression of Srebf1/2 and their downstream targets significantly decreased in miR-93 KO hepatocytes (Fig. 4j). In addition, miR-93 deficiency enhanced both basal and maximal respiratory capacities in hepatocytes under basal and OA/PA-treated conditions (Fig. 4k,l). Furthermore, ATP levels and mitochondrial DNA copy number increased in miR-93 KO hepatocytes, indicating improved mitochondrial function (Fig. 4m,n).
We also observed the relationship between miR-93 overexpression and lipid metabolism in hepatic steatosis by transducing primary hepatocytes with AAV-miR-93. Although miR-93 overexpression alone did not substantially increase lipid accumulation, it significantly elevated TG and cholesterol levels under OA/PA treatment (Extended Data Fig. 4a-d). Moreover, miR-93 overexpression under OA/PA conditions reduced lipid catabolism gene expression, while upregulating DNL and cholesterol biosynthesis genes (Extended Data Fig. 4e,f). Mitochondrial function and DNA copy number decreased following miR-93 overexpression and OA/PA treatment (Extended Data Fig. 4g-j). Collectively, these findings indicate that miR-93 deficiency mitigates hepatic lipid accumulation by promoting FAO and mitochondrial function while reducing TG and cholesterol biosynthesis, providing mechanistic insights into its role in MASLD progression.
SIRT1 is a direct target of miR-93
To identify the molecular target of miR-93 in MASLD progression, bioinformatic analysis predicted six potential target genes. Among these, SIRT1 emerged as the most compelling candidate (Fig. 5a). Consistent with these predictions, miR-93 overexpression significantly reduced Sirt1 expression, whereas miR-93 KO markedly increased Sirt1 levels in hepatocytes (Extended Data Fig. 5a,b).
Further analysis identified a conserved miR-93 binding site within the 3’ untranslated region (UTR) of SIRT1 mRNA (Fig. 5b). To confirm miR-93 directly targets SIRT1, we performed luciferase reporter assays in HepG2 cells transfected with WT or mutant 3’ UTR SIRT1 constructs. miR-93 overexpression significantly suppressed luciferase activity in WT, but not mutant, 3’UTR constructs (Fig. 5c). Similarly, AAV-miR-93 administration in hepatocytes reduced Sirt1 mRNA and protein levels (Fig. 5d,e), whereas miR-93 suppression elevated Sirt1 expression (Fig. 5f,g).
In MASLD mouse models, miR-93 overexpression greatly reduced Sirt1, whereas miR-93 KO significantly upregulated Sirt1 (Fig. 5j,k and Extended Data Fig. 6a,b). Given that cellular NAD+ levels regulate Sirt1 gene expression and protein activity21, 22, miR-93 KO mice exhibited increased NAD+ concentrations and SIRT1 activity in hepatocytes and liver tissues (Fig. 5h,i,l,m). In contrast, miR-93 overexpression reduced both NAD+ levels and SIRT1 activity (Extended Data Fig. 6c,d). In liver samples from patients with MASLD, SIRT1 and FAO genes were downregulated, whereas cholesterol and lipid synthesis genes were upregulated compared to healthy controls (Fig. 5n,o). Correlation analysis further revealed a negative association between miR-93 and SIRT1, and SIRT1-related FAO target genes. Conversely, miR-93 positively correlated with cholesterol and lipid synthesis genes (Fig. 5p). Together, these findings establish SIRT1 as a direct target of miR-93 and demonstrate that miR-93 modulates the balance between lipid synthesis and oxidation, contributing to MASLD progression.
miR-93/SIRT1 axis regulates hepatic steatosis via the LKB1-AMPK signaling pathway
Previous studies demonstrated that SIRT1 promotes FAO and inhibits DNL and cholesterol biosynthesis in the liver.23, 24 This regulation is mediated by the LKB1–AMPK signaling pathway, a key player in MASLD pathogenesis.18, 19 Based on our findings, we hypothesized the metabolic improvements observed in miR-93-deficient mice were mediated by the SIRT1/LKB1/AMPK axis. miR-93 KO mice on both HFHFr diet and GAN diet exhibited significant LKB1 and AMPK activation, and notable reduction in overall and active cleaved SREBF1/2 (Fig. 6a, Extended Data Fig. 7a). Similar effects were observed in hepatocytes of miR-93 KO mice (Fig. 6b). In contrast, miR-93 overexpression resulted in decreased phosphorylation of LKB1 and AMPK in both the livers of HFHFr diet-fed mice and hepatocytes (Extended Data Fig. 7b,c). Under NCD conditions, miR-93 KO or overexpression moderately changed LKB1 and AMPK phosphorylation (Extended Data Fig. 7d,e).
We further elucidated the role of the miR-93/SIRT1 axis in regulating hepatic lipid metabolism. In hepatocytes from miR-93 KO mice, lentiviral Sirt1 knockdown (shSirt1) significantly attenuated elevated SIRT1 levels and LKB1-AMPK phosphorylation (Fig. 6c). Moreover, miR-93 deficiency enhanced the expression of Sirt1 and fatty acid oxidation-related genes, while inhibiting cholesterol biosynthesis and DNL. Sirt1 knockdown abolished these effects (Fig. 6d-f). Additionally, the metabolic benefits observed in miR-93 KO mice substantially diminished following Ampk knockdown using siRNA (siAmpk) (Fig. 6g-i). Together, these results strongly suggest that the miR-93/SIRT1 axis regulates hepatic lipid and cholesterol metabolism by modulating the LKB1-AMPK signaling pathway, thereby influencing MASLD progression.
miR-93 promotes hepatic steatosis through SIRT1 modulation
Next, we performed in vivo lentiviral knockdown of Sirt1 using Sirt1 shRNA (shSirt1) or Control shRNA (shControl) in HFHFr diet-fed WT and miR-93 KO mice. In WT mice, Sirt1 knockdown minimally affected body weight, fat mass, and lean mass (Fig. 7a-d). As expected, miR-93 deficiency significantly reduced hepatic steatosis by enhancing the LKB1-AMPK signaling pathway compared to WT control. However, Sirt1 knockdown in miR-93 KO mice significantly increased liver-to-body weight ratio compared to untreated miR-93 KO mice (Fig. 7e). Furthermore, LKB1 and AMPK phosphorylation significantly decreased in miR-93 KO mice with Sirt1 knockdown, suggesting SIRT1 is crucial for LKB1-AMPK activation (Fig. 7f,g). Histological analysis showed increased hepatic lipid accumulation with elevated metabolic parameters in miR-93 KO mice following Sirt1 knockdown (Fig. 7h-m). Additionally, Sirt1 knockdown exacerbated hepatic steatosis in both WT and miR-93 KO mice by decreasing FAO and increasing DNL and cholesterol biosynthesis (Fig. 7n,o). These findings indicate that SIRT1 is a pivotal regulator in hepatic lipid metabolism, and its modulation by miR-93 plays a central role in the pathogenesis of MASLD.
Niacin alleviates MASLD via modulation of the miR-93/SIRT1 axis
Despite progress in gene therapies, effective FDA-approved treatments for MASLD remain lacking due to limited efficacy and adverse effects.12, 13 Given the pivotal role of miR-93 in MASLD progression, we explored its potential as a therapeutic target. Using a high-throughput screening system, we aimed to identify FDA-approved drugs that modulate miR-93 expression. We developed a miR-93 inhibitor screening system with the miR-93 promoter driving a luciferase reporter (Fig. 8a). Among a library of 150 FDA-approved drugs, screening revealed niacin most effectively inhibited miR-93 expression (Fig. 8b). Dose-response studies confirmed niacin inhibition of the miR-93 promoter in primary hepatocytes (Fig. 8c).
Niacin, also known as vitamin B3 or nicotinic acid, is essential for regulating lipid and cholesterol levels and participating in NAD+ production, which modulates SIRT1 activity.25 Thus, we administered AAV-Control or AAV-miR-93 to WT mice on an HFHFr diet for eleven weeks, followed by niacin supplementation for an additional five weeks (Fig. 8d). Interestingly, niacin decreased miR-93 level in AAV-Control mice, but showed no effect in AAV-miR-93 mice (Fig. 8e). Furthermore, Niacin did not affect body weight in either group (Fig. 8f); however, in AAV-Control mice, but not AAV-miR-93 mice, niacin significantly reduced the liver-to-body weight ratio (Fig. 8g). Histological analysis and metabolic assessments revealed substantial improvements in hepatic TG, cholesterol, and serum AST and ALT levels in AAV-Control mice receiving niacin. Niacin benefits were limited in AAV-miR-93 mice (Fig. 8h-m). Furthermore, niacin supplementation in AAV-Control mice increased Sirt1 mRNA and protein levels, enhanced LKB1-AMPK signaling, and improved FAO with reduced lipid and cholesterol synthesis. Conversely, niacin did not affect lipid metabolism genes in AAV-miR-93-injected mice (Fig. 8n-q). These results suggest niacin effectively improves MASLD by modulating SIRT1 through miR-93 regulation, though its efficacy diminishes with elevated miR-93 levels (Fig. 8r).