Browsing by Author "Mendell, Jerry R."

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    Essential metabolic, anti-inflammatory, and anti-tumorigenic functions of miR-122 in liver
    (The Journal of Clinical Investigation, 2012-08-01) Hsu, Shu-hao; Wang, Bo; Kota, Janaiah; Yu, Jianhua; Costinean, Stefan; Kutay, Huban; Yu, Lianbo; Bai, Shoumei; La Perle, Krista; Chivukula, Raghu R.; Mao, Hsiaoyin; Wei, Min; Clark, K. Reed; Mendell, Jerry R.; Caligiuri, Michael A.; Jacob, Samson T.; Mendell, Joshua T.; Ghoshal, Kalpana
    miR-122, an abundant liver-specific microRNA (miRNA), regulates cholesterol metabolism and promotes hepatitis C virus (HCV) replication. Reduced miR-122 expression in hepatocellular carcinoma (HCC) correlates with metastasis and poor prognosis. Nevertheless, the consequences of sustained loss of function of miR-122 in vivo have not been determined. Here, we demonstrate that deletion of mouse Mir122 resulted in hepatosteatosis, hepatitis, and the development of tumors resembling HCC. These pathologic manifestations were associated with hyperactivity of oncogenic pathways and hepatic infiltration of inflammatory cells that produce pro-tumorigenic cytokines, including IL-6 and TNF. Moreover, delivery of miR-122 to a MYC-driven mouse model of HCC strongly inhibited tumorigenesis, further supporting the tumor suppressor activity of this miRNA. These findings reveal critical functions for miR-122 in the maintenance of liver homeostasis and have important therapeutic implications, including the potential utility of miR-122 delivery for selected patients with HCC and the need for careful monitoring of patients receiving miR-122 inhibition therapy for HCV.
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    Impaired regeneration in LGMD2A supported by increased Pax7 positive satellite cell content and muscle specific microRNA dysregulation
    (Muscle & Nerve, 2013-05) Rosales, Xiomara Q.; Malik, Vinod; Sneh, Amita; Chen, Lei; Lewis, Sarah; Kota, Janaiah; Gastier-Foster, Julie M.; Astbury, Caroline; Pyatt, Rob; Reshmi, Shalini; Rodino-Klapac, Louise R.; Clark, K. Reed; Mendell, Jerry R.; Sahenk, Zarife
    Introduction—Recent in vitro studies suggest that CAPN3 deficiency leads initially to accelerated myofiber formation followed by depletion of satellite cells (SC). In normal muscle, upregulation of miR-1 and miR-206 facilitates transition from proliferating SCs to differentiating myogenic progenitors. Methods—We examined the histopathological stages, Pax7 SC content, and muscle specific microRNA expression in biopsy specimens from well-characterized LGMD 2A patients to gain insight into disease pathogenesis. Results—Three distinct stages of pathological changes were identified that represented the continuum of the dystrophic process from prominent inflammation with necrosis and regeneration to prominent fibrosis, which correlated with age and disease duration. Pax7-positive SCs were highest in fibrotic group and correlated with down-regulation of miR-1, miR-133a, and miR-206. Conclusions—These observations, and other published reports, are consistent with microRNA dysregulation leading to inability of Pax7-positive SCs to transit from proliferation to differentiation. This results in impaired regeneration and fibrosis.