Hepatocyte-intrinsic SMN deficiency drives metabolic dysfunction and liver steatosis in spinal muscular atrophy

Authors:
Damien Meng-Kiat Leow , Yang Kai Ng , Loo Chien Wang , Hiromi Wl Koh , Tianyun Zhao , Zi Jian Khong , Tommaso Tabaglio , Gunaseelan Narayanan , Richard M Giadone , Radoslaw M Sobota , Shi-Yan Ng , Adrian Kk Teo , Simon H Parson , Lee L Rubin , Wei-Yi Ong , Basil T Darras , Crystal Jj Yeo 
In:
Source:
Publication Date: (2024)
Issue: : e173702
Research Area:
Gastroenterology
Cells used in publication:
Induced Pluripotent Stem Cell (iPS), human
Species: human
Tissue Origin:
Culture Media:
Experiment

Induced Hepatocyte (iHep) Differentiation

...From day 10 onwards, the RPMI/B27 basal differentiation medium was replaced with hepatocyte culture media (#CC-3198) (Lonza, Basel, Switzerland). On days 10, 13, 15, 17, 20 and 22, the cells were supplemented with 30 ng/mL of Human Oncostatin M IS (#130-114-942) (Miltenyi Biotec, North Rhine-Westphalia, Germany) and 50 ng/mL of Human HGF (#130-103-437) (Miltenyi Biotec, North Rhine-Westphalia, Germany). On day 24, the iHeps were harvested for further processing. The schematic representation of the differentiation protocol is as depicted in Supplementary Fig. S2.

Abstract

Spinal Muscular Atrophy (SMA) is typically characterized as a motor neuron disease, but extraneuronal phenotypes are present in almost every organ in severely affected patients and animal models. Extra-neuronal phenotypes were previously underappreciated as patients with severe SMA phenotypes usually died in infancy; however, with current treatments for motor neurons increasing patient lifespan, impaired function of peripheral organs may develop into significant future comorbidities and lead to new treatment-modified phenotypes. Fatty liver is seen in SMA animal models , but generalizability to patients and whether this is due to hepatocyteintrinsic Survival Motor Neuron (SMN) protein deficiency and/or subsequent to skeletal muscle denervation is unknown. If liver pathology in SMA is SMN-dependent and hepatocyteintrinsic, this suggests SMN repleting therapies must target extra-neuronal tissues and motor neurons for optimal patient outcome. Here we showed that fatty liver is present in SMA and that SMA patient-specific iHeps were susceptible to steatosis. Using proteomics, functional studies and CRISPR/Cas9 gene editing, we confirmed that fatty liver in SMA is a primary SMN-dependent hepatocyte-intrinsic liver defect associated with mitochondrial and other hepatic metabolism implications. These pathologies require monitoring and indicate need for systematic clinical surveillance and additional and/or combinatorial therapies to ensure continued SMA patient health.