Conjugated linoleic acids (CLAs) can serve as a nutritional intervention to regulate quality, function, and fat infiltration in skeletal muscles, but the specific cytological mechanisms remain unknown. Here, we applied single-nucleus RNA-sequencing (snRNA-seq) to characterize the cytological mechanism of CLAs regulates fat infiltration in skeletal muscles based on pig models. We investigated the regulatory effects of CLAs on cell populations and molecular characteristics in pig muscles and found CLAs could promote the transformation of fast glycolytic myofibers into slow oxidative myofibers. We also observed three subpopulations including SCD⁺/DGAT2⁺, FABP5⁺/SIAH1⁺, and PDE4D⁺/PDE7B⁺ subclusters in adipocytes and CLAs could increase the percentage of SCD⁺/DGAT2⁺ adipocytes. RNA velocity analysis showed FABP5⁺/SIAH1⁺ and PDE4D⁺/PDE7B⁺ adipocytes could differentiate into SCD⁺/DGAT2⁺ adipocytes. We further verified the differentiated trajectory of mature adipocytes and identified PDE4D⁺/PDE7B⁺ adipocytes could differentiate into SCD⁺/DGAT2⁺ and FABP5⁺/SIAH1⁺ adipocytes by using high intramuscular fat (IMF) content Laiwu pig models. The cell-cell communication analysis identified the interaction network between adipocytes and other subclusters such as fibro/adipogenic progenitors (FAPs). Pseudotemporal trajectory analysis and RNA velocity analysis also showed FAPs could differentiate into PDE4D⁺/PDE7B⁺ preadipocytes and we discovered the differentiated trajectory of preadipocytes into mature adipocytes. Besides, we found CLAs could promote FAPs differentiate into SCD⁺/DGAT2⁺ adipocytes via inhibiting c-Jun N-terminal kinase (JNK) signaling pathway in vitro. This study provides a foundation for regulating fat infiltration in skeletal muscles by using nutritional strategies and provides potential opportunities to serve pig as an animal model to study human fat infiltrated diseases.

Despite advances in therapeutic approaches, lung cancer remains the leading cause of cancer-related deaths. To understand the molecular programs underlying lung cancer initiation and maintenance, we focused on stem cell programs that are normally extinguished with differentiation but can be reactivated during oncogenesis. Here, we have used extensive genetic modeling and patient-derived xenografts (PDXs) to identify a dual role for Msi2: as a signal that acts initially to sensitize cells to transformation, and subsequently to drive tumor propagation. Using Msi reporter mice, we found that Msi2-expressing cells were marked by a pro-oncogenic landscape and a preferential ability to respond to Ras and p53 mutations. Consistent with this, genetic deletion of Msi2 in an autochthonous Ras/p53-driven lung cancer model resulted in a marked reduction of tumor burden, delayed progression, and a doubling of median survival. Additionally, this dependency was conserved in human disease as inhibition of Msi2 impaired tumor growth in PDXs. Mechanistically, Msi2 triggered a broad range of pathways critical for tumor growth, including several novel effectors of lung adenocarcinoma. Collectively, these findings reveal a critical role for Msi2 in aggressive lung adenocarcinoma, lend new insight into the biology of this disease, and identify potential new therapeutic targets.