Human-like adrenal features in Chinese tree shrews revealed by multi-omics analysis of adrenal cell populations and steroid synthesis.

The Chinese tree shrew ( Tupaia belangeri chinensis) has emerged as a promising model for investigating adrenal steroid synthesis, but it is unclear whether the same cells produce steroid hormones and whether their production is regulated in the same way as in humans. Here, we comprehensively mapped the cell types and pathways of steroid metabolism in the adrenal gland of Chinese tree shrews using single-cell RNA sequencing, spatial transcriptome analysis, mass spectrometry, and immunohistochemistry. We compared the transcriptomes of various adrenal cell types across tree shrews, humans, macaques, and mice. Results showed that tree shrew adrenal glands expressed many of the same key enzymes for steroid synthesis as humans, including CYP11B2, CYP11B1, CYB5A, and CHGA. Biochemical analysis confirmed the production of aldosterone, cortisol, and dehydroepiandrosterone but not dehydroepiandrosterone sulfate in the tree shrew adrenal glands. Furthermore, genes in adrenal cell types in tree shrews were correlated with genetic risk factors for polycystic ovary syndrome, primary aldosteronism, hypertension, and related disorders in humans based on genome-wide association studies. Overall, this study suggests that the adrenal glands of Chinese tree shrews may consist of closely related cell populations with functional similarity to those of the human adrenal gland. Our comprehensive results (publicly available at http://gxmujyzmolab.cn:16245/scAGMap/) should facilitate the advancement of this animal model for the investigation of adrenal gland disorders.

Functional characterization of RIP2 in large yellow croaker (Larimichthys crocea), a protein involved in the host antiviral responses via NF-κΒ, IRF3/7 related signaling.

As an adaptor protein functions essentially in the activation of NF-κΒ and MAPK signaling pathways mediated by NOD1 and NOD2, RIP2 plays important roles in the host innate immune responses. In the present study, the RIP2 ortholog termed Lc-RIP2 was identified and characterized in large yellow croaker (Larimichthys crocea). It was revealed that Lc-RIP2 is consisted of an open reading frame (ORF) of 1695 bp, encoding a protein of 564 aa, with an N-terminal kinase domain and a C-terminal caspase activation and recruitment domain (CARD). Subcellular localization assays demonstrated that Lc-RIP2 was a cytosolic protein, which was broadly distributed in the examined tissues/organs, and could be induced in response to poly I:C, LPS, PGN, and Pseudomonas plecoglossicida stimulations in vivo according to qRT-PCR analysis. Notably, Lc-RIP2 overexpression in vitro was sufficient to abolish SVCV proliferation in EPC cells, and could significantly induce the activation of NF-κB, IRF3, IRF7, and IFN1 promoters. In addition, luciferase assays found that Lc-RIP2 could cooperate with Lc-MAVS, Lc-TRAF3, Lc-TRAF6, Lc-IRF3, and Lc-IRF7 in NF-κB activation, associate with Lc-TRIF, Lc-MAVS, Lc-TRAF3, Lc-IRF3, and Lc-IRF7 in IRF3 activation, enhance Lc-TRIF, Lc-MAVS, Lc-TRAF3, and Lc-TRAF6 mediated IRF7 activation, and Lc-IRF3 mediated IFN1 activation, whereas suppress NF-κB activation when co-expressed with Lc-TRIF. Co-immunoprecipitation (Co-IP) assays also demonstrated that Lc-RIP2 interacts separately with Lc-TRIF, Lc-MAVS, Lc-TRAF3, Lc-TRAF6, Lc-IRF3, and Lc-IRF7. It is thus collectively indicated that Lc-RIP2 function dominantly in the regulation of the host innate immune signaling.