BMPER is a marker of adipose progenitors and adipocytes and a positive modulator of adipogenesis

Perivascular Adipocytes' Adipogenesis Is Defined by Their Anatomical Location in the Descending Thoracic Aorta

Cardiovascular diseases such as hypertension alter thoracic aorta structure. The role that the outer layer of the aorta, its perivascular adipose tissue (PVAT), plays in the pathogenesis of these alterations is poorly understood. In the descending thoracic aorta, PVAT is organized into three distinct strips: one located anterior to the aorta (AP) and two positioned laterally (LP). Genetic tracing indicates differences in the ontogeny of LP and AP, but the implications of these developmental differences and PVAT distribution on adipocyte development remain unknown. We hypothesize that the anatomical location of adipocyte progenitors influences their adipogenic potential and vasoactive functions. PVAT from LP and AP was collected from male SD rats at 10 wks of age (n = 7) to harvest adipocyte progenitors that were differentiated to adipocytes in adipogenic media. Adipogenesis was evaluated after induction and we performed next-generation RNA-seq on progenitors and adipocytes. We then employed Gene Set Enrichment Analysis for enrichment and network analyses. LP progenitors exhibited a 1.13-fold higher adipogenesis rate compared to those from AP. DEG analysis revealed LP had higher expression of adipogenic regulators and basal collagens Col4a2 and Col4a4. When challenged with angiotensin-II, adipocyte progenitors from LP maintained their adipogenic capacity and adipocytes from the same site maintained their secretion of adiponectin at higher rates than AP cells. However, treatment with a Piezo1 mechanoreceptor agonist reduced LP's adipogenic capacity and diminished their adiponectin secretion. These findings highlight site-specific differences in adipogenic activity, extracellular matrix composition, and the secretion of the vasoactive adipokine adiponectin between the LP and AP PVAT strips of the thoracic aorta, suggesting potential functional distinctions in vascular health and disease.

Single-Nucleus RNA Sequencing Reveals Muscle-Region-Specific Differences in Fibro-Adipogenic Progenitors Driving Intramuscular Fat Accumulation

BACKGROUND

Ectopic fat deposition refers to lipid accumulation that affects metabolic function and tissue characteristics. Japanese Black cattle are distinguished by their high intramuscular fat content, which contributes to their distinctive character. However, the genetic mechanisms underlying these traits remain unclear. This study compared gene expression patterns in different muscle regions to identify genes associated with intramuscular fat accumulation. First, we conducted RNA sequencing to analyze differences in gene expression profiles among the sternocleidomastoid, pectoralis minor, and pectoralis major muscles. In addition, single-cell nuclear RNA sequencing was conducted to investigate the cellular composition of these muscle tissues.

RESULTS

Distinct gene expression patterns were observed among the different muscles. In the pectoralis, which contains a high proportion of intramuscular fat, adipocyte-related genes such as FABP4, SCD, and ADIPOQ were highly expressed. In addition, lipases such as PNPLA2, LPL, MGLL, and LIPE were predominantly expressed in intramuscular fat, whereas PLA2G12A, PLD3, and ALOX15 were specifically expressed in myofibers. Moreover, a subclass of fibro-adipogenic progenitor cells that differentiate into intramuscular adipocytes was found to express genes related to microenvironment formation, including ICAM1, TGFBRs, and members of the COL4A family.

CONCLUSIONS

This study provides novel insight into the genetic regulation of intramuscular fat accumulation. It improves our understanding of the molecular mechanisms underlying their distinctive meat characteristics.

Single-cell transcriptomics of clinical grade adipose-derived regenerative cells reveals consistency between donors independent of gender and BMI

Adipose-derived regenerative cells (ADRCs) also referred to as the stromal vascular fraction, provide an ample source of stem cells with widespread regenerative therapeutic use. Being heterogenous in nature, possibly affecting the clinical outcome after stem cell treatment, the ADRC- donor, -BMI, and -gender may have a large impact on ADRC composition and quality but this remains largely unexplored. Herein, we provide a comprehensive single-cell RNA sequencing ADRC mapping across two cell trial intervention studies but found no gender- or BMI-related variations, except for a minor female increase in PI16/CD55-expressing stem cells. Indeed, ADRC heterogeneity was surprisingly minimal between donors. This provides important decision-making support on adipose stem cell donor selection for stem cell treatments, and suggest that donor, gender and BMI should be regarded as less influential.

Anatomical location, sex, and age modulate adipocyte progenitor populations in perivascular adipose tissues

Perivascular adipose tissue (PVAT) regulates vascular function due to its capacity to synthesize vasoactive products and its mechanical properties. PVATs most abundant cells are adipocytes, and their populations are maintained by the maturation of adipocyte progenitor cells (APC), which may play a pivotal role in the pathogenesis of cardiovascular diseases. However, the distribution of APC within PVAT depots, their potential variation in spatial location, and the influence of sex and age on their abundance remain unknown. We hypothesize that APC abundance in PVAT is affected by location, age, sex and that APC subtypes have specific spatial distributions. PVAT from thoracic and abdominal aorta, and mesenteric arteries, and AT from interscapular, gonadal, and subcutaneous depots from 13-week and 30-week-old females and males Pdgfrα-CreERT2 x LSL-tdTomato mice (n = 28) were analyzed. Abdominal aorta PVAT had fewer progenitors than mesenteric PVAT and gonadal AT. Aging reduced the abundance of APC in the thoracic aorta but increased their numbers in mesenteric PVAT. Females had more APC than males in mesenteric PVAT and gonadal AT depots. APC exhibited unique spatial distribution in the aorta and mesenteric PVAT where they localized neighboring vasa vasorum and arteries. APC subtypes (APC1, APC2, APC3, diff APC) were identified in all PVAT depots. Thoracic aorta PVAT APC3 were located in the adventitia while diff APC were in the parenchyma. This study identified variability in APC populations based on depot, age, and sex. The distinctive spatial distribution and the presence of diverse APC subtypes suggest that they may contribute differently to cardiovascular diseases-induced PVAT remodeling.

Transcriptome analysis of adipose tissue and muscle of Laiwu and Duroc pigs

Fat content is an important trait in pig production. Adipose tissue and muscle are important sites for fat deposition and affect production efficiency and quality. To regulate the fat content in these tissues, we need to understand the mechanisms behind fat deposition. Laiwu pigs, a Chinese indigenous breed, have significantly higher fat content in both adipose tissue and muscle than commercial breeds such as Duroc. In this study, we analyzed the transcriptomes in adipose tissue and muscle of 21-d-old Laiwu and Duroc piglets. Results showed that there were 828 and 671 differentially expressed genes (DEG) in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), respectively. Functional enrichment analysis showed that these DEG were enriched in metabolic pathways, especially carbohydrate and lipid metabolism. Additionally, in the longissimus muscle (LM) and psoas muscle (PM), 312 and 335 DEG were identified, demonstrating enrichment in the cell cycle and metabolic pathways. The protein-protein interaction (PPI) networks of these DEG were analyzed and potential hub genes were identified, such as FBP1 and SCD in adipose tissues and RRM2 and GADL1 in muscles. Meanwhile, results showed that there were common DEG between adipose tissue and muscle, such as LDHB, THRSP, and DGAT2. These findings showed that there are significant differences in the transcriptomes of the adipose tissue and muscle between Laiwu and Duroc piglets (P < 0.05), especially in metabolic patterns. This insight serves to advance our comprehensive understanding of metabolic regulation in these tissues and provide targets for fat content regulation.

Adipose tissue-derived stem cells, in vivo and in vitro models for metabolic diseases

The primary role of adipose tissue stem cells (ADSCs) is to support the function and homeostasis of adipose tissue in physiological and pathophysiological conditions. However, when ADSCs become dysfunctional in diseases such as obesity and cancer, they become impaired, undergo signalling changes, and their epigenome is altered, which can have a dramatic effect on human health. In more recent years, the therapeutic potential of ADSCs in regenerative medicine, wound healing, and for treating conditions such as cancer and metabolic diseases has been extensively investigated with very promising results. ADSCs have also been used to generate two-dimensional (2D) and three-dimensional (3D) cellular and in vivo models to study adipose tissue biology and function as well as intracellular communication. Characterising the biology and function of ADSCs, how it is altered in health and disease, and its therapeutic potential and uses in cellular models is key for designing intervention strategies for complex metabolic diseases and cancer.

White Adipose Tissue Heterogeneity in the Single-Cell Era: From Mice and Humans to Cattle

Adipose tissue is a major modulator of metabolic function by regulating energy storage and by acting as an endocrine organ through the secretion of adipokines. With the advantage of next-generation sequencing-based single-cell technologies, adipose tissue has been studied at single-cell resolution, thus providing unbiased insight into its molecular composition. Recent single-cell RNA sequencing studies in human and mouse models have dissected the transcriptional cellular heterogeneity of subcutaneous (SAT), visceral (VAT), and intramuscular (IMAT) white adipose tissue depots and revealed unique populations of adipose tissue progenitor cells, mature adipocytes, immune cell, vascular cells, and mesothelial cells that play direct roles on adipose tissue function and the development of metabolic disorders. In livestock species, especially in bovine, significant gaps of knowledge remain in elucidating the roles of adipose tissue cell types and depots on driving the pathogenesis of metabolic disorders and the distinct fat deposition in VAT, SAT, and IMAT in meat animals. This review summarizes the current knowledge on the transcriptional and functional cellular diversity of white adipose tissue revealed by single-cell approaches and highlights the depot-specific function of adipose tissue in different mammalian species, with a particular focus on recent findings and future implications in cattle.

Mesenchymal stromal cells as conductors of adipose tissue remodeling

Adipose tissue exhibits a remarkable capacity to expand, contract, and remodel in response to changes in physiological and environmental conditions. Here, we describe recent advances in our understanding of how functionally distinct tissue-resident mesenchymal stromal cell subpopulations orchestrate several aspects of physiological and pathophysiological adipose tissue remodeling, with a particular focus on the adaptations that occur in response to changes in energy surplus and environmental temperature. The study of adipose tissue remodeling provides a vehicle to understand the functional diversity of stromal cells and offers a lens through which several generalizable aspects of tissue reorganization can be readily observed.