親代肥胖改變子代脂肪前驅細胞組成、轉錄體特徵及分化潛力

Abstract

肥胖主要源於脂肪組織的過度積累，尤其是白色脂肪組織（white adipose tissue, WAT）的擴張。研究指出，兒童及青少年階段的脂肪重塑機制決定成年後的脂肪細胞數量，而親代代謝狀態也可能對子代出生後的代謝產生長期影響。然而，親代肥胖是否在子代出生早期就已改變脂肪前驅細胞的組成、轉錄調控以及分化潛力仍不清楚。本研究以C57BL/6J小鼠為模型，以一般飲食組（Chow Diet, ChowD）與高脂飲食組（HFD）建立母體肥胖子代（MO-F1）、父母雙方肥胖子代（PO-F1）與代謝正常子代（Ln-F1）三組。結果顯示，MO-F1與PO-F1出生第九天的體重與iWAT重量顯著上升，並伴隨棕色脂肪組織與肝臟內脂質堆積的現象。體外iWAT基質血管細胞（stromal vascular fraction, SVF）分化後，MO-F1與PO-F1的產熱基因表現顯著下降，其中MO-F1同時表現出較高的脂肪分化能力。進一步以單細胞RNA定序（scRNA-seq）分析，iWAT SVF中包含三群主要脂肪前驅細胞的細胞群（ASC1a、ASC1b、ASC1c）。其中，ASC1a在MO-F1中比例最高且偏向脂肪生成、ASC1b在PO-F1中富集且呈現促發炎與代謝失衡特徵，而ASC1c則在Ln-F1組中比例最高，但在三組子代皆呈現具有維持細胞穩定與抗肥胖潛力，顯示不同的親代肥胖在出生早期就已改變子代脂肪前驅細胞細胞群的組成與功能。此外，子代脂肪細胞不僅受到脂肪前驅細胞群的影響，也可能受到上游轉錄因子的調控。結合先前實驗室bulk-RNA sequence的結果與不同類型的脂肪細胞模型，初步結果顯示在不同組別間（Ln-F1, MO-F1, PO-F1）候選轉錄因子早在胚胎期的表現量就已存在趨勢性的差異，但在出生後第九天的表現量在組間則無顯差。進一步透過loss-of-function實驗初步探討候選轉錄因子的在脂肪分化中的潛在調控角色，未來可結合gain-of-function以及不同親代肥胖的SVF，直接比較不同親代肥胖下，子代脂肪前驅細胞在基因調控與分化功能上的差異。綜合上述，本研究證實親代肥胖自胚胎期可能就已影響子代脂肪前驅細胞的轉錄調控，且同時改變出生後脂肪組織的細胞組成與代謝功能，顯示親代代謝狀態可跨代影響子代脂肪前驅細胞的調控，為日後暸解肥胖的跨代代謝潛在機制提供研究方向。

Obesity primarily results from excessive expansion of adipose tissue, particularly the enlargement of white adipose tissue (WAT). Previous studies indicate that adipose tissue remodeling during childhood and adolescence largely determines adult adipocyte numbers, and that parental metabolic status can exert long-lasting effects on offspring metabolism. However, whether parental obesity alters adipose progenitor composition, transcriptional regulation, and differentiation potential during early postnatal development remains unclear. In this study, we established three groups of C57BL/6J offspring—metabolically normal controls (Ln-F1), maternal-obesity offspring (MO-F1), and parental-obesity offspring (PO-F1) - by providing parents either a chow diet (ChowD) or a high-fat diet (HFD). At postnatal day 9 (P9), both MO-F1 and PO-F1 displayed higher body weight and heavier iWAT mass compared with Ln-F1, along with greater lipid accumulation in brown adipose tissue (BAT) and the liver. Upon in vitro differentiation of iWAT stromal vascular fraction (SVF) cells, MO-F1 and PO-F1 showed lower expression of thermogenic genes, whereas MO-F1 additionally exhibited higher adipogenic capacity. Single-cell RNA sequencing (scRNA-seq) identified three major adipose progenitor clusters within iWAT SVF—ASC1a, ASC1b, and ASC1c. ASC1a was more abundant in MO-F1 and displayed a transcriptional profile associated with adipogenesis; ASC1b was enriched in PO-F1 and showed signatures related to inflammation and metabolic imbalance; ASC1c was more prevalent in Ln-F1 and exhibited features linked to cellular homeostasis and potential anti-obesity properties. These findings indicate that parental obesity modifies offspring adipose progenitor composition and functional states as early as the neonatal stage. Because progenitor identity is further shaped by upstream transcriptional regulators, we integrated previous bulk RNA-seq data from our laboratory with multiple adipocyte differentiation models to examine candidate regulators. Preliminary analyses revealed group-specific trends in the expression of several transcriptional regulators during embryonic development, although such differences were not evident at P9. Loss-of-function experiments provided initial evidence supporting the regulatory roles of these candidates in adipocyte differentiation. Future studies involving gain-of-function approaches and SVF derived from different parental obesity groups will help clarify how parental metabolic status influences transcriptional regulation and differentiation potential in offspring adipose progenitors. Taken together, our findings suggest that parental obesity may shape the transcriptional programming of adipose progenitors as early as embryogenesis and subsequently alter postnatal adipose tissue cellular composition and metabolic function. These results provide insight into how parental metabolic status may exert intergenerational effects on offspring adipose development and obesity susceptibility.