Department of Nephrology, The Second Xiangya Hospital of Central South University, Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, Hunan, China; Department of Nephrology & Immunology, The Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha, Hunan, China.
Department of Nephrology, The Second Xiangya Hospital of Central South University, Hunan Key Laboratory of Kidney Disease and Blood Purification, Changsha, Hunan, China.
Mol Cell Endocrinol. 2025 Jan 1;595:112418. doi: 10.1016/j.mce.2024.112418. Epub 2024 Nov 16.
Lipoapoptosis in Proximal tubular epithelial cells (PTCs) are substantial in the etiology of diabetic kidney disease (DKD), yet the underlying mechanisms warrant further investigation. Acyl-CoA synthetase long-chain family member 5 (ACSL5) facilitates the formation of acyl-CoA, however, the precise role of ACSL5 in lipoapoptosis of PTCs in DKD remains inconclusive.
Transcriptomic data analysis identified the hub gene Acsl5 associated with lipid metabolism in DKD. The expression of ACSL5 was examined in high-fat diet/streptozotocin (HFD/STZ)-induced diabetic mice and high glucose/palmitic acid (HGPA)-induced mouse proximal tubular epithelial cell (BUMPT). Oil Red O staining, free fatty acids (FFA) ELISA assay, Western Blot, and morphological changes were employed to assess lipid deposition and lipoapoptosis. Furthermore, knockdown and overexpression of ACSL5 were conducted in BUMPT cells, followed by morphological assessment, Oil Red O staining, FFA ELISA assay and Western Blot analysis. Using the ChEA3 database, we predicted that STAT3 may transcriptionally regulate ACSL5. Subsequently, we knocked down STAT3 and evaluated Acsl5 expression via RT-qPCR. Additionally, we investigated whether STAT3 modulates the impact of ACSL5 on lipoapoptosis through Western Blot analysis.
We demonstrated, for the first time, a notable upregulation of ACSL5 expression in PTCs in HFD/STZ-induced diabetic mice, accompanied by increased the expression of FATP2, lipid accumulation and heightened lipoapoptosis. In HGPA-treated BUMPT cells, ACSL5 knockdown reduced the expression of FATP2, lipid deposition and lipoapoptosis, whereas its overexpression elevated the expression of FATP2 and exacerbated these effects. These findings strongly suggest that ACSL5 may exacerbate lipoapoptosis in PTCs within a diabetic milieu. From a molecular mechanism perspective, ACSL5 expression decreased after Stat3 knockdown. Concurrent knockdown of Stat3 and overexpression of Acsl5 led to a mitigation of lipoapoptosis compared to sole Acsl5 overexpression. Furthermore, STAT3 promotes the activation of ACSL5 promoter under HGPA conditions.
In summary, our research identified ACSL5 as an important contributor exacerbating lipoapoptosis in the renal proximal tubules within diabetic environments. In addition, we found that ACSL5 is transcriptionally regulated by STAT3.
近端肾小管上皮细胞（PTCs）中的脂肪凋亡在糖尿病肾病（DKD）的发病机制中很重要，但潜在的机制仍需要进一步研究。酰基辅酶 A 合成酶长链家族成员 5（ACSL5）有助于酰基辅酶 A 的形成，然而，ACSL5 在 DKD 中 PTCs 脂肪凋亡中的精确作用仍不清楚。
转录组数据分析确定了与 DKD 中脂质代谢相关的枢纽基因 Acsl5。在高脂肪饮食/链脲佐菌素（HFD/STZ）诱导的糖尿病小鼠和高葡萄糖/棕榈酸（HGPA）诱导的小鼠近端肾小管上皮细胞（BUMPT）中检查 ACSL5 的表达。采用油红 O 染色、游离脂肪酸（FFA）ELISA 测定、Western Blot 和形态学改变来评估脂质沉积和脂肪凋亡。此外，在 BUMPT 细胞中进行了 ACSL5 的敲低和过表达，然后进行形态评估、油红 O 染色、FFA ELISA 测定和 Western Blot 分析。使用 ChEA3 数据库，我们预测 STAT3 可能转录调控 ACSL5。随后，我们通过 RT-qPCR 评估了 STAT3 敲低后的 Acsl5 表达。此外，我们还通过 Western Blot 分析研究了 STAT3 是否通过调节 ACSL5 对脂肪凋亡的影响。
我们首次证明，在 HFD/STZ 诱导的糖尿病小鼠中，PTCs 中 ACSL5 的表达显著上调，同时 FATP2 的表达增加，脂质堆积增加，脂肪凋亡加剧。在 HGPA 处理的 BUMPT 细胞中，ACSL5 的敲低减少了 FATP2 的表达、脂质沉积和脂肪凋亡，而过表达 ACSL5 则增加了 FATP2 的表达并加剧了这些作用。这些发现强烈表明，ACSL5 可能在糖尿病环境中加剧 PTCs 的脂肪凋亡。从分子机制的角度来看，Stat3 敲低后 ACSL5 的表达减少。Stat3 敲低和 Acsl5 过表达的联合敲低与单独 Acsl5 过表达相比，导致脂肪凋亡减轻。此外，STAT3 在 HGPA 条件下促进 ACSL5 启动子的激活。
总之，我们的研究确定 ACSL5 是一种重要的促发因子，可加剧糖尿病环境中肾脏近端小管的脂肪凋亡。此外，我们发现 ACSL5 是由 STAT3 转录调控的。
