Sphingomyelin phosphodiesterase acid like 3B (SMPDL3b) regulates Perilipin5 (PLIN5) expression and mediates lipid droplet formation.
Sphingomyelin phosphodiesterase acid like 3B (SMPDL3b) regulates Perilipin5 (PLIN5) expression and mediates lipid droplet formation.
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DOI：
10.1016/j.gendis.2021.12.014
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发表时间：
2022-11
期刊：
影响因子：
6.8
通讯作者：
Fornoni A
中科院分区：
文献类型：
--
作者：
Mallela SK;Ge M;Molina J;Santos JV;Kim JJ;Mitrofanova A;Al-Ali H;Marples B;Merscher S;Fornoni A
脂滴（ld）是一种脂质储存细胞器，其中心疏水核心是中性脂质，被包裹在一层磷脂中。虽然脂质（主要是胆固醇和甘油三酯）的储存被认为是ld的主要功能，但研究表明它们在维持脂质稳态和调节各种信号通路方面具有重要功能。异常脂质积累已被认为是肥胖、糖尿病、癌症、神经系统疾病、心血管疾病、胰岛素抵抗、肝脏疾病和肾脏疾病等几种人类疾病的关键特征。lld在先天免疫、对抗感染和SARS-CoV-2的复制中发挥重要作用。因此，严格调节LD代谢是细胞正常运作所必需的。我们之前报道了LD积累和肾脏疾病进展的重要作用，包括糖尿病肾病和局灶节段性肾小球硬化（FSGS）。在FSGS中，我们发现肾小球LD积累与鞘磷脂酶磷酸二酯酶如3b （SMPDL3b）的表达下降相一致，我们发现这种酶可以调节足细胞中神经酰胺-1-磷酸水平，2,3表明SMPDL3b在鞘脂代谢中起作用。然而，SMPDL3b是否调控LD稳态尚不清楚。本研究旨在确定SMPDL3b是否调节永生化人足细胞的LD稳态，足细胞是终末分化细胞，在肾小球滤过屏障中起关键作用。我们发现SMPDL3b定位于ld， SMPDL3b表达的减少与ld数量的增加、甘油三酯（TAG）和胆固醇酯水平的升高、脂肪酸摄取的增加和脂肪分解的减少有关。SMPDL3b表达减少导致PLIN5、热休克同源蛋白（HSC70）和溶酶体相关膜蛋白2A （LAMP2A）表达增加。Selonsertib治疗纠正了永生化人足细胞中观察到的所有表型，降低了SMPDL3b的表达。为了研究SMPDL3b在LD稳态中的作用，我们从SMPDL3b表达降低的永活人足细胞（siSMPDL3b）和对照足细胞（Ctrl）中分离LD组分。Western blot分析分离的LD部分显示SMPDL3b蛋白在LD中表达，并且与Ctrl足细胞相比，在siSMPDL3b足细胞中的表达降低（图1a， B）。有趣的是，ld中SMPDL3b的减少与ld的数量（图1c）和强度（图1d）以及细胞甘油三酯（TAG）的增加（图1c）有关。1 E)和胆固醇酯水平（图1 F），表明SMPDL3b在人足细胞LD稳态和LD脂质组成中起重要作用。
Lipid droplets (LDs) are lipid storage organelles with a central hydrophobic core of neutral lipids that is enclosed in a monolayer of phospholipids. Though the storage of lipids, mainly cholesterol and triglycerides, was thought to be the primary function of LDs, studies have shown that they have important functions in maintaining lipid homeostasis and modulating various signaling pathways. Abnormal lipid accumulation has been recognized as a key feature in several human diseases such as obesity, diabetes, cancer, neurological diseases, cardiovascular diseases, insulin resistance, liver diseases and kidney diseases. LDs play an important role in innate immunity, in the fight against infections, and in the replication of SARS-CoV-2. Hence a tight regulation of LD metabolism is essential for proper functioning of a cell. We previously reported an important role for LD accumulation and the progression of kidney diseases, 1 including diabetic kidney disease and focal segmental glomerulosclerosis (FSGS). In FSGS, we found that glomerular LD accumulation coincided with decreased expression of sphingomyelinase phosphodiesterase like 3b (SMPDL3b), an enzyme we showed to regulate ceramide-1-phosphate levels in podocytes, 2, 3 suggesting a role for SMPDL3b in sphingolipid metabolism. However, if SMPDL3b regulates LD homeostasis is unknown. The present study was aimed at determining if SMPDL3b regulates LD homeostasis in immortalized human podocytes, which are terminally differentiated cells that have a key role in the glomerular filtration barrier. We found that SMPDL3b is localized to LDs and that reduced expression of SMPDL3b is associated with an increase in the number of LDs, increased levels of triglycerides (TAG) and cholesterol esters, increased uptake of fatty acids and decreased lipolysis. Reduced expression of SMPDL3b leads to an increase in PLIN5, heat shock cognate protein (HSC70) and lysosome-associated membrane protein 2A (LAMP2A) expression. Selonsertib treatment corrected all the phenotypes observed in immortalized human podocytes with reduced SMPDL3b expression.To investigate the role of SMPDL3b in LD homeostasis, LD fractions were isolated from immortalized human podocytes with decreased SMPDL3b expression (siSMPDL3b) and of control podocytes (Ctrl). Western blot analysis of isolated LD fractions revealed SMPDL3b protein expression in LD, and demonstrated decreased expression in siSMPDL3b podocytes when compared to Ctrl podocytes (Fig. 1 A, B). Interestingly, reduced presence of SMPDL3b in LDs was associated with an increase in the number (Fig. 1 C) and intensity (Fig. 1 D) of LDs as well as of cellular triglyceride (TAG)(Fig. 1 E) and cholesterol ester levels (Fig. 1 F), suggesting an important role for SMPDL3b in LD homeostasis and the lipid composition of LDs in human podocytes.
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影响因子：
19.6
作者：
Mitrofanova A;Molina J;Varona Santos J;Guzman J;Morales XA;Ducasa GM;Bryn J;Sloan A;Volosenco I;Kim JJ;Ge M;Mallela SK;Kretzler M;Eddy S;Martini S;Wahl P;Pastori S;Mendez AJ;Burke GW;Merscher S;Fornoni A
通讯作者：
Fornoni A
CMA 破坏 Plin5 降解导致 NAFLD 中脂质稳态失衡
影响因子：
6.7
作者：
Ma, Shuo Y.;Sun, Ke S.;Han, Ying
通讯作者：
Han, Ying
DOI：
10.1016/j.bbalip.2019.158517
发表时间：
2019-12-01
影响因子：
4.8
作者：
Mallela, Shamroop Kumar;Mitrofanova, Alla;Fornoni, Alessia
通讯作者：
Fornoni, Alessia
影响因子：
6
作者：
Tan, Yanjie;Jin, Yi;Ren, Zhuqing
通讯作者：
Ren, Zhuqing
影响因子：
16.6
作者：
Mitrofanova, A.;Mallela, S. K.;Fornoni, A.
通讯作者：
Fornoni, A.