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A stress response p38 MAP kinase inhibitor SB202190 promoted TFEB/TFE3-dependent autophagy and lysosomal biogenesis independent of p38.

ABSTRACT: TFEB (transcription factor EB) and TFE3 (transcription factor E3) are "master regulators" of autophagy and lysosomal biogenesis. The stress response p38 mitogen-activated protein (MAP) kinases affect multiple intracellular responses including inflammation, cell growth, differentiation, cell death, senescence, tumorigenesis, and autophagy. Small molecule p38 MAP kinase inhibitors such as SB202190 are widely used in dissection of related signal transduction mechanisms including redox biology and autophagy. Here, we initially aimed to investigate the links between p38 MAP kinase and TFEB/TFE3-mediated autophagy and lysosomal biogenesis. Unexpectedly, we found that only SB202190, rather than several other p38 inhibitors, promotes TFEB and TFE3 to translocate from the cytosol into the nucleus and subsequently enhances autophagy and lysosomal biogenesis. In addition, siRNA-mediated Tfeb and Tfe3 knockdown effectively attenuated SB202190-induced gene expression and lysosomal biogenesis. Mechanistical studies showed that TFEB and TFE3 activation in response to SB202190 is dependent on PPP3/calcineurin rather than on the inhibition of p38 or MTOR signaling, the main pathway for regulating TFEB and TFE3 activation. Importantly, SB202190 increased intracellular calcium levels, and calcium chelator BAPTAP-AM blocked SB202190-induced TFEB and TFE3 activation as well as autophagy and lysosomal biogenesis. Moreover, endoplasmic reticulum (ER) calcium is required for TFEB and TFE3 activation in response to SB202190. In summary, we identified a previously uncharacterized role of SB202190 in activating TFEB- and TFE3-dependent autophagy and lysosomal biogenesis via ER calcium release and subsequent calcium-dependent PPP3/calcineurin activation, leading to dephosphorylation of TFEB and TFE3. Given the importance of p38 MAP kinase invarious conditions including oxidative stress, the findings collectively indicate that SB202190 should not be used as a specific inhibitor for elucidating the p38 MAP kinase biological functions due to its potential effect on activating autophagy-lysosomal axis.

SUBMITTER: Yang C

PROVIDER: S-EPMC7264467 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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A stress response p38 MAP kinase inhibitor SB202190 promoted TFEB/TFE3-dependent autophagy and lysosomal biogenesis independent of p38.

Yang Chuanbin C Zhu Zhou Z Tong Benjamin Chun-Kit BC Iyaswamy Ashok A Xie Wen-Jian WJ Zhu Yu Y Sreenivasmurthy Sravan Gopalkrishnashetty SG Senthilkumar Krishnamoorthi K Cheung King-Ho KH Song Ju-Xian JX Zhang Hong-Jie HJ Li Min M

Redox biology 20200128

TFEB (transcription factor EB) and TFE3 (transcription factor E3) are "master regulators" of autophagy and lysosomal biogenesis. The stress response p38 mitogen-activated protein (MAP) kinases affect multiple intracellular responses including inflammation, cell growth, differentiation, cell death, senescence, tumorigenesis, and autophagy. Small molecule p38 MAP kinase inhibitors such as SB202190 are widely used in dissection of related signal transduction mechanisms including redox biology and a ...[more]

PMID: 32037305

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Project description:Transcription factor EB (TFEB), a well-known master regulator of autophagy and lysosomal biogenesis, is a member of the microphthalmia family of transcription factors (MiT family). Over the years, TFEB has been shown to have diverse roles in various physiological processes such as clearance for intracellular pathogenic factors and having developmental functions such as dendritic maturation, as well as osteoclast, and endoderm differentiation. However, in the present study, we propose a novel mechanism for TFEB governing pluripotency of mouse ESCs (mESCs) by regulating the pluripotency transcriptional network (PTN) in these cells. We observed high levels of TFEB mRNA and protein levels in undifferentiated mESCs. Interestingly, we found a reduction of Nanog and Sox2 levels in TFEB knockout (KO) mESCs while pluripotency was maintained as there was an upregulation of TFE3, a potent stem cell maintenance factor. In consistent, double knockout of TFEB/TFE3 (TFEB/3 DKO) reduced mESC pluripotency, as indicated by the loss of ESC morphology, reduction of ESC markers, and the emergence of differentiation markers. We further discovered that Nanog was a TFEB target gene in undifferentiated mESCs. TFEB also promoted sex-determining region Y-box2 (Sox2) transcription by forming a heterodimer with Sox2 in mESCs. Notably, Sox2, Oct4, and Nanog were also binding to the TFEB promoter and thus generating a feed-forward loop in relation to TFEB. Although high levels of nuclear TFEB are expected to enhance autophagy-lysosomal activity, undifferentiated mESC remarkably displayed low basal autophagy-lysosomal activity. Overexpression or knockout of TFEB did not affect the expression of TFEB lysosomal-autophagy target genes and TFEB also had a lesser binding affinity to its own lysosomal promoter-target genes in mESCs compared to differentiated cells. Collectively, these findings define a newly incorporative, moonlighting function for TFEB in regulating PTN, independent of its autophagy-lysosomal biogenesis roles.

Dataset Information

A stress response p38 MAP kinase inhibitor SB202190 promoted TFEB/TFE3-dependent autophagy and lysosomal biogenesis independent of p38.

Publications

A stress response p38 MAP kinase inhibitor SB202190 promoted TFEB/TFE3-dependent autophagy and lysosomal biogenesis independent of p38.

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