ARMC5 selectively degrades SCAP-free SREBF1 and is essential for fatty acid desaturation in adipocytes.
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ABSTRACT:
PROVIDER: PRJNA1101577 | ENA |
REPOSITORIES: ENA
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Project description:Background: Armadillo repeat containing 5 (ARMC5)-CUL3 complex was recently identified as an E3 ubiquitin ligase of full-length SREBF. Although ARMC5 was involved in SREBF2 pathway in the adrenocortical cells and might participate in the development of primary bilateral macronodular adrenal hyperplasia (PBMAH), the role of ARMC5 in adipocytes has not been investigated. Methods and Results: Adipocyte-specific Armc5 knockout mice were generated. In the white adipose tissue (WAT) of these mice, all the stearoyl-CoA desaturase (Scd) were drastically downregulated under refed condition and high fat-high sucrose diet. Consistently, unsaturated fatty acids were decreased, while saturated fatty acids were increased in the WAT of these mice. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-Seq) peaks at the SREBF1-binding sites were markedly diminished around the Scd1 locus in the WAT of adipocyte-specific Armc5 knockout mice. Armc5-deficient 3T3-L1 adipocytes also exhibited downregulation of Scd. Mechanistically, disruption of Armc5 restored decreased full-length SREBF1 in the CHO cells deficient for Scap, an escort protein required for the transport of SREBF from the ER to the Golgi. In HEK293T cells, overexpression of Scap inhibited ARMC5-mediated degradation of full-length SREBF1, and overexpression of Armc5 increased nuclear SREBF1/full-length SREBF1 ratio in the presence of exogenous Scap in HEK293T cells. Conclusions: ARMC5 exerts selective removal of SCAP-free SREBF1 and stimulates SCAP-mediated SREBF1 processing, hence is essential for fatty acid desaturation in vivo.
2025-04-08 | GSE264274 | GEO
Project description:Background: Armadillo repeat containing 5 (ARMC5)-CUL3 complex was recently identified as an E3 ubiquitin ligase of full-length SREBF. Although ARMC5 was involved in SREBF2 pathway in the adrenocortical cells and might participate in the development of primary bilateral macronodular adrenal hyperplasia (PBMAH), the role of ARMC5 in adipocytes has not been investigated. Methods and Results: Adipocyte-specific Armc5 knockout mice were generated. In the white adipose tissue (WAT) of these mice, all the stearoyl-CoA desaturase (Scd) were drastically downregulated under refed condition and high fat-high sucrose diet. Consistently, unsaturated fatty acids were decreased, while saturated fatty acids were increased in the WAT of these mice. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-Seq) peaks at the SREBF1-binding sites were markedly diminished around the Scd1 locus in the WAT of adipocyte-specific Armc5 knockout mice. Armc5-deficient 3T3-L1 adipocytes also exhibited downregulation of Scd. Mechanistically, disruption of Armc5 restored decreased full-length SREBF1 in the CHO cells deficient for Scap, an escort protein required for the transport of SREBF from the ER to the Golgi. In HEK293T cells, overexpression of Scap inhibited ARMC5-mediated degradation of full-length SREBF1, and overexpression of Armc5 increased nuclear SREBF1/full-length SREBF1 ratio in the presence of exogenous Scap in HEK293T cells. Conclusions: ARMC5 exerts selective removal of SCAP-free SREBF1 and stimulates SCAP-mediated SREBF1 processing, hence is essential for fatty acid desaturation in vivo.
2024-12-19 | GSE262941 | GEO
Project description:ARMC5 selectively degrades SCAP-free SREBF1 and is essential for fatty acid desaturation in adipocytes
| PRJNA1094961 | ENA
Project description:ARMC5 is an armadillo domain (ARM)-containing protein. We found that Armc5 KO mice had an increased incidence of neural tube defects (NTDs). ARMC5 is the substrate recognition component of a ubiquitin ligase that targets POLR2A, the largest subunit of RNA polymerase II (Pol II). Surprisingly, the absence of ARMC5 caused the accumulation of not only POLR2A, but most of the other 11 Pol II subunits associated with POLR2A, indicating that the degradation of the whole Pol II complex is compromised. This did not lead to generalized Pol II stalling or a generalized decrease in mRNA transcription. In neural progenitor cells, ARMC5 KO only dysregulated 106 genes, some of which are known to be involved in neural tube development. FOLH1, critical for folate metabolism and vital in neural tube development, was downregulated in the KO intestine, suggesting that it is a downstream effector gene for NTD. To assess whether ARMC5 gene mutation was associated with human NTD, we conducted whole-exome sequencing of 511 patients with myelomeningocele, a severe form of NTD. Nine deleterious single nucleotide variants were discovered in the ARMC5 coding sequence. Four of them were validated in that they weakened the interaction between ARMC5 and POLR2A; consequently, POLR2A ubiquitination was decreased. This proves that our findings in mice are relevant to human NTD; it also supports the role of Pol II in mediating NTD pathogenesis. Our findings indicate that mutations in ARMC5 increase the risk of NTD and support the role of Pol II in NTD pathogenesis. Further investigation is needed to determine the cause-and-effect relationship between an enlarged Pol II pool and NTD and to validate the potential role of downregulated FOLH1 expression in NTD pathogenesis.
2023-12-06 | PXD047533 | Pride
Project description:ARMC5 is an armadillo domain (ARM)-containing protein. We found that Armc5 KO mice had an increased incidence of neural tube defects (NTDs). ARMC5 is the substrate recognition component of a ubiquitin ligase that targets POLR2A, the largest subunit of RNA polymerase II (Pol II). Surprisingly, the absence of ARMC5 caused the accumulation of not only POLR2A, but most of the other 11 Pol II subunits associated with POLR2A, indicating that the degradation of the whole Pol II complex is compromised. This did not lead to generalized Pol II stalling or a generalized decrease in mRNA transcription. In neural progenitor cells, ARMC5 KO only dysregulated 106 genes, some of which are known to be involved in neural tube development. FOLH1, critical for folate metabolism and vital in neural tube development, was downregulated in the KO intestine, suggesting that it is a downstream effector gene for NTD. To assess whether ARMC5 gene mutation was associated with human NTD, we conducted whole-exome sequencing of 511 patients with myelomeningocele, a severe form of NTD. Nine deleterious single nucleotide variants were discovered in the ARMC5 coding sequence. Four of them were validated in that they weakened the interaction between ARMC5 and POLR2A; consequently, POLR2A ubiquitination was decreased. This proves that our findings in mice are relevant to human NTD; it also supports the role of Pol II in mediating NTD pathogenesis. Our findings indicate that mutations in ARMC5 increase the risk of NTD and support the role of Pol II in NTD pathogenesis. Further investigation is needed to determine the cause-and-effect relationship between an enlarged Pol II pool and NTD and to validate the potential role of downregulated FOLH1 expression in NTD pathogenesis.
2023-12-06 | PXD047572 | Pride
Project description:Pulmonary function after birth is dependent upon surfactant lipids that reduce surface tension in the alveoli. The sterol-responsive element-binding proteins (SREBPs) are transcription factors regulating expression of genes controlling lipid homeostasis in many tissues. To identify the role of SREBPs in the lung, we conditionally deleted the SREBP cleavage-activating protein gene, Scap, in respiratory epithelial cells (Scap∆/∆) in vivo. Prior to birth (E18.5), deletion of Scap decreased the expression of both SREBPs and a number of genes regulating fatty acid and cholesterol metabolism. Nevertheless, Scap∆/∆ mice survived postnatally, surfactant and lung tissue lipids being substantially normalized in adult Scap∆/∆ mice. Although phospholipid synthesis was decreased in type II cells from adult Scap∆/∆ mice, lipid storage, synthesis, and transfer by lung lipofibroblasts were increased. mRNA microarray data indicated that SCAP influenced two major gene networks, one regulating lipid metabolism and the other stress-related responses. Deletion of the SCAP/SREBP pathway in respiratory epithelial cells altered lung lipid homeostasis and induced compensatory lipid accumulation and synthesis in lung lipofibroblasts. To identify the role of SREBPs in the lung, we conditionally deleted the SREBP cleavage-activating protein gene, Scap, in respiratory epithelial cells (Scap∆/∆) in vivo.Lung cRNA was hybridized to the murine genome MOE430 V2 chips.
2011-01-08 | E-GEOD-26496 | biostudies-arrayexpress
Project description:ARMC5 is a protein containing an armadillo domain (ARM) and a BTB domain. Its gene knockout caused many phenotypes, including dwarfism, compromise T-cell immunity, and adrenal gland hypertrophy. ARMC5 mutation in humans is associated with bilateral macronodular adrenal gland hypertrophy. We found that AMC5 KO mice suffered from an increased incidence of neural tube defects (NTDs). We revealed that ARMC5 complexed with CUL3 and POLR2A and was part of a novel POLR2A-specific ubiquitin ligase (E3). This E3 was the dominant DNA damage-independent POLR2A-specific E3 in developing neural tubes and neural precursor cells under a physiological condition. ARMC5 gene knockout (KO) caused diminished POLR2A ubiquitination and compromised POLR2A degradation via proteasomes. Surprisingly, the absence of this E3 did not lead to generalized Pol II stalling and the subsequent generalized decrease of mRNA transcription but caused an enlarged Pol II pool size, which dysregulated 108 genes in NPCs, including some known to neural development. ARMC5 KO in the intestine downregulated FOHL1 expression, which was essential in folate absorption. Whole-exome sequencing of 511 myelomeningocele (MM) patients revealed nine highly deleterious mutations in the ARMC5 coding sequence. A significant deleterious mutation Arg429Cys found in MM patients drastically weakened the interaction between ARMC5 and POLR2A, supporting our hypothesis that such mutations in ARMC5 increased the NTD risks by compromising the POLR2A-specific E3 activity. Our results indicated that this novel ARMC5-CUL3-RBX1 E3 played a critical role in Pol II pool homeostasis, and ARMC5 mutation was a modifier of NTD risks in mice and humans.
2023-12-01 | GSE169582 | GEO
Project description:CRTC2 is a critical transcription cofactor that induces the glucose homeostatic genes by activating CREB. However, energy homeostasis is maintained by multiple pathways, therefore, it is possible that CRTC2 may interact with other transcription factors, especially under metabolic stress. Thereby, CRTC2 liver-specific knockout mice were created and the global proteome, phosphoproteome and acetylome from liver tissue under the high fat diet conditions were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and bioinformatics analysis. As expected, differentially expressed proteins (DEPs) are enriched in metabolic pathways that were subsequently corroborated by animal experiments. The consensus DEPs from these datasets were used as seed proteins to generate a protein-protein interaction (PPI) network using STRING and GeneMANIA identified fatty acid synthase (FASN) as the mutually relevant protein. Additional local-PPI (LPPI) analysis of CRTC2 and FASN with DEPs, SREBF1 was found to be a common mediator. CRTC2/CREB and SREBF1 are transcription factors, DNA-binding motif analysis showed multiple CRTC2/CREB regulated genes also possess SREBF1 binding motifs that unveil the possible induction by CRTC2/SREBF1 complex, which is reinforced by structural analysis. Thus, CRTC2/SREBF1 complex plausibly modulate the transcription of multiple proteins that fine-tune the cellular metabolism under metabolic stress.
2023-10-24 | PXD039817 | Pride
Project description:ARMC5 is a protein containing an armadillo domain (ARM) and a BTB domain. Its gene knockout caused many phenotypes, including dwarfism, compromise T-cell immunity, and adrenal gland hypertrophy. ARMC5 mutation in humans is associated with bilateral macronodular adrenal gland hypertrophy. We found that AMC5 KO mice suffered from an increased incidence of neural tube defects (NTDs). We revealed that ARMC5 complexed with CUL3 and POLR2A and was part of a novel POLR2A-specific ubiquitin ligase (E3). This E3 was the dominant DNA damage-independent POLR2A-specific E3 in developing neural tubes and neural precursor cells under a physiological condition. ARMC5 gene knockout (KO) caused diminished POLR2A ubiquitination and compromised POLR2A degradation via proteasomes. Surprisingly, the absence of this E3 did not lead to generalized Pol II stalling and the subsequent generalized decrease of mRNA transcription but caused an enlarged Pol II pool size, which dysregulated 108 genes in NPCs, including some known to neural development. ARMC5 KO in the intestine downregulated FOHL1 expression, which was essential in folate absorption. Whole-exome sequencing of 511 myelomeningocele (MM) patients revealed nine highly deleterious mutations in the ARMC5 coding sequence. A significant deleterious mutation Arg429Cys found in MM patients drastically weakened the interaction between ARMC5 and POLR2A, supporting our hypothesis that such mutations in ARMC5 increased the NTD risks by compromising the POLR2A-specific E3 activity. Our results indicated that this novel ARMC5-CUL3-RBX1 E3 played a critical role in Pol II pool homeostasis, and ARMC5 mutation was a modifier of NTD risks in mice and humans.
2023-12-01 | GSE169350 | GEO
Project description:Nonalcoholic steatohepatitis (NASH), a severe form of nonalcoholic fatty liver disease, is characterized by hepatic steatosis and hepatocellular injury and progresses to cirrhosis and hepatocellular carcinoma. Sterol regulatory element-binding proteins (SREBPs) are master regulators of lipogenesis. Liver-specific PTEN knockout (KO) mice show constitutive upregulation of SREBP through PI3K-Akt pathway activation, leading to spontaneous fatty liver and subsequent HCC development. SREBP cleavage-activating protein (SCAP) plays a critical role in SREBP activation. We sought to determine the impact of SREBP inhibition on NASH and HCC development. To this end, we additionally inhibited SREBP pathway in liver-specific PTEN mice by ablating SCAP and generated liver-specific PTEN/SCAP double KO (DKO) mice. However unexpectedly, inhibition of SCAP/SREBP pathway markedly exacerbated liver injury (5weeks), fibrosis (5months), and carcinogenesis (7 months) in PTEN KO mice. To elucidate the mechanisms of liver injury in liver-specific PTEN/SCAP DKO mice, we conducted transcriptome analyses of the livers.
2022-04-05 | GSE169104 | GEO