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This study mainly shows the role of endoplasmic reticulum transmembrane and coiled coil domains 1 (TMCO1) in the regulatory mechanism of hepatocellular carcinoma (HCC). Invasion and migration capacity were detected by Transwell and wound healing after TMCO1 and TOMM20 overexpression and knockdown, and mitochondrial function was detected through reactive oxygen species (ROS), mitochondrial permeability transition pore (mPTP), mitochondrial membrane potential (MMP), and ATP production. A model of subcutaneous tumor formation in nude mice was established to detect the effect of TMCO1 on tumor formation. The results showed that overexpression of TMCO1 significantly promoted HCC cell metastasis, promoted cell proliferation and ATP production, inhibited cell apoptosis, mPTP opening and ROS production, mediated the increase of MMP level and cytoskeletal remodeling. However, knocking down TMCO1 can have the opposite effect. More importantly, knocking down TOMM20 can block the regulation effect of TMCO1, and TOMM20 overexpression can alleviate the inhibitory effect of knocking down TMCO1 on the development of liver cancer cells. In animal models, knockdown of TMCO1 expression significantly inhibited the growth of subcutaneous implant tumors. This suggests that TMCO1 may be a potential and valuable therapeutic target for liver cancer. [ABSTRACT FROM AUTHOR]

Background and purpose: Transmembrane and coiled-coil domains 1 (TMCO1) is a recently discovered endoplasmic reticulum calcium channel protein that has been found to be associated with the progression of various tumors, however, its role in cervical cancer has not yet been clarified. This study aimed to investigate the effects of TMCO1 on the proliferation and migration of cervical cancer HeLa cells. Methods: By transfecting cervical cancer HeLa cells with plasmids, cells with stable overexpression of TMCO1 and cells with stable knockdown of TMCO1 were obtained. Cell counting kit-8 (CCK-8) assay, clone formation assay and EdU labeling assay were used to detect cell proliferation ability, transwell assay was used to detect cell migration ability, and proteomic analysis was performed on the cells that stably overexpressed TMCO1 and control cells. Results: TThe CCK-8 experiment and clone formation experiment showed that overexpression of TMCO1 in cervical cancer HeLa cells significantly increased their proliferation ability (P<0.05). EdU labeling experiments showed that overexpression of TMCO1 in cervical cancer HeLa cells significantly increased the number of cells undergoing active DNA synthesis (P<0.01). After knocking down TMCO1 in cervical cancer HeLa cells, the expression of cell cycle inhibitory protein p27 increased, and the phosphorylation of histone H3 decreased. Clonogenesis experiments showed that knocking down TMCO1 significantly inhibited the proliferation of cervical cancer HeLa cells (P<0.001). EdU labeling experiments showed that after knocking down TMCO1 in cervical cancer HeLa cells, the number of cells undergoing active DNA synthesis was significantly reduced(P<0.05). Transwell experiment showed that overexpression of TMCO1 in cervical cancer HeLa cells significantly increased their migration ability (P<0.001), while knocking down TMCO1 significantly inhibited the migration of cervical cancer HeLa cells (P<0.001). The pathways related to extracellular matrix adhesion and PI3K-AKT signaling were significantly upregulated in the cells with stable overexpression of TMCO1, while ribosome related pathways were downregulated in proteomic analysis. Conclusion: Overexpression of TMCO1 significantly promotes the proliferation and migration of cervical cancer cells, while knockdown of TMCO1 significantly inhibits the proliferation and migration of cervical cancer HeLa cells. TMCO1 may affect the proliferation and migration of HeLa cells by regulating cell adhesion and signal transduction. [ABSTRACT FROM AUTHOR]

Background: Maintaining homeostasis of Ca2+ stores in the endoplasmic reticulum (ER) is crucial for proper Ca2+ signaling and key cellular functions. Although Ca2+ depletion has been known to cause ER stress which in turn activates the unfolded protein response (UPR), how UPR sensors/transducers respond to excess Ca2+ when ER stores are overloaded remain largely unclear. Results: Here, we report for the first time that overloading of ER Ca2+ can directly sensitize the IRE1α-XBP1 axis. The overloaded ER Ca2+ in TMCO1-deficient cells can cause BiP dissociation from IRE1α, promote the dimerization and stability of the IRE1α protein, and boost IRE1α activation. Intriguingly, attenuation of the over-activated IRE1α-XBP1s signaling by a IRE1α inhibitor can cause a significant cell death in TMCO1-deficient cells. Conclusions: Our data establish a causal link between excess Ca2+ in ER stores and the selective activation of IRE1α-XBP1 axis, underscoring an unexpected role of overload of ER Ca2+ in IRE1α activation and in preventing cell death. [ABSTRACT FROM AUTHOR]

Ca2+ release from the endoplasmic reticulum (ER) is an essential event in the modulation of Ca2+ homeostasis, which is coordinated by multiple biological processes, ranging from cell proliferation to apoptosis. Deregulated Ca2+ homeostasis is linked with various cancer hallmarks; thus, uncovering the mechanisms underlying Ca2+ homeostasis dynamics may lead to new anticancer treatment strategies. Here, we demonstrate that a reported Ca2+-channel protein TMCO1 (transmembrane and coiled-coil domains 1) is overexpressed in colon cancer tissues at protein levels but not at messenger RNA levels in colon cancer. Further study revealed that TMCO1 is a substrate of ER-associated degradation E3 ligase Gp78. Intriguingly, Gp78-mediated TMCO1 degradation at K186 is under the control of the iASPP (inhibitor of apoptosis-stimulating protein of p53) oncogene. Mechanistically, iASPP robustly reduces ER Ca2+ stores, mainly by competitively binding with Gp78 and interfering with Gp78-mediated TMCO1 degradation. A positive correlation between iASPP and TMCO1 proteins is further validated in human colon tissues. Inhibition of iASPP-TMCO1 axis promotes cytosolic Ca2+ overload-induced apoptotic cell death, reducing tumor growth both in vitro and in vivo. Thus, iASPP-TMCO1 represents a promising anticancer treatment target by modulating Ca2+ homeostasis. [ABSTRACT FROM AUTHOR]

In eukaryotic cells, Endoplasmic Reticulum (ER) is an interconnected membranous organelle and plays important roles in protein synthesis and lipid metabolism. We have previously demonstrated that TMCO1 is an ER Ca2+ channel actively preventing ER Ca2+ overloading. Recently, we also found that TMCO1 deficiency in mouse granulosa cells (GCs) caused abnormal Ca2+ signaling, ER stress and enhanced reactive oxygen species (ROS). In this study, we further examined the roles of TMCO1 in lipid metabolism and mitochondrial functions. Intriguingly, we found that TMCO1 deletion reduced the number of lipid droplets (LDs) and the content of triglyceride (TG), which was due to ER stress associated degradation (ERAD) of the important enzyme in catalyzing TG synthesis, diacylglycerol acyltransferase 2 (DGAT2). Hypofunction in transforming non-esterification fatty acid (NEFA) to TG caused NEFA deposit, a potential risk of mitochondrial dysfunction. Furthermore, in TMCO1 deficient cells, mitochondria volume decreased and inefficient oxidative phosphorylation was detected, which underlined enhanced mitophagy and impaired mitochondrial functions. Taken these data together, we for the first time revealed the role of TMCO1 in regulating lipid-metabolism and mitochondrial function. This study may provide new insights into understanding TMCO1 defect syndrome. • Cellular LDs significantly reduced upon TMCO1 deletion. • ER stress caused by TMCO1 deletion resulted in DGAT2 degradation, which led to the reduction of LDs and the increase of FAs. • Mitophagy augmented and mitochondria volume decreased in TMCO1 deficient cells. • Mitochondrial morphology and function were impaired due to the elevated FAs, a potential risk of mitochondrial dysfunction. [ABSTRACT FROM AUTHOR]

Craniofacial dysmorphism, skeletal anomalies, and impaired intellectual development syndrome-1 (CFSMR1; OMIM# 213980) is a rare autosomal recessive disorder characterized by the clinical triad of developmental delay and/or intellectual disability, a typical facial gestalt with brachycephaly, highly-arched bushy eyebrows, synophrys, hypertelorism, wide nasal bridge, and short nose, as well as multiple vertebrae and rib malformations, such as bifid and fused ribs and abnormal vertebral segmentation and fusion. Biallelic loss-of-function variants in TMCO1 cause CFSMR1. We report on two unrelated Egyptian patients with a phenotype suggestive of CFSMR. Single whole-exome sequencing in patient 1 and Sanger sequencing of TMCO1 in patient 2 revealed the same homozygous TMCO1 nonsense variant c.187C > T/p.(Arg63*) in both affected individuals; patients' healthy parents were heterozygous carriers of the variant. Congenital hearing loss in patients 1 and 2 is an occasional finding in individuals affected by CFSMR. Camptodactyly and syndactyly, which were noted in patient 2, have not or rarely been reported in CFSMR. Review of the literature revealed a total of 30 individuals with the clinically recognizable and unique phenotype of CFSMR1, including the patients reported here, who all carried biallelic TMCO1 variants. Six different TMCO1 variants have been reported in the 30 patients from 14 families, comprising three nonsense, two 2-bp deletions, and a splice donor site variant. All disease-associated TMCO1 variants likely represent null alleles resulting in absence of the encoded protein. TMCO1 has been proposed to act as a Ca2+ channel, while other data revealed TMCO1 as a mitochondrial protein and a component of the translocon at the endoplasmic reticulum, a cellular machinery important for the biogenesis of multi-pass membrane proteins. RAB5IF / C20orf2 4 has recently been identified as causative gene for craniofacial dysmorphism, skeletal anomalies, and impaired intellectual development syndrome-2 (CFSMR2; OMIM# 616994). Heterodimerization of RAB5IF/C20orf24 and TMCO1 and their interdependence may suggest a pathophysiological role of ER-mitochondria interaction underlying CFSMR. [ABSTRACT FROM AUTHOR]

Transmembrane and coiled-coil domains 1 (TMCO1) has a highly conserved amino acid sequence among species, indicating a critical role of TMCO1 in cell physiology. The deficiency of TMCO1 in humans is associated with cerebrofaciothoracic dysplasia (CFTD), glaucoma, osteogenesis and the occurrence of cancer. TMCO1 was recently identified as an endoplasmic reticulum (ER) Ca2+ load-activated Ca2+ (CLAC) release channel, which prevents ER Ca2+ overload and maintains calcium homeostasis in the ER. However, the structural basis of the molecular function of TMCO1 channel remains elusive. To determine the structure of TMCO1, we screened the expression of TMCO1 in Escherichia coli and insect cell expression systems. TMCO1 from Dictyostelium discoideum (DdTMCO1) was successfully expressed in Escherichia coli with a high yield. The pure recombinant protein was obtained by affinity chromatography and size exclusion chromatography. The solution NMR of DdTMCO1 in DPC micelles showed three α-helical transmembrane regions. • The expression of TMCO1s from different species was screened in E. coli and insect cell overexpression systems. • TMCO1 from Dictyostelium discoideum (DdTMCO1) purified from inclusion bodies gave a high yield. • DdTMCO1 in DPC micelles exhibited dispersed NMR signals. • Structure of DdTMCO1 was explored. [ABSTRACT FROM AUTHOR]