Molecular and Cellular Response of Co-cultured Cells toward Cobalt Chloride (CoCl₂)-Induced Hypoxia

Abstract

Cobalt chloride (CoCl2) is a well-known hypoxia mimetic mediator that induces hypoxia-like responses. CoCl2, a mediator confirmed to alleviate hypoxia-inducible factor-1 (HIF-1), has been associated with a variety of hypoxic responses. HIF-1 is the foremost transcriptionfactor that is particularly activated during hypoxia and regulates various genes. Therefore, this study aimed to investigate the cellular and molecular responses of the co-cultured cells under the influence of the CoCl2-induced hypoxic condition. Mono- and co-cultured C2C12 and 3T3-L1 cells were exposed to CoCl2, and a significant induction in HIF-1, reactive oxygen species and lipid peroxidase and a reduction in glutathione and catalase were observed. The expressions of proapoptotic genes like Bax, p53, caspase-9, and caspase-3 were notably increased, whereas the antiapoptotic gene, i.e., Bcl2, was downregulated during hypoxia in mono- as well as co-cultured C2C12 cells. However, the co-cultured C2C12 cells show significantly lower induction in oxidative stress and expression of apoptotic genes in comparison to monocultured C2C12 cells. Whereas, the co-cultured 3T3-L1 cells show comparatively higher oxidative stress and apoptotic event in comparison to monocultured 3T3-L1 cells. The reason may be the communication between the cells and some soluble factors that help in cell survival/death from hypoxia. Moreover, it may also be due to the fact that fat and muscle cells interact and communicate via proximity and mutual ability when growing together. Therefore, the co-culture system provides a unique approach to intercellular communication between the two different cell types.

Autophagy/ Apoptosis Induced by Geraniol through HIF-1α/BNIP3/Beclin-1 Signaling Pathway in A549 CoCl2 Treated Cells

“…41,42 This study showed that the IC50 value of CoCl2(6.2 mM) disrupted the oxidant/antioxidant balance in A549 cells, which results in the incidence of lipid peroxidation with a subsequent reduction in the TAC level. This finding further corroborates earlier observations of Tripathi et al 32 of MDA parallels with the elevation in the TAC level. This finding is similar to that of Khan and his colleagues.…”

“…Cobalt ion possesses a cytocidal activity and induces hypoxia followed by the upregulation and downregulation of apoptotic and anti-apoptotic proteins subsequently, which stimulates apoptotic cell death. 32 Also, Chen et al showed that CoCl2 upregulates the HIF-1α as well as autophagic proteins (LC3, BNIP3, and Beclin-1) in theC2C12-hypoxic model. 51 These reports and our current results confirmed the link between CoCl2, hypoxia, autophagy signaling, and apoptotic cell death.…”

“…The A549 cells were stained with 10μL trypan blue dye (0.4% solution) and to count unstained live and blue stained dead cells under a phase contrast microscopewithahemocytometer. 32 The mean percentages of live and dead cells per experiment were expressed as mean ± SD of three autonomous experiments.…”

Protective Effects of Adiponectin against Cobalt Chloride-Induced Apoptosis of Smooth Muscle Cells via cAMP/PKA Pathway

“…It is worth noting that CoCl 2 can produce oxidative stress, induce cell damage, reduce cell mitochondrial membrane potential, activate caspase family, and ultimately induce apoptosis. Based on this biological characteristic, CoCl 2 can be used for hypoxic preconditioning in many cell types [ 26 ]. We found that APN pretreated could increase SOD activity and decrease MDA levels which is affected by CoCl 2 .…”

Tangeretin Ameliorates Glucose-Induced Podocyte Injury through Blocking Epithelial to Mesenchymal Transition Caused by Oxidative Stress and Hypoxia

“…In addition, the current study employed 33 mM glucose and cobalt chloride (CoCl 2 ) in order to induce oxidative stress and hypoxia in podocytes. CoCl 2 is shown to artificially induce hypoxia and accumulates HIF-1α protein as a hypoxia-mimetic agent through activating ERK1/2 and PI3K signaling pathways [ 27 , 28 ].…”