High resolution respirometry of isolated mitochondria from adult Octopus maya (Class: Cephalopoda) systemic heart

Mitochondrial respirometry is key to understand how environmental factors model energetic cellular process. In the case of ectotherms, thermal tolerance has been hypothesized to be intimately linked with mitochondria capability to produce enough adenosine triphosphate (ATP) to respond to the energetic demands of animals in high temperatures. In a recent study made in Octopus maya was proposed the hypothesis postulating that high temperatures could restrain female reproduction due to the limited capacity of the animals’ heart to sustain oxygen flow to the body, affecting in this manner energy production in the rest of the organs, including the ovarium Meza-Buendia AK et al. (2021). Unfortunately, until now, no reports have shown temperature effects and other environmental variables on cephalopod mitochondria activity because of the lack of a method to evaluate mitochondrial respiratory parameters in those species’ groups. In this sense and for the first time, this study developed a method to obtain mitochondrial respirometry data of adult Octopus maya’s heart. This protocol illustrates a step-by-step procedure to get high yield and functional mitochondria of cephalopod heart and procedure for determining the corresponding respiratory parameters. The procedure described in this paper takes approximately 3 to 4 hours from isolation of intact mitochondria to measurement of mitochondrial oxygen consumption.

The role of mitochondria and mitochondrial hormone receptors on the bioenergetic adaptations to lactation

The most recognized role of mitochondria is producing more than 90% of the total cellular energy in the form of ATP. In addition, mitochondrial function encompasses the maintenance of antioxidant balance, the regulation of intracellular calcium concentrations, the progression of cell death, and the biosynthesis of purines, hemes, lipids, amino acids and steroid hormones. Mitochondria are also important hormone targets. Estrogens, progestagens, and prolactin, are among the hormones that can impact mitochondrial function and modulate the underlying adaptations to changing bioenergetic and metabolic needs. Lactation represents a metabolic challenge with significant increases in energy requirements and fluctuating levels of hormones. To meet these bioenergetic demands, liver mitochondria increase their state 3 and 4 respiration, adjust superoxide dismutase activity, and elevate succinate dehydrogenase-related respiration. Skeletal muscle mitochondria respond by increasing their respiratory control ratio and adjusting catalase activity. In this review, these adaptations are described considering the lactation hormonal milieu.

Proapoptotic Index Evaluation of Two Synthetic Peptides Derived from the Coneshell Californiconus californicus in Lung Cancer Cell Line H1299

Lung cancer is one of the most common types of cancer, accounting for approximately 15% of all cancer cases worldwide. Apoptosis is the dominant defense mechanism against tumor development. The balance between pro- and antiapoptotic members of the Bcl-2 protein family can determine cellular fate. The venom of predatory marine snails Conus is estimated to have 100-400 toxins called conotoxins. The family of α-conotoxins is known to consist of selective antagonists of nicotinic acetylcholine receptors (nAChRs). Lung cancer cells overexpress several subunits of nAChRs and are considered as an excellent target for new anticancer drugs. We compared the cytotoxic effect of two synthetic peptides derived from Californiconus californicus, Cal14.1a, and Cal14.1b, which only differ by one amino acid in their sequence, and compared their proapoptotic balance by Bax and Bcl-2 mRNA expression. We determined the caspase-3 and -7 activation to demonstrate apoptosis induction. Results showed that Cal14.1a induces a high Bax/Bcl-2 ratio in H1299 (lung cancer cells). Although Cal14.1b has a cytotoxic effect on H1299 cells, reducing cell viability by 30%, it does not increase the Bax/Bcl-2 ratio, which could be explained by the Glu in the 15th residue, which is crucial for the ability of Cal14.1a to induce apoptosis.

(-)-Epicatechin stimulates mitochondrial biogenesis and cell growth in C2C12 myotubes via the G-protein coupled estrogen receptor

We have reported on the capacity of (-)-epicatechin ((-)-EPI) to stimulate mitochondrial biogenesis (MiB) in mouse skeletal muscle (SkM). However, the mechanisms mediating the effects of (-)-EPI are not fully understood. We previously identified a role of the G-protein coupled estrogen receptor (GPER) in modulating the vascular effects of (-)-EPI. We therefore tested the hypothesis that GPER mediates (at least in part) the stimulatory effects of (-)-EPI on MiB in SkM cells. As an in vitro model, we employed mouse SkM-derived C2C12 myoblasts differentiated into myotubes. Using confocal microscopy, we detected GPER at the cell surface and cytoplasm in C2C12 myotubes. Treatment with (-)-EPI (3 and 10μM) resulted in the stimulation of MiB as per increases in mitochondrial inner (MitoTracker Red FM fluorescence staining) and outer membrane (porin protein levels) markers, transcription factors involved in MiB stimulation (i.e., nuclear respiratory factor-2 [NRF-2] and mitochondrial transcription factor A [TFAM] protein levels) and citrate synthase (CS) activity levels. (-)-EPI-treated myotubes were longer and wider compared to vehicle-treated myotubes. The effects of (-)-EPI on myotube mitochondria and cell size were larger in magnitude to those observed with the GPER agonist G-1. The chemical blockade and down-regulation (siRNA) of GPER evidenced a partial and complete blockade of measured endpoints following (-)-EPI- or G-1-treatment, respectively. Altogether, results indicate that GPER is expressed in muscle cells and appears to mediate to a significant extent, the stimulatory effects of (-)-EPI on MiB. Thus, GPER activation may account for the stimulatory effects of (-)-EPI on SkM structure/function.

A non-hepatotropic parasite infection increases mortality in the acetaminophen-induced acute liver failure murine model: possible roles for IL-5 and IL-6

We evaluated the effects of a non-hepatotropic parasite infection (Taenia crassiceps) on the outcome of acetaminophen-induced acute liver failure in mice. Uninfected and T. crassiceps infected mice orally received either 300 mg/kg acetaminophen or water as vehicle (n = 5 per group). Survival analysis, hepatocyte necrosis, alanine aminotransferase (ALT) levels, CYP2E1 protein, interleukin (IL-) 5, and IL-6 were assessed for all groups. All infected mice died within 16 h after exposure to acetaminophen (Tc+APAP group), whereas only one-third of uninfected animals exposed to acetaminophen (APAP group) died. Uninfected (Control group) and infected (Tc group) mice that received the vehicle showed no liver damage. Tc+APAP mice exhibited massive liver necrosis characterised by marked balloning degeneration of hepatocytes and higher serum ALT compared to Control, Tc, and APAP animals. Liver tissue from Tc+APAP mice also displayed increased expression of CYP2E1 protein and higher mRNA and protein levels of IL-5 and IL-6 compared to the other groups. These findings suggest that non-hepatotropic parasite infections may increase mortality following acute liver failure by promoting hepatocyte necrosis via IL-5 and IL-6-dependent CYP2E1 overproduction. This study identifies new potential risk factors associated with severe acute liver failure in patients.

Hepatic diseases related to triglyceride metabolism

Triglycerides participate in key metabolic functions such as energy storage, thermal insulation and as deposit for essential and non-essential fatty acids that can be used as precursors for the synthesis of structural and functional phospholipids. The liver is a central organ in the regulation of triglyceride metabolism, and it participates in triglyceride synthesis, export, uptake and oxidation. The metabolic syndrome and associated diseases are among the main concerns of public health worldwide. One of the metabolic syndrome components is impaired triglyceride metabolism. Diseases associated with the metabolic syndrome promote the appearance of hepatic alterations e.g., non-alcoholic steatosis, steatohepatitis, fibrosis, cirrhosis and cancer. In this article, we review the molecular actions involved in impaired triglyceride metabolism and its association with hepatic diseases. We discuss mechanisms that reconcile the chronic inflammation and insulin resistance, and new concepts on the role of intestinal micro-flora permeability and proliferation in fatty liver etiology. We also describe the participation of oxidative stress in the progression of events leading from steatosis to steatohepatitis and fibrosis. Finally, we provide information regarding the mechanisms that link fatty acid accumulation during steatosis with changes in growth factors and cytokines that lead to the development of neoplastic cells. One of the main medical concerns vis-a-vis hepatic diseases is the lack of symptoms at the onset of the illness and, as result, its late diagnosis. The understandings of the molecular mechanisms that underlie hepatic diseases could help design strategies towards establishing markers for their accurate and timely diagnosis.