Mitochondrial fission protein 1 (Fis1) and mitochondrial dynamics protein of 51 kDa (Mid51) regulate stress-induced mitochondrial fragmentation implicated in cardiovascular disease. Using homologous sequence analysis and structure-guided design, we identified a linear peptide inhibitor (CVP-240) targeting the Fis1/Mid51 protein-protein interaction (PPI) and optimized it into a macrocyclic derivative (CVP-764). Both compounds bind Mid51 with high affinity, selectively disrupt Fis1/Mid51 signaling over Drp1-dependent interactions, and exhibit nanomolar binding in fluorescence polarization assays using FAM-conjugated tracers. In H9c2 cardiomyocytes, CVP-240 and CVP-764 preserve mitochondrial membrane potential, reduce reactive oxygen species, maintain mitochondrial network integrity, and improve cell viability under stress. Macrocyclization enhances proteolytic and serum stability and confers intrinsic cell permeability without the need for a cell-penetrating sequence. In silico ADMET profiling and preliminary in vivo toxicity studies support a favorable safety profile, establishing CVP-764 as a promising lead for targeting pathological mitochondrial fission.

The mitochondrial E3 ubiquitin ligase membrane-associated RING-CH-type finger 5 (MARCH5) and the GTPase Mitofusin 2 (Mfn2) both play crucial roles in regulating mitochondrial dynamics, which are essential for cellular homeostasis. Dysregulation of the MARCH5/Mfn2 signaling has been implicated in mitochondrial dysfunction, a key factor in cardiovascular diseases (CVDs). To investigate the therapeutic potential of targeting this interaction, we developed a novel peptide, CVP-220, designed to specifically disrupt the MARCH5/Mfn2 protein interaction. Using a hypoxia-reoxygenation (H/R) injury model in rat cardiomyocyte cell lines, CVP-220 demonstrated significant cardioprotective effects. Treatment with CVP-220 enhanced cell viability by 30 % compared to untreated controls and reduced reactive oxygen species (ROS) production by 45 %, suggesting improved mitochondrial function. Notably, CVP-220 selectively modulated MARCH5-mediated ubiquitination of Mfn2 without affecting other MARCH5 interactions, thereby preserving mitochondrial fusion and preventing fragmentation under stress conditions. A plausible binding mode of CVP-220 on Mfn2 was suggested through a combination of molecular docking and molecular dynamics simulations and was experimentally validated by mutational analysis. These findings highlight CVP-220 as a promising tool for modulating mitochondrial dynamics and mitigating mitochondrial damage in cardiac cells, with potential implications for therapeutic strategies targeting mitochondrial dysfunction in CVDs. Further investigation into the role of MARCH5/Mfn2 signaling in cardiac pathology could pave the way for novel peptide-based treatments.

Living organisms are constructed from proteins that assemble into biomolecular complexes, each with a unique shape and function. Our knowledge about the structure-activity relationship of these complexes is still limited, mainly because of their small size, complex structure, fast processes, and changing environment. Furthermore, the constraints of current microscopic tools and the difficulty in applying molecular dynamic simulations to capture the dynamic response of biomolecular complexes and long-term phenomena call for new supplementary tools and approaches that can help bridge this gap. In this paper, we present an approach to comparing biomolecular and origami hierarchical structures and apply it to comparing bacterial microcompartments (BMCs) with spiral-based origami models. Our first analysis compares proteins that assemble the BMC with an origami model called "flasher", which is the unit cell of an assembled origami model. Then, the BMC structure is compared with the assembled origami model and based on the similarity, a physical scaled-up origami model, which is analogous to the BMC, is constructed. The origami model is translated into a computer-aided design model and manufactured via 3D-printing technology. Finite element analysis and physical experiments of the origami model and 3D-printed parts reveal trends in the mechanical response of the icosahedron, which is constructed from tiled-chiral elements. The chiral elements rotate as the icosahedron expands and we deduce that it allows the BMC to open gates for transmembrane passage of materials.

INTRODUCTION:Cardiovascular diseases are the main cause of mortality in the world. Their most common expression is ischemic heart disease (IHD) such as myocardial infarction (MI). Physical rehabilitation is a common practice for IHD patients. Yet, there is no definition of when is the most effective time to start physical rehabilitation. However, it is recommended to start it as soon as possible. There is a growing interest in understanding the relationship between IHD and cardiomyocytes mitochondrial dynamics processes. Mitochondrial imbalance after MI accelerates cardiac damage. Peptide-based drugs are an effective and safe treatment option.AIMS:To examine rehabilitation and peptide intervention post-MI to assess optimal time to start a physical activity and mitochondrial function post-MI.BACKGROUND:Early training as well as peptide treatment will protect the cardiac muscle post-MI from accelerated damage.METHODS:Sixty rats will be divided into 6 groups: Six groups will undergo ischemia-reperfusion (I/R) surgery, by a 30 minute occlusion of their left anterior descending artery (LAD) followed by reperfusion. Three groups will start moderate-intensity exercise training for 8 weeks at different time-points post-MI (3, 7, or 21 days). Another group will be injected with synthetic peptide 5' pre-reperfusion. A sedentary group and a sham group will be used as controls. Results will be assessed by a mitochondrial function test, echocardiography, blood inflammatory and biochemical markers, pressure/volume loops, an exercise test and histology.RESULTS:Improvement of cardiac physiology following exercise training, and mitochondrial treatment will shed light on the preferred timing of cardiac rehabilitation and the mitochondrial damage post-MI.

Chagas disease and leishmaniasis are both neglected tropical diseases that affect millions of people around the world. Leishmaniasis is currently the second most widespread vector-borne parasitic disease after malaria. The World Health Organization records approximately 0.7–1 million newly diagnosed leishmaniasis cases each year, resulting in approximately 20,000–30,000 deaths. Also, 25 million people worldwide are at risk of Chagas disease and an estimated 6 million people are infected with Trypanosoma cruzi. Pentavalent antimonials, amphotericin B, miltefosine, paromomycin, and pentamidine are currently used to treat leishmaniasis. Also, nifurtimox and benznidazole are two drugs currently used to treat Chagas disease. These drugs are associated with toxicity problems such as nephrotoxicity and cardiotoxicity, in addition to resistance problems. As a result, the discovery of novel therapeutic agents has emerged as a top priority and a promising alternative. Overall, there is a need for new and effective treatments for Chagas disease and leishmaniasis, as the current drugs have significant limitations. Peptide-based drugs are attractive due to their high selectiveness, effectiveness, low toxicity, and ease of production. This paper reviews the potential use of peptides in the treatment of Chagas disease and leishmaniasis. Several studies have demonstrated that peptides are effective against Chagas disease and leishmaniasis, suggesting their use in drug therapy for these diseases. Overall, peptides have the potential to be effective therapeutic agents against Chagas disease and leishmaniasis, but more research is needed to fully investigate their potential.

Human protein kinases are highly-sought-after drug targets, historically harnessed for treating cancer, cardiovascular disease, and an increasing number of autoimmune and inflammatory conditions. Most current treatments involve small molecule protein kinase inhibitors that interact orthosterically with the protein kinase ATP-binding pocket. As a result, these compounds are often poorly selective and highly toxic. Part I of this series reviews the role of PKC isoforms in various human diseases, featuring cancer and cardiovascular disease, as well as translational examples of PKC modulation applied to human health and disease. In the present Part II, we discuss alternative allosteric binding mechanisms for targeting PKC, as well as novel drug platforms, such as modified peptides. A major goal is to design protein kinase modulators with enhanced selectivity and improved pharmacological properties. To this end, we use molecular docking analysis to predict the mechanisms of action for inhibitor-kinase interactions that can facilitate the development of next-generation PKC modulators.

Mitochondria, the membrane-bound cell organelles that supply most of the energy needed for cell function, are highly regulated, dynamic organelles bearing the ability to alter both form and functionality rapidly to maintain normal physiological events and challenge stress to the cell. This amazingly vibrant movement and distribution of mitochondria within cells is controlled by the highly coordinated interplay between mitochondrial dynamic processes and fission and fusion events, as well as mitochondrial quality-control processes, mainly mitochondrial autophagy (also known as mitophagy). Fusion connects and unites neighboring depolarized mitochondria to derive a healthy and distinct mitochondrion. In contrast, fission segregates damaged mitochondria from intact and healthy counterparts and is followed by selective clearance of the damaged mitochondria via mitochondrial specific autophagy, i.e., mitophagy. Hence, the mitochondrial processes encompass all coordinated events of fusion, fission, mitophagy, and biogenesis for sustaining mitochondrial homeostasis. Accumulated evidence strongly suggests that mitochondrial impairment has already emerged as a core player in the pathogenesis, progression, and development of various human diseases, including cardiovascular ailments, the leading causes of death globally, which take an estimated 17.9 million lives each year. The crucial factor governing the fission process is the recruitment of dynamin-related protein 1 (Drp1), a GTPase that regulates mitochondrial fission, from the cytosol to the outer mitochondrial membrane in a guanosine triphosphate (GTP)-dependent manner, where it is oligomerized and self-assembles into spiral structures. In this review, we first aim to describe the structural elements, functionality, and regulatory mechanisms of the key mitochondrial fission protein, Drp1, and other mitochondrial fission adaptor proteins, including mitochondrial fission 1 (Fis1), mitochondrial fission factor (Mff), mitochondrial dynamics 49 (Mid49), and mitochondrial dynamics 51 (Mid51). The core area of the review focuses on the recent advances in understanding the role of the Drp1-mediated mitochondrial fission adaptor protein interactome to unravel the missing links of mitochondrial fission events. Lastly, we discuss the promising mitochondria-targeted therapeutic approaches that involve fission, as well as current evidence on Drp1-mediated fission protein interactions and their critical roles in the pathogeneses of cardiovascular diseases (CVDs).

Cardiovascular diseases (CVDs) are the most common non-communicable diseases globally. An estimated 17.9 million people died from CVDs in 2019, representing 32% of all global deaths. Mitochondria play critical roles in cellular metabolic homeostasis, cell survival, and cell death, as well as producing most of the cell’s energy. Protein–protein interactions (PPIs) have a significant role in physiological and pathological processes, and aberrant PPIs are associated with various diseases, therefore they are potential drug targets for a broad range of therapeutic areas. Due to their ability to mimic natural interaction motifs and cover relatively larger interaction region, peptides are very promising as PPI inhibitors. To expedite drug discovery, computational approaches are widely used for screening potential lead compounds. Here, we developed peptides that inhibit mitochondrial fission 1 (Fis1)/mitochondrial dynamics 51 kDa (Mid51) PPI to reduce the cellular damage that can lead to various human pathologies, such as CVDs. Based on a rational design approach we developed peptide inhibitors of the Fis1/Mid51 PPI. In silico and in vitro studies were done to evaluate the biological activity and molecular interactions of the peptides. Two peptides, CVP-241 and CVP-242 were identified based on low binding energy and molecular dynamics simulations. These peptides inhibit Fis1/Mid51 PPI (-1324.9 kcal mol−1) in docking calculations (CVP-241, -741.3 kcal mol−1, and CVP-242, -747.4 kcal mol−1), as well as in vitro experimental studies Fis1/Mid51 PPI (KD 0.054 µM) Fis1/Mid51 PPI + CVP-241 (KD 3.43 µM), and Fis1/Mid51 PPI + CVP-242 (KD 44.58 µM). Finally, these peptides have no toxicity to H9c2 cells, and they increase cell viability in cardiomyocytes (H9c2 cells). Consequently, the identified inhibitor peptides could serve as potent molecules in basic research and as leads for therapeutic development.

Protein kinases are one of the most significant drug targets in the human proteome, historically harnessed for the treatment of cancer, cardiovascular disease, and a growing number of other conditions, including autoimmune and inflammatory processes. Since the approval of the first kinase inhibitors in the late 1990s and early 2000s, the field has grown exponentially, comprising 98 approved therapeutics to date, 37 of which were approved between 2016 and 2021. While many of these small-molecule protein kinase inhibitors that interact orthosterically with the protein kinase ATP binding pocket have been massively successful for oncological indications, their poor selectively for protein kinase isozymes have limited them due to toxicities in their application to other disease spaces. Thus, recent attention has turned to the use of alternative allosteric binding mechanisms and improved drug platforms such as modified peptides to design protein kinase modulators with enhanced selectivity and other pharmacological properties. Herein we review the role of different protein kinase C (PKC) isoforms in cancer and cardiovascular disease, with particular attention to PKC-family inhibitors. We discuss translational examples and carefully consider the advantages and limitations of each compound (Part I). We also discuss the recent advances in the field of protein kinase modulators, leverage molecular docking to model inhibitor-kinase interactions, and propose mechanisms of action that will aid in the design of next-generation protein kinase modulators (Part II).

Heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) work together as a molecular chaperone complex to regulate the activity of a multitude of client protein kinases. These kinases belong to a wide array of intracellular signaling networks that mediate multiple cellular processes including proliferation. As a result, Hsp90 and Cdc37 represent innovative therapeutic targets in various cancers (such as leukemia, multiple myeloma, and hepatocellular carcinoma (HCC)) in which their expression levels are elevated. Conventional small molecule Hsp90 inhibitors act by blocking the conserved adenosine triphosphate (ATP) binding site. However, by targeting less conserved sites in a more specific manner, peptides and peptidomimetics (modified peptides) hold potential as more efficacious and less toxic alternatives to the conventional small molecule inhibitors. Using a rational approach, we herein developed bioactive peptides targeting Hsp90/Cdc37 interaction. A six amino acid linear peptide derived from Cdc37, KTGDEK, was designed to target Hsp90. We used in silico computational docking to first define its mode of interaction, and binding orientation, and then conjugated the peptide with a cell penetrating peptide, TAT, and a fluorescent dye to confirm its ability to colocalize with Hsp90 in HCC cells. Based on the parent linear sequence, we developed a peptidomimetics library of pre-cyclic and cyclic derivatives. These peptidomimetics were evaluated for their binding affinity to Hsp90, and bioactivity in HCC cell lines. Among them, a pre-cyclic peptidomimetic demonstrates high binding affinity and bioactivity in HCC cells, causing reduced cell proliferation that is associated with induction of cell apoptosis, and down-regulation of phosphorylated MEK1/2. Overall, this generalized approach of rational design, structural optimization, and cellular validation of ‘drug-like’ peptidomimetics against Hsp90/Cdc37 offers a feasible and promising way to design novel therapeutic agents for malignancies and other diseases that are dependent on this molecular chaperone complex.

Cohesin mediates the 3-D structure of chromatin and is involved in maintaining genome stability and function. The cohesin core comprises Smc1 and Smc3, elongated-shaped proteins that dimerize through globular domains at their edges, called head and hinge. ATP binding to the Smc heads induces their dimerization and the formation of two active sites, while ATP hydrolysis results in head disengagement. This ATPase cycle is essential for driving cohesin activity. We report on the development of the first cohesin-inhibiting peptide (CIP). The CIP binds Smc3 in vitro and inhibits the ATPase activity of the holocomplex. Treating yeast cells with the CIP prevents cohesin's tethering activity and, interestingly, leads to the accumulation of cohesin on chromatin. CIP3 also affects cohesin activity in human cells. Altogether, we demonstrate the power of peptides to inhibit cohesin in cells and discuss the potential application of CIPs as a therapeutic approach.

Cardiovascular diseases (CVDs) make up a group of heart and blood vessel disorders and remain the most common cause of death worldwide. Annually, approximately one in every six US healthcare dollars is spent on CVD, and by 2035 the number of Americans with CVD is anticipated to rise to 131.2 million—45% of the total US population. Peptides are naturally occurring short chains of amino acids, typically comprising 2–50 amino acids and ubiquitously found in all living organisms, which display a large diversity of biological effects that regulate most physiological processes. Since the isolation of insulin, which later became the first commercially available peptide drug, peptide therapeutics have played important roles in medical practice. Over the years, there has been a constant increase in the number of peptides entering clinical studies. Importantly, peptides demonstrate higher success rates in transitioning from phase 1 to phase 2 trials as compared to small molecules and biological drugs, and in transitioning from phase 3 to regulatory review. This chapter discusses the therapeutic potential of peptides which primarily affect organ systems other than the cardiovascular system (CVS), but which also play key roles in the CVS. For example, the neurohormones vasopressin and oxytocin, which primarily control endocrine and reproductive processes, were recently found to have cardioprotective properties. The vasodilatory and other cardiovascular effects of calcitonin gene-related protein, vasoactive intestinal peptide, amylin and glucagon-like peptide-1, and the potential cardioprotective effects of ghrelin, salusin, apelin, and urocortin are also reviewed. Together, through their gastrointestinal or neuronal actions, these noncardiovascular peptides play roles in the regulation of normal cardiovascular hemodynamics and may be used to reduce CVD-related morbidity and mortality.