Coronavirus disease 2019 (COVID-19) continues to take a heavy toll on personal health, healthcare systems, and economies around the globe. Scientists are expending tremendous effort to develop diagnostic technologies for detecting positive infections within the shortest possible time, and vaccines and drugs specifically for the prevention and treatment of COVID-19 disease. At the same time, emerging novel variants have raised serious concerns about vaccine efficacy. The SARS-CoV-2 nucleocapsid (N) protein plays an important role in the coronavirus life cycle, and participates in various vital activities after virus invasion. It has attracted a large amount of attention for vaccine and drug development. Here, we summarize the latest research of the N protein, including its role in the SARS-CoV-2 life cycle, structure and function, and post-translational modifications in addition to its involvement in liquid–liquid phase separation (LLPS) and use as a basis for the development of vaccines and diagnostic techniques.

Globally, breast cancer stands as the most prevalent form of cancer among women. The tumor microenvironment of breast cancer often exhibits hypoxia. Hypoxia-inducible factor 1-alpha, a transcription factor, is found to be overexpressed and activated in breast cancer, playing a pivotal role in the anoxic microenvironment by mediating a series of reactions. Hypoxia-inducible factor 1-alpha is involved in regulating downstream pathways and target genes, which are crucial in hypoxic conditions, including glycolysis, angiogenesis, and metastasis. These processes significantly contribute to breast cancer progression by managing cancer-related activities linked to tumor invasion, metastasis, immune evasion, and drug resistance, resulting in poor prognosis for patients. Consequently, there is a significant interest in Hypoxia-inducible factor 1-alpha as a potential target for cancer therapy. Presently, research on drugs targeting Hypoxia-inducible factor 1-alpha is predominantly in the preclinical phase, highlighting the need for an in-depth understanding of HIF-1α and its regulatory pathway. It is anticipated that the future will see the introduction of effective HIF-1α inhibitors into clinical trials, offering new hope for breast cancer patients. Therefore, this review focuses on the structure and function of HIF-1α, its role in advancing breast cancer, and strategies to combat HIF-1α-dependent drug resistance, underlining its therapeutic potential.

Lactate dehydrogenase A (LDHA) primarily catalyzes the conversion between lactic acid and pyruvate, serving as a key enzyme in the aerobic glycolysis pathway of sugar in tumor cells. LDHA plays a crucial role in the occurrence, development, progression, invasion, metastasis, angiogenesis, and immune escape of tumors. Consequently, LDHA not only serves as a biomarker for tumor diagnosis and prognosis but also represents an ideal target for tumor therapy. Although LDHA inhibitors show great therapeutic potential, their development has proven to be challenging. In the development of LDHA inhibitors, the key active sites of LDHA are emphasized. Nevertheless, there is a relative lack of research on the amino acid residues around the active center of LDHA. Therefore, in this study, we investigated the amino acid residues around the active center of LDHA. Through structure comparison analysis, five key amino acid residues (Ala30, Met41, Lys131, Gln233, and Ala259) were identified. Subsequently, the effects of these five residues on the enzymatic properties of LDHA were investigated using site-directed mutagenesis. The results revealed that the catalytic activities of the five mutants varied to different degrees in both the reaction from lactic acid to pyruvate and pyruvate to lactic acid. Notably, the catalytic activities of LDHA^M41G and LDHA^K131I were improved, particularly in the case of LDHA^K131I. The results of the molecular dynamics analysis of LDHA^K131I explained the reasons for this phenomenon. Additionally, the optimum temperature of LDHA^M41G and LDHA^Q233M increased from 35 °C to 40 °C, whereas in the reverse reaction, the optimum temperature of LDHA^M41G and LDHA^K131I decreased from 70 °C to 60 °C. These findings indicate that Ala30, Met41, Lys131, Gln233, and Ala259 exert diverse effects on the catalytic activity and optimum temperature of LHDA. Therefore, these amino acid residues, in addition to the key catalytic site of the active center, play a crucial role. Considering these residues in the design and screening of LDHA inhibitors may lead to the development of more effective inhibitors.

The three-year COVID-19 pandemic ‘has’ caused a wide range of medical, social, political, and financial implications. Since the end of 2020, various mutations and variations in SARS-CoV-2 strains, along with the immune escape phenomenon, have emerged. There is an urgent need to identify a relatively stable target for the development of universal vaccines and drugs that can effectively combat both SARS-CoV-2 strains and their mutants. Currently, the main focus in treating SARS-CoV-2 lies in disrupting the virus’s life cycle. The main protease (M^pro) is closely associated with virus replication and maturation and plays a crucial role in the early stages of infection. Consequently, it has become an important target for the development of SARS-CoV-2-specific drugs. This review summarizes the recent research progress on the novel coronavirus’s main proteases, including the pivotal role of M^pro in the virus’s life cycle, the structure and catalytic mechanism of M^pro, the self-maturation mechanism of M^pro, the role of M^pro in virus immune escape, the current methods of developing antiviral drugs targeting M^pro, and the key drugs that have successfully entered clinical trials. The aim is to provide researchers involved in the development of antiviral drugs targeting M^pro with systematic and comprehensive information.

Since the end of 2020, the SARS-CoV-2 strain has undergone several mutations, and new variants continue to emerge. The immune escape ability of the mutants has enhanced, showing robust transmissibility. The neutralizing ability of the neutralizing antibodies produced during previous infections decreased in some mutants. This poses a severe challenge to the preventive and therapeutic effectiveness of vaccines and antibody drugs. Nucleocapsid protein, one of the main structural proteins of the coronavirus, plays an important role in the life cycle of the novel coronavirus and has proven to be one of the key targets for drug development. The first key step in drug development is to obtain pure nucleocapsid proteins. However, as nucleocapsid proteins have a nucleic acid binding function and can automatically undergo liquid–liquid phase separation and agglomerate, the purification of full-length nucleocapsids is extremely challenging. In this study, a set of easy-to-operate processes for the purification of nucleocapsid protein was developed. Finally, a pure full-length nucleocapsid protein without nucleic acid contamination was obtained. Subsequently, we also targeted the nucleic acid binding domain of the nucleocapsid protein and screened for potential SARS-CoV-2 inhibitors using virtual screening and biolayer interferometry (BLI) technology. Finally, a small molecule inhibitor, Light Green SF (KD = 19.9 µM), which can bind to nucleocapsid protein, was identified. In the future, we will continue to conduct more in-depth research and attempt to develop drugs that possess a good inhibitory effect on the current novel coronavirus mutants.