Keratins (cytokeratins) are intermediate filament proteins that are mainly expressed in epithelial cells. Keratin heterodimers composed of an acidic keratin (or type I keratin, keratins K9-K28) and a basic keratin (or type II keratin, keratins K1-K8 and K71-K80) assemble to form filaments. Keratin isoforms demonstrate tissue- and differentiation-specific profiles that make them useful as research and clinical biomarkers.
The regulation of cell growth, differentiation and programmed death is coordinated by several sets of proteins that comprise essential signal transduction pathways. Many of these key regulatory proteins are encoded by proto-oncogenes, which can be activated (altered) to change the typical cell program to one of abnormal cell growth and unregulated development. Proteins encoded by proto-oncogenes include growth factors and other ligands, receptor proteins, tyrosine kinases, various regulatory proteins (i.e. GTPases) and transcription factors. Together these proteins comprise the basic elements of cell signaling pathways; altered expression or mutation of one or more of these components can lead to oncogenic growth.
Coronaviruses are a group of viruses that contain single-stranded, positive-sense RNA genomes. Several members of this group, which include severe acute respiratory syndrome coronaviruses (SARS-CoV and SARS-CoV-2) and Middle East respiratory syndrome coronavirus (MERS-CoV), are highly pathogenic and have caused significant disease outbreaks in human hosts. In order for human coronaviruses to transcribe and replicate their genomes within host cells, they must first attach and gain entry into host cells using a variety of cell surface receptors and components of the endocytic machinery.
Formation of Cleaved Caspase: During apoptosis, caspase zymogens are cleaved to form active enzymes. This cleavage is irreversible and marks the irreversible stage of apoptosis.In many diseases, abnormal regulation of apoptosis is closely related to the occurrence and development of the disease.
Mammalian histone deacetylases can be divided into three classes on the basis of their similarity to various yeast deacetylases. Class I proteins (HDACs 1, 2, 3, and 8) are related to the yeast Rpd3-like proteins, those in class II (HDACs 4, 5, 6, 7, 9, and 10) are related to yeast Hda1-like proteins, and class III proteins are related to the yeast protein Sir2. Inhibitors of HDAC activity are now being explored as potential therapeutic cancer agents.
Cdc25 is a protein phosphatase responsible for dephosphorylating and activating cdc2, a crucial step in regulating the entry of all eukaryotic cells into mitosis (1). cdc25C is constitutively phosphorylated at Ser216 throughout interphase by c-TAK1, while phosphorylation at this site is DNA damage-dependent at the G2/M checkpoint (2). When phosphorylated at Ser216, cdc25C binds to members of the 14-3-3 family of proteins, sequestering cdc25C in the cytoplasm and thereby preventing premature mitosis (3). The checkpoint kinases Chk1 and Chk2 phosphorylate cdc25C at Ser216 in response to DNA damage (4,5).
Cannabinoid receptors mediate a number of physiological processes in the brain ranging from appetite regulation, pain, learning, and memory. The major cannabinoid receptors in the brain include CB1 and CB2 receptors, which are G-protein coupled receptors (GPCRs). CB1 interacts with other GPCRs including metabotropic glutamate receptor 1, mGluR1. Endogenous ligands, endocannabinoids, but also exogenously introduced compounds such as tetrahydrocannabinol (THC), activate cannabinoid receptors by promoting the exchange of GDP for GTP, leading to a cascade of signaling pathways that are activated to drive various functions.
