Hydrogen is the lightest atom and composes roughly half of the atomic content in macromolecules, yet their location can only be inferred or predicted in most macromolecular structures. This is because hydrogen can rarely be directly observed by the most common structure determination techniques (such as X-ray crystallography and electron cryo-microscopy). However, knowledge of hydrogen atom positions, especially for enzymes, can reveal protonation states of titratable active site residues, hydrogen bonding patterns, and the orientation of water molecules. Though we know they are present, this vital layer of information, which can inform a myriad of biological processes, is frustratingly invisible to us. The good news is that, even at modest resolution, neutron crystallography (NC) can reveal this layer and has emerged this century as a powerful tool for elucidating enzyme catalytic mechanisms. Due to its strong and coherent scattering of neutrons, incorporation of deuterium into the protein crystal amplifies the power of NC. This is especially true when solvation and the specific participation of key water molecules are crucial for catalysis. Neutron data allow the modeling of all three atoms in water molecules and have even revealed previously unobserved and unique species such as hydronium (D3O+) and deuteroxide (OD-) ions as well as lone deuterons (D+). Herein, we briefly review why neutrons are ideal probes for identifying catalytically important water molecules and these unique water-like species, limitations in interpretation, and four vignettes of enzyme success stories from disparate research groups. One of these groups was that of Dr. Chris G. Dealwis, who died unexpectedly in 2022. As a memorial appreciation of his scientific career, we will also highlight his interest and contributions to the neutron crystallography field. As both the authors were mentored by Chris, we feel we have a unique perspective on his love of molecular structure and admiration for neutrons as a tool to query those structures.

Cutaneous Squamous Cell Carcinoma (cSCC) is an increasingly common malignancy of the skin and the leading cause of death from skin cancer in adults over the age of 85. Fibroblast Growth Factor Receptor 2 (FGFR2) has been identified as an important effector of signaling pathways that lead to the growth and development of cSCC. In recent years, there have been numerous studies evaluating the role FGFR2 plays in multiple cancers, its contribution to resistance to anti-cancer therapy, and new drugs that may be used to inhibit FGFR2. This review will provide an overview of our current understanding of FGFR2 and potential mechanisms in which we can target FGFR2 in cSCC. The goals of this review are the following: 1) to highlight our current knowledge on the role of FGFR2 in healthy skin and contrast this with its role in the development of cancer; 2) to further explain the specific molecular mechanisms that FGFR2 uses to promote tumorigenesis; 3) to describe how FGFR2 contributes to more invasive disease, 4) to describe its immunosuppressive effects in skin, and 5) to evaluate its effect on current anticancer therapy and discuss therapies on the horizon to target FGFR2 related malignancy.

DNA - the repository of genetic information harbours sequences rich in Guanine that adopt non-B form four-stranded DNA secondary structures termed as G-quadruplexes (G4s). Such non-canonical structures tend to impede the progression of routine replisome and are implicated to have crucial roles in replication, transcription and epigenetic regulation while also ensuring genomic stability. It is now fully established that G4s are enzymatically unfolded by helicases, thus, preventing transient yet apparent impediments to the vital replisome progression. This unfolding of G-quadruplex ensures genetic and epigenetic stability. Given the importance of G4 biology for multiple human parasites such as, Mycobacterium tuberculosis, research efforts probing parasitic G4 biology is gaining momentum with the hope to enable therapeutic intervention. We herein shed light on G4s, conditions that lead to their formation and the mechanisms employed by cells to cause their unfolding. Towards the end, potential drug discovery avenues that arise from targeting parasitic helicases and G4 biology are summarized.

Chronic prostatitis has been found to be associated with the genesis of Benign Prostatic Hyper-plasia (BPH) and subsequent development of prostate cancer (PCa). It has been described that human papillomavirus (HPV) tends to infect the prostatic epithelium; however, correlation be-tween HPV infection and prostate pathology remains to be elucidated. Considering that HPV in-fection can affect cellular pathways, we investigated here the putative role of HPV in the expres-sion of selected miRNAs involved in inflammation, proliferation, and oncogenesis in BPH, BPH/prostatitis and PCa clinical samples. Our results demonstrated that 67.2 % of benign lesions and 93.4% of cancer samples were HPV-positive. Interestingly, we found downregulation of miR-34a, miR-143, and miR-145, as well as upregulation of miR-221 in tissue with BPH and BPH/prostatitis. In HPV-positive PCa samples, let-7c, miR-34a, miR-126, miR-221, miR-145, and miR-106a were found to be downregulated, suggesting their involvement in the formation of a pro-oncogenic microenvironment. Consistent with these results, we found that altered expression levels of miR-34a, miR-145, miR-106a, miR-21 and miR-221 showed a correlation with high-risk HPV-positive PCa samples. The differential expression of these miRNAs induced by HPV could be useful for the identification of potential therapeutic biomarkers, opening a new approach for di-agnosis, prognosis, and therapeutic targeting in prostate cancer.

The circadian clock is an autonomous timekeeping system evolved by organisms to adapt to external changes, regulating a variety of important physiological and behavioral processes. Recent studies have shown that the sirtuin family of histone deacetylases is involved in regulating the expression of clock genes and plays an important role in maintaining the normal rhythm of clock gene expression and behavior. Moreover, sirtuins are regulated directly or indirectly by the circadian clock system. The mutual regulation between the circadian clock and sirtuins is likely involved in a variety of signal transduction and metabolism processes. In this review, we discuss the molecular mechanisms and research progress on the intertwined relationship between the circadian clock and sirtuins, highlighting sirtuins as molecular links between metabolic control and circadian rhythms and offering our perspectives on future developments in the field.

p97(also known as Cdc48 or VCP) is a conserved AAA+ ATPase that plays a key role in diverse cellular pathways and processes. p97 segregates damaged or misfolded substrates from cellular organelles or membranes in corporation with its cofactors. These cofactors regulate p97’s function by its directing to different cellular pathways and have diverse effect on p97´s conformation. Recently, several high-resolution structures of substrate-engaged p97 in complex with cofactors have been resolved, providing structural insights into the molecular mechanism of substrate processing. In this review, we present a comprehensive overview of how p97 in complex with substrate recruiting and substrate processing cofactors recognize, extract, translocate, unfold and release ubiquitinated substrates.