mTOR Signaling Network in Cell Biology and Human Disease

Paxbp1 is indispensable for the maintenance of peripheral CD4 T cell homeostasis

The size and condition of the peripheral CD4 T cell population determine the capacity of the immune response. Under homeostatic conditions, the size of the peripheral CD4 T cell population is maintained through turnover and survival. However, the underlying mechanisms remain inadequately understood. Here, we observed a significant decrease in the percentage of CD4 T cells in the periphery following the targeted deletion of the Paxbp1 gene in mouse T cells. In the absence of Paxbp1, naïve CD4 T cells displayed reduced surface interleukin-7 receptor levels and a decreased capacity to respond to survival signals mediated by interleukin-7. In addition, naïve CD4 T cells deficient in Paxbp1 demonstrated impaired T cell antigen receptor signalling, compromised cell cycle entry, decreased proliferation, and increased apoptosis following stimulation, all of which contributed to the reduction in the number of peripheral CD4 T cells. Therefore, our study highlights the indispensable role of Paxbp1 in maintaining peripheral CD4 T cell homeostasis.

mTOR Signaling: Recent Progress

In the intricate landscape of human biology, the mechanistic target of rapamycin (mTOR) emerges as a key regulator, orchestrating a vast array of processes in health and disease [...].

Hair follicle stem cells promote epidermal regeneration under expanded condition

Skin soft tissue expansion is the process of obtaining excess skin mixed with skin development, wound healing, and mechanical stretching. Previous studies have reported that tissue expansion significantly induces epidermal proliferation throughout the skin. However, the mechanisms underlying epidermal regeneration during skin soft tissue expansion are yet to be clarified. Hair follicle stem cells (HFSCs) have been recognized as a promising approach for epidermal regeneration. This study examines HFSC-related epidermal regeneration mechanisms under expanded condition and proposes a potential method for its cellular and molecular regulation.

From carcinogenesis to therapeutic avenues: lncRNAs and mTOR crosstalk in lung cancer

Long non-coding RNAs (lncRNAs) have been demonstrated to have a crucial function in the modulation of the activity of genes, impacting a variety of homeostatic processes involving growth, survival, movement, and genomic consistency. Certain lncRNAs' aberrant expression has been linked to carcinogenesis, tumor growth, and therapeutic resistance. They are beneficial for the management of malignancies since they can function as cancer-causing or cancer-suppressing genes and behave as screening or prognosis indicators. The modulation of the tumor microenvironment, metabolic modification, and spread have all been linked to lncRNAs in lung cancer. Recent research has indicated that lncRNAs may interact with various mTOR signalling systems to control expression in lung cancer. Furthermore, the route can affect how lncRNAs are expressed. Emphasizing the function of lncRNAs as crucial participants in the mTOR pathway, the current review intends to examine the interactions between the mTOR cascade and the advancement of lung cancer. The article will shed light on the roles and processes of a few lncRNAs associated with the development of lung cancer, as well as their therapeutic prospects.

Everolimus-induced hyperpermeability of endothelial cells causes lung injury

The mammalian target of rapamycin (mTOR) inhibitors, everolimus (but not dactolisib), is frequently associated with lung injury in clinical therapies. However, the underlying mechanisms remain unclear. Endothelial cell barrier dysfunction plays a major role in the pathogenesis of the lung injury. This study hypothesizes that everolimus increases pulmonary endothelial permeability, which leads to lung injury. We tested the effects of everolimus on human pulmonary microvascular endothelial cell (HPMEC) permeability and a mouse model of intraperitoneal injection of everolimus was established to investigate the effect of everolimus on pulmonary vascular permeability. Our data showed that everolimus increased human pulmonary microvascular endothelial cell (HPMEC) permeability which was associated with MLC phosphorylation and F-actin stress fiber formation. Furthermore, everolimus induced an increasing concentration of intracellular calcium Ca2+ leakage in HPMECs and this was normalized with ryanodine pretreatment. In addition, ryanodine decreased everolimus-induced phosphorylation of PKCα and MLC, and barrier disruption in HPMECs. Consistent with in vitro data, everolimus treatment caused a visible lung-vascular barrier dysfunction, including an increase in protein in BALF and lung capillary-endothelial permeability, which was significantly attenuated by pretreatment with an inhibitor of PKCα, MLCK, and ryanodine. This study shows that everolimus induced pulmonary endothelial hyper-permeability, at least partly, in an MLC phosphorylation-mediated EC contraction which is influenced in a Ca2+-dependent manner and can lead to lung injury through mTOR-independent mechanisms.

mTOR signaling in hair follicle and hair diseases: recent progress

Mammalian target of rapamycin (mTOR) signaling pathway is a major regulator of cell proliferation and metabolism, playing significant roles in proliferation, apoptosis, inflammation, and illness. More and more evidences showed that the mTOR signaling pathway affects hair follicle circulation and maintains the stability of hair follicle stem cells. mTOR signaling may be a critical cog in Vitamin D receptor (VDR) deficiency-mediated hair follicle damage and degeneration and related alopecia disorders. This review examines the function of mTOR signaling in hair follicles and hair diseases, and talks about the underlying molecular mechanisms that mTOR signaling regulates.

Structural Insights into the Giardia lamblia Target of Rapamycin Homolog: A Bioinformatics Approach

TOR proteins, also known as targets of rapamycin, are serine/threonine kinases involved in various signaling pathways that regulate cell growth. The protozoan parasite Giardia lamblia is the causative agent of giardiasis, a neglected infectious disease in humans. In this study, we used a bioinformatics approach to examine the structural features of GTOR, a G. lamblia TOR-like protein, and predict functional associations. Our findings confirmed that it shares significant similarities with functional TOR kinases, including a binding domain for the FKBP-rapamycin complex and a kinase domain resembling that of phosphatidylinositol 3-kinase-related kinases. In addition, it can form multiprotein complexes such as TORC1 and TORC2. These results provide valuable insights into the structure-function relationship of GTOR, highlighting its potential as a molecular target for controlling G. lamblia cell proliferation. Furthermore, our study represents a step toward rational drug design for specific anti-giardiasis therapeutic agents.

NSD3: Advances in cancer therapeutic potential and inhibitors research

Nuclear receptor-binding SET domain 3, otherwise known as NSD3, is a member of the group of lysine methyltransferases and is involved in a variety of cellular processes, including transcriptional regulation, DNA damage repair, non-histone related functions and several others. NSD3 gene is mutated or loss of function in a variety of cancers, including breast, lung, pancreatic, and osteosarcoma. These mutations produce dysfunction of the corresponding tumor tissue proteins, leading to tumorigenesis, progression, chemoresistance, and unfavorable prognosis, which suggests that the development of NSD3 probe molecules is important for understanding the specific role of NSD3 in disease and drug discovery. In recent years, NSD3 has been increasingly reported, demonstrating that this target is a very hot epigenetic target. However, the number of NSD3 inhibitors available for cancer therapy is limited and none of the drugs that target NSD3 are currently available on the market. In addition, there are very few reviews describing NSD3. Within this review, we highlight the role of NSD3 in tumorigenesis and the development of NSD3 targeted small-molecule inhibitors over the last decade. We hope that this publication can serve as a guide for the development of potential drug candidates for various diseases in the field of epigenetics, especially for the NSD3 target.