The role of small GTPase Rac1 in ionizing radiation-induced testicular damage

Unveiling the role of miRNAs in Diminished Ovarian Reserve: an in silico network approach

MicroRNAs (miRNAs) have acquired an increased recognition to unravel the complex molecular mechanisms underlying Diminished Ovarian Reserve (DOR), one of the main responsible for infertility. To investigate the impact of miRNA profiles in granulosa cells and follicular fluid, crucial players in follicle development, this study employed a computational network theory approach to reconstruct potential pathways regulated by miRNAs in granulosa cells and follicular fluid of women suffering from DOR. Available data from published research were collected to create the FGC_MiRNome_MC, a representation of miRNA target genes and their interactions. 365 hubs were identified within the network, representing potential key regulators, and 210 nodes that act as both hubs and bottlenecks (H&BN nodes), suggesting that they may control the information flow within the network. GO enrichment analysis of the 210 H&BN nodes revealed their involvement in fundamental cellular processes relevant to ovarian function. In particular, the cluster analysis identified several shared pathways between cluster 1 and cluster 2 involved in the RAS/MAPK pathway, which plays a critical role in cell proliferation, differentiation and survival. These findings suggest that miRNAs play a significant role in DOR and highlight the potential of the RAS/MAPK pathway as a target for further investigation. Additionally, the genes identified as both hubs and bottlenecks revealed interesting connections to reproductive health in KO mice models. This in silico approach provides valuable insights into potential biomarkers and therapeutic targets for age-related reproductive disorders.

A comprehensive review on p38MAPK signaling as a potent radioprotector in testis

BACKGROUND

Previous studies have shown that the activation of p38MAPK signaling plays a crucial role in regulating gonadal cell fate decisions in both mouse and human. Excessive activation of p38MAPK by radiation significantly causes testicular damage and negatively affects the male reproductive function. Therefore, fine-tuned regulation of p38MAPK signaling is critical in both physiological and pathological conditions.

RESULT

This review summarizes the impact of p38MAPK signaling on testicular germ cells and microenvironment under normal condition. The relationship between radiation, reactive oxygen species (ROS), and p38MAPK is summarized. In conclusion, radiation exposure triggers the overactivation of p38MAPK, which is regulated by ROS, resulting in testicular damage. Various p38MAPK-targeting agents are discussed, providing guidance for developing new strategies.

Implication of Rac1 GTPase in molecular and cellular mitochondrial functions

Rac1 is a member of the Rho GTPase family which plays major roles in cell mobility, polarity and migration, as a fundamental regulator of actin cytoskeleton. Signal transduction by Rac1 occurs through interaction with multiple effector proteins, and its activity is regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). The small protein is mainly anchored to the inner side of the plasma membrane but it can be found in endocellular compartments, notably endosomes and cell nuclei. The protein localizes also into mitochondria where it contributes to the regulation of mitochondrial dynamics, including both mitobiogenesis and mitophagy, in addition to signaling processes via different protein partners, such as the proapoptotic protein Bcl-2 and chaperone sigma-1 receptor (σ-1R). The mitochondrial form of Rac1 (mtRac1) has been understudied thus far, but it is as essential as the nuclear or plasma membrane forms, via its implication in regulation of oxidative stress and DNA damages. Rac1 is subject to diverse post-translational modifications, notably to a geranylgeranylation which contributes importantly to its mitochondrial import and its anchorage to mitochondrial membranes. In addition, Rac1 contributes to the mitochondrial translocation of other proteins, such as p53. The mitochondrial localization and functions of Rac1 are discussed here, notably in the context of human diseases such as cancers. Inhibitors of Rac1 have been identified (NSC-23766, EHT-1864) and some are being developed for the treatment of cancer (MBQ-167) or central nervous system diseases (JK-50561). Their effects on mtRac1 warrant further investigations. An overview of mtRac1 is provided here.