Diabetic patients are prone to developing Alzheimer's disease (AD), in which microglia play a critical role. However, the direct effect of high glucose (HG) on microglia and the role of extracellular-signal-regulated kinase 5 (ERK5) signaling in this interaction have not been examined before. Here, these questions were addressed in microglia cultured in HG versus normal glucose (NG) conditions. Initially, HG induced microglial differentiation into the M2a phenotype with concomitant ERK5 activation. However, longer exposure to HG further induced differentiation of microglia into the M2b-like phenotype, followed by the M1-like subtype, concomitant with a gradual loss of ERK5 activation. BIX021895, a specific inhibitor of ERK5 activation, prevented M2a- differentiation of microglia, but induced earlier M2b-like polarization followed by M1-like polarization. Transfection of microglia with a sustained activated form of MEK5 (MEK5DD) prolonged the duration of the M2a phenotype, and prevented later differentiation into the M2b/M1 subtype. Conditioned media from the M2a-polarized microglia reduced neuronal cell apoptosis in hypoxic condition, while media from M2b-like or M1-like microglia enhanced apoptosis. Together, our data suggest that chronic hyperglycemia may induce a gradual alteration of microglia polarization into an increasingly proinflammatory subtype, which could be suppressed by sustained activation of ERK5 signaling.

Environmental pollutants, including chemical contaminants, heavy metals, and pesticides, have been linked to adverse effects on male reproductive health, particularly sperm quality. Non-obstructive azoospermia (NOA) is a severe form of male infertility caused by intrinsic testicular dysfunction, leading to a complete absence of sperm in the ejaculate. Busulfan, an alkylating chemotherapeutic agent widely used to treat chronic myelogenous leukemia, is known to induce NOA through its toxic effects on spermatogonial stem cells (SSCs). This study aimed to identify key molecular targets and pathways disrupted by busulfan in the testicular environment. By integrating molecular docking, single-cell RNA sequencing, and in vivo experimentation, the study identified POLE and LRAT as critical proteins. These proteins were shown to interact strongly with busulfan, leading to genomic instability and increased germ cell apoptosis during spermatogenesis. Additionally, the immune landscape of NOA-affected testes revealed significant changes in immune cell infiltration, potentially worsening the condition. These findings offer new insights into the mechanisms of busulfan-induced NOA and suggest potential therapeutic targets for preserving male fertility in chemotherapy patients. This research advances the understanding of chemotherapy-induced reproductive toxicity and emphasizes the need for strategies to reduce its negative effects on fertility.

The Cre/loxP system has been used extensively in mouse models with a limitation of one lineage at a time. Differences in function and other properties among populations of adult β-cells is termed β-cell heterogeneity, which was recently associated with diabetic phenotypes. Nevertheless, the presence of a developmentally derived β-cell heterogeneity is unclear. Here, we have developed a novel dual lineage-tracing technology, using a combination of two recombinase systems, Dre/RoxP and Cre/LoxP, to independently trace green fluorescent Pdx1-lineage cells and red fluorescent Ptf1a-lineage cells in the developing and adult mouse pancreas. We detected a few Pdx1⁺/Ptf1a⁻ lineage cells in addition to the vast majority of Pdx1⁺/Ptf1a⁺ lineage cells in the pancreas. Moreover, Pdx1⁺/Ptf1a⁺ lineage β-cells had fewer Ki-67⁺ proliferating β-cells, and expressed higher mRNA levels of insulin, Glut2, Pdx1, MafA and Nkx6.1, but lower CCND1 and CDK4 levels, compared with Pdx1⁺/Ptf1a⁻ lineage β-cells. Furthermore, more TSQ-high, SSC-high cells were detected in the Pdx1⁺Ptf1a⁺ lineage population than in the Pdx1⁺Ptf1a⁻ lineage population. Together, these data suggest that differential activation of Ptf1a in the developing pancreas may correlate with this β-cell heterogeneity.

Background: Testosterone plays a critical role in maintaining reproductive functions and well-beings of the males. Adult testicular Leydig cells (LCs) produce testosterone and are generated from stem Leydig cells (SLCs) during puberty through adulthood. In addition, macrophages are critical in the SLC regulatory niche for normal testicular function. Age-related reduction in serum testosterone contributes to a number of metabolic and quality-of-life changes in males, as well as age-related changes in immunological functions. How aging and testicular macrophages may affect SLC function is still unclear.Methods: SLCs and macrophages were purified from adult and aged mice via FACS using CD51 as a marker protein. The sorted cells were first characterized and then co-cultured in vitro to examine how aging and macrophages may affect SLC proliferation and differentiation. To elucidate specific aging effects on both cell types, co-culture of sorted SLCs and macrophages were also carried out across two ages.Results: CD51+ (weakly positive) and CD51++ (strongly positive) cells expressed typical SLC and macrophage markers, respectively. However, with aging, both cell types increased expression of multiple cytokine genes, such as IL-1b, IL-6 and IL-8. Moreover, old CD51+ SLCs reduced their proliferation and differentiation, with a more significant reduction in differentiation (2X) than proliferation (30%). Age matched CD51++ macrophages inhibited CD51+ SLC development, with a more significant reduction in old cells (60%) than young (40%). Crossed-age co-culture experiments indicated that the age of CD51+ SLCs plays a more significant role in determining age-related inhibitory effects. In LC lineage formation, CD51+ SLC had both reduced LC lineage markers and increased myoid cell lineage markers, suggesting an age-related lineage shift for SLCs.Conclusion: The results suggest that aging affected both SLC function and their regulatory niche cell, macrophages.