Biology subjects

Strauss, J. F.

Publications and source records attributed to Strauss, J. F..

12 recordsLinked to original sources

bioRxiv2025

Two Spag6 genes control sperm formation and male fertility in mice

Sperm-associated antigen 6 (SPAG6) is the mammalian orthologue of Chlamydomonas PF16, a central axonemal protein essential for flagellar motility. In mice, two homologous genes have been identified: the ancestral Spag6 on chromosome 2 and the evolutionary derived Spag6l on chromosome 16. Although Spag6 knockout mice (Spag6-/-) are phenotypically normal, the surviving Spag6l-/- males are infertile. To further investigate the roles of SPAG6 and SPAG6L, we generated compound mutants by crossing the two knockout lines. Compound heterozygous Spag6+/-; Spag6l+/- mice are fertile, while all Spag6-/-; Spag6l+/- males are infertile despite grossly normal appearance. Histological and ultrastructural analyses revealed defective spermiogenesis, including abnormal chromatin condensation, malformed acrosome and manchette, and disorganized mitochondrial and fibrous sheath. Both SPAG6 and SPAG6L bind to SPINK2, a key regulator of acrosome function, but SPAG6 has an approximately 10-fold higher binding affinity than SPAG6L. Moreover, SPAG6 modulates testicular AKAP4 and SPAG16L levels, which are critical components of the fibrous sheath and central apparatus respectively. Notably, SPAG6 suppresses tubulin acetylation, whereas SPAG6L enhances this post-translational modification, suggesting antagonistic roles in microtubule assembly. Overall, our findings demonstrate that SPAG6 and SPAG6L coordinately regulate sperm formation and male fertility during evolution.

developmental biology↗

bioRxiv2025

Reconstitution of adrenocortical functional zonation from human pluripotent stem cells

The adrenal cortex produces essential steroid hormones through a concentric zonal architecture, established by the centripetal trans-differentiation of subcapsular progenitors within a capsule-derived niche. To capture this complexity, we establish a human pluripotent stem cell-derived adrenal organoid system that faithfully recapitulates this process. RSPO3/WNT signaling from the capsule specifies definitive zone (DZ) progenitors from the adrenal primordium, which then differentiate into a cortisol-producing transitional zone and an androgen-producing fetal zone under the influence of RSPO3 and ACTH. Loss of NR0B1 impairs DZ specification and triggers direct adrenal primordium-to-fetal zone conversion, mirroring the mechanism of X-linked adrenal hypoplasia congenita. When DZ cells are encapsulated with capsule cells separately derived from pluripotent stem cells, they reconstitute zonation in vivo, forming ACTH-responsive tissue that produces both cortisol and androgens. This organoid platform offers a powerful tool to dissect human adrenal development and establishes a foundation for regenerative therapies targeting adrenal diseases.

developmental biology↗

bioRxiv2025

Regulation of Female Reproductive Aging by the Spag17 Gene

Reproductive aging in females is characterized by a decline in oocyte quantity and quality, as well as uterine and cervical dysfunction that contributes to infertility and pregnancy complications. To investigate mechanisms underlying reproductive aging, we explored the contribution of Spag17, a cilia-related gene associated with tissue homeostasis and fibrosis. Spag17 was expressed throughout the female reproductive tract; however, its expression declined with age in ovarian tissue, while high expression levels were observed in the cervix of young females during cervical tissue remodeling in the pre- and post-parturition periods. Loss of Spag17 in mice resulted in impaired fertility, obstructed labor, and maternal death. This phenotype was associated with accelerated ovarian aging, increased fibrosis, and cervical stiffness, further complicating parturition. At the molecular level, Spag17 loss activated key aging-associated pathways, including proinflammatory, profibrotic, and senescence signaling, suggesting that SPAG17 may be a critical player in female reproductive aging. TEASERSpag17 is a key modulator of female reproductive aging.

cell biology↗

bioRxiv2024

COVID-19 during pregnancy alters circulating extracellular vesicle cargo and their effects on trophoblast

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and resulting coronavirus disease (COVID-19) causes placental dysfunction, which increases the risk of adverse pregnancy outcomes. While abnormal placental pathology resulting from COVID-19 is common, direct infection of the placenta is rare. This suggests that pathophysiology associated with maternal COVID-19, rather than direct placental infection, is responsible for placental dysfunction and alteration of the placental transcriptome. We hypothesized that maternal circulating extracellular vesicles (EVs), altered by COVID-19 during pregnancy, contribute to placental dysfunction. To examine this hypothesis, we characterized maternal circulating EVs from pregnancies complicated by COVID-19 and tested their effects on trophoblast cell physiology in vitro. We found that the gestational timing of COVID-19 is a major determinant of circulating EV function and cargo. In vitro trophoblast exposure to EVs isolated from patients with an active infection at the time of delivery, but not EVs isolated from Controls, altered key trophoblast functions including hormone production and invasion. Thus, circulating EVs from participants with an active infection, both symptomatic and asymptomatic cases, can disrupt vital trophoblast functions. EV cargo differed between participants with COVID-19 and Controls, which may contribute to the disruption of the placental transcriptome and morphology. Our findings show that COVID-19 can have effects throughout pregnancy on circulating EVs and circulating EVs are likely to participate in placental dysfunction induced by COVID-19.

pathology↗

bioRxiv2022

Reconstitution of human adrenocortical specification and steroidogenesis using induced pluripotent stem cells

The mechanisms leading to adrenal cortex development and steroid synthesis in humans remain poorly understood due to the paucity of model systems. Herein, we faithfully recapitulate human fetal adrenal cortex specification processes through stepwise induction of human induced pluripotent stem cells through posterior intermediate mesoderm-like and adrenal progenitor-like states to ultimately generate fetal zone adrenal cortex-like cells (FZLCs), as evidenced by histomorphological, ultrastructural, and transcriptome features and adrenocorticotropic hormone (ACTH)-independent {Delta}5 steroid biosynthesis. Furthermore, FZLC generation is promoted by SHH and inhibited by NOTCH, ACTIVIN and WNT signaling, and that steroid synthesis is amplified by ACTH/PKA signaling and blocked by inhibitors of {Delta}5 steroid synthesis enzymes. Finally, NR5A1 promotes FZLC survival and steroidogenesis. Together, these findings provide a framework for understanding and reconstituting human adrenocortical development in vitro paving the way for cell-based therapies of adrenal insufficiency.

developmental biology↗

bioRxiv2021

The Vaginal Microbiome in Women of Reproductive Age with Healthy Weight versus Overweight/Obesity

ObjectiveEvaluate differences between the vaginal microbiome of reproductive-aged women with overweight and obesity (Ow/Ob) compared with healthy weight (HW). MethodsA cohort of 367 non-pregnant women (18-40 years) with Ow/Ob (body mass index [BMI] [≥]25 kg/m2) was case-matched with 367 women with HW (BMI 18.0-24.9 kg/m2). The study was a secondary analysis of 16S rRNA vaginal microbiome surveys through the Vaginal Human Microbiome Study (VaHMP). Groups were matched on age, race/ethnicity, income, and nulliparity status. ResultsMean age and BMI of Ow/Ob and HW groups were 26.8 versus 26.7 years and 37.0 versus 22.1 kg/m2, respectively. The overall vaginal microbiome composition differed between groups (PERMANOVA, p=0.035). Women with Ow/Ob had higher alpha-diversity compared with women with HW (Wilcoxon test, Shannon index p=0.025; Inverse Simpson index p=0.026). Lactobacillus dominance ([≥]30% proportional abundance) was observed in a greater proportion of women with HW (48.7%) compared with Ow/Ob (40.1%; p=0.026). ConclusionsThe vaginal microbiome differs in reproductive-aged women with Ow/Ob compared with women with HW, with increased alpha-diversity and decreased predominance of Lactobacillus. Observed differences in vaginal microbiome may partially explain differences in preterm birth and bacterial vaginosis risk between these populations.

microbiology↗

bioRxiv2021

Maternal Biological Age Assessed in Early Pregnancy is Associated with Gestational Age at Birth

AO_SCPLOWBSTRACTC_SCPLOWMaternal age is an established predictor of preterm birth independent of other recognized risk factors. The use of chronological age makes the assumption that individuals age at a similar rate. Therefore, it does not capture interindividual differences that may exist due to genetic background and environmental exposures. As a result, there is a need to identify biomarkers that more closely index the rate of cellular aging. One potential candidate is biological age (BA) estimated by the DNA methylome. This study investigated whether maternal BA, estimated in either early and/or late pregnancy, predicts gestational age at birth. BA was estimated from a genome-wide DNA methylation platform using the Horvath algorithm. Linear regression methods assessed the relationship between BA and pregnancy outcomes, including gestational age at birth and perceived stress during pregnancy, in a primary and replication cohort. Prenatal BA estimates from early pregnancy explained variance in gestational age at birth above and beyond the influence of other recognized preterm birth risk factors. Sensitivity analyses indicated that this signal was driven primarily by self-identified African American participants. This predictive relationship was sensitive to small variations in the BA estimation algorithm. Benefits and limitations of using BA in translational research and clinical applications for preterm birth are considered.

genomics↗

bioRxiv2020

Unique roles of vaginal Megasphaera phylotypes in reproductive health

The composition of the human vaginal microbiome has been extensively studied and is known to influence reproductive health. However, the functional roles of individual taxa and their contributions to negative health outcomes have yet to be well characterized. Here, we examine two vaginal bacterial taxa grouped within the genus Megasphaera that have been previously associated with bacterial vaginosis (BV) and pregnancy complications. Phylogenetic analyses support the classification of these taxa as two distinct species. These two phylotypes, Megasphaera phylotype 1 (MP1) and Megasphaera phylotype 2 (MP2), differ in genomic structure and metabolic potential, suggestive of differential roles within the vaginal environment. Further, these vaginal taxa show evidence of genome reduction and changes in DNA base composition, which may be common features of host dependence and/or adaptation to the vaginal environment. In a cohort of 3,870 women, we observed that MP1 has a stronger positive association with bacterial vaginosis whereas MP2 was positively associated with trichomoniasis. MP1, in contrast to MP2 and other common BV-associated organisms, was not significantly excluded in pregnancy. In a cohort of 52 pregnant women, MP1 was both present and transcriptionally active in 75.4% of vaginal samples. Conversely, MP2 was largely absent in the pregnant cohort. This study provides insight into the evolutionary history, genomic potential and predicted functional role of two clinically relevant vaginal microbial taxa.

microbiology↗

bioRxiv2019

INHIBITION OF GONADOTROPIN-STIMULATED STEROIDOGENESIS BY THE ERK CASCADE

LH and FSH are two important hormones in the regulation of granulosa cells. Their effects are mediated mainly by cAMP/PKA signaling, bit the activity of the extracellular signal-regulated kinase (ERK) signaling cascade is elevated as well. We studied the involvement of the ERK cascade in LH and FSH-induced steroidogenesis in two granulosa-derived cell lines, rLHR-4 and rFSHR-17, respectively. We found that stimulation of these cells with the appropriate gonadotropin induced ERK activation as well as progesterone production, downstream of PKA. Inhibition of ERK activity enhanced gonadotropin-stimulated progesterone production, which was correlated with increased-expression of the steroidogenic acute regulatory (StAR) protein, a key regulator of progesterone synthesis. Therefore, it is likely that gonadotropin-stimulated progesterone formation is regulated by a pathway that includes PKA and StAR, and this process is downregulated by ERK, due to attenuation of StAR expression. Our results suggest that activation of PKA signaling by gonadotropins not only induces steroidogenesis, but also activates downregulation machinery involving the ERK cascade. The activation of ERK by gonadotropins as well as by other agents, may be a key mechanism for the modulation of gonadotropin-induced steroidogenesis.

cell biology↗

bioRxiv2019

Replicated Umbilical Cord Blood DNA Methylation Loci Associated with Gestational Age at Birth

BackgroundDNA methylation is highly sensitive to in utero perturbations and has an established role in both embryonic development and regulation of gene expression. The fetal genetic component has been previously shown to contribute significantly to the timing of birth, yet little is known about the identity and behavior of individual genes.\n\nObjectivesThe aim of this study was to test the extent genome-wide DNA methylation levels in umbilical cord blood were associated with gestational age at birth (GA). Findings were validated in an independent sample and evidence for the regulation of gene expression was evaluated for cis gene relationships in matched specimens.\n\nResultsGenome-wide DNA methylation, measured by the Illumina Infinium Human Methylation 450K BeadChip, was associated with GA for 2,372 CpG probes (5% false discovery rate) in both the Pregnancy, Race, Environment, Genes (PREG - Virginia Commonwealth University) and Newborn Epigenetic Study (NEST - Duke University) cohorts. Significant probes mapped to 1,640 characterized genes and an association with nearby gene expression measures obtained by the Affymetrix HG-133A microarray was found for 11 genes. Differentially methylated positions were enriched for actively transcribed and enhancer chromatin states, were predominately located outside of CpG islands, and mapped to genes enriched for inflammation and innate immunity ontologies. In both PREG and NEST, the first principal component derived from these probes explained approximately one-half (58.1% and 47.8%, respectively) of the variation in GA. This assessment provides a strong evidence to support the importance of DNAm change throughout the gestational time period.\n\nConclusionsThese results converge on support for the role of variation in DNAm measures as an important genetic regulatory mechanism contributing to inter-individual differences in gestational age at birth. In particular, the pathways described are consistent with the well-known hypothesis of pathogen detection and response by the immune system to elicit premature labor as a consequence of unscheduled inflammation.

genomics↗

bioRxiv2018

The infection dynamics of vertically transmitted viruses in a two-population model

1There is a growing interest in vertically transmitted viruses. Field studies show that virus infection frequency often varies in space and time. In order to understand the spatial variation of virus prevalence, we designed a mathematical model describing the infection dynamics of a biparentally inherited virus in a two-population model. Model parameters are paternal and maternal transmission rates, cost of infection, and up to two migration rates. We investigated three different population structures: (1) a single panmictic host population, (2) two populations connected by unidirectional migration (mainland-island model), and (3) two populations connected by two-way migration. According to the results, the parameter space can be divided in three zones: (1) viral spread, (2) no viral spread, (3) bistability (in a single population) or stable infection polymorphism (in the two-population models). The finding of bistability is interesting and new. It shows that infected and uninfected populations can stably coexist, if migration is below a critical value, and if the cost of infection is moderately high. In summary, our results show that spatial structure of host populations is an important factor in determining geographical differences of vertically transmitted viruses.

ecology↗

bioRxiv2018

Identify and predict environmental change effects on tiger mosquitos, Aedes polynesiensis

SO_SCPLOWUMMARYC_SCPLOWTo control mosquito populations for managing vector-borne diseases, a critical need is to identify and predict their response to causal environmental variables. However, most existing attempts rely on linear approaches based on correlation, which cannot apply in complex, nonlinear natural systems, because correlation is neither a necessary nor sufficient condition for causation. Appling empirical dynamic modelling that acknowledges nonlinear dynamics on nine subpopulations of tiger mosquitos from three neighbouring reef islets of the Raiatea atoll, we identified temperature, precipitation, dew point, air pressure, and mean tide level as causal environmental variables. Interestingly, responses of subpopulations in close proximity (100-500 m) differed with respect to their causal environmental variables and the time delay of effect, highlighting complexity in mosquito-environment causality network. Moreover, we demonstrated how to explore the effects of changing environmental variables on number and strength of mosquito outbreaks, providing a new framework for pest control and disease vector ecology.

ecology↗