Spastin is an essential regulator of male meiosis, acrosome formation, manchette structure and nuclear integrity.

The development and function of male gametes is dependent on a dynamic microtubule network, yet how this is regulated remains poorly understood. We have recently shown that microtubule severing, via the action of the meiotic AAA ATPase protein clade, plays a crucial role in this process. Here, we sought to elucidate the roles of spastin, an as-yet-unexplored member of this clade in spermatogenesis. Using a SpastKO/KO mouse model, we reveal that spastin loss resulted in a complete loss of functional germ cells. Spastin plays a crucial role in the assembly and function of the male meiotic spindle. Consistent with meiotic failure, round spermatid nuclei were enlarged, indicating aneuploidy, but were still able to enter spermiogenesis. During spermiogenesis, we observed extreme abnormalities in manchette structure, acrosome biogenesis and, commonly, a catastrophic loss of nuclear integrity. This work defines an essential role for spastin in regulating microtubule dynamics during spermatogenesis, and is of potential relevance to individuals carrying spastin variants and to the medically assisted reproductive technology industry.

The katanin A-subunits KATNA1 and KATNAL1 act co-operatively in mammalian meiosis and spermiogenesis to achieve male fertility.

Katanins, a class of microtubule-severing enzymes, are potent M-phase regulators in oocytes and somatic cells. How the complex and evolutionarily crucial, male mammalian meiotic spindle is sculpted remains unknown. Here, using multiple single and double gene knockout mice, we reveal that the canonical katanin A-subunit KATNA1 and its close paralogue KATNAL1 together execute multiple aspects of meiosis. We show KATNA1 and KATNAL1 collectively regulate the male meiotic spindle, cytokinesis and midbody abscission, in addition to diverse spermatid remodelling events, including Golgi organisation, and acrosome and manchette formation. We also define KATNAL1-specific roles in sperm flagellum development, manchette regulation and sperm-epithelial disengagement. Finally, using proteomic approaches, we define the KATNA1, KATNAL1 and KATNB1 mammalian testis interactome, which includes a network of cytoskeletal and vesicle trafficking proteins. Collectively, we reveal that the presence of multiple katanin A-subunit paralogs in mammalian spermatogenesis allows for 'customised cutting' via neofunctionalisation and protective buffering via gene redundancy.

Epsilon tubulin is an essential determinant of microtubule-based structures in male germ cells.

Alpha, beta, and gamma tubulins are essential building blocks for all eukaryotic cells. The functions of the non-canonical tubulins, delta, epsilon, and zeta, however, remain poorly understood and their requirement in mammalian development untested. Herein we have used a spermatogenesis model to define epsilon tubulin (TUBE1) function in mice. We show that TUBE1 is essential for the function of multiple complex microtubule arrays, including the meiotic spindle, axoneme and manchette and in its absence, there is a dramatic loss of germ cells and male sterility. Moreover, we provide evidence for the interplay between TUBE1 and katanin-mediated microtubule severing, and for the sub-specialization of individual katanin paralogs in the regulation of specific microtubule arrays.

KATNB1 is a master regulator of multiple katanin enzymes in male meiosis and haploid germ cell development.

Katanin microtubule-severing enzymes are crucial executers of microtubule regulation. Here, we have created an allelic loss-of-function series of the katanin regulatory B-subunit KATNB1 in mice. We reveal that KATNB1 is the master regulator of all katanin enzymatic A-subunits during mammalian spermatogenesis, wherein it is required to maintain katanin A-subunit abundance. Our data shows that complete loss of KATNB1 from germ cells is incompatible with sperm production, and we reveal multiple new spermatogenesis functions for KATNB1, including essential roles in male meiosis, acrosome formation, sperm tail assembly, regulation of both the Sertoli and germ cell cytoskeletons during sperm nuclear remodelling, and maintenance of seminiferous epithelium integrity. Collectively, our findings reveal that katanins are able to differentially regulate almost all key microtubule-based structures during mammalian male germ cell development, through the complexing of one master controller, KATNB1, with a 'toolbox' of neofunctionalised katanin A-subunits.

Zinc finger RNA binding protein 2 (ZFR2) is not required for male fertility in the mouse.

BACKGROUND: Thousands of genes are expressed during spermatogenesis and male infertility has a strong genetic component. Within this study, we focus on the role of Zfr2 in male fertility, a gene previously implicated in human male fertility. To date, very little is known about the role of ZFR2 in either humans or mice. To this end, the requirement for ZFR2 in male fertility was assessed using a knockout mouse model. RESULTS: Zfr2 was found to be expressed in the testes of both humans and mice. Deletion of Zfr2 was achieved via removal of exon 2 using CRISPR-Cas9 methods. The absence of Zfr2 did not result in a reduction in any fertility parameters assessed. Knockout males were capable of fostering litter sizes equal to wild type males, and there were no effects of Zfr2 knockout on sperm number or motility. We note Zfr2 knockout females were also fertile. CONCLUSIONS: The absence of Zfr2 alone is not sufficient to cause a reduction in male fertility in mice.

DDB1- and CUL4-associated factor 12-like protein 1 (Dcaf12l1) is not essential for male fertility in mice.

Male infertility is a common condition affecting at least 7% of men worldwide and is often genetic in origin. Using whole exome sequencing, we recently discovered three hemizygous, likely damaging variants in DDB1- and CUL4-associated factor 12-like protein 1 (DCAF12L1) in men with azoospermia. DCAF12L1 is located on the X-chromosome and as identified by single cell sequencing studies, its expression is enriched in human testes and specifically in Sertoli cells and spermatogonia. However, very little is known about the role of DCAF12L1 in spermatogenesis, thus we generated a knockout mouse model to further explore the role of DCAF12L1 in male fertility. Knockout mice were generated using CRISPR/Cas9 technology to remove the entire coding region of Dcaf12l1 and were assessed for fertility over a broad range of ages (2-8 months of age). Despite outstanding genetic evidence in men, loss of DCAF12L1 had no discernible impact on male fertility in mice, as highlighted by breeding trials, histological assessment of the testis and epididymis, daily sperm production and evaluation of sperm motility using computer assisted methods. This disparity is likely due to the parallel evolution, and subsequent divergence, of DCAF12 family members in mice and men or the presence of compounding environmental factors in men.

Performance of comprehensive first trimester fetal anatomy assessment.

OBJECTIVE: Ultrasound assessment of the fetal anatomy and fetal echocardiography are feasible in the first trimester of pregnancy. This study was designed to assess the performance of a comprehensive fetal anatomy assessment in a high-risk population at a tertiary fetal medicine unit. METHODS: A retrospective review of high-risk patients undergoing comprehensive fetal anatomy ultrasound assessment between 11 weeks and 13 + 6 weeks of gestation was conducted. Findings of the early anatomy ultrasound scan were compared with those of the second trimester anatomy scan, and birth outcomes or post-mortem results. RESULTS: Early anatomy ultrasounds were performed in 765 patients. The sensitivity of the scan for detecting fetal anomalies compared to the birth outcome was 80.5% (95% CI 73.5-86.3) and specificity was 93.1% (95%CI 90.6-95.2). Positive and negative predictive values were 78.5% (95% CI 71.4-84.6) and 93.9% (95% CI 91.4-95.8), respectively. The most missed and overdiagnosed abnormalities were ventricular septal defects. The second trimester ultrasound had sensitivity of 69.0% (95% CI 55.5-80.5) and specificity of 87.5% (95% CI 84.3-90.2). CONCLUSIONS: In a high-risk population, early assessments had similar performance metrics as the second trimester anatomy ultrasound. We advocate for a comprehensive fetal assessment in the care of high-risk pregnancies.

LipidFinder 2.0: advanced informatics pipeline for lipidomics discovery applications.

SUMMARY: We present LipidFinder 2.0, incorporating four new modules that apply artefact filters, remove lipid and contaminant stacks, in-source fragments and salt clusters, and a new isotope deletion method which is significantly more sensitive than available open-access alternatives. We also incorporate a novel false discovery rate method, utilizing a target-decoy strategy, which allows users to assess data quality. A renewed lipid profiling method is introduced which searches three different databases from LIPID MAPS and returns bulk lipid structures only, and a lipid category scatter plot with color blind friendly pallet. An API interface with XCMS Online is made available on LipidFinder's online version. We show using real data that LipidFinder 2.0 provides a significant improvement over non-lipid metabolite filtering and lipid profiling, compared to available tools. AVAILABILITY AND IMPLEMENTATION: LipidFinder 2.0 is freely available at https://github.com/ODonnell-Lipidomics/LipidFinder and http://lipidmaps.org/resources/tools/lipidfinder. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Assessing the relationship between psychosocial risk and pregnancy outcomes using the perinatal integrated psychosocial assessment (PIPA) tool.

BACKGROUND: The Perinatal Integrated Psychosocial Assessment (PIPA) tool screens for anxiety, depression, and psychosocial factors in pregnancy. We aimed to assess the association between PIPA-determined psychosocial risk and obstetric and neonatal outcomes. METHODS: Cohort study of all pregnant women who gave birth at ≥20 weeks of gestation in 2017-2019 at a tertiary maternity hospital in, Sydney, Australia. Women completed PIPA at their first antenatal visit and were assigned a PIPA risk category. At-risk women were reviewed and referred for support. The association between PIPA risk category and obstetric and neonatal outcomes was evaluated using multivariable logistic regression adjusting for sociodemographic and pregnancy factors. RESULTS: In all, 5969 women completed PIPA; 71.4% were assessed no/low risk, 17.5% medium risk, and 11.1% medium-high/high risk. Compared with no/low-risk women, medium-high/high-risk women were more likely to remain in hospital for >72 hours (aOR 1.47 [95% CI 1.33-1.64]); to not be breastfeeding at discharge (aOR 1.77 [95% CI 1.20-2.61]); to have their infants experience birth complications (aOR 1.24 [95% CI 1.03-1.50]); and to be admitted to the NICU (aOR 1.63 [95% CI 1.26-2.11]). There was a modest increase in odds of cesarean birth (aOR 1.12 [95% CI 1.00-1.27]), and no association with preterm birth or low birthweight. The risk of adverse outcomes disappeared for medium-high/high-risk women referred for support. CONCLUSIONS: The PIPA tool identified one in 10 women at high psychosocial risk with increased risk of adverse obstetric and neonatal outcomes. Adverse outcomes were attenuated for high-risk women who were referred for extra support, suggesting that psychosocial review and referral for high-risk women may reduce the risk of adverse obstetric and neonatal outcomes.

The Sertoli cell expressed gene secernin-1 (Scrn1) is dispensable for male fertility in the mouse.

BACKGROUND: Male infertility is a prevalent clinical presentation for which there is likely a strong genetic component due to the thousands of genes required for spermatogenesis. Within this study we investigated the role of the gene Scrn1 in male fertility. Scrn1 is preferentially expressed in XY gonads during the period of sex determination and in adult Sertoli cells based on single cell RNA sequencing. We investigated the expression of Scrn1 in juvenile and adult tissues and generated a knockout mouse model to test its role in male fertility. RESULTS: Scrn1 was expressed at all ages examined in the post-natal testis; however, its expression peaked at postnatal days 7-14 and SCRN1 protein was clearly localized to Sertoli cells. Scrn1 deletion was achieved via removal of exon 3, and its loss had no effect on male fertility or sex determination. Knockout mice were capable of siring litters of equal size to wild type counterparts and generated equal numbers of sperm with comparable motility and morphology characteristics. CONCLUSIONS: Scrn1 was found to be dispensable for male fertility, but this study identifies SCRN1 as a novel marker of the Sertoli cell cytoplasm.

Impact of role conflicts and self-efficacy on academic performance of graduate-entry healthcare students: A lagged study.

Graduate entry healthcare students experience many challenges during their academic journey. The impact of these challenges needs to be considered to support students through their training and education. In this study, we examined the impact of experiencing these role conflicts (at the outset of the academic year), for example, family and caring responsibilities, activities with family/friends, and daily tasks/chores, on the academic performance (at the end of the academic year) of graduate-entry healthcare students. We also investigated the potential of students' self-efficacy for learning to mitigate the extent to which such role conflicts impact academic performance. Findings demonstrate that the more graduate entry healthcare students experienced conflicts between their life responsibilities and their academic responsibilities, the worse their academic performance was across the year. This negative relationship was somewhat mitigated by high self-efficacy for learning. The practical implications of our research suggest the need to provide specific mitigation strategies to support healthcare students regarding conflicts between their life/family responsibilities and their academic work.

HENMT1 is involved in the maintenance of normal female fertility in the mouse.

PIWI-interacting small RNAs (piRNAs) maintain genome stability in animal germ cells, with a predominant role in silencing transposable elements. Mutations in the piRNA pathway in the mouse uniformly lead to failed spermatogenesis and male sterility. By contrast, mutant females are fertile. In keeping with this paradigm, we previously reported male sterility and female fertility associated with loss of the enzyme HENMT1, which is responsible for stabilising piRNAs through the catalysation of 3'-terminal 2'-O-methylation. However, the Henmt1 mutant females were poor breeders, suggesting they could be subfertile. Therefore, we investigated oogenesis and female fertility in these mice in greater detail. Here, we show that mutant females indeed have a 3- to 4-fold reduction in follicle number and reduced litter sizes. In addition, meiosis-II mutant oocytes display various spindle abnormalities and have a dramatically altered transcriptome which includes a down-regulation of transcripts required for microtubule function. This down-regulation could explain the spindle defects observed with consequent reductions in litter size. We suggest these various effects on oogenesis could be exacerbated by asynapsis, an apparently universal feature of piRNA mutants of both sexes. Our findings reveal that loss of the piRNA pathway in females has significant functional consequences.

A feedback journey: employing a constructivist approach to the development of feedback literacy among health professional learners.

BACKGROUND: Feedback, if effectively provided by the teacher and utilised by the learner, enables improvement in academic performance. It is clear from current literature that the provision of feedback by teachers is not sufficient on its own to guarantee improvements as early university entrants may not be sufficiently equipped to effectively engage with feedback. Nonetheless, it is critical for health professional students to develop feedback literacy early, in order to prepare them for a professional career of lifelong learning and critical thinking. The overarching aim of this study was to identify a feasible, sustainable approach to improve feedback literacy among students on pre-qualifying health professional programmes. METHODS: The study was divided into two phases. A mixed-methods approach grounded in constructivism was employed. Participants included teachers and learners from the School of Allied Health at X University, and two internationally acclaimed educationalists. In phase 1, first year students were encouraged to use an established online platform to upload modular feedback and develop personal learning action plans aimed at improving academic performance. A follow-up survey highlighted poor engagement with this method. Thus, the second phase focused on the co-construction of a suite of modules to develop these skills, supported by academic staff. Interviews were conducted with participants to review and refine this initiative. RESULTS: Learners' engagement with the first phase of the study was poor. Thus, the second phase provided all stakeholders with the opportunity to feed into the development of a suite of modules, designed to encourage teachers and learners to work in partnership to nurture these skills. All stakeholder groups reported short- and long-term benefits with this approach, but also highlighted challenges towards its implementation. CONCLUSION: The development of feedback literacy among health professional learners is essential. The transferability of such skills has been highlighted in the literature and by all stakeholder groups involved in this study. Finding a balance between introducing these skills at a time early enough to highlight their importance among university entrants is challenging. Further balance must be achieved between the workload required to achieve these skills and current programme demands for both teachers and learners.

Performance-based assessment during clinical placement: Cross-sectional investigation of a training workshop for practice educators.

Performance-based assessment evaluates a health professional student's performance as they integrate their knowledge and skills into clinical practice. Performance-based assessment grades, however, are reported to be highly variable due to the complexity of decision-making in the clinical environment. The aim of this study was to evaluate the impact of a training workshop based on frame-of-reference principles on grading of student performance by physiotherapy practice educators. This was a prospective cross-sectional study which used a single group pre-test, post-test design. Fifty-three practice educators rated two video vignettes depicting a poor and very good student performance, using a subsection of a physiotherapy performance-based assessment tool before and after training. Overall, results showed that participants amended their scores on approximately half of all scoring occasions following training, with the majority decreasing the scores awarded. This impacted positively on scoring for the poor performance video, bringing scores more in line with the true score. This study provides evidence of the benefit of a training workshop to influence decision-making in performance-based assessment as part of a wider education program for practice educators.

Prevalence of pressure injuries and the management of support surfaces (mattresses) in adult intensive care patients: A multicentre point prevalence study in Australia and New Zealand.

BACKGROUND: Pressure injuries (PIs) are a patient safety issue that impact patient outcomes. Intensive care unit (ICU) patients are at high risk of PIs. OBJECTIVES: To report the prevalence and classification of documented PIs in adult ICU patients, the use of pressure injury risk assessment tools, and support surface management as a part of the prevention of PIs. METHODS: This was a prospective, single-day, multicentre, cross-sectional study of patients aged ≥ 16 years admitted to adult ICUs in Australia and New Zealand (ANZ), August 2016 as part of the Australian and New Zealand Intensive Care Society Clinical Trials Group (ANZICS-CTG) Point Prevalence Program. FINDINGS: Data were collected on 671 patients (58% male) in 47 ICUs. The mean [standard deviation] age and weight were 60.2 years [17.2 years] and 82.1 kg [29.7 kg], respectively, with a severity of illness score (Acute Physiology and Chronic Health Evaluation [APACHE] II) of 18.2 [8.4]. PIs were reported in 10% (70/671) of patients. Patients with a PI had a mean APACHE II score of 22.5 [standard deviation; 7.7], and 57.1% (40/70) met the criteria for sepsis on the study day. There were 107 PIs documented on the study day (N = 107) in the 70 patients with nearly half of PIs present on ICU admission (46.7%; 50/107). The sacrum was the most common location for PIs (28.9%; 31/107) and then the heels (15.9%; 17/107). All units routinely use a risk of PI assessment tool and were cared for on an active or reactive support surface. Patients with a PI were more often moved to an active support surface. CONCLUSIONS: The prevalence rate was reported at 10% for PIs for adult intensive care patients on the study day. More than half of the patients with a PI had signs of sepsis on the study day and a higher severity of illness, and more were cared for on active support surfaces. Most PIs were located at the sacrum and then the heels. All clinical sites routinely used a PI risk assessment tool.

Immunotherapy and associated immune-related adverse events at a large UK centre: a mixed methods study.

BACKGROUND: The development and rapid uptake of immune checkpoint inhibitors (CPI) has changed the outlook for patients with cancer. However, CPIs have different adverse event (AE) profiles to other systemic therapies, and prompt AE management is essential to assure optimal outcomes. In order to understand what and when adverse events are experienced, reported and managed during CPI treatment, a mixed methods study was conducted, including a case note review of patients who were receiving immunotherapy and semi-structured interviews with patients to understand their experience, management and reporting of AEs after receiving immune CPI treatment. METHODS: This mixed methods study was conducted at a large cancer hospital in the United Kingdom. A case note review identified how and where patients reported AEs. Data relating to patients with lung, bladder, prostate and head & neck cancers who received CPI treatment between 01/04/2015 and 31/07/2018 were extracted from e-prescribing databases and clinical data were included for analysis at a single time point (31 July 2018). Semi-structured interviews were conducted with patients receiving CPI treatment, exploring experience of AEs and reasons for delays in AE reporting and management. RESULTS: Sixty-two patients were included in the case note review, with 78 AEs being experienced by 36 patients (58%), including one patient experiencing 10 AEs. Serious AEs were experienced by 12 patients (19%) and ten AEs (17%) required oral steroids as treatment. The majority of AEs were reported to clinicians prior to further dosing, although milder AEs were often not addressed until subsequent clinic appointments. Interviews with 13 patients yielded major themes: variability, causality, decision making and impact. CONCLUSION: Most CPI-associated AEs are manageable if reported and treated promptly. Both the case note review and interviews found that reporting of non-serious AEs is often left until routine clinic visits, despite impacting patient experience, leaving the opportunity for AEs to be left unreported and implying a potential benefit for real time monitoring. Our study highlights a need to provide patients with reminders around AEs and their timely reporting even when apparently innocuous; patients must understand that AEs can occur at any cycle and even following treatment completion.

Expression and purification of recombinant mouse CRISP4 using a baculovirus system.

Cysteine-rich secretory protein 4 (CRISP4) is a member of the CAP superfamily protein, is highly expressed in the male reproductive tract and is required for optimal mammalian fertility. CRISPs are characterized by the presence of 16 conserved cysteine residues which forms 8 disulphide bond spread across the N-terminal CAP domain, a hinge region and a C-terminal ion channel regulatory (ICR) domain. Previous attempts to purify recombinant CRISPs as a group have resulted in misfolded and/or insoluble recombinant proteins, protein aggregates or unusable low protein yield. Thus, defining the functions of CRISPs have been impeded. In this study, we report a three-step purification protocol for expression and purification of mouse CRISP4 protein in High Five™ cells using a baculovirus expression system. Recombinant mouse CRISP4 was recognized by western blotting and structurally characterized using Circular Dichroism (CD). Using the protocol described herein, we generated high yields of soluble and correctly folded recombinant mouse CRISP4.

The PAPHIO study protocol: a randomised controlled trial with a 2 x 2 crossover design of physical activity adherence, psychological health and immunological outcomes in breast cancer survivors.

BACKGROUND: The PAPHIO study; a randomized controlled trial with 2X2 crossover design will implement a self-directed physical activity program in which participants will engage in self-monitoring and receive motivational interviewing to enhance physical activity adherence. The study aims to determine the effects of 24 weeks self-directed activity combined with motivational interviewing (MI) on (i) psychological health, (ii) quality of life (QoL) and (iii) immune function in female breast cancer survivors. METHODS: The study will recruit 64 female breast cancer survivors within 3 years of diagnosis and at least 6 months post primary treatments at Western Health Sunshine Hospital, Melbourne, Australia. They will be randomly allocated to immediate intervention (IIG group) or delayed intervention groups (DIG group) in a 1:1 ratio. All participants will be given a wearable device (Fitbit Alta HR) and undertake self-directed physical activity for 24 weeks and will receive MI for 12 weeks (IIG; during week 0 to week 12 and DIG; during week 13 to week 24). Participants' daily step count and the changes of immune cell functionality will be assessed at the beginning (week 1: T1), week 12 (T2) and week 24 (T3) of the program. Physical activity adherence will be assessed at T2 and T3. Participants will also complete four questionnaires assessing exercise self-regulation (BREQ2), exercise barrier and task self-efficacy, mental health (DASS-21) and QoL (FACT-B) at three time points (T1 to T3). Linear-mixed models will be used to assess the relationship between physical activity volume by step counting and mental health (DASS-21), QoL (FACT-B), immune biomarkers, self-regulation (BREQ2) and self-efficacy at T1, T2 and T3;between 2 groups. DISCUSSION: We expect this physical activity intervention to be acceptable and beneficial to the participants in terms of psychological and immunological well-being with the potential outcomes to be implemented more widely at relatively low cost to these or other patient populations. TRIAL REGISTRATION: Australian New Zealand Clinical trials Registry- ACTRN12619001271190. Prospectively registered on 13 September 2019.

Katanin-like 2 (KATNAL2) functions in multiple aspects of haploid male germ cell development in the mouse.

The katanin microtubule-severing proteins are essential regulators of microtubule dynamics in a diverse range of species. Here we have defined critical roles for the poorly characterised katanin protein KATNAL2 in multiple aspects of spermatogenesis: the initiation of sperm tail growth from the basal body, sperm head shaping via the manchette, acrosome attachment, and ultimately sperm release. We present data suggesting that depending on context, KATNAL2 can partner with the regulatory protein KATNB1 or act autonomously. Moreover, our data indicate KATNAL2 may regulate δ- and ε-tubulin rather than classical α-ß-tubulin microtubule polymers, suggesting the katanin family has a greater diversity of function than previously realised. Together with our previous research, showing the essential requirement of katanin proteins KATNAL1 and KATNB1 during spermatogenesis, our data supports the concept that in higher order species the presence of multiple katanins has allowed for subspecialisation of function within complex cellular settings such as the seminiferous epithelium.

GLIPR1L1 is an IZUMO-binding protein required for optimal fertilization in the mouse.

BACKGROUND: The sperm protein IZUMO1 (Izumo sperm-egg fusion 1) and its recently identified binding partner on the oolemma, IZUMO1R, are among the first ligand-receptor pairs shown to be essential for gamete recognition and adhesion. However, the IZUMO1-IZUMO1R interaction does not appear to be directly responsible for promoting the fusion of the gamete membranes, suggesting that this critical phase of the fertilization cascade requires the concerted action of alternative fusogenic machinery. It has therefore been proposed that IZUMO1 may play a secondary role in the organization and/or stabilization of higher-order heteromeric complexes in spermatozoa that are required for membrane fusion. RESULTS: Here, we show that fertilization-competent (acrosome reacted) mouse spermatozoa harbor several high molecular weight protein complexes, a subset of which are readily able to adhere to solubilized oolemmal proteins. At least two of these complexes contain IZUMO1 in partnership with GLI pathogenesis-related 1 like 1 (GLIPR1L1). This interaction is associated with lipid rafts and is dynamically remodeled upon the induction of acrosomal exocytosis in preparation for sperm adhesion to the oolemma. Accordingly, the selective ablation of GLIPR1L1 leads to compromised sperm function characterized by a reduced ability to undergo the acrosome reaction and a failure of IZUMO1 redistribution. CONCLUSIONS: Collectively, this study characterizes multimeric protein complexes on the sperm surface and identifies GLIPRL1L1 as a physiologically relevant regulator of IZUMO1 function and the fertilization process.