JIP4 is recruited by the phosphoinositide-binding protein Phafin2 to promote recycling tubules on macropinosomes

Macropinocytosis allows cells to take up extracellular material in a non-selective manner into large vesicles called macropinosomes. After internalization, macropinosomes acquire phosphatidylinositol 3-phosphate (PtdIns3P) on their limiting membrane as they mature into endosomal-like vesicles. The molecular mechanisms that mediate recycling of membranes and transmembrane proteins from these macropinosomes still need to be defined. Here we report that JIP4, a protein previously described to bind to microtubule motors, is recruited to tubulating subdomains on macropinosomes by the PtdIns3P-binding protein Phafin2. These JIP4-positive tubulating subdomains on macropinosomes contain F-actin, the retromer recycling complex, and a retromer cargo, VAMP3. Disruption of the JIP4-Phafin2 interaction, deletion of Phafin2, or inhibition of PtdIns3P production by VPS34 impairs JIP4 recruitment to macropinosomes. While knockout of JIP4 suppresses tubulation, overexpression enhances tubulation from macropinosomes. JIP4 knockout cells display increased retention of macropinocytic cargo in both early and late macropinosomes. Collectively, these data identify JIP4 and Phafin2 as components of a tubular recycling pathway that operates from macropinosomes.

‘Comfortable, safe and valued’: an analysis of the impact of COVID-19 on Hertfordshire's Community Perinatal Team

AimsThis study aimed to assess the impact that the COVID-19 pandemic has had on the Hertfordshire Community Perinatal Team (CPT) group interventions and the innovations made.BackgroundThe CPT is a multidisciplinary mental health service that runs three groups: Circle of Security (CoS), Emotional Coping Skills (ECS) and a peer support group - Wellbeing and Lifestyle. The service has received an increase in referrals during the COVID-19 pandemic.MethodMethods: Team member and client semi structured interviews were conducted with answers transcribed in real time and analysed. Patient clinical records were accessed via PARIS and analysed in order to identify patient demographics within each group and whether these had changed during the pandemic. Clinical outcome measures and client feedback were evaluated to see whether the change in groups is impacting their clinical effectiveness.ResultResults: Innovations made by the CPT include: groups becoming virtual, launching of the new Circle of Security Group which helps women tackle the ‘Ghosts in the Nursery’ and strengthen maternal bonds, restructuring existing groups, breakout room forums and incorporating communication platform apps such as Whatsapp. The Wellbeing and Lifestyle Group increased in size and reach (7 women from 7 areas in 2019 vs 12 women from 12 areas in 2021) with an increased retention rate (71% in 2019 vs 100% in 2021) and a decreased attrition rate (29% in 2019 to 0% in 2021). The Emotional Coping Skills group experienced similar changes (10 areas represented in 2019 vs 15 different areas in 2021) with an increased retention rate (58% in 2019 vs 100% in 2021) and decreased attrition rate (42% in 2019 vs 0% in 2021).ConclusionThe Hertfordshire Community Perinatal Team has responded to the pandemic by innovating existing groups and creating new forums; many of which will continue on even after the pandemic ceases. The groups have acted as a lifeline for women breaking up the monotony and isolation of lockdown life and providing an invaluable space for women to be heard.

A REVIEW REPORT ON NANOMEDICINE AND DIABETES

Nanomedicine is a branch of science that combines medicine and nanotechnology for diagnosing, sensing, delivery, and treatment purposes. It improves the ability to target specific cells and tissues. Their features such as biocompatibility, increased retention and reactivity, and low cytotoxicity make them find their application in the field of Diabetic therapy. A methodology on treating diabetes using medical nanotechnology is proposed in this paper and the methodology is yet to be tested.

ZRSR2 Mutation Induced Minor Intron Retention Drives MDS and Diverse Cancer Predisposition Via Aberrant Splicing of LZTR1

Mutations in RNA splicing factors are amongst the most common genetic alterations in myeloid malignancies. Mutations in the splicing factors SF3B1, SRSF2, and U2AF1 occur as heterozygous, missense mutations and have been shown to confer a change-of-function. In contrast, the X chromosome encoded ZRSR2 is enriched in nonsense/frameshift mutations in males, consistent with loss of function. To date however, we do not understand the basis for enrichment of ZRSR2 mutations in leukemia. Moreover, ZRSR2 is the only one of these factors that primarily functions in the minor spliceosome. While most introns are spliced by the major spliceosome, a small subset (<1%) of introns are recognized by a separate complex, the minor spliceosome. Although minor (or "U12") introns are present in only ~800 genes in humans, their sequences and positions are highly evolutionarily conserved - more so than their U2 counterparts. The high conservation of minor introns suggests key regulatory roles yet few functional roles for the minor spliceosome in regulating biological phenotypes are known. The rarity and conservation of minor introns offered a unique opportunity to investigate splicing factor mutations and identify potential tissue-specific roles of the minor spliceosome. Modeling loss-of-function mutations in ZRSR2 via a mouse model for induced deletion of Zrsr2 revealed strikingly enhanced self-renewal of Zrsr2-deficient male and female hematopoietic cells (Fig. A-C). This was in stark contrast to the effects of hotspot mutations in Sf3b1and Srsf2 and similar to those of Tet2 loss on increasing self-renewal and numbers of HSCs. Zrsr2 loss was also associated increased myeloid cells in the blood and long-term hematopoietic stem cells (HSCs) in the marrow (Fig. C). To understand the mechanistic basis by which ZRSR2 loss causes aberrant HSC self-renewal, we quantified transcriptome-wide splicing patterns in MDS patients. ZRSR2-mutant samples had widespread, dysfunctional recognition of minor introns- 48% of minor introns exhibiting significantly increased retention (Fig. D). We next systematically mimicked the effects of nonsense-mediated decay caused by minor intron retention in ZRSR2-mutants. Every gene containing a ZRSR2-regulated minor intron was targeted by 4 sgRNAs via a positive-enrichment CRISPR screen using pools of lentiviral sgRNAs in cytokine-dependent human and mouse hematopoietic cell lines. This identified several minor intron-containing genes whose downregulation conferred cytokine independence. Strikingly, just one gene was enriched in all lines (Fig. E): LZTR1, a cullin-3 adaptor for ubiquitin-mediated suppression of RAS-related GTPases which is subject to loss-of-function mutations in several cancers and the RASopathy Noonan Syndrome. Minor intron retention in LZTR1 correlated with reduced LZTR1 protein in MDS patients (Fig. F-G). Inducing mutations in either the protein-coding region of LZTR1 or its minor intron resulted in cytokine independence (Fig. H), reduced LZTR1, and dramatic accumulation of RIT1, a RAS GTPase substrate of LZTR1. In a Noonan Syndrome family wherein one child died of AML, the mother and all children carried an intronic mutation within LZTR1's minor intron (Fig. I-J). Fibroblasts from each family member revealed clear LZTR1 minor intron retention with impaired LZTR1 protein expression and RIT1 accumulation in subjects bearing the LZTR1 minor intron mutation (Fig. J). We next interrogated LZTR1 minor intron splicing across all cancers in the TCGA. While LZTR1's minor intron was efficiently excised in normal samples, a notable subset of tumors in almost all cancer types exhibited significantly increased retention within LZTR1's minor intron. These data indicate LZTR1 is frequently dysregulated via perturbed minor intron splicing - much more so than by protein-coding mutations alone. Here we uncover a heretofore unrecognized role of minor intron excision in regulating HSC self-renewal, a molecular link between ZRSR2 mutations and aberrant LZTR1 splicing and expression, and frequent LZTR1 minor intron retention in diverse cancers and cancer predisposition syndromes. Given frequent post-transcriptional disruption of LZTR1 in the absence of protein-coding mutations, our data additionally motivate study of other cancer-associated minor intron-containing genes which may be dysregulated via similar, and as-yet-undetected, aberrant splicing. Figure Disclosures Abdel-Wahab: Merck: Consultancy; Envisagenics Inc.: Current equity holder in private company; H3 Biomedicine Inc.: Consultancy, Research Funding; Janssen: Consultancy.