bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2021.06.14.448311

Functional disruption of Transferrin expression alters reproductive physiologyin Anopheles culicifacies

Dixit, R.·rani, j.·De, T. D.·chauhan, C.·kumari, S.·sharma, P.·tevatia, S.·Chakraborti, S.·pandey, K. C.·singh, N.
View original source ↗Export metadata ↓

Abstract

Iron metabolism is crucial to maintain optimal physiological homeostasis of every organism and any alteration of the iron concentration (i.e. deficit or excess) can have adverse consequences. Transferrins are glycoproteins that play important role in iron transportation and have been widely characterized in vertebrates, and insects, but poorly studied in blood-feeding mosquitoes. Here, we characterized a 2102 bp long transcript AcTrf1a encoding putative transferrin homolog protein from mosquito An. culicifacies. A detailed in silico analysis predicts AcTrf1a (ACUA023913-RA) encodes 624 amino acid (aa) long polypeptide that carries transferrin domain. AcTrf1a also showed a putative N-linked glycosylation site, a characteristic feature of most of the mammalian transferrins and certain non-blood feeding insects. Structure modelling prediction confers the presence of an iron binding site at the N-terminal lobe of the transferrin. Our spatial and temporal expression analysis under altered pathophysiological conditions showed that AcTrf1a abundantly express in the fat-body, ovary, and its response is significantly altered (enhanced) after blood meal uptake, and exogenous bacterial challenge. Additionally, a non-heme iron supplementation of FeCl3 at 1 mM concentration not only augmented the AcTrf1a transcript expression in fat-body, also enhanced the reproductive fecundity of gravid adult female mosquitoes. RNAi mediated knockdown of AcTrf1a causes a significant reduction in the egg laying/fecundity, confirmed important role of transferrin in oocyte maturation. Further detailed characterization may help to select this transcript as a unique target to impair the mosquito reproductive outcome. HighlightsO_LIInsect transferrins are mostly glycoprotein of about 60-80 kDa molecular weight, involved in myriad physiological events and serve as a major iron transport protein. C_LIO_LIHere, we identified and characterized a 2102 bp long transcript encoding putative transferrin homolog of 624 aa long peptide, carrying only one fully functional transferrin domain at N-terminal from An. culicifacies. C_LIO_LISpatial and temporal expression analysis of AcTrf1a highlights an enriched expression in fat-body and ovary during vitellogenesis. C_LIO_LIIron supplementation and dsRNA mediated knockdown experiments together confer that AcTrf1a may have key role in the iron homeostasis regulation during oogenesis, and egg maturation in the gravid female mosquitoes. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=87 SRC="FIGDIR/small/448311v1_fig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@a87ec0org.highwire.dtl.DTLVardef@197cecorg.highwire.dtl.DTLVardef@1588092org.highwire.dtl.DTLVardef@16110b4_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFig 1:C_FLOATNO Schematic presentation of iron transport from midgut to ovary by transferrin1 and oocyte reduction after AcTrf1a knockdown. Mosquito acquires iron either from blood meal or iron supplementation in sugar meal. Fat-body derived transferrin proceed towards the gut surface, load iron in its N-terminal iron-binding pocket and deliver iron to ovary. This blood meal iron is required by adult female for completion of gonotrophic cycle. (a) limited iron availability in sugar meal does not support the ovary development and hence no oogenesis; (b) when sugar meal is replaced by blood meal upregulation of transferrin protein results in rapid iron transport to various organs including ovary results in healthy ovarian growth; (c) RNAi mediated knockdown of this transporter protein transferrin in fat-body followed by blood meal, may cause reduced iron transport to ovary and consequently declines in oocyte load. C_FIG

Source connections

Explore related subjects

molecular biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Dixit, R., rani, j., De, T. D., chauhan, C., kumari, S., sharma, P., tevatia, S., Chakraborti, S., pandey, K. C., singh, N.. 2021-06-14. Functional disruption of Transferrin expression alters reproductive physiologyin Anopheles culicifacies. https://doi.org/10.1101/2021.06.14.448311

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Hypoxic Stress Induces LARP1-Driven Stress Granules That Protect mRNAs from Decay to Sustain Mitotic Cell Cycle Progression

Hypoxia is a defining feature of solid tumours that elicits extensive transcriptional and post-transcriptional adaptations. Stress granules (SGs) are frequently observed under hypoxia, yet how they assemble and whether they contribute to hypoxic gene regulation remain poorly understood. Here, we show that hypoxia induces SGs through an assembly mechanism distinct from that of classical acute stresses. Hypoxia SG formation occurs independently of the integrated stress response and instead requires the HIF1-REDD1-mTORCC1-4EBP1 axis. Remarkably, hypoxia SGs assemble despite robust ongoing translation, suggesting that additional mechanisms lower the threshold for RNA condensation. We identify LARP1 as a potential determinant of this process, where it promotes G3BP-dependent SG assembly specifically during hypoxia. Despite their distinct assembly mechanism, hypoxia and arsenite SGs recruit broadly similar RNA populations, with selective differences validated by single-molecule FISH, suggesting that conserved principles govern RNA partitioning across different SG states. Functionally, sequestration into hypoxia SGs correlates with enhance protein expression whereby a subset of mRNAs are protected from decay. Transcriptomic analyses further reveal that this protection sustains a broader gene-expression program enriched for MCM complex and mitotic cell-cycle regulators. Accordingly, disruption of hypoxia SGs reduces mitotic progression and proliferative competence during prolonged hypoxia. Together, our findings establish LARP1-mediated condensation as a mechanism that enables SG assembly despite ongoing translation and reveal that SG sequestration preserves selected mRNAs from decay to sustain the gene-expression programs required for long-term adaptation to hypoxia.

molecular biology↗
bioRxiv2026

Age-associated repression of HNF4α is a driver and potential therapeutic target in liver metabolic dysfunction

Aging is a major risk factors for metabolic dysfunction-associated steatotic liver disease (MASLD). However, the mechanisms by which aging disrupts hepatocyte transcriptional networks to drive metabolic dysfunction remain poorly understood. Hepatocyte nuclear factor 4 alpha (HNF4) is a master regulator of hepatocyte identity and metabolic homeostasis, but its role in liver aging has not been defined. Here, we perform a comprehensive multi-omic profiling of young and aged mouse livers combined with targeted HNF4 functional studies to define how aging remodels HNF4-dependent gene regulation and whether HNF4 can be a target to reverse age-associated liver dysfunction. Despite preserved HNF4 expression with age, aging was associated with reduced HNF4 chromatin occupancy and transcriptional activity, accompanied by epigenetic remodeling, including changes in histone acetylation, chromatin accessibility, and DNA methylation. Integration and comparison of HNF4 CUT&RUN with hepatocyte-specific Hnf4a deletion in young and aged livers identified high-confidence overlapping but distinct young- and old- specific HNF4 target gene networks. In young hepatocytes, HNF4 coordinates two complementary transcriptional programs: activation of genes governing hepatocyte identity, lipid metabolism, and metabolic function, while simultaneously inhibiting alternative developmental, proliferative, and inflammatory programs. Spatial transcriptomic analyses further revealed zone-specific specialization of HNF4-dependent gene programs. Aging selectively disrupted these regulatory networks, resulting in compromised liver identity and metabolic gene programs, de-repression of inflammatory pathways and alternative cellular identity programs and disrupted hepatocyte zonation, consistent with age-dependent lipidomic and metabolic changes, hepatic fat accumulation, and immune infiltration. Hepatocyte-specific Hnf4a deletion in young mice recapitulated key features of liver aging, including impaired hepatocyte identity, metabolic dysfunction, steatosis, inflammatory activation and altered hepatic immune-cell composition, while deletion in aged mice further exacerbated steatosis, inflammation, and hepatic dysfunction. Conversely, hepatocyte-specific HNF4 restoration in aged mice significantly reduced hepatic steatosis and lipid accumulation, restored fatty acid metabolic programs, and partially reversed age-associated transcriptional changes. However, inflammatory and interferon-associated programs were not uniformly reversed, revealing differential responsiveness of metabolic and inflammatory pathways to HNF4 restoration. Together, these findings identify age-associated impairment of HNF4 activity as a functional contributor to liver aging, linking dysregulation of hepatocyte identity, metabolic homeostasis, and inflammatory control to age-associated hepatic dysfunction. Importantly, the selective reversibility of metabolic defects following HNF4 restoration establishes HNF4 as a promising strategy for preserving hepatocyte homeostasis and reversing age-associated hepatic metabolic dysfunction.

molecular biology↗
bioRxiv2026

A Human Tumor Virus Recruits HSP70 Chaperone to Remodel Its Replisome on DNA

Human Merkel cell polyomavirus (MCV) large T (LT) protein functions as a replication helicase analogous to the cellular MCM complex but requires a second MCV protein, small T (sT), for efficient LT-initiated replication. Both LT and sT encode highly-conserved DnaJ domains that bind to the cellular refolding molecule, heat shock protein 70 (HSP70). Using single-molecule imaging and FRET, we find that sT recruits dimeric HSP70 to serve as a molecular bridge between sT and LT on DNA and that this complex facilitates remodeling LT into a functional double-hexameric helicase. Disruption of LT-HSP70-HSP70-sT interaction with HSP70 inhibitors or by mutations to the LT-sT DnaJ domains collapse the LT-HSP70-HSP70-sT complex, abolishing sT-enhanced LT dodecamerization and ATP-dependent DNA unwinding. Assembly of virus-free mammalian MCM3, MCM4 and MCM6 in nuclear extracts similarly recruits HSP70 to DNA suggesting that Hsp70 remodeling is used for efficient eukaryotic assembly of the multi-protein replication machinery.

molecular biology↗