Biology subjects

Hasan, N.

Publications and source records attributed to Hasan, N..

13 recordsLinked to original sources

bioRxiv2026

Lipid lowering effects of Fucus vesiculosus and Phytolacca berry extracts: An alternative approach of treating hypertriglyceridemia

Hypertriglyceridemia is commonly managed with lipid-lowering drugs such as statins; however, adverse effects, dose intolerance, and financial barriers may limit their use. Therefore, affordable and potentially safer plant-derived alternatives warrant investigation. This study evaluated the lipid-lowering effects of ethanol extracts of Fucus vesiculosus and Phytolacca berry, administered individually or in combination, in mice fed a butter-enriched diet for 12 weeks. Forty-eight mice were randomly assigned to six groups: normal control (Group 1), butter control (Group 2), statin control (Group 3), Fucus vesiculosus extract (Ext-1; Group 4), Phytolacca berry extract (Ext-2; Group 5), and the combined extracts (Group 6). Body weight, organ-to-body-weight ratios, serum lipid parameters, and histopathological changes were assessed. Group 3 showed the lowest final body weight, while Group 6 demonstrated a comparable body-weight trajectory. Organ-to-body-weight ratios varied among groups, with Group 3 generally showing the highest values and Group 6 comparatively lower ratios for several organs. Group 5 had the lowest total cholesterol concentration, followed by Group 3, whereas Group 6 showed cholesterol levels comparable to the normal control and statin groups. Notably, Group 6 exhibited the lowest serum triglyceride concentration (129.9 mg/dL). Histopathological examination revealed relatively mild hepatic alterations and limited vascular plaque formation in Group 6. The combined extracts demonstrated favorable effects on body-weight gain and serum lipid profiles, particularly triglycerides, with comparatively mild histopathological changes. Further mechanistic, dose-response, toxicity, and long-term studies are warranted before clinical application can be considered.

pharmacology and toxicology↗

bioRxiv2026

Therapeutic restoration of synaptic architecture, retinal and visual function, and prevention of retinal degeneration in a mouse model of retinal dystrophy

Vision depends on the transfer of photoreceptor signals through the retina and then to many CNS visual nuclei. While the most common inherited retinal diseases (IRDs) involve defects in rod and/or cone function, another group (referred to as congenital stationary night blindness (CSNB)) results from defects in glutamate release from photoreceptors, or conversion of the glutamatergic signal in bipolar cells. One example results from mutations in the CACNA2D4 gene, which encodes a subunit of the voltage-gated calcium channel that is critical for glutamate release from both rod and cone photoreceptors. Mutations in CACNA2D4 result in a range of phenotypes in human patients, from incomplete CSNB to rod-cone dystrophy. In the CACNA2D4 knockout mouse (2{delta}4-/-), there is slow photoreceptor degeneration, the photoreceptor-to-bipolar cell synapse is disorganized, and the retina lacks scotopic and photopic full-field electroretinogram b-waves; this also results in low visual acuity. Using adult 2{delta}4-/-mice, we show that recombinant adeno-associated virus (rAAV)-mediated gene therapy directed to rod photoreceptors prevents rod degeneration, restores synaptic organization, retinal function, and improves visual acuity under both light- and dark-adapted conditions. This rescue was maintained for up to 14 months post-treatment. Together, our results demonstrate that synaptic structure and function can be restored in the mature mouse retina in a model of complete synaptic disorganization. The results highlight the neuroprotective potential of targeting synaptic organizing proteins in retinal gene therapy.

neuroscience↗

bioRxiv2026

Metabolic Reprogramming Coordinates Mannose and Glutamine Metabolism to Maintain Glucose Homeostasis During Glycosuria

Glycosuria, whether genetically induced or triggered by SGLT2 inhibitors, activates compensatory glucose-producing pathways that limit glucose lowering in type 2 diabetes. To define these pathways, we studied renal Glut2 knockout mice, which progressively lose Slc5a2 (encoding SGLT2) expression yet maintain normoglycemia despite marked urinary glucose loss. Metabolic profiling and isotope tracing revealed coordinated adaptations in mannose and glutamine metabolism during glycosuria. Skeletal muscle reduced glucose utilization and instead oxidized mannose, while whole-body glycolysis declined, establishing a systemic glucose-sparing state. Disruption of glutamine transport or mannose utilization caused hypoglycemia in mice treated with an SGLT2 inhibitor, demonstrating dependence on these substrates to maintain glucose homeostasis during glycosuria. Multiomic profiling revealed increased expression and chromatin accessibility of mannose and glutamine transport pathways. These findings identify a kidney-driven metabolic program that preserves systemic glucose homeostasis during glycosuria and may inform strategies to optimize the glucose-lowering efficacy of SGLT2 inhibitors.

physiology↗

bioRxiv2026

Diffusion Probabilistic Models for Missing-Wedge Correction in Cryo-Electron Tomography

Interpretation of 3D cryo-electron tomography (cryo-ET) reconstructions (tomograms) is hampered by the so-called missing-wedge (MW) distortions, which arise because tilt image series used for the reconstructions are acquired in a limited angular range. While many deep-learning approaches address the correction of the MW artifacts on the level of tomograms (3D volumes), the correction at the level of 2D tilt images (generation of unacquired images) remains underexplored. We propose MW-RaMViD, a 2D tilt-image generation method for MW correction, based on Random-Mask Video Diffusion (RaMViD) method for prediction of frames in natural videos. To adapt RaMViD for cryo-ET, we add MRC image-format support, floating-point pixel intensity representation, and a controlled inference protocol enabling both one-run and progressive MW completion (generating a small number of missing tilts per step using a sliding window). We evaluate the method on a synthetic noisy tilt-series dataset and study the effects of MW completion step size and conditioning sequence length. Results show that smaller step sizes and larger conditioning windows reduce error accumulation at higher tilt angles and improve reconstruction fidelity, which was measured by Root Mean Square Error on the image level and by Fourier Shell Correlation on the tomogram level.

bioinformatics↗

bioRxiv2025

Domain-specific functions of LRIT3 in synaptic assembly and retinal signal transmission

LRIT3 is a leucine-rich repeat (LRR) protein that is expressed in the retina, and its absence causes complete congenital stationary night blindness (cCSNB), a genetically diverse disorder characterized by impaired low-light vision, myopia, and nystagmus. LRIT3 is expressed in rod and cone photoreceptors, and it trans-synaptically organizes the assembly of the glutamate signaling complex, the signalplex, on depolarizing bipolar cells (DBCs). LRIT3 is a single-pass membrane protein with extracellular LRR, IG, and FN3 domains. The mechanism by which LRIT3 controls postsynaptic receptor organization remains unknown. We address this by using rAAV to express deletion constructs in LRIT3 knockout retinas and examining LRIT3 trafficking, as well as the structural and functional recovery of the signalplex in DBCs. We show the LRR domain is required for trafficking LRIT3 to the synapse in cones, but not rod photoreceptors, although it is needed for reassembly and function of the rod BC signalplex. Neither the IG nor the FN3 domain is needed for synaptic localization of LRIT3. However, the IG domain is required for the localization of TRPM1 to the signalplex and thus function. The FN3 domain is not necessary for either DBC signalplex assembly or function. Our data demonstrates that the LRR and IG domains of LRIT3 are crucial for TRPM1 localization and retinal function, with the LRR domain playing a key role in the differential function of LRIT3 at rod and cone synapses. Notably, our results show that restoring Nyctalopin localization to the DBC signalplex alone is insufficient to restore TRPM1 expression. Based on our findings, we propose a model in which the LRR domain trans-synaptically binds with Nyctalopin, while the IG domain interacts with TRPM1.

neuroscience↗

bioRxiv2025

Gene augmentation therapy treats mature mice with complete congenital stationary night blindness (cCSNB), improving retinal function and visual acuity

Recombinant adeno-associated virus (rAAV) mediated gene therapy is an effective approach for targeting therapeutic genes to retinal photoreceptors. Complete congenital stationary night blindness (cCSNB) is a genetically heterogeneous inherited retinal disease caused by mutations in one of several genes, which are part of a large and interdependent depolarizing bipolar cell (DBC) signalplex required for normal synaptic signaling with photoreceptors. These genes include NYX, GRM6, TRPM1, GPR179, and LRIT3, and the cCSNB phenotype that results is characterized by abnormal low light vision, myopia, and nystagmus, but does not include retinal degeneration. Because of the non-progressive and recessive nature of cCSNB we investigated the potential of a gene augmentation approach in the mature retina to improve retinal function and visual acuity. We used a mouse model of cCSNB caused by the loss of LRIT3 to evaluate the efficacy of a single subretinal injection of rAAV expressing LRIT3 in either rods or cones, and the extent of restoration of retinal function and visual acuity. We show that gene augmentation by expressing LRIT3 in the rods of mature Lrit3-/- retinas restores function and scotopic visual acuity, and when expressed on cones, improves both photopic and scotopic visual acuity.

neuroscience↗

bioRxiv2025

Changes in biophysical characteristics of YghA from E. coli due to variation in pH

YghA from E. coli has been reported to be involved in conferring tolerance against furan aldehyde inhibitors which are commonly generated in thermo-acidic pretreatment of lignocellulosic biomass. In this study we report the biophysical characterization of YghA from E. coli as a function of variation in pH. Fluorescence intensity of YghA increased by 2.5-fold in acidic pH as compared to circumneutral pH. In presence of the hydrophilic 8-anilinonaphthalene-1-sulfonic acid (ANS) dye, a 68 - 79.4-fold increase in fluorescence intensity at acidic pH was observed as compared to circumneutral pH, while at basic pH the increase was only 1 to 2-fold. Secondary structure analysis by circular dichroism signal at 222 and 208 nm suggests that the secondary structure of YghA is primarily composed of alpha-helix at pH 7 and the secondary structure is abruptly lost at pH 3 and lower. In agreement with these observations, MD simulations predicted greater structural variations at low pH when compared to neutral or high pH. Interface energy calculations using computational docking protocols suggested that YghA forms relatively more stable complex with NADH. The in silico pulling assay results also show that NADH is more preferred compared to NADPH. Molecular dynamics simulations also indicate that YghA is structurally unstable at acidic pH with significant variations in the root mean square deviation values of the tetramer backbone. Residues GLU 84 at pH 7 together with PRO 24 and LEU 236 at pH 1 were identified as flexible residues and are promising target for future mutagenesis studies targeted towards improving structural stability of YghA.

biochemistry↗

bioRxiv2023

Cone Synaptic function is modulated by the leucine rich repeat (LRR) adhesion molecule LRFN2

Daylight vision is mediated by cone photoreceptors in vertebrates, which synapse with bipolar cells (BCs) and horizontal (HCs) cells. This cone synapse is functionally and anatomically complex, connecting to 8 types of depolarizing (DBC) BCs and 5 types of hyperbolizing BCs (HBCs). The dendrites of DBCs and HCs cells make invaginating ribbon synapses with the cone axon terminal, while HBCs form flat synapses with the cone pedicles. The molecular architecture that underpins this organization is relatively poorly understood. To identify new proteins involved in synapse formation and function we used an unbiased proteomic approach and identified LRFN2 (Leucine-rich repeat and fibronectin III domain-containing 2) as a component of the DBC signaling complex. LRFN2 interacts with TRPM1 and is selectively expressed at cone terminals and co-localizes with PNA, and other DBC signalplex members. In the absence of LRFN2 the cone-mediated photopic electroretinogram b-wave amplitude is reduced. In LRFN2 deficient mice, the synaptic markers: LRIT3, ELFN2, mGluR6, TRPM1 and GPR179 are properly localized. Similarly, LRFN2 expression and localization is not dependent on these synaptic proteins. These data demonstrate that LRFN2 likely interacts with TRPM1 and its absence compromises normal synaptic transmission between cones and cone DBCs cells. Significance StatementSignaling between cone photoreceptors and the downstream bipolar cells is critical to normal vision. Cones synapse with 13 different types of bipolar cells forming an invaginating ribbon synapses with 8 types, and flat synapse with 5 types, to form one of the most complex synapses in the brain. In this report a new protein, LRFN2 (Leucine-rich repeat and fibronectin III domain-containing 2), was identified that is expressed on the cones synapses. Using Lrfn2 knockout mice we show LRFN2 is required for the normal cone signaling.

neuroscience↗

bioRxiv2022

LRIT3 expression in cone photoreceptors restores post-synaptic bipolar cell signalplex assembly and function in Lrit3-/- mice.

Complete congenital stationary night blindness (cCSNB) is a heterogeneous disorder characterized by poor dim light vision, myopia, and nystagmus, that is caused by mutations in genes critical for signal transmission between photoreceptors and depolarizing bipolar cells (DBCs). One such gene, LRIT3, is required for assembly of the post-synaptic signaling complex (signalplex) at the dendritic tips of DBCs, although the number of signalplex components impacted is greater in cone DBCs than in rod bipolar cells. This difference raises the possibility that LRIT3 is expressed both pre- and post-synaptically at cone terminals. Here we show that rAAV-mediated expression of LRIT3 in cones results in robust rescue of cone DBC signalplex components and restores downstream visual function, as measured by the light adapted ERG b-wave and electrophysiological recordings of BCs and RGCs. These data show that LRIT3 successfully restores function to cone DBCs in a trans-synaptic manner, potentially paving the way for therapeutic intervention in LRIT3-associated cCSNB.

neuroscience↗

bioRxiv2020

Obesity phenotypes are preserved in intestinal stem cell enteroids from morbidly obese patients

Obesity and obesity-related comorbidities are significant health care challenges. Bariatric surgery (BS) is the most effective therapy for treating obesity and type 2 diabetes. A barrier in the development of therapeutic alternatives is incomplete mechanistic understanding of the benefits of BS and the lack of human intestinal models that recapitulate the pathophysiology of obesity. Using adult intestinal stem cell-derived enteroid cultures established from healthy lean subjects and morbidly obese patients, including post-BS cases, four phenotypes correlating patient BMI and intestinal glucose absorption were identified suggesting that enteroids retain patient phenotype heterogeneity associated with healthy and diseased state. In a sub-population of obese patients, increased dietary glucose absorption and gluconeogenesis was due to significantly higher expression of intestinal carbohydrate transporters (SGLT1, GLUT2 and GLUT5) and gluconeogenic enzymes (PEPCK1 and G6Pase) compared to enteroids from lean subjects that demonstrated low glucose absorption and lacked gluconeogenesis. Enteroids established from successful BS cases exhibited low glucose absorption similar to that observed in lean subjects. These data show that human enteroids preserve the patient phenotype in long-term cultures and represent a reliable preclinical model to study the heterogeneity of the obesity mechanisms, which is necessary to determine the efficacy of therapeutic interventions.

physiology↗

bioRxiv2020

Systematic mutational analysis of epitope-grafted ED3's immunogenicity reveals a DENV3-DENV4 bi-serospecific ED3 mutant

Dengue viruses are classified into four serotypes (DENV1[~]4), and the severe forms of dengue disease, the dengue hemorrhagic fever and shock syndrome, are caused by sero-cross-reacting antibodies. However, the residue determinants of the serospecificity and sero-cross-reactivity are yet to be identified. Here, we report an epitope grafting mutational analysis of the serospecificity and cross-serospecificity of the envelope protein domain 3 (ED3; 107 residues, [~]11.6kDa), which contains two major putative epitopes of DENVs. To this end, we constructed ED3 from DENV3 (3ED3) and DENV4 (4ED3), and six epitope-grafted variants, where we transferred epitope 1 (L304I, K305D, V309M, and S310A) and/or epitope 2 (D383N, K384S, K387T, and N389H) of 4ED3 onto 3ED3 and vice versa. Mice immunization using 3ED3 and 4ED3 generated serotype-specific antisera, as expected. Similarly, most epitope-grafted ED3s produced antisera serospecific to the template ED3 with little or no cross-recognition of ED3 of the serotype from which the epitopes were taken. This result indicated that a mere grafting of the epitope was not sufficient to transfer serospecificity, contrary to our expectations. However, one epitope grafted ED3 mutant, where epitope 1 of 3ED3 was grafted onto 4ED3 (4ED3epi1), generated antisera that was serospecific to both 4ED3 and 3ED3. The 4ED3epi1 is thus a chimeric ED3 that produces antisera possessing serospecificity to both 3ED3 and 4ED3. The 4ED3epi1 provides a unique tool for analyzing serospecificity and cross-reactivity in dengue, and we hope it will serve as a template for trivalent and eventually tetravalent antisera.

immunology↗

bioRxiv2018

Vitamin D3 regulates estrogen’s action and affects mammary epithelial organization in 3D cultures

Vitamin D3 (vitD3) and its active metabolite, calcitriol (1,25-(OH)2D3), affect multiple tissue types by interacting with the vitamin D receptor (VDR). Although vitD3 deficiency has been correlated with increased incidence of breast cancer and less favorable outcomes across ethnic groups and latitudes, randomized human clinical trials have yet to provide conclusive evidence on the efficacy of vitD3 in treating and/or preventing breast cancer. When considering that carcinogenesis is \"development gone awry\", it becomes imperative to understand the role of vitD3 during breast development. Mammary gland development in VDR KO mice is altered by increased ductal elongation and lateral branching during puberty, precocious and increased alveologenesis at pregnancy and delayed post-lactational involution. These developmental processes are largely influenced by mammotropic hormones, i.e., ductal elongation by estrogen, branching by progesterone and alveologenesis by prolactin. However, research on vitD3s effects on mammary gland morphogenesis focused on cell proliferation and apoptosis in 2D culture models and utilized supra-physiological doses of vitD3, conditions that spare the microenvironment in which morphogenesis takes place. Here, using two 3D culture models, we investigated the role of vitD3 in mammary epithelial morphogenesis. We found that vitD3 interferes with estrogens actions on T47D human breast cancer cells in 3D differently at different doses, and recapitulates what is observed in vivo. Also, vitD3 can act autonomously and affect the organization of MCF10A cells in 3D collagen matrix by influencing collagen fiber organization. Thus, we uncovered how vitD3 modulates mammary tissue organization independent of its already known effects on cell proliferation.

developmental biology↗

bioRxiv2018

LRIT3 is required for nyctalopin expression and normal ON and OFF pathway signaling in the retina

At its first synapse, the retina establishes two parallel channels that encode light increments (ON) or decrements (OFF). At the same synapse, changes in photoreceptor glutamate release are sensed by ON bipolar cells (BCs) via the metabotropic glutamate receptor 6 (mGluR6), and OFF BCs via ionotropic BCs, which differ in their synaptic configuration with the photoreceptor terminal. ON BCs form invaginating synapses that bring them in close proximity to presynaptic ribbons and the presumed sole source of glutamate release. OFF bipolar cells form flat contacts distal to the ribbon synapse. We investigated the role of LRIT3 in normal assembly and function of the mGlur6 signaling cascade present in ON BCs. We demonstrate that LRIT3 is required for nyctalopin expression and thus TRPM1 expression and function. Using glutamate imaging, whole-cell electrophysiology, and multi-electrode array extracellular recordings we demonstrate that the loss of LRIT3 impacts both the ON and OFF pathways at the level of the BCs. The effect on ON pathway signaling, a lack of ON BC response, is shared by mutants lacking mGluR6, TRPM1 GPR179 or nyctalopin. The effects on the OFF pathway are unique to LRIT3, and include a decrease in response amplitude of both OFF BC and GCs. Based on these results, we propose a working model where LRIT3 is required for either efficient glutamate release or reuptake from the first retinal synapse.\n\nSIGNIFICANCE STATEMENTAt the first visual synapse, photoreceptor cells signal to two distinct bipolar cell (BC) populations, one characterized by a depolarizing response to light onset (ON or DBCs), the other by a hyperpolarizing response (OFF or HBCs). The DBC light response depends on a G protein-coupled receptor and associated protein complex, known as the signalplex. Mutations in signalplex proteins lead to DBC pathway-specific loss of visual function. Here we show how loss of LRIT3, a previously identified signalplex protein, prevents functional assembly of the DBC signalplex and alters visual function in both ON and OFF signaling pathways. Thus, our results indicate that the function of LRIT3 at this first synapse extends beyond assembly of the DBC signalplex.

neuroscience↗