Biology subjects

Sapkota, Y.

Publications and source records attributed to Sapkota, Y..

6 recordsLinked to original sources

bioRxiv2026

Functional High Throughput Drug Screening Reveals Cyproheptadine as a Novel Treatment for LMNA -related Cardiomyopathy

ObjectivesTo define shared and variant-specific mechanisms underlying LMNA-associated dilated cardiomyopathy (DCM) and identify therapeutic candidates using human stem cell-based models. BackgroundVariants in the gene LMNA, encoding lamin A/C, cause 5-10% of dilated cardiomyopathies (DCM) and are strongly associated with heart failure and arrhythmias. Yet, the mechanisms by which LMNA variants drive disease and the distinction between shared and variant-specific phenotypes remain unclear. MethodsTo address this, we generated human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from six LMNA-DCM patients carrying three pathogenic variants (T150A, E381Afs*39, R527H) and from five healthy control patients. ResultsLMNA hiPSC-CMs exhibited nuclear membrane deformation, reduced beat rate, arrhythmias, and prolonged calcium transients. Transcriptomic and electrophysiological analyses revealed downregulation of cardiac genes and ion channels, with abnormal Ca{superscript 2} handling emerging as a shared disease mechanism. Leveraging a high-throughput functional assay, we performed an unbiased drug screen and identified cyproheptadine, an FDA-approved antihistamine, as the only compound to alleviate abnormal function across all LMNA variants. ConclusionOur findings reveal a shared disease mechanism across multiple LMNA variants driven by dysregulated Ca{superscript 2} handling. This work establishes a patient-specific drug discovery platform and identifies cyproheptadine as a promising therapeutic candidate for LMNA-associated dilated cardiomyopathy. HighlightsO_LIPatient-specific LMNA hiPSC-cardiomyocytes robustly recapitulate disease phenotypes, including nuclear defects, arrhythmias, and contractile dysfunction. C_LIO_LIDysregulated calcium handling emerges as a unifying mechanism driving pathology across distinct LMNA variants. C_LIO_LIVariant-resolved analysis reveals both shared and mutation-specific molecular and functional signatures. C_LIO_LIHigh-throughput screening identifies cyproheptadine as a potent, broadly effective rescue agent across all tested LMNA variants. C_LIO_LIThis work establishes a scalable precision medicine platform for rapid therapeutic discovery in inherited cardiomyopathies. C_LI

Cell Biology↗

bioRxiv2026

Alternative organelle targeting of OPA1 mediates fatty acid release from lipid droplets

Mitochondria and lipid droplets (LDs) are functionally coupled to coordinate fatty acid utilization and storage. However, a comprehensive understanding of mitochondria-LD alliances remains elusive. We have identified a previously unrecognized role for optical atrophy 1 (OPA1), a mitochondrial fusion factor, in the regulation of fatty acid release from LDs. We demonstrated that OPA1s exon 4 adapts an amphipathic helix to target OPA1 to LDs. OPA1 localized to LDs promote fatty acid release by facilitating the recruitment of lipases to LDs. In addition, OPA1s residence on LDs competes with its mitochondrial entry, influencing mitochondria fusion and connectivity. Furthermore, the S158N polymorphism within OPA1s exon 4 exhibiting attenuated fatty acid release from LDs is associated with changes in metabolic traits in pediatric cancer survivors. Altogether, our findings reveal that OPA1 actively mediates fatty acid release from LDs and provide a mechanistic link between OPA1 and human metabolism.

cell biology↗

bioRxiv2025

Suppression of non-canonical autophagy induces endothelial and cardiac dysfunction

BackgroundWhile roles for canonical autophagy in the pathophysiology of cardiovascular disease have been established, we have limited understanding of the non-canonical functions of autophagy proteins in this context. LC3-asssociated endocytosis (LANDO) is a novel non-canonical function of autophagy proteins, in which LC3 (microtubule-associated protein light chain 3) is conjugated to early endosome membranes using a portion of the canonical autophagy machinery, and functions in the endocytic recycling of several plasma membrane proteins. Here we ask whether perturbation of LANDO can promote cardiovascular pathogenesis. MethodsCardiac and endothelial functions were assessed by echocardiography and flow-mediated dilatation in mice lacking Rubicon (Rubcn-/-) or the WD domain of ATG16L1 (Atg16l1{Delta}WDki), two known effectors of LANDO. Mice with conditional depletion of Rubicon in the endothelial, myeloid and cardiomyocyte compartments were used as well. Three-dimensional murine cardiac vasculature leakiness was investigated by light sheet fluorescence microcopy. Endothelial activation induced by shear stress was characterized in vitro in primary endothelial cells isolated from murine lungs and human aortic endothelial cells. Associations between genetically predicted expression of candidate genes involved in LANDO and human cardiovascular parameters were studied in the Young Finns Study and the UK Biobank. ResultsCompared to littermate controls, young Rubcn-/- and Atg16l1{Delta}WDki mice showed a decrease in cardiac and endothelial functions, as did mice with endothelium-specific deficiency. VEGFR2 recycling to the plasma membrane and nitric oxide pathway during shear stress were disrupted in LANDO-deficient primary murine and human endothelial cells. Proteomic analysis in primary human aortic endothelial cells revealed an upregulation of intracellular hemoglobin subunit alpha (Hb-) upon shear stress, which was blunted when RUBCN was ablated. Genetic expression studies uncovered several candidate genes related to LANDO that correlated with cardiovascular parameters. These included the retromer complex subunit VPS29, disruption of which decreased Hb- expression levels in human endothelial cells. ConclusionsOur data support a pivotal role of non-canonical functions of autophagy proteins in recycling VEGFR2 upon shear stress activation in endothelial cells together with Hb- expression that may contribute to the etiology of cardiovascular diseases.

physiology↗

bioRxiv2023

A Novel Transcription Factor Combination for Direct Reprogramming to a Spontaneously Contracting Human Cardiomyocyte-like State

The reprogramming of somatic cells to a spontaneously contracting cardiomyocyte-like state using defined transcription factors has proven successful in mouse fibroblasts. However, this process has been less successful in human cells, thus limiting the potential clinical applicability of this technology in regenerative medicine. We hypothesized that this issue is due to a lack of cross-species concordance between the required transcription factor combinations for mouse and human cells. To address this issue, we identified novel transcription factor candidates to induce cell conversion between human fibroblasts and cardiomyocytes, using the network-based algorithm Mogrify. We developed an automated, high-throughput method for screening transcription factor, small molecule, and growth factor combinations, utilizing acoustic liquid handling and high-content kinetic imaging cytometry. Using this high-throughput platform, we screened the effect of 4,960 unique transcription factor combinations on direct conversion of 24 patient-specific primary human cardiac fibroblast samples to cardiomyocytes. Our screen revealed the combination of MYOCD, SMAD6, and TBX20 (MST) as the most successful direct reprogramming combination, which consistently produced up to 40% TNNT2+ cells in just 25 days. Addition of FGF2 and XAV939 to the MST cocktail resulted in reprogrammed cells with spontaneous contraction and cardiomyocyte-like calcium transients. Gene expression profiling of the reprogrammed cells also revealed the expression of cardiomyocyte associated genes. Together, these findings indicate that cardiac direct reprogramming in human cells can be achieved at similar levels to those attained in mouse fibroblasts. This progress represents a step forward towards the clinical application of the cardiac direct reprogramming approach. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/532629v1_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@17d6539org.highwire.dtl.DTLVardef@180a0b8org.highwire.dtl.DTLVardef@1b7cb46org.highwire.dtl.DTLVardef@182618b_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIUsing network-based algorithm Mogrify, acoustic liquid handling, and high-content kinetic imaging cytometry we screened the effect of 4,960 unique transcription factor combinations. C_LIO_LIUsing 24 patient-specific human fibroblast samples we identified the combination of MYOCD, SMAD6, and TBX20 (MST) as the most successful direct reprogramming combination. C_LIO_LIMST cocktail results in reprogrammed cells with spontaneous contraction, cardiomyocyte-like calcium transients, and expression of cardiomyocyte associated genes. C_LI

cell biology↗

bioRxiv2020

Generalizability of "GWAS hits" in clinical populations: Lessons from childhood cancer survivors

With mounting interest in translating GWAS hits from large meta-analyses (meta-GWAS) in diverse clinical settings, evaluating their generalizability in target populations is crucial. Here we consider long-term survivors of childhood cancers from the St. Jude Lifetime Cohort Study and show the limited generalizability of 1,376 robust SNP associations reported in the general population across 12 complex anthropometric and cardiometabolic phenotypes (N=2,231; observed-to-expected replication ratio=0.68, P=2.4x10-9). An examination of five comparable phenotypes in a second independent cohort of survivors from the Childhood Cancer Survivor Study corroborated the overall limited generalizability of meta-GWAS hits to survivors (N=4,212, observed-to-expected replication ratio=0.53, P=1.1x10-16). Meta-GWAS hits were less likely to be replicated in survivors exposed to cancer therapies associated with phenotype risk. Examination of complementary DNA methylation data in a subset of survivors revealed that treatment-related methylation patterns at genomic sites linked to meta-GWAS hits may disrupt established genetic signals in survivors.

genetics↗

bioRxiv2018

Large-scale genome-wide association meta-analysis of endometriosis reveals 13 novel loci and genetically-associated comorbidity with other pain conditions

Endometriosis is a common complex inflammatory condition characterised by the presence of endometrium-like tissue outside the uterus, mainly in the pelvic area. It is associated with chronic pelvic pain and infertility, and its pathogenesis remains poorly understood. The disease is typically classified according to the revised American Fertility Society (rAFS) 4-stage surgical assessment system, although stage does not correlate well with symptomatology or prognosis. Previously identified genetic variants mainly are associated with stage III/IV disease, highlighting the need for further phenotype-stratified analysis that requires larger datasets. We conducted a meta-analysis of 15 genome-wide association studies (GWAS) and a replication analysis, including 58,115 cases and 733,480 controls in total, and sub-phenotype analyses of stage I/II, stage III/IV and infertility-associated endometriosis cases. This revealed 27 genetic loci associated with endometriosis at the genome-wide p-value threshold (P<5x10-8), 13 of which are novel and an additional 8 novel genes identified from gene-based association analyses. Of the 27 loci, 21 (78%) had greater effect sizes in stage III/IV disease compared to stage I/II, 1 (4%) had greater effect size in stage I/II compared to stage III/IV and 17 (63%) had greater effect sizes when restricted to infertility-associated endometriosis cases compared to overall endometriosis. These results suggest that specific variants may confer risk for different sub-types of endometriosis through distinct pathways. Analyses of genetic variants underlying different pain symptoms reported in the UK Biobank showed that 7/9 had positive significant (p<1.28x103) positive genetic correlations with endometriosis, suggesting a genetic basis for sensitivity to pain in general. Additional conditions with significant positive genetic correlations with endometriosis included uterine fibroids, excessive and irregular menstrual bleeding, osteoarthritis, diabetes as well as menstrual cycle length and age at menarche. These results provide a basis for fine-mapping of the causal variants at these 27 loci, and for functional follow-up to understand their contribution to endometriosis and its potential subtypes.

genomics↗