Biology subjects

Desai, P. B.

Publications and source records attributed to Desai, P. B..

4 recordsLinked to original sources

bioRxiv2026

Ift43 Controls the Ciliary Levels of Gli2 and Gli3

Intraflagellar transport (IFT) drives the bidirectional movement of trains composed of IFT-A, IFT-B, and BBSome complexes that build and maintain cilia while supporting their signaling functions. Over evolution, IFT became integral to Hedgehog signaling by directing the dynamic movements of receptors and Gli transcription factors that fine-tune pathway output. The IFT-A complex contains six subunits, but the smallest, Ift43, remains poorly characterized and is absent from many ciliated species, suggesting specialized roles in signaling rather than core ciliogenesis. Here we show that loss of Ift43 in mice causes mid-gestation lethality with severe craniofacial defects, exencephaly, abdominal wall defects with exposed viscera, edema, and limb patterning defects. At the cellular level, Ift43 deficiency reduces both the number and length of cilia and blocks induction of Gli1 following pathway activation by the agonist SAG. Although Smoothened relocalizes to cilia normally, Ift43 mutants abnormally accumulate Gli2 and Gli3 at ciliary tips before stimulation and continue to generate repressor forms after activation. Conversely, Ift43 overexpression increases basal Gli2 cleavage, revealing an unanticipated role for Ift43 in regulating Gli processing. Together, these findings identify Ift43 as a key IFT-A component that links ciliary assembly to Hedgehog signal transduction and helps set the balance between Gli activator and repressor forms.

cell biology↗

bioRxiv2023

GABA(A) receptor activation drives GABARAP-Nix mediated autophagy to radiation-sensitize primary and brain-metastatic lung adenocarcinoma tumors

In non-small cell lung cancer (NSCLC) treatment, targeted therapies benefit only a subset of NSCLC, while radiotherapy responses are not durable and toxicity limits therapy. We find that a GABA(A) receptor activator, AM-101, impairs viability and clonogenicity of NSCLC primary and brain metastatic cells. Employing an ex vivo chip, AM-101 is as efficacious as the chemotherapeutic docetaxel, which is used with radiotherapy for advanced-stage NSCLC. In vivo, AM-101 potentiates radiation, including conferring a survival benefit to mice bearing NSCLC intracranial tumors. GABA(A) receptor activation stimulates a selective-autophagic response via multimerization of GABA(A) Receptor-Associated Protein (GABARAP), stabilization of mitochondrial receptor Nix, and utilization of ubiquitin-binding protein p62. A targeted-peptide disrupting Nix binding to GABARAP inhibits AM-101 cytotoxicity. This supports a model of GABA(A) receptor activation driving a GABARAP-Nix multimerization axis triggering autophagy. In patients receiving radiotherapy, GABA(A) receptor activation may improve tumor control while allowing radiation dose de-intensification to reduce toxicity. HighlightsO_LIActivating GABA(A) receptors intrinsic to lung primary and metastatic brain cancer cells triggers a cytotoxic response. C_LIO_LIGABA(A) receptor activation works as well as chemotherapeutic docetaxel in impairing lung cancer viability ex vivo. C_LIO_LIGABA(A) receptor activation increases survival of mice bearing lung metastatic brain tumors. C_LIO_LIA selective-autophagic response is stimulated by GABA(A) receptor activation that includes multimerization of GABARAP and Nix. C_LIO_LIEmploying a new nanomolar affinity peptide that abrogates autophagosome formation inhibits cytotoxicity elicited by GABA(A) receptor activation. C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/569295v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1df2f4eorg.highwire.dtl.DTLVardef@19ac26forg.highwire.dtl.DTLVardef@1533986org.highwire.dtl.DTLVardef@e59653_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

3-D Vascularized Breast Cancer Model to Study the Role of Osteoblast in Formation of a Pre-Metastatic Niche

Breast cancer cells (BCCs) preferentially metastasize to bone. It is known that BCCs remotely primes the distant bone site prior to metastasis. However, the reciprocal influence of bone cells on the primary tumor is relatively overlooked. Here, to study the bone-tumor paracrine influence, a tri-cellular 3-D vascularized breast cancer tissue (VBCTs) model is engineered which comprised MDA-MB231, a triple-negative breast cancer cells (TNBC), fibroblasts, and endothelial cells. The VBCTs are indirectly co-cultured with osteoblasts (OBs), thereby constituting a complex quad-cellular tumor progression model. MDA-MB231 alone and in conjunction with OBs led to abnormal vasculature and reduced vessel density but enhanced VEGF production. A total of 1476 significantly upregulated and 775 downregulated genes are identified in the VBCTs exposed to OBs. HSP90N, CYCS, RPS27A, and EGFR are recognized as upregulated hub-genes. Kaplan Meier plot shows HSP90N to have a significant outcome in TNBC patient survivability. Furthermore, compared to cancer tissues without vessels, gene analysis recognized 1278 significantly upregulated and 566 downregulated genes in VBCTs. DKK1, CXCL13, C3 protein and BMP4 are identified to be downregulated hub genes in VBCTs. Together, a multi-cellular breast cancer model and culture protocols are established to study pre-metastatic events in the presence of OBs.

bioengineering↗

bioRxiv2019

Ubiquitin Links Smoothened to Intraflagellar Transport to Regulate Hedgehog Signaling

In the absence of hedgehog ligand, patched-1 (Ptch1) localizes to cilia and prevents ciliary accumulation and activation of smoothened (Smo). Upon ligand binding, Ptch1 is removed from cilia, Smo is derepressed and accumulates in cilia where it activates signaling. The mechanisms regulating these dynamic movements are not well understood but defects in intraflagellar transport components including Ift27 and the BBSome cause Smo to accumulate in cilia without pathway activation. We find that in the absence of ligand-induced pathway activation, Smo is ubiquitinated and removed from cilia, and this process is dependent on Ift27 and BBSome components. Activation of hedgehog signaling decreases Smo ubiquitination, and ciliary removal, resulting in its accumulation. Blocking ubiquitination of Smo by an E1 ligase inhibitor or by mutating two lysine residues in intracellular loop three cause Smo to aberrantly accumulate in cilia without pathway activation. These data provide a mechanism to control Smos ciliary level during hedgehog signaling by regulating the ubiquitination state of the receptor. SummaryHedgehog signaling involves the dynamic movement of receptors and effectors in and out of cilia. We find that the dynamics of Smo is regulated by ubiquitination, which regulates its interaction with the intraflagellar transport system to control ciliary levels of this receptor.

cell biology↗