Biology subjects

Patel, B. B.

Publications and source records attributed to Patel, B. B..

4 recordsLinked to original sources

bioRxiv2023

Direct ionic stress sensing and mitigation by the transcription factor NFAT5

Homeostatic control of intracellular ionic strength is essential for protein, organelle and genome function, yet mechanisms that sense and enable adaptation to ionic stress remain poorly understood in animals. We find that the transcription factor NFAT5 directly senses solution ionic strength using a C-terminal intrinsically disordered region. Both in intact cells and in a purified system, NFAT5 forms dynamic, reversible biomolecular condensates in response to increasing ionic strength. This self-associative property, conserved from insects to mammals, allows NFAT5 to accumulate in the nucleus and activate genes that restore cellular ion content. Mutations that reduce condensation or those that promote aggregation both reduce NFAT5 activity, highlighting the importance of optimally tuned associative interactions. Remarkably, human NFAT5 alone is sufficient to reconstitute a mammalian transcriptional response to ionic or hypertonic stress in yeast. Thus NFAT5 is both the sensor and effector of a cell-autonomous ionic stress response pathway in animal cells.

cell biology↗

bioRxiv2021

Gene-teratogen interactions influence the penetrance of birth defects by altering Hedgehog signaling strength

Birth defects result from interactions between genetic and environmental factors, but the mechanisms remain poorly understood. We find that mutations and teratogens interact in predictable ways to cause birth defects by changing target cell sensitivity to Hedgehog (Hh) ligands. These interactions converge on a membrane protein complex, the MMM complex, that promotes degradation of the Hh transducer Smoothened (SMO). Deficiency of the MMM component MOSMO results in elevated SMO and increased Hh signaling, causing multiple birth defects. In utero exposure to a teratogen that directly inhibits SMO reduces the penetrance and expressivity of birth defects in Mosmo-/- embryos. Additionally, tissues that develop normally in Mosmo-/- embryos are refractory to the teratogen. Thus, changes in the abundance of the protein target of a teratogen can change birth defect outcomes by quantitative shifts in Hh signaling. Consequently, small molecules that re-calibrate signaling strength could be harnessed to rescue structural birth defects.

developmental biology↗

bioRxiv2019

Discovery, optimization, and cellular activities of 2-(aroylamino)cinnamamide derivatives against colon cancer

Curcumin and trans-cinnamaldehyde are acrolein-based Michael acceptor compounds that are commonly found in domestic condiments, and known to cause cancer cell death via redox mechanisms. Based on the structural features of these compounds we designed and synthesized several 2-cinnamamido-N-substituted-cinnamamide (bis-cinnamamide) compounds. One of the derivatives, (Z)-2-[(E)-cinnamamido]-3-phenyl-N-propylacrylamide (1512) showed a moderate antiproliferative potency (HT116 cell line inhibition of 32.0 {micro}M {+/-} 2.6) with proven cellular activities leading to apoptosis. Importantly, 1512 exhibited good selectivity toxicity on cancer cells over noncancerous cells (IC50 of C-166 cell lines >100 {micro}M), and low cancer cell resistance at 100 {micro}M dose (growth rate 10.1{+/-}1.1%). We subsequently carried out structure activity relationship studies with 1512. Derivatives with electron rich moiety at the aryl ring of the 2-aminocinnamaide moiety exhibited strong antiproliferative action while electron withdrawing groups caused loss of activity. Our most promising compound, 4112 [(Z)-3-(1H-indol-3-yl)-N-propyl-2-[(E)-3-(thien-2-yl)propenamido)propenamide] killed cancer cells at IC50 = 0.89 {+/-} 0.04 {micro}M (Caco-2), 2.85 {+/-} 1.5 (HCT-116) and 1.65 {+/-} 0.07 (HT-29), while exhibiting much weaker potency on C-166 and BHK normal cell lines (IC50 = 71 {+/-} 5.12 and 77.6 {+/-} 6.2 {micro}M, respectively). Cellular studies towards identifying the compounds mechanism of cytotoxic activities revealed that apoptotic induction occurs in part due to oxidative stress. Importantly, the compounds showed inhibition of cancer stem cells that are critical for maintaining the potential for self-renewal and stemness. The results presented here show discovery of Michael addition compounds that potently kill cancer cells by a defined mechanism, with minimal effect on normal noncancerous cell.

cancer biology↗

bioRxiv2018

Discovery of gene regulatory elements through a new bioinformatics analysis of haploid genetic screens

The systematic identification of regulatory elements that control gene expression remains a challenge. Genetic screens that use untargeted mutagenesis have the potential to identify protein-coding genes, non-coding RNAs and regulatory elements, but their analysis has mainly focused on identifying the former two. To identify regulatory elements, we conducted a new bioinformatics analysis of insertional mutagenesis screens interrogating WNT signaling in haploid human cells. We searched for specific patterns of retroviral gene trap integrations (used as mutagens in haploid screens) in short genomic intervals overlapping with introns and regions upstream of genes. We uncovered atypical patterns of gene trap insertions that were not predicted to disrupt coding sequences, but caused changes in the expression of two key regulators of WNT signaling, suggesting the presence of cis-regulatory elements. Our methodology extends the scope of haploid genetic screens by enabling the identification of regulatory elements that control gene expression.

bioinformatics↗