Balaji KN

References (2)

Title : Fatty acid chain length drives lysophosphatidylserine-dependent immunological outputs - Khandelwal_2021_Cell.Chem.Biol__
Author(s) : Khandelwal N , Shaikh M , Mhetre A , Singh S , Sajeevan T , Joshi A , Balaji KN , Chakrapani H , Kamat SS
Ref : Cell Chemical Biology , : , 2021
Abstract : In humans, lysophosphatidylserines (lyso-PSs) are potent lipid regulators of important immunological processes. Given their structural diversity and commercial paucity, here we report the synthesis of methyl esters of lyso-PS (Me-lyso-PSs) containing medium- to very-long-chain (VLC) lipid tails. We show that Me-lyso-PSs are excellent substrates for the lyso-PS lipase ABHD12, and that these synthetic lipids are acted upon by cellular carboxylesterases to produce lyso-PSs. Next, in macrophages we demonstrate that VLC lyso-PSs orchestrate pro-inflammatory responses and in turn neuroinflammation via a Toll-like receptor 2 (TLR2)-dependent pathway. We also show that long-chain (LC) lyso-PSs robustly induce intracellular cyclic AMP production, cytosolic calcium influx, and phosphorylation of the nodal extracellular signal-regulated kinase to regulate macrophage activation via a TLR2-independent pathway. Finally, we report that LC lyso-PSs potently elicit histamine release during the mast cell degranulation process, and that ABHD12 is the major lyso-PS lipase in these immune cells.
ESTHER : Khandelwal_2021_Cell.Chem.Biol__
PubMedSearch : Khandelwal_2021_Cell.Chem.Biol__
PubMedID: 33571455
Gene_locus related to this paper: human-ABHD12

Title : Functional role of the PE domain and immunogenicity of the Mycobacterium tuberculosis triacylglycerol hydrolase LipY - Mishra_2008_Infect.Immun_76_127
Author(s) : Mishra KC , de Chastellier C , Narayana Y , Bifani P , Brown AK , Besra GS , Katoch VM , Joshi B , Balaji KN , Kremer L
Ref : Infect Immun , 76 :127 , 2008
Abstract : PE and PPE proteins appear to be important for virulence and immunopathogenicity in mycobacteria, yet the functions of the PE/PPE domains remain an enigma. To decipher the role of these domains, we have characterized the triacylglycerol (TAG) hydrolase LipY from Mycobacterium tuberculosis, which is the only known PE protein expressing an enzymatic activity. The overproduction of LipY in mycobacteria resulted in a significant reduction in the pool of TAGs, consistent with the lipase activity of this enzyme. Unexpectedly, this reduction was more pronounced in mycobacteria overexpressing LipY lacking the PE domain [LipY(deltaPE)], suggesting that the PE domain participates in the modulation of LipY activity. Interestingly, Mycobacterium marinum contains a protein homologous to LipY, termed LipY(mar), in which the PE domain is substituted by a PPE domain. As for LipY, overexpression of LipY(mar) in Mycobacterium smegmatis significantly reduced the TAG pool, and this was further pronounced when the PPE domain of LipY(mar) was removed. Fractionation studies and Western blot analysis demonstrated that both LipY and LipY(deltaPE) were mainly present in the cell wall, indicating that the PE domain was not required for translocation to this site. Furthermore, electron microscopy immunolabeling of LipY(deltaPE) clearly showed a cell surface localization, thereby suggesting that the lipase may interact with the host immune system. Accordingly, a strong humoral response against LipY and LipY(deltaPE) was observed in tuberculosis patients. Together, our results suggest for the first time that both PE and PPE domains can share similar functional roles and that LipY represents a novel immunodominant antigen.
ESTHER : Mishra_2008_Infect.Immun_76_127
PubMedSearch : Mishra_2008_Infect.Immun_76_127
PubMedID: 17938218
Gene_locus related to this paper: myctu-Rv3097c