Disease relevance of PNPLA4

• To investigate regulatory aspects of GS2 phosphorylation, we have produced non-phosphorylated GS2 proteins by expressing the plant cDNA in E. coli and performed in vitro phosphorylation assays [1].

High impact information on PNPLA4

• The kinetics of GS2 mRNA accumulation in response to white-light illumination of etiolated or dark-adapted green plants indicates that GS2 mRNA accumulates more rapidly in plants containing mature, photosynthetically competent chloroplasts [2].
• Dinucleotide repeat polymorphism at the DXS1283E locus [3].
• Here, we present the nucleotide sequence of the pea GS2 gene promoter [4].
• A 323-bp GS2 promoter sequence is sufficient to confer light regulation to the GUS reporter gene in leaves of mature transgenic tobacco [4].
• We have recently reported that GS2 lipase is expressed in keratinocytes and has the enzymatic properties of keratinocyte RE hydrolase [5].

Biological context of PNPLA4

• DNA sequencing of a GS2 cDNA clone revealed an open reading frame for a basic protein of 253 amino acid residues [6].
• Characterization of GS2 genomic clones revealed that the gene consists of 7 exons spanning over 26 kb, with a CpG island located in the first intron [6].
• This is consistent with a function for Desnutrin/ATGL, GS2, and GS2-Like in lipolysis, but not for Adiponutrin [7].
• Molecular screening for GS2 lipase regulators: inhibition of keratinocyte retinylester hydrolysis by TIP47 [5].
• Furthermore, we document that plant extracts contain protease activity that cleaves the GS2 protein only when it is bound to 14-3-3 proteins following either phosphorylation or mimicking of phosphorylation by Ser97Asp [1].

Anatomical context of PNPLA4

• We therefore produced and screened two keratinocyte cDNA expression libraries and identified a previously sequenced gene (GS2) as a keratinocyte retinyl ester (RE) hydrolase insensitive to BNPP [8].
• The GS2 gene is expressed in all human tissues examined, including heart, brain, placenta, lung, liver, muscle, kidney, pancreas, and spleen [6].
• Our data support distinct functions for Adiponutrin and Desnutrin/ATGL and raise the possibility that GS2 may contribute significantly to lipolysis in human adipose tissue [7].
• Using an (His)6-tagged 14-3-3 protein column affinity purification method, we demonstrate that phosphorylated GS2 interacts with 14-3-3 proteins and that this interaction leads to selective proteolysis of the plastid located isoform, resulting in inactivation of the isoenzyme [1].
• A quantitative fluorescent-polymerase chain reaction (QF-PCR) test system with different short tandem repeat (STR) markers of the X chromosome (SBMA, DXS8377 and DXS1283E) together with the amelogenin locus (AMXY) was developed for the rapid detection of sex chromosome aneuploidies on uncultured amniotic fluids [9].

Associations of PNPLA4 with chemical compounds

• Overexpression of Desnutrin/ATGL, GS2, and GS2-Like, but not Adiponutrin, decreases intracellular triglyceride levels [7].
• As GS2 lipase has a robust activity that can affect the intracellular retinol levels, we postulated that its activity must be regulated [5].

Other interactions of PNPLA4

• The GS2 gene is transcribed toward Xpter, in the same direction as KAL1 but opposite to that of STS [6].
• Here, we report on the expression, regulation, and activity of GS2 and GS2-Like compared with Adiponutrin and Desnutrin/ATGL [7].

Analytical, diagnostic and therapeutic context of PNPLA4

• Gel-shift analysis detected DNA-protein complexes formed with potential transcription elements within this short, light-responsive GS2 promoter fragment [4].
• By site directed mutagenesis we were able to identify a GS2 phosphorylation site (Ser97) crucial for the interaction with 14-3-3s [1].
• The catalytic competence of gramicidin S synthetase 2 (GS2) was determined by following the kinetics of PP(i) generation using active site titration measurements with [gamma-(32)P]ATP [10].

References