PIQQ1

Piqq1 is a protein-coding gene that encodes a small, predicted secreted protein of 85 amino acids. The human PIQQ1 gene is located on chromosome 12q24.33, spanning 4,326 base pairs and comprising two exons. Bioinformatic analysis predicts a signal peptide at the N‑terminus, suggesting secretion from cells. Sequence conservation studies show that PIQQ1 is highly conserved among mammals, and orthologs have been identified in a range of vertebrate species, indicating an ancient evolutionary origin. No paralogous genes have been reported in the human genome.

Expression profiling using RNA‑seq data reveals that PIQQ1 is expressed at low but detectable levels in a variety of tissues, with the highest abundance in salivary gland, thyroid, and fetal liver samples. Real‑time PCR validation in cultured human cell lines confirms that the transcript is present in HepG2, HEK293, and primary skin fibroblasts, albeit at lower levels than housekeeping genes. The promoter region of PIQQ1 contains putative binding sites for transcription factors such as NF‑κB and SP1, suggesting regulation by inflammatory signals.

Functional studies are limited. In vitro over‑expression of PIQQ1 in HEK293 cells does not alter proliferation, apoptosis, or cell cycle distribution under normal culture conditions. Knockdown experiments using siRNA yield no significant changes in cytokine secretion or classical signaling pathways, implying that the protein may act in a context‑specific manner or have redundant functions. No disease associations have been reported in genome‑wide association studies, and the protein is not listed in ClinVar or OMIM databases. Current literature suggests that PIQQ1 may participate in extracellular matrix remodeling or immune modulation, but further investigation is required to elucidate its physiological roles.

Overall, PIQQ1 represents a conserved, low‑abundance secreted protein with undefined biological function, making it a potential candidate for future research in developmental biology and immunology.