GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE213nnn/GSE213724/primaryOK200GenomicsHomo sapiensNon-coding RNA profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE213724GEOGSEfalseEffects of overexpression on miRNA isoforms and the targetomeTranslational inhibition or degradation of messenger RNAs by microRNAs represent core regulatory mechanisms with a high grade of complexity proposed by experimental and computational approaches. One proposed important factor is isoforms of mature microRNAs (isomirs), adding numerous potential targets and functions. For a set of miRNAs (mir-34a, mir-129, mir-873, mir-133b, mir-7), we characterized the impact of their overexpression in cell culture models (HeLa, HEK293T, LUHMES, SH-SY5Y) on the detection of isomiRs. We observed an astonishing heterogeneity of isomiRs between cell lines, emphasizing a significantly increased isomiR repertoire following artificial overexpression with up to 832 different isoforms per miRNA. Performing a dilution and a time series, we validated a significantly increased isomiR repertoire after 8 hours and for precursor amounts of 0.5 µg. Proteomic analysis further argued for a significant influence of the isomiR repertoire depending on the miRNA amount. While 7mer-m8 sites revealed the highest reduction effect in general, we report an increased frequency but lower amplitude of repression with an increasing number of miR-7-5p isoforms. Our data call attention to interpreting the proposed impact of isomiRs on the targetome, especially using overexpression systems.2026/08/13GSE213724GSM6592636GSM6592637GSM6592638GSM6592639GSM6592680GSM6592681GSM6592682GSM6592643GSM6592600GSM6592644GSM6592601GSM6592645GSM6592646GSM6592602GSM6592683GSM6592640GSM6592684GSM6592641GSM6592642GSM6592607GSM6592608GSM6592609GSM6592603GSM6592647GSM6592604GSM6592648GSM6592649GSM6592605GSM6592606GSM6592610GSM6592654GSM6592655GSM6592611GSM6592612GSM6592656GSM6592613GSM6592657GSM6592650GSM6592651GSM6592652GSM6592653GSM6592618GSM6592619GSM6592658GSM6592614GSM6592615GSM6592659GSM6592616GSM6592617GSM6592660GSM6592621GSM6592665GSM6592589GSM6592666GSM6592622GSM6592623GSM6592667GSM6592624GSM6592668GSM6592661GSM6592662GSM6592663GSM6592620GSM6592664GSM6592629GSM6592669GSM6592625GSM6592626GSM6592627GSM6592628GSM6592591GSM6592592GSM6592670GSM6592593GSM6592594GSM6592671GSM6592590GSM6592632GSM6592599GSM6592676GSM6592633GSM6592677GSM6592678GSM6592634GSM6592635GSM6592679GSM6592672GSM6592595GSM6592596GSM6592673GSM6592630GSM6592597GSM6592674GSM6592675GSM6592598GSM659263128038213724Homo sapiens