Product details
Synonyms = poly(ADP-ribose) polymerase 1 , ADPRT , ADPRT 1 , ADPRT1 , ARTD1 , PARP , PARP-1 , PPOL , pADPRT-1
Antibody type = Recombinant Rabbit monoclonal / IgG
Clone = HMV334
Positive control = Placenta: A strong PARP1 positivity should be seen in all cell types except syncytiotrophoblast.
Negative control = Placenta: PARP1 positivity should be absent in the syncytiotrophoblast.
Cellular localization = Nuclear
Reactivity = Human
Application = Immunohistochemistry
Dilution = 1:100 – 1:200
Intended Use = Research Use Only
Relevance of Antibody
PARP1 is a Pleitropic gene with a critical role in DNA repair.
Biology Behind
Poly(ADP-ribose) polymerase 1 (PARP1), is a 113 kDa nuclear protein coded by the PARP1 gene on chromosome 1q42.12. PARP1 is the first detected and most abundant member of the PARP superfamily. It modulates the activity of DNA binding proteins by catalyzing their Poly(ADP-ribosyl)ation (PARylation), a post-translational modification affecting the conformation and function of affected proteins. PARP1 impacts several DNA repair processes including the pathways of nucleotide excision repair, non-homologous end joining, microhomology-mediated end joining, homologous recombinational repair, and DNA mismatch repair. PARP1 detects DNA damage and then modulates repair efficiency by ADP-ribosylation of histones, subsequent decompaction of chromatin structure, and through interaction with and modification of multiple DNA repair factors. PARP1 and PARylation also play a role in a wide range of further cellular processes such as cell death, chromatin remodeling, inflammatory response and gene transcription which can be independent of DNA damage response. PARP1 and PARylation homeostasis have also been implicated in multiple diseases, including inflammation, stroke, diabetes and cancer. Several PARP1 inhibitors have been approved as cancer drugs and they are successfully applied in an increasing number of different cancer types.
Staining Pattern in Normal Tissues
Images describing the PARP1 staining pattern in normal tissues obtained by the antibody HMV334 are shown in our “Normal Tissue Gallery”.
Brain | Cerebrum | In epithelial cells, PARP1 staining is strongest in the crypts. |
Cerebellum | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Endocrine Tissues | Thyroid | In epithelial cells, PARP1 staining is strongest in the crypts. |
Parathyroid | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Adrenal gland | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Pituitary gland | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Respiratory system | Respiratory epithelium | In epithelial cells, PARP1 staining is strongest in the crypts. |
Lung | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Gastrointestinal Tract | Salivary glands | In epithelial cells, PARP1 staining is strongest in the crypts. |
Esophagus | Strong PARP1 staining of most squamous epithelial cells. The staining intensity decreases somewhat from the basal/suprabasal to the surface cell layers. | |
Stomach | ||
Duodenum | Distinct staining of all cells. In the epithelium, the staining intensity decreases somewhat from the glands to tips of the villi. | |
Small intestine | Distinct staining of all cells. In the epithelium, the staining intensity decreases somewhat from the glands to tips of the villi. | |
Appendix | Distinct staining of all cells. In epithelial cells, PARP1 staining intensity is lowest in surface epithelial cells. | |
Colon | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Rectum | In epithelial cells, PARP1 staining is strongest in the crypts. | |
Liver | PARP1 staining of hepatocytes may vary between samples. | |
Gallbladder | Strong PARP1 positivity of all cells. | |
Pancreas | Strong PARP1 positivity of all cells. | |
Genitourinary | Kidney | Distinct PARP1 positivity of all cells.Staining is weakest in proximal tubuli. |
Urothelium | Distinct PARP1 positivity of all urothelial cells. | |
Male genital | Prostate | Strong PARP1 positivity of all cells. |
Seminal vesicles | Strong PARP1 positivity of all cells. | |
Testis | Strong PARP1 positivity of all cells. | |
Epididymis | Strong PARP1 positivity of all cells. | |
Female genital | Breast | Strong PARP1 positivity of all cells. |
Uterus, myometrium | Strong PARP1 positivity of all cells. | |
Uterus, ectocervix | Strong PARP1 staining of most squamous epithelial cells. The staining intensity decreases somewhat from the basal/suprabasal to the surface cell layers. | |
Uterus endocervix | Strong PARP1 positivity of all cells. | |
Uterus, endometrium | Strong PARP1 positivity of all cells. | |
Fallopian Tube | Strong PARP1 positivity of all cells. | |
Ovary | Strong PARP1 positivity of all cells. | |
Placenta early | Absence of PARP1 staining in the syncytiotrophoblast. Distinct PARP1 positivity of all other cells. | |
Placenta mature | Absence of PARP1 staining in the syncytiotrophoblast. Distinct PARP1 positivity of all other cells. | |
Amnion | Strong PARP1 positivity of all cells. | |
Chorion | Strong PARP1 positivity of all cells. | |
Skin | Epidermis | Strong PARP1 staining of most squamous epithelial cells. The staining intensity decreases somewhat from the basal/suprabasal to the surface cell layers. |
Sebaceous glands | Strong PARP1 positivity of all cells. | |
Muscle/connective tissue | Heart muscle | Strong PARP1 positivity of all cells. |
Skeletal muscle | Strong PARP1 positivity of all cells. | |
Smooth muscle | Strong PARP1 positivity of all cells. | |
Vessel walls | Strong PARP1 positivity of all cells. | |
Fat | Strong PARP1 positivity of all cells. | |
Stroma | Strong PARP1 positivity of all cells. | |
Endothelium | Strong PARP1 positivity of all cells. | |
Bone marrow/ lymphoid tissue | Bone marrow | Strong PARP1 positivity of all cells. |
Lymph node | Strong PARP1 positivity of all cells. | |
Spleen | Strong PARP1 positivity of all cells. | |
Thymus | Strong PARP1 positivity of all cells. | |
Tonsil | Strong PARP1 staining of all cells. In the squamous epithelium, the staining intensity decreases from the basal/suprabasal to the surface cell layers. | |
Remarks | A distinct nuclear PARP1 staining is seen in virtually all cell types. |
A nuclear PARP1 staining occurs in virtually all tissues and cell types. The level of PARP1 expression varies between tissues/cell types to some extent. The syncytiotrophoblast of the placenta is the only cell type without detectable PARP1 staining.
RNA and protein expression data of PARP1 findings are also described in the Human Protein Atlas (Tissue expression PARP1).
Positive control = Placenta: A strong PARP1 positivity should be seen in all cell types except syncytiotrophoblast.
Negative control = Placenta: PARP1 positivity should be absent in the syncytiotrophoblast.
Staining Pattern in Relevant Tumor Types
A positive PARP1 immunostaining (intensity may vary) is usually seen in tumor cells of virtually all cancer types as well as in tumor associated stromal and inflammatory cells.
The TCGA findings on PARP1 RNA expression in different tumor categories have been summarized in the Human Protein Atlas.
Compatibility of Antibodies
No data available at the moment
Protocol Recommendations
IHC users have different preferences on how the stains should look like. Some prefer high staining intensity of the target stain and even accept some background. Others favor absolute specificity and lighter target stains. Factors that invariably lead to more intense staining include higher concentration of the antibody and visualization tools, longer incubation time, higher temperature during incubation, higher temperature and longer duration of the heat induced epitope retrieval (slide pretreatment). The impact of the pH during slide pretreatment has variable effects and depends on the antibody and the target protein.
All images and data shown here and in our image galleries are obtained by the manual protocol described below. Other protocols resulting in equivalent staining are described as well.
Manual protocol
Freshly cut sections should be used (less than 10 days between cutting and staining). Heat-induced antigen retrieval for 5 minutes in an autoclave at 121°C in pH 7,8 Target Retrieval Solution buffer. Apply HMV334 at a dilution of 1:200 at 37°C for 60 minutes. Visualization of bound antibody by the EnVision Kit (Dako, Agilent) according to the manufacturer’s directions.
Potential Research Applications
- The clinical significance (prognostic/predictive) of PARP1 expression levels in cancer is unknown.
- The prevalence of PARP1 expression loss in cancer and its clinical significance is unknown.
- The role of PARP1 in disease awaits further investigation.
Evidence for Antibody Specificity in IHC
There are two ways how the specificity of antibodies can be documented for immunohistochemistry on formalin fixed tissues. These are: 1. Comparison with a second independent method for target expression measurement across a large number of different tissue types (orthogonal strategy), and 2. Comparison with one or several independent antibodies for the same target and showing that all positive staining results are also seen with other antibodies for the same target (independent antibody strategy).
Orthogonal validation: For the antibody HMV334 specificity is in line with data from three independent RNA screening studies, including the Human Protein Atlas (HPA) RNA-seq tissue dataset, the FANTOM5 project, and the Genotype-Tissue Expression (GTEx) project, which are all summarized in the Human Protein Atlas (Tissue expression PARP1). In agreement with HMV334 immunostaining data, RNA expression predominated in the bone marrow and lymphoid tissues and it was comparably low in the testis. However, it must be understood that orthogonal validation is not optimal for assessing ubiquitously expressed protein.
Comparison of antibodies: True expression of PARP1 in all cell types with PARP1 positivity seen by HMV334 is corroborated by an identical staining obtained by a commercially available independent second antibody (termed “validation antibody”). Most of all, both antibodies only showed a complete lack of nuclear staining in the syncytiotrophoblast of the placenta, and a continuous decrease of staining intensity from basal cells to surface epithelial cells of squamous epithelium at different locations.