Malte Renz, MD, PhD

All Publications

• Vulvar sarcoma outcomes by histologic subtype: a Surveillance, Epidemiology, and End Results (SEER) database review. International journal of gynecological cancer : official journal of the International Gynecological Cancer Society Johnson, S., Renz, M., Wheeler, L., Diver, E., Dorigo, O., Litkouhi, B., Behbakht, K., Howitt, B., Karam, A. 2020

  Abstract

  Vulvar cancers account for 5% of all gynecologic malignancies; only 1%-3% of those vulvar cancers are primary vulvar sarcomas. Given the rarity of vulvar sarcomas, outcome data specific to histopathologic subtypes are sparse. The aim of this study was to identify clinical and pathologic factors of primary vulvar sarcomas that are associated with survival and may inform treatment decisions.The Surveillance, Epidemiology, and End Results (SEER) database was searched for women diagnosed with vulvar sarcoma between 1973 and 2018. We identified 315 patients and reviewed their demographic, clinicopathologic, surgical, and survival information. Statistical analyses included χ2 and t-tests, Kaplan-Meier survival, and Cox regression analyses.The most common histopathologies of vulvar sarcomas were dermatofibrosarcomas (85/315, 27%) and leiomyosarcomas (72/315, 22.9%). Rhabdomyosarcomas (18/315, 5.7%), liposarcomas (16/315, 5.1%), and malignant fibrous histiocytomas (16/315, 5.1%) were less frequent. The majority of patients underwent surgery (292/315, 92.7%), which included lymph node dissections in 21.6% (63/292). Survival and lymph node involvement varied significantly with histologic subtype. The 5-year disease-specific survival for dermatofibrosarcomas, liposarcomas, and fibrosarcomas was 100% and only 60.3% and 62.5% for malignant fibrous histiocytomas and rhabdomyosarcomas, respectively. None of the patients with (dermato)fibrosarcomas, liposarcomas, or leiomyosarcomas had positive lymph nodes, in contrast to rhabdomyosarcomas and malignant fibrous histiocytomas with 77.8% and 40% positive lymph nodes, respectively. The 5-year disease-specific survival for women with positive lymph nodes was 0%.Vulvar sarcomas are heterogeneous with survival highly dependent on the histopathologic subtype. While surgical excision is the mainstay of treatment for all vulvar sarcomas, staging lymphadenectomy should be deferred for (dermato)fibrosarcomas, liposarcomas, and leiomyosarcomas as there were no cases of lymph nodes metastases.

  View details for DOI 10.1136/ijgc-2020-001516

  View details for PubMedID 32641392

• Biologic, Targeted, and Immune Therapy Berek and Hacker's Gynecologic Oncology Renz, M., Berek, J. S., Dorigo, O. Lippincott Williams & Wilkins (LWW). 2020; 7th: 36–59
• Cancer Genetics Berek and Hacker's Gynecologic Oncology Renz, M., Kurian, A. Lippincott Williams & Wilkins (LWW). 2020; 7th: 2–22
• Long-term outcome of postmenopausal women with proliferative endometrium on endometrial sampling. American journal of obstetrics and gynecology Rotenberg, O., Doulaveris, G., Fridman, D., Renz, M., Kaplan, J., Xie, X., Goldberg, G. L., Dar, P. 2020

  Abstract

  Proliferative endometrium has been reported in 15% of endometrial biopsies of women aged 50 years and older. Contrary to endometrial hyperplasia, proliferative endometrium has not been associated with the risk of endometrial cancer.This study aimed to report on the long-term outcome of postmenopausal women who received a diagnosis of proliferative endometrium.This is a retrospective cohort study of 1808 women aged 55 years and older who underwent endometrial sampling between January 1997 and December 2008. Outcome data were available through February 2018. Women with a proliferative endometrium were compared with those with an atrophic endometrium for future development of endometrial hyperplasia or cancer. A subanalysis was performed for those who presented with postmenopausal bleeding. Uni- and multivariable logistic regression analyses were used to assess for confounders.In this study, 297 women (16.4%) received a diagnosis of proliferative endometrium. Furthermore, 962 women met the inclusion criteria. Among those women, 278 had a proliferative endometrium, and 684 had an atrophic endometrium. Women with a proliferative endometrium were younger (61.2 vs 64.5 years; P<.0001) and had a higher body mass index (33.9 vs 30.6 kg/m2; P<.0001). More African American women had a proliferative endometrium. Both groups had a similar length of surveillance (11.9 vs 11.5 years; P=.27). Women with a proliferative endometrium had a higher risk of developing endometrial hyperplasia or cancer (11.9% vs 2.9%; P<.0001), any endometrial cancer (5.8% vs 1.8%; P=.002), atypical endometrial hyperplasia (2.2% vs 0.4%; P=.02), and nonatypical endometrial hyperplasia (2.0% vs 0.7%; P=.001). The risk of developing endometrial cancer and endometrial hyperplasia remained similar after excluding cases on hormonal replacement therapy (12.2% vs 3%; P=.001). On logistic regression analysis, proliferative endometrium histology (odds ratio, 3.89; 95% confidence interval, 2.03-7.49; P<.0001), age >60 years (odds ratio, 1.98; 95% confidence interval, 1.03-3.82; P=.04), and body mass index >35 kg/m2 (odds ratio, 2.3; 95% confidence interval, 1.09-4.83; P<.0001) remained significant risk factors for progression to cancer.One of the 6 postmenopausal women who underwent endometrial sampling had a proliferative endometrium. Furthermore, 11.9% of women developed endometrial hyperplasia or cancer, a 4-fold greater incidence than women with an atrophic endometrium. The findings of this study suggest that long-term monitoring is warranted for women with postmenopausal bleeding and a proliferative endometrium histology. Further studies are needed to examine if a treatment is required to negate the risk of unopposed estrogen.

  View details for DOI 10.1016/j.ajog.2020.06.045

  View details for PubMedID 32640199

• Dissecting Oligomeric States with Photoactivated Localization Microscopy: A Numerical Model. Cytometry. Part A : the journal of the International Society for Analytical Cytology Daniels, B., Wunder, C., Chen, V., Renz, M. 2020

  Abstract

  Although photoactivated localization microscopy offers the potential to interrogate protein interactions in the physiological environment of a cell, uncertainties in the detection efficiency of photoactivatable proteins lead to complications with data interpretation. Here, we present a numerical model that provides probabilities to detect neighboring molecules dependent on their oligomerization status, density, detection efficiency, and radius, and can be used to assess oligomeric states or detection efficiencies of two molecular species. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of International Society for Advancement of Cytometry.

  View details for DOI 10.1002/cyto.a.24167

  View details for PubMedID 32558006

• The role of asymptomatic screening in the detection of recurrent ovarian cancer. Gynecologic oncology reports Richardson, M. T., Routson, S., Karam, A., Dorigo, O., Levy, K., Renz, M., Diver, E. J. 2020; 33: 100595

  Abstract

  To investigate the utility of asymptomatic screening, including CA-125, imaging, and pelvic exam, in the diagnosis and management of recurrent ovarian cancer.Women with ovarian cancer whose cancer recurred after remission were categorized by first method that their provider suspected disease recurrence: CA-125, imaging, symptoms, or physical exam. Differences in clinicopathologic, primary treatment characteristics, and outcomes data including secondary cytoreductive surgery (SCS) outcome and overall survival (OS) were collected.102 patients were identified at our institution from 2003 to 2015. 20 recurrences were detected by symptoms, while 62 recurrences were diagnosed first by asymptomatic rise in CA-125, 5 by pelvic exam, and 15 by imaging in the absence of known exam abnormality or rise in CA-125.Mean time to recurrence was 18.9 months, and median survival was 45.8 months. These did not vary by recurrence detection method (all p > 0.4). Patients whose disease was detected by CA-125 were less likely to undergo SCS than those detected by other means (21.7% vs. 35.0%, p = 0.007). In addition to the 5 patients whose recurrence was detected primarily by pelvic exam, an additional 10 (total n = 15) patients had an abnormal pelvic exam at time of diagnosis of recurrence.Recurrence detection method was not associated with differing rates of survival or optimal SCS, however those patients detected by CA-125 were less likely to undergo SCS. The pelvic exam was a useful tool for detecting a significant proportion of recurrences.

  View details for DOI 10.1016/j.gore.2020.100595

  View details for PubMedID 32548232

  View details for PubMedCentralID PMC7286959

• In invasion assays, the breast cancer cell nucleus leads the way. BMC research notes Renz, M. 2020; 13 (1): 480

  Abstract

  Cancer cell metastasis determines disease prognosis. During cancer cell metastasis, the cancer cell and the cancer cell nucleus have to undergo extreme shape changes. To monitor shape changes of cancer cells and cancer cell nuclei and the positioning of the cancer cell nucleus during cancer cell invasion, a customized invasion assay with 8-μm pores and reconstituted basal membrane was imaged using fluorescence live-cell microscopy.The observed cells changed their shape from a distinct fibroblast-like spindle shape to an amoeboid shape without polarization immediately after the passage through an 8-μm pore of the invasion assay. During the process of invasion, the cancer cell centered the cancer cell nucleus over the 8-μm pore, and cancer cell nucleus and adjacent cytoplasmic areas moved first through such a pore. Seemingly testing if the largest and least deformable organelle may fit, the cancer cell nucleus led the way through the porous membrane of the invasion assay.

  View details for DOI 10.1186/s13104-020-05314-9

  View details for PubMedID 33046121

• Long-term outcome of postmenopausal women with non-atypical endometrial hyperplasia on endometrial sampling. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology Rotenberg, O., Fridman, D., Doulaveris, G., Renz, M., Kaplan, J., Gebb, J., Xie, X., Goldberg, G. L., Dar, P. 2019

  Abstract

  OBJECTIVE: To assess the long-term outcome of post-menopausal women diagnosed with non-atypical endometrial hyperplasia (NEH).METHODS: It is a retrospective study of women aged 55 and older who underwent endometrial sampling in our large academic medical center between 1997 and 2008. Women diagnosed with NEH were included in the study group and were compared to women diagnosed with atrophic endometrium on endometrial sampling. Outcome data was obtained through February 2018. The main outcomes were the risk of progression to endometrial carcinoma and the risk of persistent endometrial hyperplasia (EH). Logistic regression was used to identify covariates that remained significant risk factors for cancer progression.RESULTS: 1808 women aged 55 and older underwent endometrial sampling during the study period. The median surveillance time was 10.0years. 73 women were found to have NEH and they were compared to 742 women with atrophic endometrium (AE). When compared to women with AE, women with NEH had a significantly higher BMI (33.9 vs. 30.6, p=0.01), a higher rate of progression to type 1 endometrial cancer and persistent endometrial hyperplasia (8.2% vs. 0.8%, p<0.0001 and 21.9% vs 0.7% respectively, p<0.0001). They also had a higher rate of progression to all types of uterine cancer or persistent hyperplasia (32.9% vs 3.4%, p<0.0001). Women with NEH also had significantly higher rate of future surgical intervention (50.7% vs 15.4%, p<0.0001) and future hysterectomy (34.3% vs. 9.6%, p<0.0001). On logistic regression analysis, NEH, BMI>35, thick endometrium on ultrasound and diabetes remained significant risk factors for progression to cancer.CONCLUSIONS: Postmenopausal women with NEH are at significant risk for persistent endometrial hyperplasia (EH) and progression to uterine cancer, at higher rates than rates previously reported. Guidelines for the appropriate management of postmenopausal women with NEH are needed to decrease the rate of persistent disease or progression to cancer. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/uog.20421

  View details for PubMedID 31389091

• Immediate intraoperative sentinel lymph node analysis by frozen section is predictive of lymph node metastasis in endometrial cancer. Journal of robotic surgery Renz, M., Marjon, N., Devereaux, K., Raghavan, S., Folkins, A. K., Karam, A. 2019

  Abstract

  Sentinel lymph nodes sampling (SLN) in endometrial cancer is being evaluated as a means to gather prognostic information about lymphatic metastasis while avoiding the morbidity associated with complete lymphadenectomy. SLN ultrastaging has been advocated to identify low-volume metastases, but its value remains uncertain. This study aims to evaluate a pathological protocol for the immediate intraoperative SLN work-up using H&E staining alone. In this retrospective single-center study, patients received standardized cervical injection of indocyanine green, SLN mapping followed by pelvic lymphadenectomy with or without para-aortic lymphadenectomy. SLNs were entirely frozen, multiple H&E stained sections prepared and evaluated intraoperatively. No immunohistochemistry was performed. SLN results were compared with the complete lymphadenectomy specimen. Over 3.5 years, 90 patients were identified who underwent SLN mapping and subsequent complete pelvic lymphadenectomy. At least one SLN was detected in 79 (88%) patients. The median number of SLNs removed was 2.0. Para-aortic SLNs were detected in 7%. Final pathology showed 67% Type I tumors, 76% locally confined. The mean number of lymph nodes removed during complete lymphadenectomy was 21. In this series, only 6 patients had lymph node metastases. 5/6 were identified by the described SLN approach resulting in 83.3% sensitivity and a negative predictive value of 98.7%. Our approach permits immediate intraoperative results and helps guide the primary surgery. The immediate SLN work-up using frozen sections showed both high accuracy and negative predictive value. The comparably lower sensitivity may be related to the low number of patients with positive lymph nodes (7.6%).

  View details for PubMedID 30687881

• How to Quantify the Fraction of Photoactivated Fluorescent Proteins in Bulk and in Live Cells. Journal of visualized experiments : JoVE Chen, V., Renz, M. 2019

  Abstract

  Photoactivatable and -convertible fluorescent proteins (PA-FPs) have been used in fluorescence live-cell microscopy for analyzing the dynamics of cells and protein ensembles. Thus far, no method has been available to quantify in bulk and in live cells how many of the PA-FPs expressed are photoactivated to fluoresce. Here, we present a protocol involving internal rulers, i.e., genetically coupled spectrally distinct (photoactivatable) fluorescent proteins, to ratiometrically quantify the fraction of all PA-FPs expressed in a cell that are switched on to be fluorescent. Using this protocol, we show that different modes of photoactivation yielded different photoactivation efficiencies. Short high-power photoactivation with a confocal laser scanning microscope (CLSM) resulted in up to four times lower photoactivation efficiency than hundreds of low-level exposures applied by CLSM or a short pulse applied by widefield illumination. While the protocol has been exemplified here for (PA-)GFP and (PA-)Cherry, it can in principle be applied to any spectrally distinct photoactivatable or photoconvertible fluorescent protein pair and any experimental set-up.

  View details for PubMedID 30663670

• Synopsis of Key Gynecologic Oncology Trials Renz, M., Diver, E., Growdon, W., Dorigo, O. CRC Press. 2019

  View details for DOI 10.1201/9780429200199

• Sentinel lymph node biopsies in endometrial cancer - practice patterns among Gynecologic Oncologists in the United States. Journal of minimally invasive gynecology Renz, M., Diver, E., English, D., Kidd, E., Dorigo, O., Karam, A. 2019

  Abstract

  To evaluate practice patterns among gynecologic oncologists with regards to sentinel lymph node injection and biopsy in endometrial cancer.Observational study with no control group.Active members of the Society of Gynecologic Oncology.After IRB approval, we performed an online survey amongst active members of the Society of Gynecologic Oncology. Members were contacted via email and their answers anonymously captured. Study data were collected using REDCap.318 of 1216 listed members completed the online survey, The majority of respondents (82.7%) perform sentinel lymph node sampling for endometrial cancer staging. Most technical aspects of sentinel lymph node sampling were consistently applied by the vast majority of respondents, including the choice of indocyanine green (ICG) as lymphatic tracer (97.3%) and its injection into the cervix (100%). Other technical aspects of sentinel lymph node sampling, such as the depth of injection, varied amongst respondents. While 50.9% of the respondents perform an intraoperative assessment of the uterus by frozen section, only 17.9% assess sentinel lymph nodes by frozen section and/or touch prep. Some of the respondents' approaches are based on limited data, including (i) the use of sentinel lymph node injection and biopsy for high-risk histologies (performed by 69 - 75% of the respondents dependent upon the histology), (ii) omitting side-specific completion lymphadenectomy in the absence of sentinel node mapping (in up to 57.8%) or (iii) when lymph node metastases are present (in 39.9%).In summary, despite the growing use of sentinel lymph node injection and biopsy in endometrial cancer, practice patterns vary considerably among providers sampled by this survey. Some of the decisions are based on limited evidence and, in some instances, deviate from current published guidelines.

  View details for PubMedID 30980995

• Robotic Olympics: A novel robotic surgical training experience for residents in an obstetrics and gynecology residency program PeerJ PrePrints Renz, M., Liberman, E., Daniels, B., Isani, S., Kuo, D. Y., Nevadunsky, N. 2018

  View details for DOI 10.7287/peerj.preprints.3510v2

• Cytoplasmic self-organization established by internal lipid membranes in the interplay with either actin or microtubules bioRxiv Tang*, S., Renz*, M., Shemesh, T., Driscoll, M., Lippincott-Schwartz, J. 2018

  View details for DOI 10.1101/506436

• Internal rulers to assess fluorescent protein photoactivation efficiency. Cytometry. Part A : the journal of the International Society for Analytical Cytology Renz, M., Wunder, C. 2017

  Abstract

  Photoactivatable fluorescent proteins (PA-FPs) have been widely used to assess the dynamics of cell biological processes. In addition, PA-FPs enabled single-molecule based super-resolution imaging (photoactivated localization microscopy) and thereby provided unprecedented structural insight. For the lack of tools, however, the fraction of PA-FPs that is, actually being switched on to fluoresce, that is, the photoactivation efficiency, has been difficult to assess. Uncertainty about photoactivation efficiency has hampered an understanding of the absolute amount of PA-FPs, that is, being examined. Here, we present internal rulers to assess photoactivation efficiencies of photoactivatable proteins. These internal rulers comprise a PA-FP that is genetically directly coupled to a spectrally distinct always-on fluorescent protein. Thus, these fluorescent proteins will be expressed in the bacterial and mammalian cell in a one-to-one ratio. With these tools, we describe photoactivation efficiencies of PA-GFP and PA-Cherry in intensity-based ratiometric ensemble studies and on the single-molecule level. In ratiometric ensemble studies, we show that photoactivation efficiency depends on how the PA-FPs are exposed to 405 nm light. Using a laser-scanning microscope, hundreds of iterative low-level exposures are up to four times more efficient than a short high-power exposure. Using wide-field illumination, photoactivation was similarly efficient and instantaneous. These findings suggest that the repetitive or stochastic exposure to photons of 405 nm light results in more efficient photoactivation than a continuous flow of photons. Because of the differential photoactivation efficiency, it is crucial to assess photoactivation efficiency for any given experimental set-up. The tools we provide can be applied to any genetically encoded photoactivatable protein. Determination of photoactivation efficiency is essential for an understanding of absolute molecule numbers in ensemble studies and, most importantly, quantitative superresolution imaging. © 2017 International Society for Advancement of Cytometry.

  View details for PubMedID 29286574

• Simultaneous Endometrial Aspiration and Sonohysterography for the Evaluation of Endometrial Pathology in Women Aged 50 Years and Older OBSTETRICS AND GYNECOLOGY Rotenberg, O., Renz, M., Reimers, L., Doulaveris, G., Gebb, J., Goldberg, G. L., Dar, P. 2015; 125 (2): 414-423

  Abstract

  To evaluate the performance of simultaneous endometrial aspiration at the time of sonohysterography for screening postmenopausal women at risk for endometrial cancer.A retrospective cohort study of women older than 50 years who underwent saline-infusion sonohysterography for the evaluation of their endometrium. On completion of imaging, the remaining intracavitary saline and endometrial tissue were aspirated through the saline-infusion sonohysterography catheter and submitted for pathologic evaluation. Based on the clinical, pathologic, and ultrasonographic results, the patients underwent surgical treatment with hysteroscopy, hysterectomy, or clinical observation. Follow-up results and outcomes were collected using electronic medical records. Sensitivity, specificity, and predictive values of saline-infusion sonohysterography, endometrial aspiration, and combined approaches for endometrial aspiration and sonohysterography were assessed.Six hundred three patients underwent endometrial aspiration at the time of sonohysterography. Endometrial tissue was present in 567 (94.0%) and outcome data were available for 540 (89.5%). In 194 (35.9%) patients, final pathology was obtained by surgical intervention. The remaining 346 (64.1%) patients were monitored for at least 6 months. Thirty patients (5.6%) had cancer or endometrial hyperplasia. A sequential model, in which endometrial aspiration was done only for positive saline-infusion sonohysterography findings, yielded sensitivity of 86.7% (95% confidence interval [CI] 69-96%) and specificity of 100% (95% CI 99-100%) for detecting endometrial hyperplasia or cancer (area under the curve 0.93). Considering proliferative endometrium as abnormal endometrial aspiration reduced specificity to 88.3% (95% CI 85-91%, P<.01) without significant increase in sensitivity (100%, 95% CI 88-100%, P=.13).The high sensitivity and specificity of the sequential endometrial aspiration at the time of sonohysterography make this approach a useful and reliable screening algorithm for detecting endometrial cancer or hyperplasia in postmenopausal women at risk. Endometrial aspiration at the time of sonohysterography should be considered as an initial one-stop endometrial evaluation in this population.

  View details for DOI 10.1097/AOG.0000000000000631

  View details for Web of Science ID 000348595500021

  View details for PubMedID 25568988

• Probing the Stochastic, Motor-Driven Properties of the Cytoplasm Using Force Spectrum Microscopy CELL Guo, M., Ehrlicher, A. J., Jensen, M. H., Renz, M., Moore, J. R., Goldman, R. D., Lippincott-Schwartz, J., MacKintosh, F. C., Weitz, D. A. 2014; 158 (4): 822-832

  Abstract

  Molecular motors in cells typically produce highly directed motion; however, the aggregate, incoherent effect of all active processes also creates randomly fluctuating forces, which drive diffusive-like, nonthermal motion. Here, we introduce force-spectrum-microscopy (FSM) to directly quantify random forces within the cytoplasm of cells and thereby probe stochastic motor activity. This technique combines measurements of the random motion of probe particles with independent micromechanical measurements of the cytoplasm to quantify the spectrum of force fluctuations. Using FSM, we show that force fluctuations substantially enhance intracellular movement of small and large components. The fluctuations are three times larger in malignant cells than in their benign counterparts. We further demonstrate that vimentin acts globally to anchor organelles against randomly fluctuating forces in the cytoplasm, with no effect on their magnitude. Thus, FSM has broad applications for understanding the cytoplasm and its intracellular processes in relation to cell physiology in healthy and diseased states.

  View details for DOI 10.1016/j.cell.2014.06.051

  View details for Web of Science ID 000340944700013

  View details for PubMedID 25126787

• Optical highlighters: Applications to cell biology The Fluorescent Protein Revolution Renz, M., Lippincott-Schwartz, J. CRC Press, Taylor and Francis. 2014
• Fluorescence microscopy-A historical and technical perspective CYTOMETRY PART A Renz, M. 2013; 83 (9): 767-779

  Abstract

  For a little more than a century, fluorescence microscopy has been an essential source of major discoveries in cell biology. Recent developments improved both visualization and quantification by fluorescence microscopy imaging and established a methodology of fluorescence microscopy. By outlining basic principles and their historical development, I seek to provide insight into and understanding of the ever-growing tools of fluorescence microscopy. Thereby, this synopsis may help the interested researcher to choose a fluorescence microscopic method capable of addressing a specific scientific question.

  View details for DOI 10.1002/cyto.a.22295

  View details for Web of Science ID 000323480200003

  View details for PubMedID 23585290

• Plasticity of the asialoglycoprotein receptor deciphered by ensemble FRET imaging and single-molecule counting PALM imaging PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Renz, M., Daniels, B. R., Vamosi, G., Arias, I. M., Lippincott-Schwartz, J. 2012; 109 (44): E2989-E2997

  Abstract

  The stoichiometry and composition of membrane protein receptors are critical to their function. However, the inability to assess receptor subunit stoichiometry in situ has hampered efforts to relate receptor structures to functional states. Here, we address this problem for the asialoglycoprotein receptor using ensemble FRET imaging, analytical modeling, and single-molecule counting with photoactivated localization microscopy (PALM). We show that the two subunits of asialoglycoprotein receptor [rat hepatic lectin 1 (RHL1) and RHL2] can assemble into both homo- and hetero-oligomeric complexes, displaying three forms with distinct ligand specificities that coexist on the plasma membrane: higher-order homo-oligomers of RHL1, higher-order hetero-oligomers of RHL1 and RHL2 with two-to-one stoichiometry, and the homo-dimer RHL2 with little tendency to further homo-oligomerize. Levels of these complexes can be modulated in the plasma membrane by exogenous ligands. Thus, even a simple two-subunit receptor can exhibit remarkable plasticity in structure, and consequently function, underscoring the importance of deciphering oligomerization in single cells at the single-molecule level.

  View details for DOI 10.1073/pnas.1211753109

  View details for Web of Science ID 000311149900008

  View details for PubMedID 23043115

• Multiscale diffusion in the mitotic Drosophila melanogaster syncytial blastoderm PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Daniels, B. R., Rikhy, R., Renz, M., Dobrowsky, T. M., Lippincott-Schwartz, J. 2012; 109 (22): 8588-8593

  Abstract

  Despite the fundamental importance of diffusion for embryonic morphogen gradient formation in the early Drosophila melanogaster embryo, there remains controversy regarding both the extent and the rate of diffusion of well-characterized morphogens. Furthermore, the recent observation of diffusional "compartmentalization" has suggested that diffusion may in fact be nonideal and mediated by an as-yet-unidentified mechanism. Here, we characterize the effects of the geometry of the early syncytial Drosophila embryo on the effective diffusivity of cytoplasmic proteins. Our results demonstrate that the presence of transient mitotic membrane furrows results in a multiscale diffusion effect that has a significant impact on effective diffusion rates across the embryo. Using a combination of live-cell experiments and computational modeling, we characterize these effects and relate effective bulk diffusion rates to instantaneous diffusion coefficients throughout the syncytial blastoderm nuclear cycle phase of the early embryo. This multiscale effect may be related to the effect of interphase nuclei on effective diffusion, and thus we propose that an as-yet-unidentified role of syncytial membrane furrows is to temporally regulate bulk embryonic diffusion rates to balance the multiscale effect of interphase nuclei, which ultimately stabilizes the shapes of various morphogen gradients.

  View details for DOI 10.1073/pnas.1204270109

  View details for Web of Science ID 000304881700050

  View details for PubMedID 22592793

• Probing protein heterogeneity in the plasma membrane using PALM and pair correlation analysis NATURE METHODS Sengupta, P., Jovanovic-Talisman, T., Skoko, D., Renz, M., Veatch, S. L., Lippincott-Schwartz, J. 2011; 8 (11): 969-975

  Abstract

  Photoactivated localization microscopy (PALM) is a powerful approach for investigating protein organization, yet tools for quantitative, spatial analysis of PALM datasets are largely missing. Combining pair-correlation analysis with PALM (PC-PALM), we provide a method to analyze complex patterns of protein organization across the plasma membrane without determination of absolute protein numbers. The approach uses an algorithm to distinguish a single protein with multiple appearances from clusters of proteins. This enables quantification of different parameters of spatial organization, including the presence of protein clusters, their size, density and abundance in the plasma membrane. Using this method, we demonstrate distinct nanoscale organization of plasma-membrane proteins with different membrane anchoring and lipid partitioning characteristics in COS-7 cells, and show dramatic changes in glycosylphosphatidylinositol (GPI)-anchored protein arrangement under varying perturbations. PC-PALM is thus an effective tool with broad applicability for analysis of protein heterogeneity and function, adaptable to other single-molecule strategies.

  View details for DOI 10.1038/NMETH.1704

  View details for Web of Science ID 000296891800022

  View details for PubMedID 21926998

• Bright Monomeric Photoactivatable Red Fluorescent Protein for Two-Color Super-Resolution sptPALM of Live Cells JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Subach, F. V., Patterson, G. H., Renz, M., Lippincott-Schwartz, J., Verkhusha, V. V. 2010; 132 (18): 6481-6491

  Abstract

  Rapidly emerging techniques of super-resolution single-molecule microscopy of living cells rely on the continued development of genetically encoded photoactivatable fluorescent proteins. On the basis of monomeric TagRFP, we have developed a photoactivatable TagRFP protein that is initially dark but becomes red fluorescent after violet light irradiation. Compared to other monomeric dark-to-red photoactivatable proteins including PAmCherry, PATagRFP has substantially higher molecular brightness, better pH stability, substantially less sensitivity to blue light, and better photostability in both ensemble and single-molecule modes. Spectroscopic analysis suggests that PATagRFP photoactivation is a two-step photochemical process involving sequential one-photon absorbance by two distinct chromophore forms. True monomeric behavior, absence of green fluorescence, and single-molecule performance in live cells make PATagRFP an excellent protein tag for two-color imaging techniques, including conventional diffraction-limited photoactivation microscopy, super-resolution photoactivated localization microscopy (PALM), and single particle tracking PALM (sptPALM) of living cells. Two-color sptPALM imaging was demonstrated using several PATagRFP tagged transmembrane proteins together with PAGFP-tagged clathrin light chain. Analysis of the resulting sptPALM images revealed that single-molecule transmembrane proteins, which are internalized into a cell via endocytosis, colocalize in space and time with plasma membrane domains enriched in clathrin light-chain molecules.

  View details for DOI 10.1021/ja100906g

  View details for Web of Science ID 000277445400039

  View details for PubMedID 20394363

• Dynamics of the CapG actin-binding protein in the cell nucleus studied by FRAP and FCS CHROMOSOME RESEARCH Renz, M., Langowski, J. 2008; 16 (3): 427-437

  Abstract

  FRAP (fluorescence recovery after photobleaching) and FCS (fluorescence correlation spectroscopy) are spectroscopic methods for monitoring the dynamic distribution of proteins inside the nucleus of living cells. As an example we report our studies on the intracellular mobility of the actin-binding protein CapG in live breast cancer cells. This Gelsolin-related protein is a putative oncogene. It appears to be overexpressed especially in metastasizing breast cancer. Furthermore, the CapG protein is known to be involved in the motility control of non-muscle benign cells. Its increased expression triggers an increase in cell motility of benign cells. Thus it can be expected that in cancer cells overexpressing the CapG protein, motility, invasiveness and metastasis might be particularly promoted. Since the nuclear CapG fraction seems to be pivotal to the increase in cell motility, we focused our studies on the CapG mobility in cell nuclei of live breast cancer cells. Using FCS and FRAP we showed that the eGFP-tagged CapG is monomeric and characterized its diffusional properties on the microsecond to minute timescale. This information about the mobility and compartmentalization of CapG might help to provide insight into its function within the cell nucleus and give clues about its altered cellular function in malignant dedifferentiation.

  View details for DOI 10.1007/s10577-008-1234-6

  View details for Web of Science ID 000255680800007

  View details for PubMedID 18461482

• Invasive breast cancer cells exhibit increased mobility of the actin-binding protein CapG INTERNATIONAL JOURNAL OF CANCER Renz, M., Betz, B., Niederacher, D., Bender, H. G., Langowski, J. 2008; 122 (7): 1476-1482

  Abstract

  The CapG protein, a Gelsolin-related actin-binding protein, is expressed at higher levels in breast cancer, especially in metastasizing breast cancer, than in normal breast epithelium. Furthermore, it is known that an increased expression of the CapG protein triggers an increase in cell motility. According to in vitro experiments, it was supposed that it is the nuclear fraction of the protein, which causes the increase in cell motility. Here, we examined the dynamical distribution of the CapG protein within the living cell, i.e. the import of the CapG protein into the nucleus. The nuclear import kinetics of invasive, metastasizing breast cancer cells were compared to the import kinetics of non-neoplastic cells similar to normal breast epithelium. FRAP kinetics showed a highly significant increase in the recovery of photobleached CapG-eGFP in the cancer cells, so that a differentiation of invasive, metastasizing cells and non-invasive, non-metastasizing cells on the basis of transport processes of the CapG protein between the nucleus and the cytoplasm seems to be possible. Comprehension of the mobility and compartmentalization of the CapG protein in normal and in cancer cells in vivo could constitute a new basis to characterize the invasiveness and metastasizing potential of breast cancer.

  View details for DOI 10.1002/ijc.23215

  View details for Web of Science ID 000253441100004

  View details for PubMedID 18059028

• Intrazelluläre Mobilität und Funktion des CapG-Proteins: eine Analyse anhand lebender neoplastischer und nichtneoplastischer Brustepithelzellen Renz, M. HHU Düsseldorf. 2008 ; Dissertation 150

  Abstract

  The CapG protein, a Gelsolin related actin-binding protein, is overexpressed in breast cancer, especially in metastasizing breast cancer. The CapG protein is known to be involved in the control of motility of non-muscle cells. Its increased expression is described to trigger an increase in cell motility of benign cells. Thus it can be expected that in cancer cells, which overexpress the CapG protein, motility, invasiveness and metastasizing are especially promoted. In this work it was achieved via fluorescence labeling of the CapG protein to visualize the dynamics of cellular processes as migration and invasiveness and to analyze the kinetics of the intracellular distribution of the CapG protein. Differences of the intracellular mobility of CapG between non-neoplastic and neoplastic breast epithelial cells could be demonstrated, correlations of increased tumor cell motility and accelerated intracellular CapG mobility revealed and a causal context of CapG expression and distribution on one hand and invasiveness and metastasizing on the other could be made probable, so that a differentiation of tumor cells applying kinetic analysis of single live cells seems to be possible.