I have worked for 35 years in various fields of biomedical research, including virology, cell biology, molecular biology, cell signaling, cancer biology.
Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, w... more Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin r...
One of the several still unexplained aspects of the mechanism by which the Cdc34/SCF RING-type ub... more One of the several still unexplained aspects of the mechanism by which the Cdc34/SCF RING-type ubiquitin ligases work is the marked stimulation of Cdc34 autoubiquitination, a phenomenon of unknown mechanism and significance. In in vitro experiments with single-lysine-containing Cdc34 mutant proteins of Saccharomyces cerevisiae, we found that the SCF-mediated stimulation of autoubiquitination is limited to specific N-terminal lysines modified via an intermolecular mechanism. In a striking contrast, SCF quenches autoubiquitination of C-terminal lysines catalyzed in an intramolecular manner. Unlike autoubiquitination of the C-terminal lysines, which has no functional consequence, autoubiquitination of the N-terminal lysines inhibits Cdc34. This autoinhibitory mechanism plays a nonessential role in the catalytic cycle, as the lysineless (K0)Cdc34(DeltaC) is indistinguishable from Cdc34(DeltaC) in ubiquitination of the prototype SCF(Cdc4) substrate Sic1 in vitro, and replacement of the C...
Proline-rich protein tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family. We... more Proline-rich protein tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family. We used Pyk2 knockout (Pyk2-KO) mice to study the role of Pyk2 in cutaneous wound repair. We report that the rate of wound closure was delayed in Pyk2-KO compared with control mice. To examine whether impaired wound healing of Pyk2-KO mice was caused by a keratinocyte cell-autonomous defect, the capacities of primary keratinocytes from Pyk2-KO and wild-type (WT) littermates to heal scratch wounds in vitro were compared. The rate of scratch wound repair was decreased in Pyk2-KO keratinocytes compared with WT cells. Moreover, cultured human epidermal keratinocytes overexpressing the dominant-negative mutant of Pyk2 failed to heal scratch wounds. Conversely, stimulation of Pyk2-dependent signaling via WT Pyk2 overexpression induced accelerated scratch wound closure and was associated with increased expression of matrix metalloproteinase (MMP)-1, MMP-9, and MMP-10. The Pyk2-stimulated increase...
Acute mu and kappa opioids activate the ERK/MAPK phosphorylation cascade that represents an integ... more Acute mu and kappa opioids activate the ERK/MAPK phosphorylation cascade that represents an integral part of the signaling pathway of growth factors in astrocytes. By this cross-talk, opioids may impact neural development and plasticity among other basic neurobiological processes in vivo. The mu agonist, [D-ala2,mephe4,glyol5]enkephalin (DAMGO), induces a transient stimulation of ERK phosphorylation, whereas kappa agonist, U69,593, engenders sustained ERK activation. Here we demonstrate that acute U69,593 and DAMGO stimulate ERK phosphorylation by utilization of different secondary messengers and protein kinase C (PKC) isoforms upstream of the growth factor pathway. Immortalized astrocytes transfected with either antisense calmodulin (CaM), a mutant mu opioid receptor that binds CaM poorly or a dominant negative mutant of PKCepsilon were used as a model system to study mu signaling. Evidence was gained to implicate CaM and PKCepsilon in DAMGO stimulation of ERK. DAMGO activation of ...
Seborrheic keratosis (SK) is the most common skin tumor seen by dermatologists in everyday practi... more Seborrheic keratosis (SK) is the most common skin tumor seen by dermatologists in everyday practice. Although the lesions are mostly benign, many patients still elect to have asymptomatic SK removed. The historical standards of treatment are cryosurgery and electrocautery, two surgical options that are effective at lesion removal but have high rates of postoperative adverse events such as treatment-site scarring and pigmentary alterations. The cosmetic outcomes of SK treatment modalities are of keen interest to dermatologists, as the American population becomes increasingly more diverse. In this article, the inclusion of darker Fitzpatrick skin types into clinical studies investigating post-treatment side effects of SK therapy is reviewed. The recent approval of a 40% hydrogen peroxide topical formulation is discussed in light of these issues, and several non-invasive topical treatments that optimize cosmetic outcomes of SK lesion removal are highlighted. Finally, treatment strategi...
Temporary cardiac pacemakers used in periods of need during surgical recovery involve percutaneou... more Temporary cardiac pacemakers used in periods of need during surgical recovery involve percutaneous leads and externalized hardware that carry risks of infection, constrain patient mobility and may damage the heart during lead removal. Here we report a leadless, battery-free, fully implantable cardiac pacemaker for postoperative control of cardiac rate and rhythm that undergoes complete dissolution and clearance by natural biological processes after a defined operating timeframe. We show that these devices provide effective pacing of hearts of various sizes in mouse, rat, rabbit, canine and human cardiac models, with tailored geometries and operation timescales, powered by wireless energy transfer. This approach overcomes key disadvantages of traditional temporary pacing devices and may serve as the basis for the next generation of postoperative temporary pacing technology.
ABSTRACTBACKGROUNDThe efficacy of an anthracycline antibiotic doxorubicin (DOX) as a chemotherape... more ABSTRACTBACKGROUNDThe efficacy of an anthracycline antibiotic doxorubicin (DOX) as a chemotherapeutic agent is limited by dose-dependent cardiotoxicity. DOX is associated with activation of intracellular stress signaling pathways including p38 MAPKs. While previous studies have implicated p38 MAPK signaling in DOX-induced cardiac injury, the roles of the individual p38 isoforms, specifically, of the alternative isoforms p38γ and p38δ, remain uncharacterized.OBJECTIVESTo determine the potential cardioprotective effects of p38γ and p38δ genetic deletion in mice subjected to acute DOX treatment.METHODSMale and female wild-type (WT), p38γ-/-, p38δ-/- and p38γ-/-δ-/- mice were injected with 30 mg/kg DOX and their survival was tracked for ten days. During this period cardiac function was assessed by echocardiography and electrocardiography and fibrosis by PicroSirius Red staining. Immunoblotting was performed to assess the expression of signaling proteins and markers linked to autophagy.R...
Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, w... more Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin r...
One of the several still unexplained aspects of the mechanism by which the Cdc34/SCF RING-type ub... more One of the several still unexplained aspects of the mechanism by which the Cdc34/SCF RING-type ubiquitin ligases work is the marked stimulation of Cdc34 autoubiquitination, a phenomenon of unknown mechanism and significance. In in vitro experiments with single-lysine-containing Cdc34 mutant proteins of Saccharomyces cerevisiae, we found that the SCF-mediated stimulation of autoubiquitination is limited to specific N-terminal lysines modified via an intermolecular mechanism. In a striking contrast, SCF quenches autoubiquitination of C-terminal lysines catalyzed in an intramolecular manner. Unlike autoubiquitination of the C-terminal lysines, which has no functional consequence, autoubiquitination of the N-terminal lysines inhibits Cdc34. This autoinhibitory mechanism plays a nonessential role in the catalytic cycle, as the lysineless (K0)Cdc34(DeltaC) is indistinguishable from Cdc34(DeltaC) in ubiquitination of the prototype SCF(Cdc4) substrate Sic1 in vitro, and replacement of the C...
Proline-rich protein tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family. We... more Proline-rich protein tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family. We used Pyk2 knockout (Pyk2-KO) mice to study the role of Pyk2 in cutaneous wound repair. We report that the rate of wound closure was delayed in Pyk2-KO compared with control mice. To examine whether impaired wound healing of Pyk2-KO mice was caused by a keratinocyte cell-autonomous defect, the capacities of primary keratinocytes from Pyk2-KO and wild-type (WT) littermates to heal scratch wounds in vitro were compared. The rate of scratch wound repair was decreased in Pyk2-KO keratinocytes compared with WT cells. Moreover, cultured human epidermal keratinocytes overexpressing the dominant-negative mutant of Pyk2 failed to heal scratch wounds. Conversely, stimulation of Pyk2-dependent signaling via WT Pyk2 overexpression induced accelerated scratch wound closure and was associated with increased expression of matrix metalloproteinase (MMP)-1, MMP-9, and MMP-10. The Pyk2-stimulated increase...
Acute mu and kappa opioids activate the ERK/MAPK phosphorylation cascade that represents an integ... more Acute mu and kappa opioids activate the ERK/MAPK phosphorylation cascade that represents an integral part of the signaling pathway of growth factors in astrocytes. By this cross-talk, opioids may impact neural development and plasticity among other basic neurobiological processes in vivo. The mu agonist, [D-ala2,mephe4,glyol5]enkephalin (DAMGO), induces a transient stimulation of ERK phosphorylation, whereas kappa agonist, U69,593, engenders sustained ERK activation. Here we demonstrate that acute U69,593 and DAMGO stimulate ERK phosphorylation by utilization of different secondary messengers and protein kinase C (PKC) isoforms upstream of the growth factor pathway. Immortalized astrocytes transfected with either antisense calmodulin (CaM), a mutant mu opioid receptor that binds CaM poorly or a dominant negative mutant of PKCepsilon were used as a model system to study mu signaling. Evidence was gained to implicate CaM and PKCepsilon in DAMGO stimulation of ERK. DAMGO activation of ...
Seborrheic keratosis (SK) is the most common skin tumor seen by dermatologists in everyday practi... more Seborrheic keratosis (SK) is the most common skin tumor seen by dermatologists in everyday practice. Although the lesions are mostly benign, many patients still elect to have asymptomatic SK removed. The historical standards of treatment are cryosurgery and electrocautery, two surgical options that are effective at lesion removal but have high rates of postoperative adverse events such as treatment-site scarring and pigmentary alterations. The cosmetic outcomes of SK treatment modalities are of keen interest to dermatologists, as the American population becomes increasingly more diverse. In this article, the inclusion of darker Fitzpatrick skin types into clinical studies investigating post-treatment side effects of SK therapy is reviewed. The recent approval of a 40% hydrogen peroxide topical formulation is discussed in light of these issues, and several non-invasive topical treatments that optimize cosmetic outcomes of SK lesion removal are highlighted. Finally, treatment strategi...
Temporary cardiac pacemakers used in periods of need during surgical recovery involve percutaneou... more Temporary cardiac pacemakers used in periods of need during surgical recovery involve percutaneous leads and externalized hardware that carry risks of infection, constrain patient mobility and may damage the heart during lead removal. Here we report a leadless, battery-free, fully implantable cardiac pacemaker for postoperative control of cardiac rate and rhythm that undergoes complete dissolution and clearance by natural biological processes after a defined operating timeframe. We show that these devices provide effective pacing of hearts of various sizes in mouse, rat, rabbit, canine and human cardiac models, with tailored geometries and operation timescales, powered by wireless energy transfer. This approach overcomes key disadvantages of traditional temporary pacing devices and may serve as the basis for the next generation of postoperative temporary pacing technology.
ABSTRACTBACKGROUNDThe efficacy of an anthracycline antibiotic doxorubicin (DOX) as a chemotherape... more ABSTRACTBACKGROUNDThe efficacy of an anthracycline antibiotic doxorubicin (DOX) as a chemotherapeutic agent is limited by dose-dependent cardiotoxicity. DOX is associated with activation of intracellular stress signaling pathways including p38 MAPKs. While previous studies have implicated p38 MAPK signaling in DOX-induced cardiac injury, the roles of the individual p38 isoforms, specifically, of the alternative isoforms p38γ and p38δ, remain uncharacterized.OBJECTIVESTo determine the potential cardioprotective effects of p38γ and p38δ genetic deletion in mice subjected to acute DOX treatment.METHODSMale and female wild-type (WT), p38γ-/-, p38δ-/- and p38γ-/-δ-/- mice were injected with 30 mg/kg DOX and their survival was tracked for ten days. During this period cardiac function was assessed by echocardiography and electrocardiography and fibrosis by PicroSirius Red staining. Immunoblotting was performed to assess the expression of signaling proteins and markers linked to autophagy.R...
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